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Ultrathin devices are rapidly developing for skin‐compatible medical applications and wearable electronics. Powering skin‐interfaced electronics requires thin and lightweight energy storage devices, where solution‐processing enables scalable fabrication. To attain such devices, a sequential deposition is employed to achieve all spray‐coated symmetric microsupercapacitors (μSCs) on ultrathin parylene C substrates, where both electrode and gel electrolyte are based on the cheap and abundant biopolymer, cellulose. The optimized spraying procedure allows an overall device thickness of ≈11 µm to be obtained with a 40% active material volume fraction and a resulting volumetric capacitance of 7 F cm−3. Long‐term operation capability (90% of capacitance retention after 104 cycles) and mechanical robustness are achieved (1000 cycles, capacitance retention of 98%) under extreme bending (rolling) conditions. Finite element analysis is utilized to simulate stresses and strains in real‐sized μSCs under different bending conditions. Moreover, an organic electrochromic display is printed and powered with two serially connected μ‐SCs as an example of a wearable, skin‐integrated, fully organic electronic application. [ABSTRACT FROM AUTHOR]

Flexible sensors have versatile applications in a home environment to create better ambient intelligence, which still have high fabrication costs and disposable value. As a proof‐of‐concept example to resolve these problems, the graphite‐based sensors on a disposable paper cup by laser patterning to measure the water level and temperature are proposed. The optimal process parameters of graphitic film, sensing mechanisms, and the sensor performance are investigated in the experiments. Moreover, the paper cup with graphitic sensors is simulated by the finite element method to analyze the experimental results. This fast and low‐cost manufacturing method may open up avenues for the development of disposable flexible electronics in smart home necessities. [ABSTRACT FROM AUTHOR]

Paper has always been of great importance as a printing and packaging material. Due to its potential for recyclability and reusability, which result in a low environmental impact, it is expected that this importance will soar over the coming years. Nevertheless, even though paper has been in use for decades, many research questions are still open, especially in the field of mechanics. One of these questions is the appropriate size of a representative volume element (RVE) of the microstructure of paper. Therefore, a finite element network model of interconnected fibers was developed which represents the microstructure of paper. In order to create the network model realistically, geometry and material quantities were taken from experimental investigations. Additionally, single fibers and fiber bonds were investigated beforehand in order to incorporate their proper behavior into the network. Based on this, the networks were generated and subsequently loaded by applying mixed displacement and traction boundary conditions. The resulting effective stresses were compared to determine the necessary RVE size. Two approaches were considered for modeling the RVE: (i) one single "large" network, and (ii) a certain number of smaller networks whose average yielded a statistically representative effective response. As a result, the second approach turned out to be less computationally intensive due to smaller models and the possibility to run calculations simultaneously. Concluding, it was possible to determine the size of the RVE which will be used to investigate various individual microstructural effects on the macrostructure in the future. [ABSTRACT FROM AUTHOR]

In this contribution, the causes leading to the undesired unevenness on the exterior surface of a paper‐based sandwich structure during the manufacturing process are investigated. This provides insight into the manufacturing parameters that need to be adjusted to reduce this waviness. A finite element model of the pressing process is developed in the commercial software ABAQUS and then used to analyze the formation of the surface unevenness. The sandwich structure adopted in the model consists of a decorative layer, an intermediate layer, a corrugated core and a bottom layer. In particular, the core has a sinusoidal structure with various geometry parameters, which are adjusted in the model to investigate the effect on the waviness of the top surface. The results of the quasi‐static process simulation correlate well with the experimental results. A subsequent parameter study based on the design of experiments (DoE) shows the relationship between the material parameters of the intermediate/bottom layer and the resulting waviness. [ABSTRACT FROM AUTHOR]

Strain sensors which are embeded in AMOLED are introduced and studied in this paper. High accuray strain sensing are achieved, resolution of the sensors are about 0.05%. By combing the strain sensors in the panel, mechanical behaviors can be monitored and studied in real time. The snesors are used to conduct the foldable AMOLED mechanical and reliability study. Dynamic and static strains and related mechanism are introduced and discussed. Finite element simulation models considering the mechanical properties of materials including hyperelasticity, viscoelasticity and creep are established. Finally, the strain sensors and finite element anlysis are combined to study the mechanical response of AMOLED under dynamic folding, static folding, and different temperature and humidity environments. [ABSTRACT FROM AUTHOR]

A moisture-dependent and temperature-dependent constitutive model for paper materials was proposed and implemented into a finite element model of the paper hydroforming process. Experimental hydroforming was conducted at temperatures of 23°C and 110 °C and moisture contents of 6.9 and 10.6 (respectively corresponding to 50 and 80% relative humidity). The proposed model, which also included the effects of drying, captured the extent of forming of all experimental results within reasonable accuracy. For the moisture content and temperature conditions in this study, the phenomenon of drying was found to be the reason why the application of temperature had a much greater effect on the degree of forming than hydroforming at various moisture contents. A simulation-based parametric study was conducted in order to identify the importance of various process and material parameters. This parametric study confirmed many previous empirical findings and was capable of quantifying the extent to which these process and material parameters affect the three-dimensional formability of paper. The coefficient of friction was identified as one of the most important factors when determining the extent of forming. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates the skiving and cutting stock problem (SCSP) encountered in the paper and plastic film industries, in which a set of nonstandard reels generated from previous cutting processes are used to produce finished rolls through the skiving and cutting process. First, reels are skived together lengthwise to form a reel‐pyramid (a polygon), and then the reel‐pyramid is cut into finished rolls of small widths. Depending on if a reel can be divided lengthwise into subreels to form the reel‐pyramid, the problem can be classified into divisible SCSP (DSCSP) and indivisible SCSP (ISCSP). In this paper, two integer programming (IP) models are proposed for DSCSP and ISCSP, respectively. A sequential value correction procedure combined with the two IP models (SVCTIP) is developed to solve the two SCSPs. The effectiveness of the SVCTIP is demonstrated through extensive computational tests. [ABSTRACT FROM AUTHOR]

In recent years, the development of high‐speed railways in China has been rapid. High‐speed railway bridges play an essential role whenever the railway intersects with existing facilities in three dimensions. With the increasing speed of high‐speed railways and increasingly complex geographical locations, the span of bridges is constantly increasing. Based on their advantages, steel structures in large‐span bridges are beginning to replace traditional concrete structures. Taking the steel cover beam technology applied in the Fuqiangbao Tremendous Bridge as a starting point, this paper uses Rhino parameterized modeling and Abaqus software to conduct finite element analysis on the stress of steel cover beams. It compares and analyzes stress under different conditions. The results show that the steel cover beam's most unfavorable and unstable position in this paper is at the support on the stress side. This provides a reference for monitoring the steel cover beam after its application in the Fuqiangbao Tremendous Bridge and technical accumulation for the application of steel cover beam technology. [ABSTRACT FROM AUTHOR]

The numerical simulation of paperboard creasing and folding processes is of increasing importance for the design and production of safe and reliable packaging systems. The extreme material anisotropy and the complexity of these processes require however simulation capabilities which are seldom available in commercial codes. Several approaches have been proposed in the literature over the years, in most cases making use of non-linear material models developed ad hoc for this purpose. These models, some of which are very effective and accurate, are not in general available in commercial codes and are often based on the definition of a large number of parameters. In this paper, the possibility to obtain acceptable, first-hand simulation results using only features already available in a commercial code is investigated. An advanced continuum constitutive model, recently presented in the literature, has been used as a reference for tuning the model and for assessing its accuracy. It is shown how standard features, usually available in state-of-the-art commercial codes, can be employed to deal with the extreme material anisotropy, obtaining qualitatively good results in both the creasing and folding phases. The used standard model accounts for the extremely high anisotropy by means of embedded shell elements, playing the role of reinforcements in the fibre direction. The matrix is assumed to be isotropic and elastoplastic, with properties determined based on the behaviour in the thickness direction. The adopted plasticity model is a modified Drucker-Prager model with a cutoff on the tensile pressure side, available in the used commercial code. The procedure adopted for the identification of the small number of required material parameters is also discussed. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The main challenge faced by many mechanical engineering educators is the implementation of real solutions during their courses. One alternative can be a realistic case study, where the students can be engaged in the development and analysis process currently applied in the industry. This kind of teaching process not only can be used to improve the quality of teaching‐learning process but also the students can have opportunities to solve real engineering problem. Therefore, this paper reports a realistic case implemented in mechanical engineering courses given in bachelor's and master's degrees. The component under evaluation has been selected considering the student's interest, this criterion was also taken to involve several students into a real project process to their learning development. The same problem was solved during an academic semester, it was solved using different approaches and student's abilities. This procedure can be replicated for students and teachers by following steps. The first step in this process was to describe the theoretical basis for modal analysis to understand how it was structured a numerical finite element model. This model was then solved and simulated using Hypermesh, Optistruct, and HyperView software to obtain numerical modal parameters. On the other, hand, the experimental modal parameters were obtained using a three‐dimensional scanning vibrometer on 60 samples. It is well noted that the implementation of engineering software commonly used at the industry would increase students' confidence. This allows students to perform real problem‐solving activities to develop outcomes as establish goals, plan task, meet deadlines. These activities are extremely important to the actual automotive industry. Therefore, this paper shows an engineering solution process to provide a learning alternative to teach the modal finite method solutions correlation with experimental solutions. [ABSTRACT FROM AUTHOR]

Smart windows are attractive because of their numerous advantages such as elegance in construction design and energy conservation. Smart windows with variable transmission are especially desirable for obvious reasons. The simplest way to make a variable transmission smart window is to use two patterned polarizers, and control the transmission by changing the relative position of the two polarizers. We have demonstrated a high‐dichroic‐ratio polarizer by photoalignment and proposed a simple one‐step photo‐copy method to realize a continuous axis varying polarizer. The patterned polarizer shows high optical performance, and its thickness is as thin as 100 nm, which is favorable in practical window applications. [ABSTRACT FROM AUTHOR]

A replaceable buckling‐restrained flange cover plate (BRFCP) was previously proposed to improve seismic performance of beam‐to‐column joints. Quasi‐static tests were conducted to investigate the seismic performance of beam‐to‐column joints using three different formats of restraint plates for BRFCP: no restraint plate, separated restraint plate, and integral restraint plate. The test results showed that both separated and integral restraint plates restrained the core plate buckling under compression and increased the beam‐to‐column joints load resistances. This paper first validates finite element models (FEMs) using test results. Then the validated FEMs are used to investigate influences from different BRFCP design parameters (such as core plate thickness, restraint plate thickness and length, restraining gap size, and restraint plate blot prestress force) to the beam‐to‐column joint load–drift hysteretic responses. Finally, the paper proposes a design range of each investigated design parameter and a BRFCP design procedure. [ABSTRACT FROM AUTHOR]

Planetary Threaded Roller Bearing (PTRB) is a new bearing suitable for the heavy load linear drive mechanism. The load is transferred internally through annular threads, affecting the bearing capacity of the thread's contact load distribution characteristics. The structure of PTRB is discretized to study the contact load distribution of PTRB. The axial stiffness of the thread's teeth, its axial stiffness, and the contact stiffness of contact points are calculated. Moreover, a 1D equivalent spring network model is proposed based on discretized structure and stiffness. The PTRB contact load calculation model is proposed using the direct stiffness method and a 1D equivalent spring network model. Finally, the accuracy of the model proposed in this paper for calculating the contact load distribution of threaded teeth is verified by comparing the results obtained from theoretical model calculations, finite element methods, and experiments. The theoretical model proposed in this paper can provide theoretical guidance for PTRB parameters. [ABSTRACT FROM AUTHOR]

The development process of the composite structures is always an ongoing process, to gain more the benefits of the composite work between steel and concrete. This process has created a wide range of types of shear connections. Different types of perfobond shear connections have been developed to overcome the disadvantages of the conventional headed stud connections. The new types like the Y, puzzle, clothoid, etc. shape perfobond plates have been studied due to their beneficial ultimate resistance and deformation capacity. The Y‐type perfobond rib shear connection is a superior alternative to the conventional perfobond due to its improved performance characteristics, such as higher ductility and stiffness, and greater resistance against uplifting force. In this paper the focus in on Y‐shape perfobond shear connections. A finite element model for a push‐out test has been developed to analyze the influence of structural parameters on the behavior of the connection. The model was verified by the experimental test completed at the Department of Structural Engineering, in Budapest University of Technology and Economics. The FE model was developed on Atena GID software. In this paper the effect of the angle of the inclined Y parts and the geometrical dimensions of the inclined Y parts are analyzed on the resistance, degradation tendencies, deformation capacity and the stiffness of the connection, conclusions are drawn, and beneficial structural details are recommended. [ABSTRACT FROM AUTHOR]

This work is part of the European RFCS "FISHWALL" project entitled "Fire and Seismic performances of hybrid fire walls in case of single‐storey industrial and commercial steel buildings". The aim of the project is to design a hybrid firewall solution using sandwich panels for single‐storey buildings connected with the unprotected steel structure by means of fusible links, made of aluminium bolts. In this respect, the paper shows the results of preliminary numerical analyses performed on existing case studies of single‐storey steel buildings located in low and moderate seismicity zones and they were used: i) to estimate the seismic forces acting on the fusible links and ii) to subsequently design the specimens to be tested in the laboratory. In this respect, several finite elements models were developed in order to consider the widest range of configurations of the firewall with respect to the direction of the portal frame composing the steel buildings, i.e. firewall parallel and orthogonal to the portal frames. Based on the estimated forces, the design of the six different specimens was performed and it is thoroughly shown in the paper. [ABSTRACT FROM AUTHOR]

2 Gupta P, Duarte CA, Dhankhar A. Accuracy and robustness of stress intensity factor extraction methods for the generalized/extended finite element method. Later in § 3.1, we refer to GDD-DCM as "the displacement correlation method of Gupta, Duarte, and Dhankhar", specifically acknowledging the contribution to the DCM family in Reference 2. At no point in Reference 1 do we make any statement about the convergence or lack thereof of the stress intensity factors computed with the DCM in combination with displacement fields computed with G/XFEM. [Extracted from the article]

This paper presents mixed finite element formulations to approximate the hyperelasticity problem using as unknowns the displacements and either stresses or pressure or both. These mixed formulations require either finite element spaces for the unknowns that satisfy the proper inf‐sup conditions to guarantee stability or to employ stabilized finite element formulations that provide freedom for the choice of the interpolating spaces. The latter approach is followed in this work, using the Variational Multiscale concept to derive these formulations. Regarding the tackling of the geometry, we consider both infinitesimal and finite strain problems, considering for the latter both an updated Lagrangian and a total Lagrangian description of the governing equations. The combination of the different geometrical descriptions and the mixed formulations employed provides a good number of alternatives that are all reviewed in this paper. [ABSTRACT FROM AUTHOR]

ABSTRACT In digital healthcare engineering (DHE) for aging monopile‐type offshore wind turbines, predictive health analysis is essential for robust future maintenance planning. This paper presents the development of a DHE module for the predictive health analysis of corroded monopile‐type offshore wind turbines, focusing on wind and rotor blade rotation effects. An empirical formula for predicting time‐variant corrosion wastage is derived from a statistical analysis of a decade‐long corrosion wastage database and applied to predict the corrosion depth of a 5 MW monopile‐type offshore wind turbine, serving as an illustrative example. Nonlinear finite element analyses using LS‐DYNA are performed on the corroded turbine tower under combined wind‐induced loads and rotor‐induced thrust forces. Two types of corrosion wastage, pitting, and uniform (general) corrosion, are considered. The health condition of the corroded tower is evaluated based on serviceability limit state and ultimate limit state criteria. The methodology developed in this paper will be integrated into the DHE system currently being developed by the authors for aging monopile‐type offshore wind turbines. [ABSTRACT FROM AUTHOR]

This paper outlines the planning of a bridge in central Germany. Scheduled for construction in mid‐2024, this new bridge is a replacement for a century‐old pedestrian bridge crossing the Lahn river. The proposed bridge will be an airtight‐welded arch bridge, employing steel cross‐sections in both the arch and tension member. Designed as a single‐span, the arches extend 48.0m over the Lahn. The two arches have a flat rise of 4.65m, supporting the roadway through 9 inclined flat steel hangers. This paper delves into the structural engineering aspects, exploring challenges inherent in the design process. An examination of the parametric design process, facilitated through 3‐D modeling in Rhino® and Grasshopper®, will be presented, along with insights into their interface with the finite element modeling software, RFEM®. This process enables an engineering approach to form‐finding and structure optimisation through iterative design checks for various elements and stages of the structural analysis. [ABSTRACT FROM AUTHOR]

This paper proposes a hybrid data‐driven and physics‐based simulation technique for seismic response evaluation of steel Buckling‐Restrained Braced Frames (BRBFs) considering brace fracture. Buckling‐Restrained Brace (BRB) fracture is represented by cumulative plastic deformation capacity. A dataset, consisting of 95 past BRB laboratory tests and 120 simulated BRB responses generated using the finite element method, is first developed. An Artificial Neural Network‐based (ANN) predictive model is then trained using the training dataset to estimate the cumulative plastic deformation of BRBs. The prediction capability of the ANN‐based predictive model is validated using the training dataset and an existing regression‐based predictive model. In the second part of the paper, an hybrid simulation technique combining the data‐driven model and physics‐based numerical modeling is presented to conduct the nonlinear time history analysis, followed by 1) validation against a full‐scale BRBF testing and 2) demonstration of the proposed simulation technique using a six‐story BRBF. The results confirm that the proposed predictive model can predict the BRB fracture with sufficient accuracy. Furthermore, the hybrid data‐driven physics‐based simulation technique can be used as a powerful tool for dynamic analysis of BRBFs considering BRB fracture. [ABSTRACT FROM AUTHOR]

The paper portrays a comprehensive computational procedure for determining the global structural resistances of two existing bridges made of I‐73 and KA‐61 precast post‐tensioned concrete girders using advanced statistical assessment methods in combination with nonlinear fracture mechanics‐based finite element method analysis. Although this combination is a powerful tool for realistic modeling of structures, its practical application is still very time consuming. Therefore, a statistical sampling approach for the determination of the structural design resistance is compared to selected efficient semi‐probabilistic methods based on the estimation of coefficient of variation—estimation of coefficient of variation (ECoV) method according to fib Model Code 2010 and improved approach called Eigen ECoV method. Load‐bearing capacity is determined for the ultimate as well as several serviceability limit states. The sensitivity of the input parameters burdened with uncertainties on the response of the structure is quantified using a sensitivity analysis supported by a surrogate model based on polynomial chaos expansion. The paper shows that the applicability of nonlinear modeling with respect to uncertainties is possible when using these ECoV methods and a surrogate model and can be applied in a routine manner. The shortcomings and advantages of all the used safety design/assessment methods are discussed. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to carry out parameter design and dynamic stability verification experiment of controllable damping ferrofluid bearing. A new type of ferrofluid bearings is designed, and its internal magnetic fields are simulated by the finite element analysis software ANSYS. In this paper, the coefficient of magnetic leakage is taken as the optimization object, and the optimal parameters of ferrofluid bearings are updated. At the same time, the working principle of the ferrofluid bearings test platform is introduced, which includes a servomotor with a controller, an eddy displace sensor, an amplifier and a power supply. Finally, the dynamic stability of ferrofluid bearing is verified by experiments. The experimental results show that when the applied current is less than or equal to 0.08 A, the amplitude of the rotor supported by the ferrofluid bearing decreases with the applied current increment. Besides, the dynamic stability of the rotor is also related to the rotational speed. When the applied current is 0.08 A, the amplitude of the rotor supported by the ferrofluid bearing firstly increases and then decreases with the rotational speed increment. It is proved that the ferrofluid bearings have a strong function of the dynamic stability, which can suppress the vibration of the rotor, and have high accuracy of both position and rotation. [ABSTRACT FROM AUTHOR]

This paper investigates the vibration characteristics, both linear and non‐linear, of beams made from functional gradient materials (FGMs) with layers of Terfenol‐D attached to the top and bottom surfaces. Given the porosities that can occur during the manufacture of FGMs, the study examines the vibrational behaviour of beams with porosities. Euler–Bernoulli beam theory and the von‐Kármán non‐linear deformation field are used to formulate a fundamental equation predicting the free dynamic vibration of Terfenol‐D FGM structures with porosities. To complete this analysis, the paper also presents the application of two advanced methods. The first method involves employing the generalised finite element method (GFEM) associated with the reduced quadrature finite element method (RQFEM). GFEM offers a versatile and powerful approach, while RQFEM provides a specific method for studying dynamic phenomena. The second method utilises a semi‐analytical approach, the variational iteration method (VIM), which examines and complements the first method. Furthermore, we have demonstrated substantial alignment between the proposed solution and the results of finite element analysis, as well as with the existing literature, underscoring the effectiveness and accuracy of our analytical approach. The study also explores the influences of material property distribution, thermal loading, and porosity volume fraction on the linear and non‐linear behaviour of Terfenol‐D FGM beams. This comprehensive exploration furnishes valuable information on the intricate interplay of factors affecting vibration dynamics and control mechanisms in these advanced composite structures, offering insightful perspectives into the potential application of Terfenol‐D FGM beams in various fields. [ABSTRACT FROM AUTHOR]

Summary: H‐shaped circular arc is a relatively novel type of open‐web steel arch, and currently, no reports have been published concerning its in‐plane stability. In this paper, the elastic and elastic–plastic in‐plane stability of the H‐shaped hollow circular arch is studied by theoretical deduction combined with numerical simulation. First, the overall shear rigidity of the H‐shaped circular arch is calculated, and the elastic buckling load formula of the arch is proposed and verified considering double shear deformation under full‐span radial and uniform loading. The overall elastic buckling load deduced in this paper is reasonable according to the finite element analysis. The results indicate that the influence of shear deformation on the overall elastic buckling load of the arch decreases with the increase of the span length. The arch‐bearing capacity is the largest when the rise‐span ratio is 0.25. Second, the restriction conditions necessary for avoiding local buckling of the chordal web before integral buckling of the H‐shaped steel hollow circular arch are analyzed. Finally, the elastic–plastic failure mechanism of the H‐shaped arch under full‐span radial and uniform loading is examined, and the formula for determining the ultimate bearing capacity that is achievable before failure under full‐span radial and uniform loading is proposed. ANSYS analysis shows that under the radial uniform loading, the chordal bars will yield near 1/4L and 3/4L, and ultimately, the structural failure of the lower chord occurs in the vicinity of 1/4L. The formulas presented in this paper agree well with the results obtained from the finite element analysis and can be used as a reference for engineering applications. [ABSTRACT FROM AUTHOR]

This paper presents the development of an Air‐Cored Axial Flux Permanent Magnet Generator (ACAF PMG) integrated for direct battery charging scheme for urban and rural micro‐wind turbine applications rated at 1 kW. The proposed generator has a Single Stator Double Rotor configuration with a relatively short axial length. In this paper, the analytical model for generator sizing is presented and the main parameters are defined. Novel analytical model is presented to determine the required number of turns for each phase in order to produce a balanced voltage in the three phases. The generator is electromagnetically analyzed using Finite Element model and simulated using Matlab/Simulink to predict its performance under several operating conditions. The effect of retainment ring type on the generator performance is also demonstrated. The machine is harnessed to a battery bank via a three‐phase fully controlled converter using six bridge thyristors to regulate the output voltage delivered from the generator to the battery. Generator model and simulation results are validated via experimental tests. The preliminary experimental results showed a good match with the simulation results. Moreover, the proposed machine is compared favourably with other counter machines of similar configuration and power ratings in terms of machine size, power‐to‐weight ratio, and voltage regulation. This paper therefore demonstrates the concrete benefits of utilizing the axial flux PMG in scavenging energy to generate electrical power from micro wind turbines. [ABSTRACT FROM AUTHOR]

Sanding production of the underground gas storage (UGS) in the depleted reservoir will cause the decline of effective storage capacity, and the erosion of well string and auxiliary equipment, and other engineering problems. A deep understanding of the sanding production contributes to maintaining the injection and production capacity of gas storage and the long‐term safety of the UGS. In this paper, core samples of five main sedimentary microfacies were drilled from the UGS in middle China. The mechanical properties with different conditions of the moisture content in multi‐cycling injection–production process were tested. The critical drawdown pressure (CDP) calculation methods for the UGS were established based on the stress analysis near the wellbore and the Mogi–Coulomb criterion. Adopting the finite element method simulation on the geological model of the target UGS, the geo‐stress of the formation was calculated by inversed analysis and validated based on the Kaiser effect of rock. Then, the CDP of two target wells of the UGS were investigated. The effects of the water moisture and the cycling times of the injection–production process on the CDP were also analyzed. The geo‐stress distribution shows that the horizontal maximum principal stress ranges from 53 to 68 MPa, and the horizontal minimum principal stress is 46–58 MPa in the target reservoir section, and the vertical minimum principal stress is 69–77 MPa in the target reservoir. The calculated CDP changed with the types of the sedimentary microfacies in the range of [6.27, 8.77] MPa, in which the CDP of the mixed mud and sand flat sedimentary facies was the lowest. The weakness of the CDP with the increasing of the moisture content and the cycling times were analyzed quantitively. [ABSTRACT FROM AUTHOR]

Highlights This paper presents a comprehensive study on anisotropic heat transmission behaviors in quartz fiber fabrics. Considering the random distribution characteristic of fibers within the yarn, an innovative two‐scale finite element method (tFEM) is introduced, incorporating multiple micro‐scale fiber models (MMFM) based on scanning electron microscope (SEM) observations. MMFM are divided into 8 distinct models to capture intricate fiber arrangements. The macro‐scale fabric model is constructed based on the geometric structure analysis by Micro‐CT technology. Both micro‐ and macro‐scale models are assembled with the air matrix to form the two‐phase composite model. The Hot‐Disk thermal analysis instrument is applied to measure the anisotropic thermal conductivity (ATC). Numerical results from MMFM shows more excellent agreements with the experimental ones at 3D orthogonal directions of fabrics, i.e., the error rates of the thermal conductivity in the warp, weft and thickness directions between numerical and experimental methods are all less than 3%, which indicates the tFEM including MMFM in this paper is more accurate than the tFEM including OSMFM. In addition, the temperature distribution and heat transmission differences due to fiber arrangements are simulated and illustrated through the MMFM. Afterwards, temperature drop and isothermal characteristics are demonstrated in this study. Effects of fiber arrangements on steady heat transfer behaviors at micro‐scale are illustrated. Isothermal and temperature‐drop characteristics at micro‐ and macro‐scale are simulated and studied. The transverse isotropy of thermal conductivity at micro‐scale and the anisotropy of that at macro‐scale are revealed. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive analysis, electromagnetic evaluation, and prototyping of a novel motor structure called the sinusoidal rotor switched reluctance motor. In this innovative design, a significant departure from the conventional switched reluctance motor is observed, as modifications are made to the rotor with the goal of reduction torque ripple and radial force characteristics. Importantly, despite these advancements, the proposed motor retains the weight and volume characteristics of the traditional, type. The key attributes of these motors have been thoroughly assessed using the three‐dimensional finite element method, complemented by a sensitivity analysis aimed at identifying the most optimal configuration within the proposed design. The findings reveal that the suggested structure successfully achieves a notable reduction in torque ripple and radial force when compared to the traditional counterpart, albeit with an expected reduction in average torque. These features render the new topology particularly well‐suited for applications that prioritise noise and vibration reduction. Furthermore, the effectiveness of the proposed topology is corroborated through experimental tests, providing empirical evidence of its advantages and potential for practical applications. [ABSTRACT FROM AUTHOR]

Summary: The material point method is a versatile technique which can be used to solve various types of solid mechanics problems, especially those involving large deformations. However, the capability of the material point method to track a load‐displacement response can deteriorate once a limit point, such as snap‐through or snap‐back, in the response is encountered. One way of overcoming this is to use path following techniques, such as an arc‐length method. This technique is well established in finite element analysis but not within any material point method formulation. This paper provides for the first time an arc‐length controlled implicit, quasi‐static material point method. The modifications to the standard arc‐length scheme to allow for the stable execution of an arc‐length solver within the material point method are detailed. The capability of the material point‐based arc‐length method is demonstrated through a number of problems, which include linear elastic, non‐linear elastic, linear elastic‐perfectly plastic and linear elastic‐plastic softening material behaviour under large deformations. The techniques presented in this paper are essential for arc‐length techniques to be applied effectively to the material point method and the combination of these techniques makes the method suitable for new problems that cannot be solved with existing implicit material point approaches. [ABSTRACT FROM AUTHOR]

In this paper, the effects of Maxwell nanoliquid transmission with MWCNT nanotube are investigated over two circular wires with opposite currents and a stretching sheet. The innovation of this paper is the examination of MWCNT nanotube temperature and nanofluid velocity and also magnetic potential and magnetic effect in the three different places of two circular wires on the sheet. The finite element method is utilized for calculating differential equations. By increasing the distance from two wires on the stretching sheet, the amount of MWCNT nanotube temperature increased, and a large vortex forms at the bottom of the sheet. Overall, the MWCNT nanotube velocity around the two circular wires at the beginning of the sheet is 46.09% higher than the middle of the sheet and 20% higher than the end of the sheet, also the MWCNT nanotube magnetic potential around the two circular wires at the beginning of the sheet is 13.40% higher than the middle of the sheet and 23% higher than the end of the sheet. The second part of the essay relates to the using response surface methodology (RSM) method in the Design‐Expert software. Based on the results obtained from the MWCNT nanotube velocity graphs and the heat transfer cantors, and magnetism effects in the Design‐Expert software, the best optimization occurred for u = 0.07, T = 1.15, and H = 4.531. [ABSTRACT FROM AUTHOR]

Numerous studies have shown that highly strain‐rate dependent behavior is present in the mechanical properties of Hydroxyl‐terminated polybutadiene(HTPB)propellants, and many experts and scholars have attempted to develop constitutive models to describe such rate‐dependent properties of propellants. From the linear viscoelastic model to the Zhu‐Wang‐Tang model, the strain‐rate dependent properties of viscoelastic materials have been described to some extent. But due to the highly nonlinear mechanical behavior exhibited in propellant materials, the nonlinear behavior of propellants at different strain rates is difficult to be captured in the above constitutive models which are all based on linear elasticity. Therefore, in this paper, a nonlinear viscoelastic constitutive model was proposed based on the parallel rheological framework, in which the hyperelastic and viscoelastic flow laws were embedded. Because of the excellent ability to capture the nonlinear behavior of the material, the parallel rheological framework was used to predict the mechanical response at six sets of experiments with different rates. Surprisingly, this constitutive structure model performed good prediction of the mechanical properties of the material by comparison between theoretical calculations and experimental data. The constitutive model was verified by finite element method with numerical simulation software, and the robustness of the constitutive model was checked by a new set of experimental data. A good foundation was established for the accurate description of the propellant constitutive model strain‐rate dependent characteristics by the results of this paper, which could provide a new method for the rapid prediction and evaluation of the propellant mechanical response. [ABSTRACT FROM AUTHOR]

Based on a recent review on blind bolted connections to concrete‐filled steel tubes, there is a need to improve the performance of anchored blind bolts in such composite connections. This paper presents a study on the pull‐out behavior of anchored blind bolts under applied tensile load in terms of stiffness, yield strength, ultimate strength and load‐displacement response. A finite element (FE) model with concrete damage plasticity model was developed for parametric study. Effects of key parameters, such as concrete strength, bolt grade, embedment length, tube thickness and tube grade, on the tensile behavior of the connection were studied to identify the key parameters influencing the behavior. Finally, a predictive model based on component method was proposed to estimate the structural behavior of the blind‐bolted connections. [ABSTRACT FROM AUTHOR]

The building sector is actively researching and reviewing technical solutions for de‐construction, driven by the increasing importance of sustainability requirements, as outlined in the EU Commission's 'Green Deal,' which aims to achieve net‐zero greenhouse gas emissions by 2050. Two key research areas in efficient structural design strategies are the performance of hybrid structures, which combine mechanical properties and architectural appearance of different materials, and the techniques and mechanical properties of connections between structural components that enable deconstruction and reuse. However, there is a scarcity of studies and methods focused on demountable and hybrid structural systems, limiting the understanding of their overall structural performance at a real‐structure floor level. In this paper, a finite element model is presented to conduct a comparative study between the traditional floor system with welded stud connections and the demountable floor system with coupler‐embedded bolted connectors. The numerical results showed that the serviceability loading capacity of the demountable floor system was 8% lower, and the difference in ultimate resistance was further enlarged. Reusing a demountable floor system, analysed in the case study, had little effect on the ultimate resistance, but it is difficult to exclude local plastic deformation after the first life cycles. [ABSTRACT FROM AUTHOR]

The work reported in the present paper is part of a European research program aimed at developing a hybrid tension‐leg floating platform, suitable for combined offshore wind and wave energy exploitation. Eight (8) fatigue tests on welded tubular joint specimens are performed, which represent the full penetration brace‐to‐cylindrical column welded connections of the project prototype structure. The large‐diameter columns are reinforced internally with a grid of longitudinal and transverse stiffeners fillet welded to the shell. The specimens are approximately 1/6‐scale physical models made of S355 grade steel, and subjected to cyclic loading under constant load amplitude histories. The brace‐to‐cylinder welds are semiautomatic, and high‐frequency mechanical impact treatment is applied in four specimens. The experiments are supported by post‐fracture metallographic examination and finite element analyses. The results indicate two locations for fatigue crack initiation: brace‐to‐cylinder crown and cylinder‐to‐stiffener connection. [ABSTRACT FROM AUTHOR]

As a joints play a significant role in load transfer both in persistent and accidental situation an attempt to improve structural robustness under column loss situation was made. Based on previously conducted experimental tests of bolted double side steel end‐plate joints and numerical analysis a development to increase load‐capacity and rotational capacity of joints under column loss scenario was presented. Finite element method using Abaqus software with 3D numerical models were employed. Validated and complex models with geometrical and material non‐linearity with fracture simulation were applied. The application of additional double rings to bolted steel flush end‐plate joint lead to significant increase of load‐capacity and rotational‐capacity. The change of failure mode of joint were also obtained compared to the original specimen. [ABSTRACT FROM AUTHOR]

Assessment of the structural behaviour of steel and steel‐concrete composite plate girders exposed to web shear buckling is essential when it comes to their implementation involving heavy loads and/or long spans. In this paper, numerical model of a benchmark steel‐concrete composite girder capable of capturing this phenomenon has been developed using the ABAQUS software. The developed finite element model, based on a series of large‐scale girders planned to be tested in the future, has been evaluated and elaborated on. That includes the implementation of appropriate analysis procedures, element types and contact behaviour in the study of the post‐critical buckling behaviour of steel and steel‐concrete composite plate girders. The advantages and disadvantages as well as recommendations for the future use of the investigated modelling strategies have been scrutinized. In the end, this study demonstrates the parameters with the most significant influence on the structural behaviour of composite girders exposed to shear loading. [ABSTRACT FROM AUTHOR]

The design of joints of steel frames is often simplified, assuming that they have a fully rigid or ideally pinned behaviour. This wrong assumption is sometimes acquiesced by national technical codes, which mainly focus on the behaviour of simple connections and neglect the role of the joints in terms of global structural behaviour, particularly under lateral loads. In this paper, a numerical study about the evaluation of the influence of partial‐strength/semi‐rigid joints on the seismic performance of one‐storey steel buildings is presented. For this purpose, a population of real steel buildings has been considered, for which column bases and/or beam‐to‐column joints were originally designed as infinitely resistant/rigid restraints, but that, after the application of the component method, were found to be characterized by a partial‐strength/semi‐rigid behaviour. Finite element models of the examined buildings were developed, assuming both the theoretical and the actual joint behaviour. Fragility curves were constructed through nonlinear dynamic analyses, so to evaluate the seismic vulnerability of the structures and assess whether they need joint reinforcement, or, otherwise, if they already ensure adequate seismic safety. [ABSTRACT FROM AUTHOR]

Rotate vector (RV) reducers have advantages of high torque ratio, and extremely reliable functioning under dynamic load conditions, and so forth, and they are extensively used in precision transmissions, such as industrial robots. The torsional stiffness of RV reducers is a main parameter affecting the meshing vibration and transmission performance. In addition, the variable loads and tooth modifications have significant influence on the torsional stiffness of RV reducers. In this paper, a new method of calculating torsional stiffness for RV reducers considering variable loads and tooth modifications is presented. The dynamic stress and deformation of meshing teeth are calculated based on Hertz formulation, and the number of meshing teeth is determined by analyzing the dynamic stress of meshing teeth. Then, the torsional stiffness of RV reducers is obtained. Finite element method is applied to calculate the deformation of cycloidal‐pin gear in the maximum force position δmax. The influence of variable applied loads and different tooth modifications of cycloidal‐pin gear transmission on torsional stiffness are also studied. The results show that variable applied loads and different tooth modifications influence the torsional stiffness of RV reducers by changing teeth deformation and clearance, respectively. [ABSTRACT FROM AUTHOR]

This paper aims to develop a numerical methodology to investigate the penetration process of nanoneedles into cells and the corresponding force and indentation length. The finite element approach via the explicit dynamic method handles convergence difficulties in the nonlinear phenomenon. The cell is modeled as an isotropic elastic hemiellipsoidal shell with a thickness of 200 nm, which represents the lipid membrane and actin cortex, encapsulating cytoplasm that is regarded as an Eulerian body because of its fluid‐type behavior. Nanoneedles with diameters 400, 200, and 50 nm are considered for model development based on available experimental data. The Von Mises strain failure criterion is used for rupture detection. A parameter study using 1, 2.5, 5, 7.5, and 10 kPa shows that Young's modulus of the HeLa cell membrane is about 5 kPa. Moreover, a failure strain of 1.2 chosen among 0.2, 0.4, 0.6, 0.8, 1, and 1.2 matches best the experimental data. In addition, a diameter study shows that the relations between force‐diameter and indentation length‐diameter are linear and polynomial, respectively. Furthermore, regarding the experimental data and by using contour of minimum principal stress around needle and an analytical equation for calculation of buckling force of a woven fabric, we proposed that for a given cell, membrane structural stability—a function of the coupled effect of Young's modulus and actin meshwork size—contributes directly to needle insertion success rate for that type of cell. [ABSTRACT FROM AUTHOR]

To solve the problems mechanically caused by parallel direct‐drive permanent magnet motors (DD‐PMSM). This paper proposes a concave‐core stator direct‐drive permanent magnet motor (CCSDD‐PMSM) structure. In this study, an auxiliary yoke structure is proposed to optimise the magnetic circuit and analyse the cogging torque to achieve the minimum detent force. Based on the unit motor and combined with the magnetomotive force to analyse the symmetry of different winding distributions, the stability characteristics of the motor are studied. The magnetic field distribution of the motor load air gap is calculated using the finite element method. The contribution of different spatial order harmonics to the motor output torque is calculated using the Maxwell tensor method. The torque calculation expression of the CCSDD‐PMSM is given. Finally, an experimental prototype is made to verify the accuracy of the analysis in this paper. [ABSTRACT FROM AUTHOR]

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A series of pull‐out tests were conducted on semi‐grouting sleeve and steel bar connections to investigate the mechanical behavior of the connectors. Taking the steel bar diameter, anchorage length, and grouting material strength as the parameters. The test results showed that when the anchorage length was small and the grouting material strength was low, sufficient anchorage strength cannot be provided, specimens were subjected to bond slip failure, which belongs to the brittle failure. When the anchorage strength between the steel bar and the grouting material was sufficient, the steel bar breaking occurred on the specimens, which belongs to the ductile failure. Then, the semi‐grouting sleeve and steel bar connection was modeled by finite element software, and the bond slip between the steel bar and grouting material was simulated by COMBIN39 element. The results indicated that the failure mode of the specimen obtained by finite element simulation was the same as the test result. The ultimate bearing capacity of the specimen was highly similar to the test result, which verified the feasibility of the modeling method in this paper. Next, the number of specimens and parameter levels were increased through finite element modeling, and the influences of steel bar diameter, anchorage strength, and grouting material strength on the ultimate bearing capacity of semi‐grouting sleeve and steel bar connections were analyzed. The results testified that the ultimate bearing capacity of the specimen increased with the increase of steel bar diameter. In a certain range, the ultimate bearing capacity of the specimen increased with the raising of anchorage length and grouting material strength. While the anchorage length increased, the ultimate bearing capacity of the specimen did not necessarily increase because of the uneven distribution of stress. The steel bar diameter had the most significant influence on the ultimate bearing capacity of the specimen, while the grouting material strength had the most negligible impact, that was, increasing the steel bar diameter is the most effective method to improve the ultimate bearing capacity of the specimen. Finally, according to the results of finite element analysis, the calculation method of ultimate bearing capacity with different failure modes was obtained, and it has been proved to be effective and accurate by the comparison of calculated results and test results. The results of this paper have great significance for improving the calculation theory and design method of relevant engineering. [ABSTRACT FROM AUTHOR]

As a non‐destructive inspection method, micro‐computed tomography has been employed for determining local properties of a cellulose‐based product, specifically pressboard. Furthermore, by utilizing the determined properties in a detailed numerical model, by means of a finite element analysis, we demonstrate a continuum anisotropic viscoelastic‐viscoplastic model. Through such a combination of non‐invasive experiments with accurate computations in mechanics, we attain a better understanding of materials and its structural integrity at a pre‐production stage increasing the success of the first prototype. In detail, this combination of micro‐computed tomography and finite element analysis improves accuracy in predicting materials response by taking into account the local material variations. Specifically, we have performed indentation tests and scanned the internal structure of the specimen for analysing the densification patterns within the material. Subsequently, we have used a developed material model for predicting the response of material to indentation. We have computed the indentation test itself by simulating the mechanical response of high‐density cellulose‐based materials. In the end, we have observed that pressboard, having initially a heterogeneous density distribution through the thickness, shows a shift in the densification to the more porous part after indentation. The densification maps of the simulated results are presented by comparing with the experimental results. A reasonable agreement is observed between the experimental and the simulated densifications patterns, which suggests that the proposed methodology can be used to predict densification also for other fibre‐based materials during manufacturing or in service loading. [ABSTRACT FROM AUTHOR]

During the multistage fracturing of shale gas horizontal wells, casing damage frequently occurs, making it essential to evaluate casing stress and deformation. This paper establishes a mathematical model of thermo‐hydro‐mechanical coupling and a finite element model of casing‐cement sheath‐formation (CCF). This paper examines the effects of temperature, casing thickness, nonuniform in situ stress, mechanical properties of cement sheath, and treating pressure on the stress and deformation of CCF. Finally, the study investigates the variation of local in situ stress at the heel and casing stress from toe to heel. The results show that the low temperature of CCF, high elastic modulus of cement sheath, small casing thickness, high treating pressure, and large nonuniform in situ stress can exacerbate casing stress. After pumping off, the local in situ stress and its nonuniformity near heel gradually increased, and the effective stress of casing increases compared with the pumping on the process. As the fracturing stages increase, the effective stress of casing at heel increases, and the casing at heel preferentially damages. The results provide a theoretical basis and guidance for maintaining wellbore integrity and preventing casing damage in the multistage fracturing of shale gas horizontal wells. [ABSTRACT FROM AUTHOR]

The mismatching constraint effect on crack propagation through the heat‐affected zone (HAZ) in a welded joint is presented in this paper. It is shown that due to this effect, the fracture behavior of an overmatched welded joint depends on the mechanical properties and the size of the region of the crack tip location, as well as on the properties and the size of surrounding regions. The finite element analysis of high‐strength low‐alloyed (HSLA) steel welded joints with crack tips in the heat‐affected zone is performed based on previous experimental work. Two locations of the crack tip are analyzed: fine‐grained HAZ (FGHAZ) and coarse‐grained HAZ (CGHAZ). In both cases, after the initial propagation of the crack in FGHAZ or CGHAZ, its propagation is directed toward more ductile base metal, thus increasing the fracture resistance of a welded joint. Some new observations about the reasons for such behavior due to crack tip strain fields are presented as well. Highlights: The behavior of the crack with the tip located in fine‐grained heat‐affected zone (FGHAZ) is under the significant influence of adjacent coarse‐grained HAZ (CGHAZ) and WM.Strain at the crack tip in CGHAZ is absorbed by more ductile regions, causing more favorable stress conditions.In both cases, overmatching changed the crack propagating direction toward weaker and more ductile base metal (BM). [ABSTRACT FROM AUTHOR]

In curved liquid crystal display, the glass substrate is in the state of bending, and the bending stress is generated inside the glass. Under the effect of stress photoelastic effect, the display will produce light leakage, which is called stress‐Mura. Based on the theory of stress photoelasticity and the finite element analysis of panel forming, this paper deduces the light leakage intensity of curved LCD (liquid crystal display) by using the Jones matrix, and puts forward a scheme to improve the design of curved curvature of LCD, which is verified by experiments. [ABSTRACT FROM AUTHOR]

This paper focuses on the Y type perfobond shear connectors of steel‐concrete composite beams with the aim to investigate the influence of the structural parameter of the connection to the resistance and ductility of the structures. The Y shaped shear connections are a new shape developed with the benefits of resisting a higher shear force by the transversal bars and a bigger area of the concrete dowels surrounded by the Y shaped plate. This type of shear connection has significant resistance against vertical separation. In this paper, an advanced finite element model for a push‐out test with a Y type perfobond shear connector has been developed and validated by the experimental test. The aim of this research is to investigate different parameters such as the concrete strength, perfobond yield stress, the existence of the transversal bars on the structural behavior. The results showed that the concrete strength has a major effect as using a higher concrete resistance gave a higher ultimate resistance with a higher ductility. The existence of the transverse bars shows a major effect on the ductility load level. On the contrary, the effect of changing the diameter of the bars on the ductility load level was slightly noticeable. While using deferent steel grades for the perfobond plate significantly affected the ultimate resistance, but not the ductility load level. In further studies more parameters will be checked, and a formula and a guideline could be developed for a design purpose. [ABSTRACT FROM AUTHOR]

Acknowledging the potential of system‐based design approaches, most international design standards for steel structures include preliminary versions of such alternative design methods. The Direct Design Method (DDM) is one of these approaches, which allows designing steel structures directly using advanced numerical analyses without requiring further member checks. This paper presents the DDM design (and verification) procedure and summarizes the key aspects of the advanced finite element model necessary for the determination of the system strength, with an emphasis on cold‐formed stainless steel portal frames. Through the design of two frames, the DDM design procedure is illustrated and the resulting cross‐sections are compared with those derived using the traditional two‐step design approach in the Eurocode and ASCE design frameworks. The results demonstrate that the DDM verification process is simpler and more direct, and that lighter structures are obtained when designing using the DDM for strength considerations. Finally, this paper also highlights that allowing larger deformations in the ultimate limit state design for the DDM does not have additional negative effects on the serviceability requirements if compared to the traditional two‐step design approach. [ABSTRACT FROM AUTHOR]

One of the benefits of using corrugated web girders is the increase of lateral‐torsional buckling resistance. Different approaches have been presented to obtain the value of the critical moment as a function of the cross‐section geometry. Previous research works consider that the increase in buckling resistance must be accredited to a higher warping constant. The paper presents a systematic finite element numerical analysis of girders with different corrugated web shapes. Bending with respect to the weak axis shows that corrugated web implies higher moment of inertia. Torsion analysis results clearly demonstrate that the increase of torsion resistance is mainly due to higher torsional constant. The paper compares the elastic critical moment values obtained by using finite element elastic buckling analysis with the values provided by theoretical expressions introducing equivalent section properties. Results show that the equivalent section properties approach provides values very close to those obtained using finite elements. Finally, the paper presents closed form expressions to directly compute approximate equivalent section properties of any girder with corrugated web, which compare very satisfactory with those values obtained with finite element buckling analysis. [ABSTRACT FROM AUTHOR]

Flexible OLED displays have become a development trend. CPI film in a flexible panel can improve the bending performance of the panel. However, CPI film is prone to plastic deformation in the bending process, which will affect the reliability and service life of OLED panel. Finite element analysis is employed in this paper to analyze how CPI film affects the bending performance of a flexible OLED panel. The simulation results show that the optimization of the structure of water‐drop‐shaped bending can improve the plastic deformation of CPI film. The reasonable position of CPI film in the stacked structure can also improve its plastic deformation. The increase of the thickness of the OCA located below the CPI film can significantly reduce its plastic deformation. The analysis method used in this paper can help improve the bending performance of a flexible OLED panel. [ABSTRACT FROM AUTHOR]