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• CaV 6 O 16 ·3H 2 O paper was prepared by hydrothermal method combined with cutting and drying process. • CaV 6 O 16 ·3H 2 O paper can be directly applied as a cathode for LIBs. • The self-standing CaV 6 O 16 ·3H 2 O paper electrode shows good electrochemical performance. CaV 6 O 16 ·3H 2 O three-dimensional (3D) tubular structure has been constructed by a simple hydrothermal method without using any surfactants or additives. The tubular structure is composed of ultralong CaV 6 O 16 ·3H 2 O nanobelts with good tailorability. By simply cutting and drying the 3D tubular structure, a CaV 6 O 16 ·3H 2 O paper has been successfully prepared. Electrochemical performance of the CaV 6 O 16 ·3H 2 O paper as the self-standing cathode for lithium-ion batteries (LIBs) was investigated for the first time. It delivers an initial discharge capacity of 463.9 mAh g−1 at 50 mA g−1 and maintains at 162.3 mAh g−1 after 50 cycles. This work provides the possibility for designing high-performance, long service life and lightweight LIBs for implantable medical devices. [ABSTRACT FROM AUTHOR]

Although SiO 2 as an anode for lithium-ion batteries has an attractive high theoretical capacity (1965 mAh g−1), violent volume changes and poor electrical conductivity during alloying reaction limit its lithium storage performance. Here, we report a SNTs@NC composite anode loaded on flexible CNTs conducting paper (CP). The conductive network of CP promotes the rapid migration of Li ions and electrons, and the multi-dimensional skeleton formed by CNTs and SNTs@NC is conducive to the steady deposition of Li-ions. The excellent flexibility effectively defuses the impact of internal stress on the pole plate structure, showing a longer service life and better cycling stability compared with the traditional copper foil. The composite anode has the advantages of simple preparation, low cost and little environmental pollution, and as an innovative collector, CP effectively eliminates the influence of the volume effect of the anode on the electrochemical performance. This work may provide a novel way for the commercial development of SiO 2 anode or the preparation of flexible self-supporting electrode. [Display omitted] [ABSTRACT FROM AUTHOR]

Parallel-connected digital valve arrays are commonly utilized in the pilot stage of the proportional directional valve to enhance dynamic performance and reliability. However, when the digital valve array is driven by a digital signal, it is difficult to optimally assign the signal pulses to each valve. If the assignment is not well executed, it can significantly reduce the switching uniformity of the digital valves or lead to performance degradation of the system. In this paper, a model-based sliding mode control strategy based on the intelligent distribution of control law is proposed and successfully applied to a proportional valve driven by digital valve arrays. The intelligent distribution strategy encompasses a logic distribution algorithm and a circular sliding distribution algorithm that automatically assigns control laws to different valves based on the rolling of the PWM signal cycle. Experimental results confirm that the proposed strategy not only simultaneously reduces the total number of valve switches and enhances the switching uniformity among the valves, but also adapts to the variation in the number of valves. The proposed strategy is not limited to the application of digital valve arrays, it is also applicable in other fields of multi-actuators driven by digital signals, and can simultaneously improve the control accuracy, lifetime, and maintenance friendliness. • A digital proportional valve is proposed, where the pilot stage consists of fixed orifices and digital valve arrays. • The intelligent distribution strategy is designed based on a logic distribution and a circular sliding distribution. • The proposed MSMC with intelligent distribution can be adapted to DVAs with any number of valves. [ABSTRACT FROM AUTHOR]

• Digital Twin approach for monitoring and prognosis of ship-specific fatigue damage. • Approach using publicly available wave condition data in lieu of onboard sensors. • Fatigue prognosis using Monte Carlo simulations to account for wave variability. This paper proposes a Digital Twin approach for the monitoring and prognosis of vessel-specific fatigue damage. During design, fatigue damage estimates are based on conservative assumptions regarding operational conditions and structural response. However, variability in the vessel-specific operations from those assumed during design needs to be considered when supporting engineering-based decisions for maintenance deferrals and service life extensions. The use of Digital Twins is proposed to provide this necessary vessel-specific decision support. Digital Twins typically rely on sensor-based data to update their models, however structural health sensors for fatigue monitoring can be prohibitively expensive to install and maintain in ship structures, so the proposed method addresses this by instead combining publicly available vessel-specific operational data (global vessel position data coupled with metocean hindcast data) with computational models to monitor the environmental exposure and track the vessel fatigue accumulation over time. This approach is demonstrated through a case study of a containership that has been in operation for seven years. The results of proposed approach are compared against the fatigue estimate obtained using the design reference wave conditions. The Digital Twin is then used to forecast the remaining fatigue life, in order to support inspection and maintenance scheduling and operational decision-making. [ABSTRACT FROM AUTHOR]

Vanadium Flow Batteries (VFBs) are a stationary energy storage technology, that can play a pivotal role in the integration of renewable sources into the electrical grid, thanks to unique advantages like power and energy independent sizing, no risk of explosion or fire and extremely long operating life. The first part of this paper presents the main features and the basic performance parameters of VFB, which determine their electric, hydraulic, thermal, and aging feature. The latter part outlines the strengths and weaknesses of the technology, the services that it can provide to the grid, and a short economic analysis. After presenting the fundaments of the technology, prospects and trends of VFBs deployment are outlined. Most of the considerations highlighted in this paper are inspired to studies performed on an industrial-size VFB operated at the Electrochemical Energy Storage and Conversion Lab (EESCoLab) at the University of Padua (Italy). [ABSTRACT FROM AUTHOR]

Internet of Things (IoT) represents an important area that is evolving rapidly in the context of digitalization efforts related to the Construction 4.0 era. This paper deals with the Internet of Things applications within the construction industry in selected phases of the facility's life cycle, namely the construction and operational phases. In particular, relevant examples of its use were collected, discussed and supplemented with several review papers on a given topic. Results of the analysis show that the potential of the Internet of Things usage is wide and varied in connection with the complexity of the construction projects and the long-term service life of the facilities. The concepts of the Internet of Things usage in the above-mentioned life cycle phases are mostly different focusing e.g., on quality, health and safety issues within the case of construction phase or smart concepts and energy management during the operational phase. Furthermore, one common theme was identified for both investigated phases of the life cycle, namely the interconnection of Building Information Modelling and the Internet of Things. It can be expected that the importance of such interconnection will continue to rise as construction projects implemented with the support of the Building Information Modelling become more and more common in the future. [ABSTRACT FROM AUTHOR]

Proton exchange membrane fuel cell (PEMFC) is a highly promising renewable energy conversion technology. However, durability issues have hindered their large-scale commercialization process. Performance degradation prediction is an essential component of PEMFC prognostics and health management and is critical for extending the service life of fuel cell. Given that, this paper proposes a novel data-driven prediction model that fuses multi-head self-attention (MHSA) mechanism and bi-directional long short-term memory (BiLSTM). This model can effectively capture different types of dependencies from large-scale high-dimensional data and achieve global information modeling. Specifically, the preprocessed historical voltage data and PEMFC system operating parameters are fed into the proposed prediction model. Where BiLSTM understands the contextual information and temporal dependencies in sequence data by calculating the hidden states in both forward and backward directions. MHSA captures the complex relationships and extracts key information in the input sequence by simultaneously learning multiple sets of attention weights between different locations. Finally, the proposed model is validated based on the health monitoring data under stationary and quasi-dynamic conditions. The validation results indicate that the proposed model can ensure absolute errors of less than 0.6 × 10−3 V for at least 71.9% of the prediction results under stationary and quasi-dynamic conditions (less than 1.2 × 10−3 V for at least 97.6% of prediction results). • A prediction model fusing BiLSTM network and MHSA mechanism is proposed. • MHSA mechanism is used to further extract the key information form the sequence. • Considered the impact of different dimensions of health monitoring data on PEMFC. • Quantified the potential of the MHSA mechanism in improving predictive accuracy. • The proposed model achieves accurate predictions under different current conditions. [ABSTRACT FROM AUTHOR]

Membrane electrode assemblies (MEAs) have been subjected to alternating hygrothermal conditions, and frequent load changes significantly reduces the proton exchange membrane fuel cells (PEMFCs) lifetime. PEMs with a reinforced layer of e-PTFE have gained widespread application with the PEMFC development. However, the fatigue mechanism beyond the glass transition temperature remains to be elucidated. In this study, two accelerated stress tests (AMFT-85 and AMFT-95) are designed to investigate the PEM response to humidity under varying operating temperatures. In-situ fatigue experiments are conducted to comprehensively examine the fatigue mechanism of MEAs through the integration of electrochemical property characterization, mechanical property evaluation, and surface morphology analysis. The polarization curve results indicate that the AMFT-95 condition accelerates output performance degradation. The catalyzer-coated membrane displays a diminishing trend regarding of final strain, ultimate tensile strength, fracture toughness, and glass transition temperature due to the formation of cracks and delamination induced by cyclic stresses during physical fatigue. This decreasing trend becomes more pronounced with higher operating temperatures. Furthermore, elevated temperatures decreased the viscoelastic properties of the membranes, rendering catalyzer-coated membranes more susceptible to creep-fatigue failure and microstructural damage. This study proposes an experimental approach to enhance the understanding of physical fatigue in PEMs, contributing to mitigate fatigue failure and enhance PEMFC service life. • These paper focus on the temperature on CCM mechanical degradation mechanism. • The results confirm the relationship between temperature and cracks. • Elevated temperature degraded CCMs have lower glass transition temperatures. • Mechanical degradation is more severe above glass transition temperature. [ABSTRACT FROM AUTHOR]

Hydrogen storage cylinder is an important component in high-pressure gaseous hydrogen (HPGH 2) storage system, and plays a key role in hydrogen-powered transportation including land vehicles, ships and aircrafts. Over the past decade, the number of hydrogen fuel cell vehicles (HFCVs) has rapidly increased worldwide. In order to promote the application of hydrogen storage cylinder, guide its design, manufacture, inspection and testing, a series of regulations, codes and standards have been issued. The Chinese national standard, GB/T 42612, for type IV hydrogen storage cylinders has also been issued. This paper first gives a brief overview to these regulations, codes and standards. Furthermore, the specifications including scope, category, filling cycles, service life, materials, design, manufacture, qualification tests and periodic inspections are analyzed and compared. Issues about evaluation method for hydrogen compatibility of non-metallic materials, welded joints of plastic liner, joint between boss and liner are also discussed. Notably, the performance requirements in GB/T 42612 are generally in accordance with the international ones, but the requirements of materials, design and manufacture are more detailed. • The regulations, codes and standards for on-board high-pressure hydrogen storage cylinders are compared. • An in-depth analysis of scope, category, filling cycles, service life, materials, design, manufacture, etc. is provided. • The requirements for materials, design and manufacture in GB/T 42612 are more detailed than the others. • NDT methods for welded joints of plastic liner and joints between plastic liner and metal boss need to be developed. • Effective periodic inspection methods other than visual inspection need to be further researched. [ABSTRACT FROM AUTHOR]

Polymer-blend High Density Polyethylene (PHDPE) sheet materials have been developed in China as an alternative to the High Density Polyethylene (HDPE) materials for the manufacture of geocells. It is necessary to evaluate the creep properties of the geocell-reinforced structures to provide a reference for design of their service life and improve their application potential. In this paper, the Stepwise Isothermal Method (SIM) based accelerated creep testing, in which the test temperature was gradually increased but the load was kept constant, was employed obtain the long-term creep behavior of PHDPE and HDPE geocell sheets. Conventional creep tests were also carried out to assess the accuracy of the creep prediction. Furthermore, the Modified Burgers (MB) model and the Mon-linear Three-component (NLTC) model were proposed to predict long-term creep deformations of the PHDPE geocell sheets. The experimental results indicated that SIM creep tests could predict long-term creep deformations. The creep resistance of all three PHDPE, PHDPE-A, PHDPE-B, and PHDPE-C, was better than that of HDPE due to the addition of nylon 6 for the polymer-blending modification in HDPE. Comparison of the experimental data with the predicted data also confirmed that the MB and NLTC models could accurately model the viscoelastic-plastic creep behavior of PHDPE geocell sheets. • The creep behavior of polymer-blend geocells was investigated by conducting the accelerated creep test. • The comparison of creep resistance of polymer-blend geocells and high-density polyethylene geocells was presented in this study. • The predicted accuracy and suitability of the stepped isothermal method were verified in this study. • Two viscoelastic-plastic models were proposed to predict the long-term creep deformation of polymer-blend geocells. [ABSTRACT FROM AUTHOR]

Compaction construction is one of the most critical factors affecting road performance and durability. To improve the construction quality and service life of road, intelligent compaction (IC) technology has received continuous attention. In contrast to traditional compaction construction, IC improves the compaction quality and uniformity of each road layer through real-time monitoring and adjustment of the compaction process. Intelligent compaction measurement values (ICMVs) were proposed to provide quantitative indexes for compaction quality monitoring and basis for dynamic regulation of compaction conditions. However, the current ICMVs have problems such as low accuracy and stability, and poor applicability under different working conditions, which limit the application of IC technology. To address these shortcomings, this paper conducts a state-of-the-art review of ICMVs, outlining the past research achievements and discussing future development directions. In this paper, the vibrating dynamical models of compaction was firstly summarized and the future research directions are proposed. Next, the existing calculation models of ICMVs are systematically investigated and the significant factors that affected ICVMs calculations are summarized. Solutions to eliminating influences from those factors are discussed in further, e.g., by a combined effort in improving calculations models for ICMVs and advancing the multiple regression analysis method. • The article reviews the dynamical models of intelligent compaction. • The review article compares the calculation methods of five different ICMV models. • The review article examines significant factors that affect the ICMVs and their influcial mechanisms. • Suggestions for future research on ICMVs in subgrade and pavement construction are drawn. [ABSTRACT FROM AUTHOR]

Self-healing products sense and repair damage and should help to improve product circularity and safety. Such products are at an early stage in research and development. Existing models for product life extension in life cycle assessment (LCA) were not developed for self-healing products. It is timely and urgent therefore to develop a framework for life cycle assessment for self-healing products so that their environmental impact can be optimised early at the design stage. This paper presents a new framework for LCA, based on a restoration of a product's function, and thus linking self-healing to product life extension and user acceptance. The model used within this framework uses the probabilities of self-healing, failure and user acceptance at the end of each life to quantify a product's service life extension and consequential avoided or delayed new production. The model takes into consideration multiple healing cycles with varying healing efficiencies. A case study scenario of self-healing propeller blades of an unmanned air vehicle employed for site inspection was used to test the application of the framework. The paper shows the positive contribution of self-healing in reducing life cycle impact. Sensitivity analysis revealed a tipping point where the benefits of avoided emissions outweigh the embedded impacts of self-healing technology. This clearly shows the importance of the life cycle assessment framework to understand under which conditions the environmental gains of using self-healing products are maximised. [ABSTRACT FROM AUTHOR]

• A novel leakage model test system was proposed. • Deformation, uneven settlement and deterioration of the segment were simulated during service. • A non-linear growth trend in water leakage was observed. • Decreased contact stress and gasket aging aggravate leakage. With the increasing mileage and operation time of China's subsea tunnels, tunnels are entering a period of high disaster. Water leakage is one of the most common disasters. To study the mechanism of water leakage in subsea shield tunnels during the service period, a model test study was carried out by proposing a novel tunnel seepage leakage model test system in this paper. The system consists of a model frame, ground stress loading system, hydraulic pressure loading system, temperature control system, and monitoring system. Through 3D printing, the tunnel segments were innovatively made of resin. The process of uneven settlement, seawater erosion, joint deformation, gasket stress relaxation, and water leakage during the service period were successfully simulated by heating the model segments and local overloading. The test results showed that the joint deformation with service life could be approximately divided into three stages: non-linear rapid growth, linear growth, and non-linear slow growth. And the joint deformation and the aging of the gasket resulted in the decrease of the contact stress of the segment joint. Both exacerbated the leakage in the joint. By the time the service life reaches 16th year, the waterproofing performance no longer met the waterproofing standard for subsea tunnels. The developed test device and method are practical in predicting water surges in subsea tunnels during service life. This paper provides new insights into long-term waterproofing performance testing of shield tunnels under complex conditions. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM), epitomized by powder bed fusion (PBF), has emerged as one of the fastest-growing, most dynamic, and highly focused techniques within the advanced manufacturing sector. Nevertheless, as the primary factor determining cost and quality of PBF-produced parts, amounts of metal powder feedstock remains unused and requires recycling after each PBF build. Due to the unique thermal history experienced by individual particles during manufacturing, recycled powders exhibit variations in chemical composition, particle morphology, size, size distribution, microstructure, and even thermal-physical properties. Moreover, these alterations are influenced by the inherent properties of the metal powder, machine setup, and manufacturing process. Consequently, the repeatability and reproducibility of the recycled powders cannot be defined uniformly. Using Ti6Al4V, Inconel 718, AlSi10Mg, and stainless steel metal powders as examples, this paper reviews recent literature specifically addressing recyclability and reusability of the recycled powders, in particular the subsequent effects of the reused powder on powder beds, process operation, and product properties in PBF builds. By exploring the interaction between energy beam, powder and melt pool, we discuss the formation mechanism and composition of the recycled powders, and analyze the impact of powder building cycles and varying powder characteristics on powder bed properties, manufacturing processes, part microstructures, and mechanical properties. Additionally, we discuss the solutions for identifying end-of-life powder and introduce strategies to enhance powder reusability. In doing so, we seek to provide a comprehensive understanding of powder feedstock for building an optimized processing window, with a view to contributing to extending the service life of metal powders. Recycled powders exhibit variations in chemical composition, particle morphology, size, size distribution, microstructure, etc. By exploring the interaction between the energy beam, powder and melt pool, this paper discuss the formation mechanism and composition of the recycled powders. Furthermore, the impact of reused powder on powder bed properties, manufacturing processes, part microstructures, and mechanical properties are analyzed. Additionally, the solutions for identifying end-of-life powder and strategies to enhance powder reusability are introduced. [Display omitted] • The stronger interaction results in the characteristics changes of recycled powder. • Understanding thermal history of the powder is helpful for powder characterization. • Timely tuning of process parameters is useful to powder recycling and part quality. [ABSTRACT FROM AUTHOR]

Lithium-ion battery is a kind of energy storage devices with complex internal reaction and many factors affecting its performance. Accurate prediction of its SOH (State of Health) is of great significance to prolong its service life and improve safety performance. However, the current prediction for SOH has the difficulties of selecting health factors and using data-driven methods with opaque mechanisms. In this paper, a data-driven model will be established with the capacity change during aging of lithium-ion batteries as a health indicator to realize precise prediction of capacity degradation. Firstly, the feature parameters were extracted and analyzed from the battery cyclic aging test dataset. Two in-situ nondestructive characterization methods, incremental capacity analysis curve and differential thermal voltammetry curve, were utilized to resolve the evolution paths of the feature parameters. After that, a data-driven battery capacity degradation estimation is realized based on the GEP (Gene Expression Programming) algorithm, the performance is compared with the existing vehicle-end and cloud-end models, and a higher-accuracy SOH stacking model is developed with an increase of less than 1 ms in computational time. The results indicated that the GEP model proposed in this paper has obvious advantages in terms of physical explain-ability, computational efficiency and robustness. • Establishing a high-precision battery SOH estimation model based on the GEP algorithm. • The relationship between ICA and DTV curves with aging evolution laws is revealed. • Fusion of GEP model with existing vehicle-end and cloud-end models using stacking strategy. [ABSTRACT FROM AUTHOR]

Artificial neural networks (ANNs) have been widely employed in performance testing and life prediction throughout the entire life cycle of coatings due to their self-learning and arbitrary function approximation capabilities. This paper reviews the application research combined with the technologies including optimization algorithms, coating preparation, electrochemistry, machine vision, image processing, non-destructive testing, and simulation so as to optimize formulation design, optimize preparation process parameters, identify micro defects, and predict the service life of coating. In addition, the potential problems encountered in the practical application of neural networks are presented and some corresponding solutions are also proposed. This paper reviews the applied research of ANN in optimizing formulation design, optimizing preparation process parameters, identifying micro-defects and predicting coating service life by combining optimization algorithms, coating preparation processes, electrochemistry, machine vision, image processing, non-destructive testing and simulation. • The use of ANN throughout the coating lifecycle is described. • The process parameters for coating preparation can be optimized with ANN. • Various coating defects can be identified and localized by means of ANN. • The stage of deterioration and lifetime of coatings can be predicted using ANN. • Issues related to the use of ANN in coating preparation and service are discussed. [ABSTRACT FROM AUTHOR]

Offshore wind turbines (OWTs) experience persistent nonlinear vibrations due to constantly changing environmental and operational conditions. These nonlinear dynamic responses significantly affect structural safety and introduce uncertainties in predicting fatigue and service life. However, understanding the complex nonlinear characteristics of OWTs is challenging because multiple factors collectively contribute to structural nonlinear vibrations. To quantitatively assess the nonlinear effects on OWT dynamic responses during operation, this paper systematically analyzes long-term monitoring data from a 4 MW monopile OWT site at Rudong Wind Farm in China using a nonlinear effect separation method based on a time-varying kernel function. This method separates the nonlinear components using the measured wave surface elevation and dynamic response data and statistically analyzes the long-term variation of nonlinear effect by combining comprehensive evaluation indicators. The correctness of the method applied to OWTs has been first verified using the shutdown condition data under calm sea conditions. Then, the influence of operating conditions, sensor placement, rotor speed, and other parameters on the nonlinear effects have been investigated through statistical analysis of the real-time evaluation results to reveal the nonlinear evolution process and its contributing factors. An unexpected discovery emerged during the monitoring process: the dynamic response of the OWT during the passage of Typhoon 'In-FA' was measured. Consequently, this paper emphasizes the abnormal nonlinear behavior of OWTs under typhoon conditions. The analysis results indicate that under typhoon conditions, the nonlinear effects in the structural response substantially increase, potentially contributing over 20% to the overall response. This finding suggests that current structural designs do not fully consider the nonlinear effects, potentially posing risks to safe operation. The insights from this study will also contribute to the structural design of OWTs, aiding in risk reduction and economic loss mitigation. • A novel systematic study on the nonlinear performances of OWT is conducted. • A nonlinear model for nonlinear component separation is established. • Real-time evaluation and statistical characteristics analysis are realized. • Influence factors of nonlinear effects of OWTs in field conditions are discussed. • Influences of the typhoon on nonlinear performances are discussed. [ABSTRACT FROM AUTHOR]

• Built an apparatus to study non-condensable gas interactions with refrigerant. • Two non-condensable gas fault intensities were imposed at various test conditions. • Ideal Gas assumption causes theory to overestimate non-condensable gas. • A new model quantifies non-condensable gas in typical residential air-conditioners. Non-condensable gas (NC) can be introduced into a vapor compression refrigeration cycle through improper installation or service, and decrease system efficiency, increase burden on the compressor, and reduce the compressor life span. Therefore, detecting this fault early can prevent energy waste and prolong the operating life of the system. However, diagnostic methods are not widely available, and neither are methods to quantify NC amounts based on easily measured variables. Therefore, an experimental test apparatus was built to provide data to improve understanding of NC-refrigerant interactions. Two NC fault intensities (50%, 100%), each at four charge levels (70%, 80%, 100%, 120%), were tested under five different ambient temperatures (0-40°C). Dry nitrogen gas was used for the NC. The results showed that the theoretical estimation method is inaccurate. The trends of the results from experimental tests are consistent with those from theoretical calculations, but the thresholds obtained from experimental tests are larger than those from theoretical calculations. This paper explains these differences, and provides a model to quantify the NC fault intensity using easily-measured variables. The specific model is applicable to typical residential air-conditioner and heat pump systems that use R410A refrigerant, but the general findings are applicable to other refrigerants. [ABSTRACT FROM AUTHOR]

The valve core is an essential part of the control valve and it is often exposed to cavitation. Although cavitation of control valve is a traditional research topic, there is still a lack of multi-view and visualized cavitation detection approach. This paper proposes an imaging method based on single high-speed camera-multiple mirrors (SHCMM) cavitation detection to study the cavitation area near the valve core. We used the transparent valve body made of polymethyl methacrylate (PMMA) to analyze the flow field in the valve. SHCMM is used to capture the cavitation image of the valve. The image processing is used to analyze the cavitation characteristics, and the visualization of the cavitation is enhanced by feature recognition. Finally, we discuss the positive role of SHCMM in auxiliary fault diagnosis of the control valve, which provides a new idea for prolonging the service life of the control valve. [Display omitted] • Multi-view enhanced visual detection for cavitation of control calve based on SHCMM. • Cavitation contour information is quantitatively identified by cavitation position and area. • SHCMM can combine with artificial intelligence to provide image data for valve diagnosis. [ABSTRACT FROM AUTHOR]

• This paper focused on the reliability of settlement prediction of immersed tunnel. • This paper focused on impact of time-dependent effects on settlement prediction. • A time-dependent expression for foundation modulus is proposed. • Several extreme conditions are considered in the future settlement prediction. The focus of immersed tunnel research has primarily revolved around settlement monitoring or prediction. However, there has been a lack of discussion regarding the time-dependent effects on settlement prediction, which could lead to obvious misjudgments in subsequent maintenance work. This paper addresses this issue by applying the physics-informed machine learning (PIML) algorithm to conduct an inverse analysis of the foundation modulus of the Hong Kong-Zhuhai-Macau Bridge (HZMB) tunnel, thereby identifying its variation tendency with time. The proposed time-dependent expression of foundation modulus demonstrates that the time-dependent effect is related to both post-construction settlement and the accumulation of back silting, which is significant and could persist throughout the entire service life of the HZMB tunnel. In further studies on settlement prediction for the HZMB tunnel, the results show that errors in prediction can exceed 30 mm at certain monitoring points. This error can be mitigated by considering the time-dependent effect, thereby significantly enhancing the reliability of predictions. [ABSTRACT FROM AUTHOR]

• A finite element model to simulate the lined pipe wrinkles is developed. • The manufacturing process of the lined pipe is considered in the paper. • The different effects of friction on two types of wrinkles are investigated. • The effect of friction on maximum amplitude of wrinkles is investigated. Transporting corrosive hydrocarbons using lined pipe is an economical method and has been widely applied in inshore and offshore pipelines. However, when the lined pipe is subjected to bending, wrinkling behavior will occur. Wrinkle can pose a serious threat to the service life and structural integrity of the lined pipe. In this paper, the effect of the friction coefficient between the liner and carrier on the wrinkling behavior of liner under bending is studied. First, a finite element model of lined pipe is established. Second, the influence of friction coefficient on the starting time and amplitude of first type of wrinkles is studied. In the end, the influence of friction coefficient on the amplitude and shape of the second type of wrinkles is examined. The results show that the friction coefficient can affect both the first and the second type of wrinkles, but their effects are different. The friction coefficient can contribute to the first type of wrinkles. Friction coefficient will facilitate the appearance of the first type of wrinkles. While, the friction coefficient showed a strong inhibitory effect on the second type of wrinkles, which inhibited the maximum amplitude and shape of the wrinkles. [ABSTRACT FROM AUTHOR]

Pleated cartridge dust collectors are widely used in various industrial production environments, in its use, pulse-jet cleaning is a crucial step. Despite the importance of pulse-jet cleaning, there was a widespread problem of uneven cleaning in the upper part of the filter cartridge. In this paper, a built-in open-hole dust cleaner (BODC) was developed to improve the pulse-jet cleaning performance, ameliorate the problem of uneven cleaning and prolong the filter cartridge's service life. The filtration and pulse-jet cleaning test system was established to verify the effect of BODC. Based on the comprehensive comparison and analysis of pulse-jet pressure at the four types of measuring points, the best BODC in this experiment is 6 mm 4 holes with composite pressure of 1.52 MPa. The best BODC and ordinary nozzle were compared with respect to pressure drop. The results showed that the change rule of pressure drop of BODC is similar to that of the ordinary nozzle. The average filtration cycle of BODC and ordinary nozzle was 1300 s and 928 s, respectively. The dust emission concentration of the dust collectors of both cleaning methods during filtration was 1.354 mg/m3 and 1.412 mg/m3, respectively. A significant improvement in cleaning uniformity has been demonstrated when the BODC is used. Ultimately, the best BODC in this experiment was applied on site at the excavation face of Donghuantuo Coal Mine, which resulted in an average dust removal efficiency of 95.2% for total dust and 93.2% for respirable dust, with no residual dust left in the upper part of the filter cartridge after cleaning. [Display omitted] [ABSTRACT FROM AUTHOR]

• We selected an adequate junction temperature estimation model and optimized key variables in a step-by-step manner. • We analyzed statistically the dispersion degree of the PV module's operating temperature. • The application scope and scenarios of the model were determined. • We have verified the process at an existing PV station in Zhejiang Province, China. Junction temperature is an important factor affecting the power generation efficiency and service life of photovoltaic (PV) modules, and it is also the main parameter for calculating temperature rise loss of PV stations. At present, the real-time junction temperature estimation models of PV modules under natural environmental conditions reveal such problems as low accuracy and restricted application scenarios. In this paper, we propose a method which requires the following actions: analyzing the influence factors of the junction temperature of PV modules; selecting an adequate junction temperature estimation model based on the main influence factors (such as radiative cooling, wind speed, irradiance and thermal delay effect) and the capability of PV stations to obtain calculation parameters; optimizing and selecting the key variables step by step that are involved in the model. Then, we analyze the coincidence probabilities of the model under different environmental conditions and the discrete degree of the operating temperature of PV modules to obtain ideal application scenarios of the model. This provides an accurate reference for on-site engineers to apply the model. The example verification shows that the coincidence probabilities of the real-time junction temperature estimation model within the error range of ±1.5 °C, ±2.5 °C, ±3.5 °C and ±5.0 °C reach 72.61 %, 88.65 %, 95.29 % and 98.51 %, respectively, which features high estimation accuracy, convenient use, high efficiency and wide application scenarios. [ABSTRACT FROM AUTHOR]

In this paper are presented results of tests and analyses of complex dynamic loads carried out on the bucket-wheel excavator SchRs 650/5 × 24 Krupp, as well as assessment of service life of vital welded structures of a bucket-wheel excavator boom subjected to cyclic loading with a variable amplitude through the use of experimental tests carried out in order to determine operational strength and growth of a fatigue crack for one structural part. Bucket-wheel excavator was built by "Thyssen Krupp" company, Germany. Outer loads, or in other words digging forces for the overburden and coal have been calculated on the basis of measured values of actual current intensity of the bucket-wheel drive and recorded output values of changeable loads. Correlations between the power of the bucket-wheel drive system and adequate hourly production, depending on the overall digging resistance which affects the stress condition of the bucket-wheel, were also determined. Results of the theoretical and experimental analysis of natural and forced oscillations of the support structure for various exploitation conditions are presented in first part of the paper. Deformations ε i determined by tensometric measurements on the rotating shaft of the bucket-wheel were converted into tangential stresses through the introduction of the modulus of elasticity and Poisson's ratio, which, along with the polar moment of inertia of the cross-section, define the moment of rotation on the bucket-wheel shaft. Through the use of the load - strength comparison method (maximization of the ratio of load and strength indicators) the application factor of the gear with the largest number of turns K A has been determined. In the second part of the paper methodological approach for the assessment of service life of vital welded structures of a bucket-wheel excavator boom was presented. Assessment was done in order to determine operational strength and growth of a fatigue crack, through the use of experimental tests. Realized researches and results presented in this paper offer great possibilities for the analyses of behaviour of vital welded structures of the bucket-wheel boom. By the application of the measurement device with 8 channels for registration and processing of electric signals HBM Spider 8 and measurement tapes HBM 6/350 × XY31 deformations were measured at vital welded structures of the boom in the area of the bucket-wheel. The objective of the test is to determine if there is a possibility of occurrence of plastic deformations or initial cracks due to fatigue at vital welded structures and to obtain data which define crack growth. • Specific digging resistances per knife at highest loads are 20% higher than the average value for overall measurements. • Hourly production N(Q e) show that the bucket-wheel excavator during operation cannot reach the designed capacity of Q t =4212 [m3/h]. • Determined application factor K A =1.6 is smaller than the one prescribed in standards for the gearbox of the excavator drive (K A =1.75-2.0). • In exploitation there is a possibility of the occurence of resonance due to their matching, and therefore of the occurence of damaging of critical cross-sections. • Fracture mechanics parameters have shown that the service life of the welded structure if a new edge crack occuris 4.55 years. [ABSTRACT FROM AUTHOR]

If a shear loaded joint is subjected to impact, vibration and/or load reversal, slip-resistant connections (Category B or C) with preloaded bolts are recommended to prevent effectively movement of the connected parts. The slip-resistance is mainly influenced by the characteristic of the faying surfaces and the preload of the bolts. For structural stability and durability of the steelwork, the level of preload has to be guaranteed over the whole service life of the structure and the loss of preload has to be estimated in the design of the joints otherwise maintenance-work is required. As a participant of the RFCS-Project SIROCO, Fraunhofer IGP investigates the slip factor under ultra-long-term sustained loading and the related loss of preload in the bolts. For the determination of the slip factor a test procedure is given in EN 1090-2. This paper gives comments on the test procedure, especially on the initial load level and the testing time of the extended creep tests (ECT). Furthermore the relation between the load-displacement of different surface treatments during slip is discussed. Based on the investigations a method called "step test" is developed, which allows the definition of the initial load level for the ECT for the first time. In addition, results are presented with a testing time up to 1009 days. Finally, remaining preloads in bolts are shown for the ultra-long-term test duration. This paper deals with the displacement-time and preload-time behavior of slip-resistant connections over an ultra-long-term period of time. Unlabelled Image • The slip load can be determined independently from a fix displacement criterion • The developed step test helps to identify the initial load for extended creep tests • Ultra-tong-term extended creep tests of different surfaces do not show tertiary creep • It is proposed to limit the duration of the extended creep test to 5–7 days [ABSTRACT FROM AUTHOR]

The operation of tidal pumping station has an energetic impact on energy course of massive water pumping for a long time. Thus, a multi-objective optimal operation model was developed to optimize the operation scheme and reduce the energy consumption of the tidal pumping station. In the model, a day is divided into several sub-periods according to the regulation of water level in tidal reach. The partition of sub-periods, the number and blade angle of operating units in each sub-period are adjusted to minimize daily operation energy consumption. And the less switching times, the better the reliability and durability of the unit, the lower the failure rate. Therefore, the reduction of wearing parts' service life is quantified for each switching time in the form of cost. A case study is performed with the tidal pumping station of the South-to-North Water Transfer Project in China. In this paper, energy consumption and switching times are quantified as costs respectively, and the result shows that the daily energy consumption could be saved about 2.28%–6.56%, and the switching times reduced at least 60%. Therefore, this paper could provide an effective optimal operation scheme for the tidal pumping station whose operation is affected by tides. [ABSTRACT FROM AUTHOR]

This paper presents a harvester that collects vibrational energy. The piezoelectric sheet deforms under mass inertia and then generates electricity according to the piezoelectric effect. At the same time, when designing the equipment, the incentive model is selected as the non-contact type to avoid mechanical collision and wear inside the structure and improve the service life of the device. An equivalent damping analysis is performed for the cantilever and combined with the control equations of the Lagrangian. The simulation analysis obtains the native frequency of the rectangular and circular piezoelectric sheets under the mode analysis. Through experimental proof that the device reaches the maximum output voltage 67.19 V when magnet 1 in the mass mutually repels magnet 1 in the housing and magnet 2 in the mass and magnet 2 in the housing. For an external resistance of 10 KΩ, the maximum power output of the device is 165 mW. The device can convert the vibrational energy in the environment into electricity and supply power to other devices through circuit storage. [ABSTRACT FROM AUTHOR]

• A novel fatigue analysis framework with cyclone time-varied features is developed. • Effects of cyclone frequency and direction misalignment on turbine fatigue life are studied. • In-situ data supported cyclone direction/intensity evolution regularity is explored. • Location dependent fatigue accumulation is revealed from two selected sites. Wind turbines are designed to harvest kinetic energy of the wind, which are more susceptible to the impact of tropical cyclones compared with other high-rise structures. Most of the existing research of cyclone (hurricane/typhoon) impacts on wind turbine merely concentrated on its short-term failure (strength or stability failure). However in this paper, it is evidently demonstrated that cyclones can also have a significant impact on the long-term failure (fatigue failure) of a wind turbine. In this study, a novel framework is developed in the fatigue life evaluation of a wind turbine, in which two external factors, i.e., the progressive change of cyclone direction and intensity observed at a specific site, combined with one internal factor, i.e., a parked wind turbine with feathered or unfeathered blades are considered. Subsequently, the effect of cyclone-normal-wind direction misalignment and cyclone average recurrence intervals are included to have a synthetic assessment on the damage potential of cyclones. The proposed fatigue analysis framework can be also extended to other structures, e.g., the hybrid wind-tidal energy conversion system in cyclone-prone regions. [ABSTRACT FROM AUTHOR]

We describe an inexpensive paper-based sensor for rapid detection of low concentrations (ppm) of hydrogen cyanide gas. A piece of filter paper pre-spotted with a dilute monocyanocobinamide [CN(H 2 O)Cbi] solution was placed on the end of a bifurcated optical fiber and the reflectance spectrum of the CN(H 2 O)Cbi was monitored during exposure to 1.0–10.0 ppm hydrogen cyanide gas. Formation of dicyanocobinamide yielded a peak at 583 nm with a simultaneous decrease in reflectance from 450–500 nm. Spectral changes were monitored as a function of time at several relative humidity values: 25, 50, and 85% relative humidity. With either cellulose or glass fiber papers, spectral changes occurred within 10 s of exposure to 5.0 ppm hydrogen cyanide gas (NIOSH recommended short-term exposure limit). We conclude that this sensor could provide a real-time end-of-service-life alert to a respirator user. [ABSTRACT FROM AUTHOR]

• Types and causes of fatigue failure in main bearings of Tunnel Boring Machines (TBMs) are reviewed. • It is described based on the authors' practical experiences during inspecting and maintenance of over 100 sets of TBM main bearings made by various manufacturers. • The properties of different structural designs of the main bearing and their effect on the fatigue life of the main bearing are presented. A large-scale tunnel boring machine (TBM) is currently the most advanced equipment for underground tunnel excavation. The main bearing, carrying all the load and moment from the cutterhead, is hailed as the heart of TBMs, which connects the cutterhead and main drive system. Due to the harsh underground working conditions, the main bearing is prone to fatigue failures, which decreases its service life and could lead to extremely high replacement cost. To enhance the service life, different types of main bearings are used in TBMs depending on the geological structures. To develop a reasonable asset management and maintenance solution, it is crucial to understand the types of fatigue failures of the main bearings. This paper reviews the types and causes of fatigue failures in TBM main bearings based on practical experiences during the inspection and maintenance of over 100 sets of TBM main bearings made by different manufacturers. Fatigue failures in the TBM main bearings, including fatigue wear of components, etching cracks, peelings, rustiness, crushing damages, and bolt fractures, are mainly caused by overload, poor lubrication, foreign objects entering the main bearing interior, and non-standard operation and maintenance. The properties of different structural designs and their effects on the fatigue life of the main bearings are also presented. Furthermore, the selection of main bearings under different working conditions is discussed in order to reduce the occurrence of bearing failures. Finally, future research directions for TBM main bearings are elaborated. [ABSTRACT FROM AUTHOR]

• The gradual transition of the plowshare from the initial wear stage to the stable wear stage. • Changes in wear size are concentrated at the edge of the plowshare. • Dp value is less than 0.2, the wear mechanism is micro-plowing. • The coupling of abrasive wear, impact wear and corrosive wear exacerbates the wear of the plowshare. The ploughshare represents a pivotal component of high-speed plough. The condition of the ploughshare's wear and tear directly affects a soil tilling operation. This paper carries out experimental field wear studies on the ploughshare of a high-speed plough to investigate the changes in mass, thickness, cutting edge parameters, wear profile, 3D wear morphology, microscopic wear morphology, and tissue composition of the 65Mn ploughshare in 35 ha, 70 ha, 105 ha, and 140 ha cultivation areas, and calculates the degree of penetration (D p value) of the wear surface to analyze the wear mechanism, with a view to prolonging the service life of the ploughshare from the perspective of its design and materials. The results showed that the ploughshare showed adaptive wear changes in response to cultivation, most pronounced in the first 35 ha. The wear rate of the ploughshare shows a decreasing trend with the increase of the cultivated area, indicating a gradual transition from the initial wear stage to the stable wear stage. During cultivation, the stresses are concentrated in the ploughshare cutting edge area, and the wear size of the cutting edge varies significantly. Wear of the ploughshare in parts other than the cutting edge is dominated by a reduction in thickness. The roughness of the wear surface stabilized at about 0.4 μm throughout the wear period. With the change of Y-axis position, the wear mechanism changes from impact wear to micro-ploughing, and finally the form of micro-ploughing action decreases gradually. The D p values of the calculated wear surface grooves are all less than 0.2, and the wear mechanism is micro-plowing. Observation of the microscopic wear morphology reveals traces of corrosive wear in addition to abrasive wear, where the soil reacts chemically with the metal and cracks the surface and subsurface layers of the metal. The coupling of abrasive wear, impact wear and corrosive wear exacerbates the wear of the ploughshare. [ABSTRACT FROM AUTHOR]

From the data, structural defects and cracks evolution patterns are identified to determine a statistically significant service life of approximately 5500 h. In this paper, a statistical analysis of failure form and work time of MHJ is conducted. Microscopic test of cracks reveals four main forms of type of cracks. Improper weld technology causes defects in the metallographic structure of weld seam. Improper design causes fatigue cracks of weld seam. Improper machining of parts causes stress concentration and cracks. Improper structural design causes uneven load-bearing capacity of the overall weld structure. According to the above problems, weld structure are optimized. Detailed research is conducted on weld technology of key weld bead. The differences in microstructure and weld efficiency of three different weld technologies are determined by microscopic tests on three key weld seam structures. Therefore, it is concluded that weld bead of MHJ can use full fusion of 9–12 passes multi-pass weld form. This method can achieve a balance between weld efficiency and weld quality. According to simulation analysis and comparison, lifespan after optimization of MHJ increases from 5863 h to 10,374.8 h. Structural performance of MHJ is greatly improved after optimization. Effectiveness of optimal design is verified by zero feedback within 5 years. • Optimizing the structure to increase load-bearing capacity and weldability. • 9–12 passes multi-pass weld is a reasonable weld technology parameter. • Lifespan after optimization of MHJ increases from 5863 h to 10374.8 h. [ABSTRACT FROM AUTHOR]

• Phase-field virtual modelling method (PFVM) is proposed for dynamic fracture in elasto-plastic materials. • Full-field uncertainties of PFVM enable reliable tracking of non-deterministic cracks. • The exceptional capability of PFVM in complex 3D conditions is demonstrated. • PFVM is validated in practical cases with both precision and efficiency. In modern engineering, dynamic fracture failure because of unexpected load or human faults may lead to catastrophic disasters. Preventive structure design and real-time maintain suggestions based on accurate numerical simulation are critical, especially when plasticity develops. It remains a challenge to efficiently model dynamic crack propagation in elasto-plastic materials while the uncertain factors in service life may significantly increase the difficulty. In this paper, a phase-field virtual modelling method (PFVM), based on the features of the novel extended support vector regression (X-SVR) method, is proposed to tackle this non-deterministic problem. The phase field method is adopted for its outstanding performance in complex fracture problems, which provides solid reference data for the virtual model's training and verification. The PFM application to dynamic elasto-plastic fracture problems is validated in two practical engineering examples. The integrated virtual modelling technique is then proven capable of instantly providing precise crack propagation prediction under multiple complex uncertainties, making up-to-date numerical dynamic fracture simulation achievable and affordable. The proposed PFVM method can minimize the contradiction between accurate modelling and high computational cost and can be utilized in various extensions like sensitivity analysis or design optimization. [ABSTRACT FROM AUTHOR]

Metal material corrosion is often an unavoidable phenomenon in our daily lives and industrial production, which shortens the service life of metal materials and causes huge economic losses. Therefore, achieving high-quality corrosion protection is crucial for reducing metal corrosion. In recent years, advanced two-dimensional layered materials (2DLM) have shown great potential for applications in the anti-corrosion field due to unique structure and excellent performance, and have received extensive attention from researchers. However, the majority of current research on anticorrosive coatings is based on synthetic materials, and there are few summarized reports on natural material-based anticorrosive coatings. This undoubtedly lacks a systematic understanding of the rapidly evolving 2DLM in anti-corrosion coating applications. In this review, 2DLM are categorized into natural, traditional, and emerging 2DLM from the point of view of material attributes, and systematically sorted and reviewed the research on their applications in the field of anti-corrosion coatings. The structures and properties of various 2DLM are first briefly introduced. The recent research progress on 2DLM in anti-corrosion coating applications is then reviewed with emphasis. The types of anti-corrosion coatings based on various 2DLM and the performance of these coatings are systematically summarized. Furthermore, the advantages and limitations of anti-corrosion coatings based on various 2DLM are comparatively discussed. At the end of this paper, the challenges for the future preparation and application of 2DLM in the field of anti-corrosion coatings are outlooked. This review aims to utilize existing research on traditional and emerging materials to expand the development of natural materials in anticorrosive coatings, providing valuable insights for future research and the design of anticorrosive coatings. • Advanced 2DLM contribute to efficient corrosion protection. • Presentation of recent advances in coatings based on natural/traditional/emerging 2DLM. • Discusses advantages and limitations of different 2DLM for coating applications. • Summary and outlook on challenges and prospects of 2DLM in anti-corrosion coatings. [ABSTRACT FROM AUTHOR]

The intermediate layer could not only delay the passivation of the titanium matrix and prolong the service life of the metal oxide anode but also directly affected the crystallization behavior and crystal structure of its surface catalytic layer, thus affecting the electrocatalytic activity of the anode. This paper's thermal decomposition method prepared the ruthenium iridium tin metal oxide anodes with different layers of the iridium-tantalum interlayer. XRD and SEM were used to characterize the prepared electrode. Cyclic voltammetry, linear sweep voltammetry, accelerated life test et al were used to analyze the electrode performance. The results showed that the electrochemical roughness increased, the volt-ampere capacity increased, the charge transfer resistance decreased, and the electrocatalytic activity increased after adding the iridium-tantalum intermediate layer. The anode stability was greatly improved, and the accelerated life was prolonged. Among them, the greatest changes were observed when one iridium-tantalum interlayer was added, with the electrochemical roughness increasing from 283.33 % to 616.67 %, the volt-ampere charge increasing from 25.11 mC·cm−2 to 47.24 mC·cm−2, the charge transfer resistance decreasing from 1.754 Ω·cm2 to 0.684 Ω·cm2, and the enhanced electrolysis lifetime extending from 288 h to 504 h. Both the anode's service life and electrocatalytic performance were greatly increased. [ABSTRACT FROM AUTHOR]

This paper presents the results of a reliability analysis of the service life of hydraulic structures made of C50 coral aggregate seawater concrete (CASC) in the splash zone of the South China Sea. The analysis was conducted using the ChaDuraLife V1.0 software, which is based on reliability theory and modified chloride diffusion theory. Several parameters such as the surface free chloride concentration (C s), chloride binding capacity (R), free chloride diffusion coefficient (D f), apparent chloride diffusion coefficient (D a), and time-dependent index (m) were considered in this analysis. The (1-m) boundary condition is adopted in this study. The effect of concrete cover thickness on the service life of CASC structures was discussed. The influence of rebar types and external protective measures on the service life was also investigated. Durability recommendations for C50CASC hydraulic structures in the splash zone were proposed. The minimum concrete cover thickness needed to achieve the service life of 30a to 100a was determined to provide theoretical support for the application of CASC in island and reef engineering. The results found that the best technical measures for extending the service life were the application of 2205 duplex stainless steel bars and silane protective coating on the surface of concrete structures. A concrete cover thickness of 6–7 cm could achieve the service life of 50a, while a thickness of 8.5–10 cm, could achieve the service life of 100a. • A reliability analysis of the service life of C50CASC structures in the splash zone of the South China Sea was conducted. • The influence of concrete cover thickness on the service life of CASC structures was discussed. • Durability recommendations for C50CASC structures in the splash zone of the South China Sea were proposed. • The minimum concrete cover thickness needed to meet the service life of 30a to 100a was determined. [ABSTRACT FROM AUTHOR]

• The dynamic model of the rotating pre-twisted dovetailed blade is established with consideration of the macro-micro rough interface topography. • The inner mechanical relationship between natural frequency and macro-micro topography parameter is revealed. • Different rotational speed, pre-twisted angle, microscopic geometrical parameters, and macroscopic geometrical deviations are discussed. • The proposed dynamic model provides a quantitative and effective prediction for the free vibration of the dovetailed blade under elastic connection with rough contact. The dynamic characteristic of the dovetailed blade plays a key role in the performance and service life of the whole aero-engine. Due to the current manufacturing accuracy and process, the macro-micro contact topography is random and various, which causes the change of the contact response in the blade root as well as the vibration of the blade body. In this paper, a new dynamic model of the pre-twisted rotating dovetailed blade under the flexible connection is established to investigate the free vibration of the blade with macro-micro rough contact topography. First, the elastic boundary of the blade root is quantified by the connection stiffness deduced from the rough contact theory. The governing equation of the blade is formulated by the thin shell theory, and the orthogonal polynomials are employed as the admissible displacement function to calculate the natural frequency though the Ritz method. Then, the effectiveness of the proposed model is validated by comparing it with the theoretical and experimental data. Finally, the influences of the pre-twisted angle, the rotational speed, the macroscopic geometrical deviation, and microscopic topography parameters on free vibration of the blades are investigated in detail. The results show that the natural frequencies have the crossover phenomenon as the parameters vary. The macro-micro topography parameters of the contact interface have a stronger ability to influence the frequency when the rotating speed is low than the high rotating speed. The presented work builds a bridge between the vibration characteristic of the blade body and the macro-micro rough contact topography of the dovetailed joint, which is very meaningful to guide the design of the aero-engine. [ABSTRACT FROM AUTHOR]

Epoxy asphalt has excellent fatigue resistance, making it a valuable addition to recycled asphalt mixtures. However, the lack of sufficient understanding of the cracking mechanism in epoxy-modified recycled asphalt mixtures (EMRAM) hinders its widespread application. The purpose of this paper was to investigate the damage and crack characteristics of EMRAM based on a three-dimensional meso-heterogeneous model. The coarse aggregates were first randomly generated using the secondary Delaunay algorithm. Meanwhile, the fracture parameters of each component material and asphalt-aggregate interface in EMRAM were tested through three-point bending tests and direct shear tests, respectively. Cohesive zone model elements were then inserted at the aggregates, asphalt mastic, and interfaces between different materials to establish a three-dimensional meso-heterogeneous model of EMRAM. Finally, based on the established model, the damage degree of each composition material in EMRAM was quantitatively analyzed to identify the vulnerable aspects of EMRAM during the crack propagation stage. Optimization strategies were proposed accordingly. The results demonstrated that the model established in this study can accurately represent the meso-heterogeneous of EMRAM and effectively simulate its cracking behavior. EMRAM was more susceptible to developing internal damage within the aggregates, followed by relatively noticeable damage at the interface and the internal regions epoxy-modified fine aggregate mastic. The cracking resistance of EMRAM showed a trend of initially increasing and then decreasing with an increase in the volume fraction of coarse aggregates with a size above 4.75 mm. The optimal range for the volume fraction of coarse aggregates in EMRAM was within 35–44 %. The fracture energy of EMRAM was improved by more than 30 % after gradation optimization compared to EMRAM with gradation at the median value of AC20. Within the designed service life, EMRAM durable pavement can save at least 30 % more in economic costs compared to ordinary asphalt concrete pavement. • The order of material damage proportion from high to low is BA > EFAM-BA > EAFAM-BA > EFAM. • The optimal range for the volume fraction of coarse aggregates in EMRAM was within 35–44 %. • The fracture energy of EMRAM was improved by more than 30 % after gradation optimization compared to EMRAM with gradation at the median value of AC20. • EMRAM durable pavement saves at least 30 % more in economic costs compared to ordinary asphalt concrete pavement. [ABSTRACT FROM AUTHOR]

The high strength and durability of cement-based materials are pivotal for energy conservation and carbon emission reduction. By employing solid water mixing technology, a cement-based material with a significantly high compressive strength was developed. However, the concurrent increase in brittleness prompted the exploration of carbon fiber as a potential bridging agent to improve toughness. This paper investigates the role of carbon fiber reinforcement in enhancing the mechanical properties, durability, and service life of cement paste with a super low water-to-cement (w/c) ratio. The results demonstrated that the addition of 0.3 vol% carbon fiber led to an 18.4 % increase in 28-day flexural strength compared to the control group, as well as a 15.3 % increase in flexural compression ratio. Furthermore, under the same carbon fiber content, the drying shrinkage rate after 150-day exhibited a decrease of 20.3 %, and there was a notable decrease of 35.80 % in compressive strength loss rate after 200 freezing-thawing cycles. Service life was significantly improved. It showed that carbon fiber could improve the toughness and durability of hardened cement paste. [Display omitted] • Solid water mixing technology is an innovative method for super low w/c ratio cement. • Incorporating carbon fiber enhances toughness of super low w/c ratio cement. • Carbon fiber can reduce shrinkage, improve freeze resistance and extend service life. [ABSTRACT FROM AUTHOR]

Concrete structures in cold regions are exposed to harsh environmental conditions, including freeze–thaw cycles, which lead to frost damage and degradation. Accurate simulation of the freeze–thaw damage process is essential for assessing concrete structures' performance and service life. This paper presents a novel approach for simulating microcracks propagation in concrete during freeze–thaw cycles based on a fatigue phase-field model, in which a fatigue degradation function is introduced in the energy functional. The commercial software COMSOL is employed to implement the proposed model using a segregated scheme. The proposed model is validated against experimental results presented in the literature. Additionally, three cases are studied to get insight into the freeze–thaw damage. The results demonstrate the effectiveness of the fatigue phase-field model in capturing crack propagation in concrete under freeze–thaw cycles. The developed model offers valuable insights for assessing and designing concrete structures in cold regions. • A fatigue phase-field model is proposed to model freeze–thaw damage in concrete. • A fatigue degradation function is introduced in the energy functional. • The developed model is successfully implemented using the commercial software COMSOL. • Numerical examples show the accuracy and availability of the proposed method. [ABSTRACT FROM AUTHOR]

Previous research has mainly explored how corrosion affects the fatigue performance of bridge cables, with less focus on their residual load-bearing capacity throughout their service life. In this paper, a calculation method for predicting the residual strength and service life of the bridge cable was presented. After inspecting cables operational for 21 years, tensile and fatigue tests were conducted on the steel wires to assess their mechanical degradation. Based on outcomes from accelerated corrosion examinations and finite element simulations conducted under diverse stress conditions, a fitting equation of steel wire corrosion rate varying with stress was presented. Then, the corrosion state prediction model and equivalent strength calculation model of steel wire were established. Due to the discrepancy between the number of test specimens and the total number of steel wires, the overall load-bearing capacity results may be biased. To overcome this discrepancy, a method for calculating the residual strength of cables that considered the coefficient of variation was applied. Finally, the service lifetime prediction framework for cables was developed based on residual strength and rupture rate criterion. The results showed that the strength of the 1# and 2# cables was reduced by 0.5% and 5.63%, respectively. The remaining life of the 1# and 2# cables was estimated at 7.603 and 7.873 years, respectively. • A corrosion prediction model for steel wires considering stress states has been established. • A service lifetime prediction framework for cables was developed based on residual strength and rupture rate criterion. [ABSTRACT FROM AUTHOR]

• Describes a method for fatigue crack growth model optimisation using crack growth measurements for spectrum loading. • Method is demonstrated for small cracks in Aluminium Alloy 7050-T7451 grown under fighter wing root spectrum loading. • Method allows predictions that outperform a model based on the growth of small cracks under constant amplitude loading. The fatigue cracks in a fighter aircraft that pose the greatest threat to structural integrity and availability are usually less than 1 mm for most of their lives. However, it has long been recognised that small cracks can grow significantly faster than long cracks at the same stress intensity range (ΔK). This means predictions for small cracks growing under realistic spectrum loading can be significantly non-conservative when using linear elastic fracture mechanics and long crack-based empirical rate data. Previous work showed empirical rate data based on small cracks grown under constant amplitude (CA) loading could significantly improve predictions. However, such data still have limitations related to an inability to predict the spectrum history effects that influence small cracks. This paper presents a method to optimise a model to predict fatigue crack growth rates for cracks loaded with realistic spectra. This method is demonstrated for small cracks in Aluminium Alloy 7050-T7451 grown under fighter wing root spectrum loading. Numerical optimisation is used to select model parameters that minimise fatigue crack growth rate prediction errors for a training dataset. This purpose-built model consistently outperformed a generic model based on the growth of small cracks under CA loading. [ABSTRACT FROM AUTHOR]

• Deriving/estimating plain strain fracture toughness for ASTM A322 material. • Developing flaw tolerance limit plots for ASTM A322 and ASTM A722 material. • Estimating remaining service life of existing post-tension grouted anchors. Brittle failure of grouted post-tensioned anchors used in trunnion girders at dams has given rise to concerns and questions surrounding their continued use and remaining service life. This paper reviews the brittle failure of five grouted post-tensioned anchor rods due to stress corrosion cracking at dams in California. To provide an early warning system to dam owners and expand on available resources for practicing engineers, this study derives plain strain fracture toughness from the failed grouted post-tension anchors using cross sectional photos. Using derived and available fracture toughness values, flaw tolerance limit plots, which can quickly illuminate the severity of a defect for various anchor diameters, were developed for semicircular and straight fronted flaw types using linear elastic fracture mechanics and stress intensity factors for both ASTM A322 and ASTM A722 materials. To help demonstrate the use of flaw tolerance limit plots and estimate the remaining service life of an in-situ anchor, an example problem was developed. [ABSTRACT FROM AUTHOR]

Due to their outstanding mechanical properties, fiber-reinforced polymer composite (FRPC) structures have become a prominent research topic. Yet, to surpass existing performance limits, their design potential should be expanded beyond conventional empirical methods. Moreover, because of the high manufacturing costs, the protection of FRPC structures should be considered in the design phase to extend their service life. In this paper, we introduce an innovative configuration wherein metal coatings are strategically applied to the surfaces of FRPC structures. This technique aims to protect the internal matrix and fiber materials, and to inhibit the interlaminar delamination of composite laminates. Then, a corresponding full-scale topology optimization framework is built based on a density-based method. The coating, matrix, and fiber materials are considered collectively, avoiding issues such as excessive computation, non-convex optimization, and fiber discontinuity. Furthermore, a dual variable scale filtering (DVSF) method and its simplified scheme are presented to optimize coating thickness based on the physical information obtained from finite element analysis. Meanwhile, the co-evolution of solid topology and fiber morphology, driven by algorithms, facilitates the parallel optimization of multiple geometric features. Several typical examples, including wing ribs, are provided to illustrate the effectiveness and superiority of our approach, highlighting its engineering relevance. [ABSTRACT FROM AUTHOR]

The Ion Gel Artificial Muscle (IGAM) is an emerging electro-responsive chemical actuator that holds significant potential for flexible actuation. This paper investigates the regulatory and enhancement mechanism of Sodium Polystyrene Sulfonate (PSS) on the electro-responsive fatigue resistance of IGAM by cross-linking with varying amounts of PSS, aiming to achieve high performance and durability. The study is conducted based on control variables and proposes four primary evaluation metrics. The results indicated that the optimal PSS amount of 0.75 mL yielded the highest values for peak difference (32.4 mN/g), response speed of output force density (0.07818 mN/g·s), and operating life of the IGAM (10,800 s). Additionally, under the excitation of short time reversible voltage, the quasi-impulse density of IGAM reached 10915 mN·s/g. Furthermore, the elastic modulus and internal resistance were found to be the lowest at 27.2 MPa and 1.55 Ω, respectively, while the area-specific capacitance increased to 400 nF/cm2. This phenomenon occurred due to the protonation of the sulfonyl groups, which were highly electronegative, on the PSS molecule. As a result, cross-linking hydrogen bonds were formed with the sodium alginate (SA) molecule, leading to the wrapping of its network and the formation of a regular three-dimensional ion gel network inside the IGAM. Both PSS and SA were polyanionic electrolytes, capable of increasing the number of anions present. This, in turn, facilitates the migration of hydrated cations within the IGAM, thereby enhancing its electro-responsive performance to suit various circumstances. • The electro-responsive fatigue resistance of IGAM is investigated through cross-linking with PSS. • Enhanced IGAM exhibits exceptional performance and durability to adapt diverse circumstances. • Four evaluation metrics are proposed to assess the electro-responsive fatigue resistance of IGAM. • The IGAM demonstrates the highest values when an optimal PSS amount of 0.75 mL is utilized. • The migration of hydrated cations within IGAM is facilitated by the cross-linking of SA with PSS. [ABSTRACT FROM AUTHOR]

The microstructure affects the service life and performance in thermal barrier coatings (TBCs). A series of yttria-stabilized zirconia (YSZ) coatings with embedded micro-agglomerated particles (EMAP) are prepared using plasma co-spraying technology. The thermal conductivity and thermal cycling behavior between EMAP coatings with various transfer speeds and traditional YSZ coating are explored. Experimental and finite element simulations are conducted to explore the effect of pore structure characteristics on the thermomechanical properties of coatings. Results show that the thermal conductivity of EMAP coatings is lower than that of traditional YSZ coating, with EMAP coating deposited at 200 mm/s transfer speed having the lowest thermal conductivity. The thermal cycling life of EMAP coatings at transfer speeds of 600 mm/s and 800 mm/s is improved by 20.00 % and 58.33 % compared to traditional YSZ coating. This paper suggests the mechanism of excellent thermal insulation and service life of porous coatings. • A tailored-composite structure for optimizing the pore distribution of TBCs has been developed. • The large pores area accounting for 94.62 % greatly improves the thermal insulation performance of TBCs. • The large pore area accounting for 46.25 % increased the thermal cycling life of 58.33 % of TBCs. • Failure mechanism and thermal conductivity of TBCs are systematically studies by experiment and FE method. [ABSTRACT FROM AUTHOR]

The adhesively bonded structure, comprising carbon fiber-reinforced polymer (CFRP) and ultra-high-performance concrete (UHPC), enhances structural strength while reducing brittleness and strain softening behavior. However, the adhesively bonded structure is inevitably influenced by temperature variations throughout its service life. When the adhesive layer's temperature surpasses the glass transition temperature (T g), significant damage occurs to the bond layer joint. To investigate the debonding behavior of the CFRP-UHPC interface at various temperatures, a series of three-point-bending tests were conducted at room temperature, 120 % T g , 150 % T g , and 160 % T g. This study introduced a temperature degradation factor, employing a proposed maximum load capacity prediction formula to adjust both the test results and data from other researchers. By adjusting the cohesion parameters with the temperature degradation factor, a temperature-dependent mixed-mode cohesive zone model (CZM) was developed. The model's validity was confirmed through finite element (FE) analysis, considering two distinct experimental scenarios. The paper concludes that the proposed model effectively simulates interface debonding behavior across varying temperatures. [ABSTRACT FROM AUTHOR]

High-pressure angle valves have suffered from eccentric jet flow characteristic in the diffuser pipe section due to the inherent structures and throttling effect. The eccentric jet flow will continuously scour the valve body and lead to washout on the side wall of the valve seat, largely impacting the valve service life and safety. With regard to this issue, this paper has conducted a numerical characterization study to investigate the influences of valve spool structures including the prototype, parallel and spherical spools on the eccentric jet flow in the first diffuser pipe section of a high-pressure angle valve. Results show that the parallel and spherical valve spool structures can achieve a lower pressure difference across the pipe section than the prototype spool structure, while the spherical spool has shown the minimum pressure difference in the first diffuser pipe section. Moreover, compared with the prototype and parallel spools, separated flows are distributed more uniformly on both side walls in the first diffuser pipe section for the valve with the spherical spool. The relative uniformly distributed separation vortexes makes the high-speed mainstream along the pipe center line and can successfully mitigate the eccentric jet flow. The motivation of this work is to reveal the influencing mechanisms of spool structures on the eccentric jet characteristic in high-pressure angle valves and provide useful guidelines for advanced angle valve design with low erosion and long service life. • The influences of valve spool shapes on the eccentric jet flow characteristic are studied in a high-pressure angle valve. • Separated flows are distributed more uniformly in the first diffuser section of the valve with spherical spool. • The spherical spool achieves a smaller pressure difference across the diffuser pipe than the prototype and parallel spools. • The spherical spool is beneficial for suppressing the eccentric jet flow characteristic. [ABSTRACT FROM AUTHOR]

• In this paper, the effect of mismatched line impedances in the system on the precise current distribution among ESUs is considered. A current compensation term is introduced into the droop coefficient. By adjusting the weight of the compensation term, precise current distribution among the energy storage units is achieved on the basis of rapid equilibrium. • The control strategy proposed achieves precise current distribution by altering the droop coefficient. Compared to traditional current distribution strategies, the use of proportional-integral controllers can be reduced. In the presented study, a novel droop control method has been developed for distributed energy storage systems, which ensures the precision of current sharing and the balance of state of charge (SOC). A strategy that has been newly introduced facilitates a logical allocation of SOC and ensures precise sharing of current in autonomous island DC microgrids. Within the framework of droop control, a linkage is established between the SOC value and the converter's output current. By mitigating the impact of disparate line impedance on SOC equilibrium, the service life of energy storage units (ESUs) is significantly improved. The droop coefficient has been augmented with the inclusion of a current compensation term. It has been ascertained that the ratio of SOC to output current within the droop coefficient can be determined independently, utilizing the state information of SOC. By incorporating accurate current sharing that considers SOC, ESUs with higher SOC levels output larger currents, while those with lower SOC levels output smaller currents. A newly devised control approach is distinguished by its reliance on low-bandwidth communication. This method ensures the stabilization of the DC bus voltage, maintaining it at a pre-set level, achieved through the application of a voltage restoration technique. [ABSTRACT FROM AUTHOR]

Under the external electric field, the voids in polycrystalline interconnect lines will exhibit different morphology evolution when crossing grain boundary. Predicting the void crossing process caused by electromigration is an important aspect to improve the reliability of miniaturized integrated circuits. Based on the basic theoretical framework of microstructural evolution in solid materials, a new multi-phase-field model is established in this paper to simulate the process of void crossing grain boundary under anisotropic surface diffusion caused by electromigration in bicrystal interconnect line. Through asymptotic analysis, the compatibility of the multi-phase-field model with the sharp interface model in the limit case is proven. The corresponding finite-element program is developed and the reliability of the model is verified by comparing the numerical simulation with the theoretical solution. The results indicate that the process of void crossing grain boundary is governed by the crystal orientation and the misorientation difference of two adjacent grains. Under different misorientation differences, the void in (110) crystal orientation has two evolutional bifurcation trends: void splitting and tilting drift, while the void in (100) and (111) crystal orientation always remains as a whole and drifts along the direction of the electric field. The void in (111) crystal orientation is the easiest to cross the grain boundary, the fastest to cross the grain boundary, and the influence of the misorientation difference is minimal. This can prevent the void from being pinned by the grain boundary and extending along the grain boundary to cause failure, so as to effectively improve the reliability of the interconnects and extend the service life of the integrated circuit. • A MPF model of anisotropic surface diffusion induced by EM is developed. • The undetermined parameters in the MPF model are determined by asymptotic analysis. • The process of void crossing grain boundary depends on the crystal orientation and Δ θ 0. • Only in (110) crystal orientation, void splitting exists at the grain boundary. • Void in (111) crystal orientation is the fastest and easiest to cross the GB. [ABSTRACT FROM AUTHOR]