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The clamp plays a vital role in supporting and suppressing vibration in pipeline systems. The vibration stress analysis of clamps is an essential basis for evaluating the strength of clamps, which is crucial for ensuring the safety and stability of the aero-engine pipeline system. However, there is a lack of relevant research to analyze the vibration response of the clamp. To make up for this defect, the precise modeling and vibration stress analysis of the clamp are carried out in this article. First, simulation and experimental testing are conducted on a bracket-clamp-additional mass system under the base excitation. The maximum stress errors of simulation and experiment under the excitation of sweep-frequency and fixed-frequency are 6.64% and 23.16%, respectively. Then, the influence of different excitation amplitude and additional masses on the surface stress of the clamp is analyzed. It is found that the surface stress of the clamp increases with the increase of the additional mass, and the effect of excitation amplitude on the surface stress of the clamp has a linear law. The simulation and experiment work in this article provides a deeper insight into the physical understanding for the design of clamp-pipeline system, and the precise clamp modeling idea proposed can also be extended to other specifications of engine clamp modeling. [ABSTRACT FROM AUTHOR]

Skin cancer is a significant global health concern, with increasing incidence rates and a high number of deaths each year. Early detection plays a crucial role in improving survival rates, but current screening methods, such as total body skin examination, often lead to unnecessary invasive excisions. This research aims to explore the use of dynamic infrared thermography (DIRT) in combination with other technologies to potentially eliminate the need for biopsies in the future and gather information about the stage or depth of malignant skin lesions. The study involves data acquisition using a thermal camera and a finite element skin model. The FEM skin model employed in this research follows the commonly used five-layer model and is constructed in Siemens Simcenter 3D to be able to simulate the cryogenic cooling on the skin. It is possible to improve the thermal images by choosing an appropriate cooling method, cooling sequence and optimised measurement setup. While the FEM skin model shares certain similarities with the measurement data, there is room for further enhancements to optimise its performance. The acquired data is analysed to assess the effectiveness of the combined technique compared to existing clinical and diagnostic methods. [ABSTRACT FROM AUTHOR]

To meet the needs for higher-ranked roads and traffic loads, rigid slab pavements with cement-bound bedding material and joints were analysed instead of the traditionally used unbound construction method. Since the bearing capacity and drainage of the upper base course are essential, the results of recently introduced laboratory fatigue tests for permeable concrete were considered. Additionally, fatigue tests were also conducted on concrete and natural stone slabs. The structural response of the superstructure was determined by introducing an finite-element-model that considers bound behaviour in the joints and between the slab-bedding-interface. With the derived fatigue criterions and the structural primary response of the FE Model, the deterioration under traffic load can be evaluated. The main objective of this paper is the development of a design procedure for slab pavements with cement-bound joints and bedding on a pervious concrete base course to deduce suitable standard structures in accordance with Austrian directives. [ABSTRACT FROM AUTHOR]

AbstractThe purpose of this article is to establish mathematical model for an early detection method of polyethylene pipe damage using linear guided waves and then perform a digital analysis to determine the efficiency of the technique in identifying different defects in pipeline materials. This method enhances the reliability of engineering pipeline infrastructures for both industrial and life-support purposes while also enabling the prevention of critical incidents such as ruptures, punctures, fissures, fatigue, and other events that may result in the release of transported agents into the surrounding environment. [ABSTRACT FROM AUTHOR]

This paper deals with the application of a generalised analytical continuum foundation model recently proposed by the senior author to the dynamic analysis of beams. Specifically, analytical and numerical solutions of the problem of the free vibration of a beam on an equivalent two-parameter model and a simplified Winkler-type model are presented. In the two-parameter representation, a novel approach is used in which the shear parameter is taken care of by moving it from the soil-beam interface to the beam proper in the form of a geometric stiffness so that it serves as an enhancement to the conventional elastic beam stiffness. By doing so, the familiar Winkler support is maintained while the shear interaction among the springs is realised at the same time. Additional end springs are introduced to account for the shear continuity extending beyond the ends. The analytical and numerical results are compared with those obtained from the finite element software, Abaqus, by means of which the calibration factor is determined. The model is validated using measured data from the literature. The results are also compared with other existing models. Both the single- and two-parameter variants of the model performed remarkably well, especially the two-parameter variant. [ABSTRACT FROM AUTHOR]

The paper investigates the stress–strain state of a thin-walled deployable N-shaped composite boom during elastic folding. A finite element model using ANSYS 2021 R2 software (explicit formulation) is developed, considering boundary conditions, loads, and analysis parameters. Numerical calculations are performed for various cylindrical mandrel radii, revealing a strong dependence on maximum stress on the mandrel radius. Results indicate reliable folding without damage for a mandrel radius of 20 mm or more. This study solves the complex problem of modeling elastic folding, providing essential information for engineers to achieve an optimal design. [ABSTRACT FROM AUTHOR]

Armor steel is widely used for ballistic resistance in military infrastructures and vehicles. However, the high areal density of monolithic steel plates presents challenges in balancing protection and maneuverability. This study focuses on a novel armor design, invented by the authors: An N-shaped perforated armor plate (NPAP). The NPAP consists of a perforated plate, an inclined plate, and a back plate. A validated finite element (FE) model was used to analyze the dynamic damage behavior of the NPAP target and projectile under ballistic impact. Numerical simulation revealed that the NPAP target combined the edge and obliquity effects, resulting in asymmetric interaction and causing yaw and fracture of the projectile. The kinetic energy of the steel core after penetrating the NPAP target decreased by 84.7–88.0% compared to the initial kinetic energy. The NPAP target showed a 20.7–43.9% lower residual depth of penetration (RDOP) compared to the monolithic target. Furthermore, the effects of the dip angle of the inclined plate and plate thickness configurations on the ballistic performance of NPAP were examined. The results indicated that the NPAP target's ballistic performance is more susceptible to the impact location on the perforated plate with a larger dip angle of the inclined plate. Additionally, the NPAP target with a thin perforated plate and a thick back plate configuration exhibited better ballistic performance, given the constant thickness of the inclined plate. [ABSTRACT FROM AUTHOR]

The present study introduces a one-dimensional finite element (FE) model that utilizes third-order deformation kinematics to analyze the flexural vibration of two-layered composite beams with partial shear slip. The proposed model incorporates a three-node straight beam element, utilizing the field-consistent approach and full numerical integration of the stiffness matrix. This approach is adopted to effectively address stress oscillation and shear locking issues, ensuring accurate and reliable results. The analysis focuses on the third-order deformation kinematics of longitudinal displacement within the beam depth, examining each of the two layers individually. The interface between the two material layers is joined using deformable shear connectors, which are represented as dispersed shear springs over the length of the beam. This study focuses on conducting a flexural vibration analysis of two-layered composite beams. The analysis includes the examination of both free vibration and forced vibration responses while considering or omitting the influence of damping under various loading conditions. The validity of the proposed FE model is assessed by the utilization of a two-dimensional model developed within the ABAQUS software. Additionally, the suggested model is evaluated through the process of verification by comparing it with previously published results. [ABSTRACT FROM AUTHOR]

The high-velocity penetration impact characteristics of fiber metal hybrid (FMH) cylindrical shells are investigated. A finite element (FE) model of such a shell subjected to an internal high-velocity projectile impact is established based on ABAQUS software to predict impact parameters, in which the impact damage failures of FRP, metal, and virtual cohesive layers are considered, respectively. Both literature and experimental results are utilized to verify the current model, with the influences of critical parameters on the residual velocity and specific energy absorption properties being discussed. The outputs provide valuable references for evaluating the high-velocity impact resistance of such structures. [ABSTRACT FROM AUTHOR]

A micromechanical model implemented with the finite element method (FEM) using the representative volume element (RVE) approach is developed to investigate the creep compliance behavior of carbon nanotube (CNT)-polymer nanocomposites. Effects of the CNT waviness, orientation, volume fraction and aspect ratio on the creep compliance of the nanocomposite are examined. Contribution of the interphase region formed due to the interaction between CNTs and matrix to the nanocomposite creep behavior is considered. The nanocomposite creep behavior is affiliate on the waviness and orientation of CNTs. Increasing the volume fraction and length of CNT and interphase thickness improves the nanocomposite creep performance. [ABSTRACT FROM AUTHOR]

The conventional British pendulum tester (BPT) utilises a cuboid rubber slider and measures the skid resistance between its front slider edge and a test surface. This standard test method is known to produce erroneous skid resistance measurements on grooved pavements, owing to impacts between the straight slider edge of BPT and the vertical walls of pavement grooves. To overcome the problem, this study replaced the cuboid slider with a curved slider having an external radius of 100 mm, constructed of the same rubber material as the standard BPT rubber slider. The ability of the proposed improved device to eliminate the vertical-wall impact problem and provide correct skid resistance measurements of a grooved surface was verified experimentally and numerically. A full-scale prototype was fabricated for this purpose. Experimental validation tests involving the standard cuboid-slider BPT and the curved-slider BPT were conducted, and the test results were analysed with the aid of finite-element numerical models. The results confirmed that the proposed curved-slider BPT can provide more consistent and accurate skid resistance measurements compared to the standard BPT, for both grooved and ungrooved pavements. [ABSTRACT FROM AUTHOR]

Void beneath the slab corner as a significant problem of airport pavement maintenance is always paid more attention by airport operators. The objective of this paper is to establish neural network models to predict the void sizes and load position based on the monitored strain values. A finite element model was established and validated by the data collected from a full-scale test pavement. Pavement strain values of 3168 scenarios considering different pavement structure parameters, load positions and void sizes were calculated. The simulated bottom strains at concrete pavement slabs were analysed for different void sizes and loading conditions. A coefficient and its warning thresholds were proposed to predict the occurrence of voids. Then, two Genetic Algorithm Backpropagation (GA-BP) neural network models were developed to predict void sizes and load position using the numerical simulation results as the training dataset. [ABSTRACT FROM AUTHOR]

This study addressed the issue of distortion in evaluating the seismic damage state of railway bridge piers using the original Park-Ang damage index. By constructing a parameterized co-simulation program with two finite element models, OpenSees and Abaqus, five sets of flexural failure and five sets of flexural-shear failure rectangular pier quasi-static test results were selected to validate the rationality of the calculation program. Four hundred and eighty parameterized calculations were conducted using this program. The combination coefficient β and critical damage index DI within the Park-Ang damage index were modified using nonlinear regression algorithm and convolutional neural network algorithm. The adaptability of the damage index calculation was ultimately verified through an engineering case study of a simply supported beam bridge. The research findings are as follows: 1) The main factor influencing β is the longitudinal reinforcement ratio, while the axial compression ratio, shear span ratio, volumetric stirrup ratio, aspect ratio, concrete strength, and steel strength are secondary parameters influencing β. 2) Compared to the nonlinear regression algorithm, the convolutional neural network algorithm can better establish a calculation model between pier structural parameters and β, clarifying their relationship. 3) It is recommended to use critical values of 0.11, 0.29, 0.49, and 1.00 for assessing pier damage as no, slight, moderate, severe, and collapse damage when using the damage index calculation model. 4) The Park-Ang index corrected by convolutional neural networks demonstrates improved accuracy and computational stability, making it suitable for practical assessment of seismic damage in bridge structures. Highlights: The original Park-Ang damage index has been modified to suit railway rectangular bridge piers. The possibility of flexural-shear failure in railway bridge piers has also been taken into consideration. In addition to the nonlinear regression algorithm, a convolutional neural network algorithm has been applied in the construction of the damage index calculation model. A simple supported beam bridge engineering case has been used to validate the applicability of the damage index calculations. [ABSTRACT FROM AUTHOR]

Anthropomorphic Test Devices (ATDs) with high biofidelity and compatibility play a crucial role in vehicle safety. This study focuses on enhancing the neck of Hybrid III finite element model by optimising its design and material. The improved Hybrid III model (IH3) is validated through neck calibration tests. Comparing to experimental results,IH3 has a peak torque error of only 1.00% and 5.11%and a 60.04% improvement in calculation efficiency. Then MLH3 with low stiffness and equivalent muscles and ligaments is designed and tested. The results of MLH3 show higher biofidelity than l than Hybrid III. Finally, both IH3 and MLH3 have been tested in a 100% frontal rigid barrier test, with IH3 showing significant accuracy and computational efficiency, indicating that it could replace the current Hybrid III neck for simulation analysis. MLH3 has potential engineering application value in the future, as it improves upon the limitations of the Hybrid III neck's biofidelity and more closely resembles the real human neck. [ABSTRACT FROM AUTHOR]

AbstractThe copper mesh provides effective lightning strike protection for composite structures, while its efficiency can be compromised in scarf-repaired composite structures. In this study, after verified by test results, a numerical analysis procedure was employed to predict the lightning ablation damage and residual bending performances of scarf-repaired composite laminates with copper mesh protection. Initially, the ablation damage and bending damage mechanisms of good repaired and poor repaired composite laminates were analyzed. Then, the impact of lightning strike attachment position and repair design parameters including overlap length and thickness of adhesive layer on the lighting protection performances was investigated. The results indicate that ablation damage of composite and adhesive materials near the repair area significantly compromises structural integrity and reduces the bending strength. The predominant bending failure mode of scarf-repaired woven composite laminates after lightning strike is fiber failure in warp direction, accompanied by small areas of matrix failure and delamination failure. The reestablishment level of the electrical path varies with overlap length and thickness of adhesive layer, subsequently affecting the ablation damage area and depth. This study can provide a reference for the design and process control of scarf-repair in copper mesh protected composite structures. [ABSTRACT FROM AUTHOR]

Metatarsalgia occurring in individuals with pes cavus is typically associated with abnormal loading patterns in the forefoot resulting from structural alterations. Simultaneously, the frequent overstress of the plantar fascia (PF) caused by the persistence of this foot deformity may further exacerbate the chronic pain induced by metatarsal overload. We aimed to investigate and quantify the effects of PF stiffness on the internal biomechanics of pes cavus using a computational modelling approach. A patient-specific finite element model of the foot-ankle complex using the actual three-dimensional geometry of idiopathic pes cavus bones and soft tissues was reconstructed. A sensitivity study was conducted to evaluate the effects of varying elastic modulus (0–700 MPa) of the PF on the metatarsal stress distribution, and force transmission through the metatarsophalangeal (MTP) and tarsometatarsal (TMT) joints in the pes cavus. The results indicated that variations in PF stiffness led to stress redistribution in the metatarsal region. Peak stress gradually reduced with decreasing stiffness until the PF was released, eventually resulting in a reduction of 22.39% compared to the reference value of 350 MPa. Furthermore, adjusting the PF stiffness to twice the reference value (700 MPa) increased the contact forces through the TMT and MTP joints by up to 23% and 116%, respectively. The reduction of PF stiffness alleviated focal metatarsal loading, and therefore, surgical fascia release can be considered to alleviate metatarsalgia in patients with pes cavus. [ABSTRACT FROM AUTHOR]

The usage of sandwich structures has been increasing in the field of defense, transportation, and aerospace applications due to the many advantages like, thickness to mass ratio, high bending stiffness, and strength. In this present work, the vibration assessment of the dual-core sandwich beam with biomimetic core and multiwalled carbon nanotube (MWCNT) reinforced composite face layers has been performed. The lamellar honeycomb (LHC) core is a biomimetic design developed here from the pistachio shell structure and manufactured by 3D printing process. The mechanical characteristics of biomimetic core are measured using an alternative dynamic technique and impulse excitation test was used to assess the material properties of MWCNT composite laminates. Using finite element software, a numerical model is created for a composite dual-core sandwich beam containing MWCNTs and a biomimetic core. The developed numerical model is validated with experimental and available literature results in terms of natural frequencies and it shows good agreements. Additionally, parametric studies are performed to investigate the natural frequencies of MWCNT composite dual-core sandwich beam with biomimetic cores for ply orientation angles, aspect ratio, and support conditions. The MWCNT reinforcement in the facesheets and LHC core enhances the structural performance and stiffness of the laminated composite dual-core sandwich beam. This research will provide the valuable insights to engineers and scientists for the construction of large capacity ships and race boat structures. [ABSTRACT FROM AUTHOR]

AbstractPorous titanium exhibits excellent mechanical properties and clarifying its dynamic deformation behavior with the rate-temperature effect can offer the significant insights for the structural design of materials. This article delves into the coupling effect of rate and temperature, as well as the local deformation mechanisms of porous titanium subjected to high-temperature and high-strain-rate conditions (−823 K and −8000/s, respectively). A dynamic balance formula for rate-temperature competition has been introduced for application in high-temperature and high-strain-rate conditions. The local relative deformation observed at the end face exceeds 300% than other regions, while the degree of end surface densification reaches 61.5%. [ABSTRACT FROM AUTHOR]

In this study, a simulation and test-based procedure is created and applied to develop mechanical pyroshock test setup. In order to build an effective design, preliminary input parameters are defined with finite element simulations. The agreement between impact simulations and experimental data was achieved for resonant plate, metallic anvil plate and gun system. The obtained Shock Response Spectrum (SRS) curves are not well fitted to explicit finite element simulations for nonmetallic anvil plate materials, such as felt, which also have significant contribution to results. Therefore, further improvement is established by using test-based Response Surface Method (RSM). After validating the relationship statistically, response optimizer was used to find the best combination of design parameters to achieve target SRS curve. Finally, the prediction was checked experimentally to show the effectiveness of the developed methodology. [ABSTRACT FROM AUTHOR]

Use of helical piles has become increasingly popular since last few decades for numerous advantages and installation convenience. They may consist of isolated helical plate welded to a central shaft or continuous screw type piles. The load transfer mechanism of helical piles is complex compared to the conventional vertical driven piles. Although limited contributions are available on the performance of helical piles including theoretical and experimental studies, still there are major scopes for further research. The authors have conducted a series of laboratory experimentations on axial load-settlement characteristics of model helical piles made of high tension steel in soft clayey soil, followed by 3D finite element analysis using ABAQUS. The numerical results were found to be close to the experimental observations. Using the numerical model, extensive parametric studies were conducted. The load-settlement response was found to be mostly logarithmic. The pile capacity was found to be influenced significantly by the pitch and embedded pile length. The FEM analysis revealed maximum plastic strain and displacement to develop adjacent to the pile-tip and the interface, while negligible at the boundaries. The interface shear stress distributions are also studied. From the entire investigation, a set of important conclusions are drawn. [ABSTRACT FROM AUTHOR]

Needled composites have stronger interlaminar properties compared to two-dimensional fiber composite structures due to the introduction of z-directional fibers in the fiber composite layup. An effective multi-scale finite element model is developed in this paper for the complex structure of needle-punched composites. Three scales, namely fRVE, pRVE, and lRVE, are modeled from the fiber scale, the delamination scale, and the laminate scale. using ABAQUS, periodic boundary conditions are applied to the RVEs at different scales to obtain the effective mechanical properties of various RVEs. Meanwhile, the effect of needling density on the needled composites is predicted by applying the above multi-scale model. The increase of needling density can enhance the out-of-plane effective mechanical properties of the composites, but it also weakens the in-plane effective mechanical properties. The maximum error of the elastic modulus calculation is 17.68% with that of the reference, thus verifying the rationality of the multi-scale model. [ABSTRACT FROM AUTHOR]

Carbon fibre reinforced polymer (CFRP) plays an increasingly important role in many fields, and the non-destructive testing (NDT) for its defects is drawing more and more attention. In this paper, a finite element model is established and the surface temperature difference between the defective and non-defective areas is selected as the characteristic quantity to systematically study the impact of three parameters, such as scanning direction, laser power and scanning speed, on the detection effect in the line laser scanning thermography NDT system. Qualitatively, the scanning direction is consistent with the carbon fibre orientation, the higher the laser power, and the slower the scanning speed is, the more favourable the defect detection. Further, the data obtained from the simulation are fitted, and the results show that the scanning speed and laser power have exponential and linear relationships with the maximum temperature difference, respectively. A related experimental system was established, the laser power was set to 7-, 10-, 13- and 15 W as well as the scanning speed to 10-,20-, 40- and 50 mm/s, to investigate the temperature variation of CFRP specimens containing artificial defects. The experimental results show that a greater laser power or lower scanning speed can obtain better defect detection compared with a smaller power or higher scanning speed. [ABSTRACT FROM AUTHOR]

For offshore perforated mudmats installed on low-permeability clay, the underneath suction force is an important component of the uplift resistance during removal and can be effectively reduced by perforation. Since the perforation may result in partial drainage of the soil, the effect of the uplift rate on the drainage condition and suction force is analysed in this study using the small strain finite element with the modified Cam Clay (MCC) model. Considering that water can stably accumulate beneath the mudmat, soft porous elastic water elements are used to simulate the interface and the compression is blocked by the proposed "equivalent thickness element". The trend of increasing and then decreasing suction force with reducing normalized extraction rate V is studied, curve fitting is provided, and the mechanism is interpreted from both element-scale and macro-scale perspectives. The effects of soil strength heterogeneity, preload, and perforation width on suction force with drainage conditions are also discussed. [ABSTRACT FROM AUTHOR]

AbstractModern helicopter rotor blades are made of composite materials. Due to the harsh service environment, the blades may be impacted by hail and other falling objects at low velocity. The damage behavior of composite rotor blades subjected to low-velocity impact is studied here. Low-velocity impact experiment is conducted on a composite helicopter rotor blade, and the impact force and the damage are measured. Based on the experiment, a finite element model is developed and validated to predict the impact damage of the blade. With the model, a parametric study is performed to investigate the effects of impact energy, impact locations, and foam core on impact responses of the composite blades. The results show that the rib is the most vulnerable part to damage, associated with severe deformation, and delamination rapid expanding under low-velocity impact. The foam crush region is close to the blade top surface below the impact point. The interface between the skin and internal part is especially sensitive to increase in impact energy. Impacts near the leading edge produce higher impact force, while impacts near the trailing edge cause large deformation and small impact force. Better impact performance will be achieved when modulus and density of the foam are increased. [ABSTRACT FROM AUTHOR]

In this paper, the spoke structure of a non-pneumatic tire is optimized. The finite element model of the spoke structure is created and structural dynamic analysis is made using ABAQUS. The optimization goal is to simultaneously reduce three characteristics of the spoke structure, the mass, vertical displacement and acceleration. Simulations are performed according to the center composite design table, and the objective function is estimated using response surface analysis (RSA), random forest regression (RFR), gradient boosting regression (GBR) and artificial neural network (ANN). The genetic algorithm is used for minimization, and the optimization results of each objective function are analyzed through verification simulation. As a result of the optimization, the error between the predicted value and the actual value is 18.6% for RSA 3.1% for RFR, 1.7% for GBR, and 15.0% for the ANN. The ANN proposes the optimum design variables which derive output values smaller than the current minimum value because the ANN properly represents the nonlinear characteristics of the spoke model generated in this study. Highlights Simulation based optimization of the spoke structure of a non-pneumatic tire Various regression models are used and their accuracy is compared A two-step genetic algorithm is used for optimization [ABSTRACT FROM AUTHOR]

AbstractThis study focuses on the mechanical properties of 316 L stainless steel lattice structures. Three types of lattice structures with varying topology cells were designed and fabricated by additive manufacturing (AM) techniques. The experimental test and numerical simulation were employed to investigate compressive response and failure mechanisms of lattice structures. The results indicate that decreasing the porosity or unit cell size of lattice structures can significantly improve mechanical performance. Furthermore, it is noted that lattice structures with face-centered cubic with(vertical) Z-struts (FCCZ) cells exhibit the highest elastic modulus, compressive strength, and energy absorption, along with distinct failure modes in comparison to other types of lattice structures. [ABSTRACT FROM AUTHOR]

Hammerhead pier is the preferred option in many bridge sites for its limited ground occupation. Since the bearing reactions act on the short cantilever ends of the cap beam, it is usually treated as stress-disturbed region (D region) in structural concrete. Although finite element model (FEM) can predict the response of such structures, the calculation efficiency will be sharply decreased once it enters nonlinearity. Therefore, strut-and-tie model (STM) has been promoted as an alternative approach for analyzing D regions. In this study, a loading pattern was defined to relate the axial force and bending moment of the pier column with the eccentric load ratio. Sectional analysis method and associated codes were developed to generate the STM. In addition, a full-scale hammerhead pier specimen subject to varying eccentric loads was tested. Besides, nonlinear FEM was also established to numerically investigate the response of the pier. The results indicate that the proposed STM has general applicability for modeling the hammerhead pier and shows better prediction than the FEM. The failure pattern of the hammerhead pier with a prefabricated cap beam was defined. Combining the mechanical analysis of STM and experimental results, the recommended design details for hammerhead piers were proposed. [ABSTRACT FROM AUTHOR]

Dance is a difficult sport, especially in modern dance and ballet, which requires dancers to complete many difficult movements and jumps. These movements place a significant load on the knee joint and have long been prone to causing knee joint damage. However, traditional dance knee protectors often have problems such as poor protection effect and discomfort due to their thickness. In order to improve the comfort and effectiveness of dance knee joint protectors, this article analyzed a high-performance ferroelectromagnetic nanocomposite material dance knee joint protector. In this paper, the preparation process and properties of ferromagnetic nanocomposites were analyzed in detail. The geometric modeling of the wrapped knee protector was established, and its mechanical properties were simulated using the finite element model. In this paper, the traditional dance knee protector and the ferromagnetic nanocomposite knee protector analyzed in this paper were tested several times respectively, and their performances in tensile strength, tensile modulus, compressive strength, compressive modulus, bending strength and flexural modulus were compared. [ABSTRACT FROM AUTHOR]

Ambient vibration measurements of a cable-stayed bridge in Taiwan were first conducted to identify its dominant modal parameters with a reliable stochastic subspace identification algorithm recently developed. A finite element model is then constructed based on the identified frequencies and shape vectors of four vertically bending, one torsional, and one horizontally bending modes. This model is also updated by adjusting the girder-pier connection with the addition of a rotational spring to reflect the actual conditions and its accuracy is demonstrated with less than 1% of error for the first two vertically bending modes. As a solid application for probing the environmental effects in structural health monitoring, the vibration measurements of 24 hours were further conducted and combined with the well calibrated model to investigate the controlling factor for its variation in modal frequencies. It is found that the frequencies of the first two vertically bending modes are closely correlated to the root-mean-square velocity representing the traffic excitation intensity. Moreover, it is shown with the updated model that the daily variations in the frequencies of the first two vertically bending modes can be reasonably simulated by modifying the coefficient of the rotational spring merely in a limited range. [ABSTRACT FROM AUTHOR]

Deterioration of bond between steel reinforcement and concrete due to corrosion significantly affects the durability, strength, and serviceability of reinforced concrete (RC) structures. This paper discusses the effects of reinforcement corrosion on the bond deterioration of RC members through cracking and tension stiffening behaviours. A series of RC members were tested under direct tensile force. A bond reduction model due to the corrosion was proposed by combining the experimental results and available data in the literature. Average widths of tensile crack on the corroded RC members were precisely estimated based on the proposed bond reduction model. Moreover, a simplified numerical model using three-dimensional non-linear finite element (FE) analysis was performed to reproduce the average response of the tensile members. A good agreement of load-concrete strain behaviour was achieved between experimental and analysis results. The constitutive model of concrete including the effect of reinforcement corrosion under tension for FE modelling was discussed. The findings demonstrate the effective evaluation of member responses deteriorated by reinforcement corrosion. Thus, the study will be valuable in improving the assessment of structural durability and performance. [ABSTRACT FROM AUTHOR]

Finite Element Model simulations are widely used to validate experimental and field observations. Out of these, modelling and comparing the stability of dams under various loading conditions presents significant challenges for researchers and practitioners, none more than the concrete-faced rockfill dams that are present in Australia (e.g. Cethana dam) and around the globe. A review shows that the construction sequence of such dams has not been incorporated in the initial configuration of concrete-faced rockfill dams. In this research, static analysis has been conducted for 2D and 3D finite element models of the Kotmale concrete-faced rockfill dam (CFRD) with and without the construction stage. Both 2D and 3D analysis of the case study dam using MIDAS FEA NX software and static analysis have been conducted. A linear elastic material model and a nonlinear material model (Duncan and Chang EB Model) were used to model the rockfill material. The resulting deformations were compared with the in-situ measurements to identify the accuracy of the developed cases. Results show that construction stage inclusion and the nonlinear material model agree well with the in-situ measurements, warranting the need for such advancements in Finite Element Analysis. Such an inclusion can model future settlement behaviour reasonably well, which can lead to the development of appropriate management measures. [ABSTRACT FROM AUTHOR]

Adjustable Ring Mode (ARM) laser technology combined with Beam Oscillation optics module was introduced to effectively enhance weld quality in joining aluminium alloys. This study developed a three-dimensional (3-D) thermo-mechanical finite element (FE) model to analyze the distribution of thermally induced residual stresses in laser-welded 3003 aluminium alloy. The accuracy of model was validated through comparisons with experimental weld cross-sections and further reinforced by X-ray diffraction residual stress measurements. The transient temperature field and stress distribution during the welding process were investigated using the verified model. Additionally, the hardness and microstructure of the welded samples were examined through micro-hardness tests and scanning electron microscopy. Results showed that welding with beam oscillation resulted in less penetration but higher hardness and finer columnar grain size in the fusion zone. Additionally, the influence of varying standoff distances between two sequential weld beads on residual stress distribution was investigated. Numerical findings revealed that higher residual stress concentrations were located at the weld seam and dominated by tensile longitudinal residual stress and compressive transverse residual stress. As the distance between weld beads increased, transverse and equivalent residual stresses decreased, while longitudinal residual stress away from the bead increased. [ABSTRACT FROM AUTHOR]

The addition of a stainless steel wire mesh (SSWM) at the bottom of ultra-high performance concrete (UHPC) was proposed for improving the flexural strength of UHPC and solving the problem of low initial cracking performance. A method combining experiments and numerical simulations was used to study the ability of the SSWM to enhance the flexural strength of UHPC and evaluate its cracking resistance. The wire diameter, mesh size, number of steel wire mesh layers, and length of the SSWM were the geometric parameters considered in the experiments. The experimental results showed that the flexural strength of UHPC is improved by SSWM, and the load–deflection curve, ductility, strain distribution, and failure mode of UHPC were assessed. The flexural strength and failure modes of UHPC were evaluated accurately using a numerical model. The wire diameter, mesh size, number of steel wire mesh layers, and wire mesh length parameters were analyzed using the model. The relationship between the flexural strength and the geometric parameters was obtained through an in-depth study of the parameter analysis results using multiple linear regression. [ABSTRACT FROM AUTHOR]

The purpose of this study is to study the applicability of Discrete Ply Modeling (DPM) to crushing of composite tubes and to study the effect of stacking sequence and trigger geometry on the Specific Energy Absorption (SEA). The model was first validated with experimental results after which various stacking sequences were simulated to optimize it with an aim to increase the SEA. The stacking sequence [90/02/90/03/90/0/90] performed the best in terms of SEA value. As a result, the confidence of the DPM has been proven for some draping sequences but seems to be less confident to simulate the trigger effect. [ABSTRACT FROM AUTHOR]

This study investigates the deformation and stability of shored mechanically stabilized earth (SMSE) walls using numerical analysis. A finite element (FE) model is developed in Plaxis, and parametric sensitivity analysis is conducted to identify the most influential input parameters on the maximum lateral facing displacements of the mechanically stabilized earth (MSE) and soil nail (SN) walls and global factor of safety (FS) of the SMSE wall. Predictive equations are developed for these responses using multiple linear regression. The suitability and adequacy of the developed predictive equations are assessed by evaluating the summary of fit statistics. It is observed that the governing failure mechanism of the SMSE wall is a bilinear failure plane. Its inclination angle is 10° less than that of the Rankine failure surface. The external stability of the SMSE wall is more critical compared to the conventional MSE wall. It is concluded that special attention should be given to the interfaces and connections due to the vulnerability to reinforcement-facing connection failure. [ABSTRACT FROM AUTHOR]

AbstractThe study aimed to investigate the dynamic characteristics of the cervical spine and determine the effect of the material properties of the cervical spinal components on it. A finite element model of the head-cervical spine was developed based on CT scan data, and the first six orders of modes (e.g. flexion-extension, lateral bending, and vertical, etc.) were verified by experimental and simulation studies. The material sensitivity study was conducted by varying elasticity modulus of cervical hard tissues (cortical bone, cancellous bone, endplates, and posterior elements) and soft tissues (intervertebral disc and ligaments). The results showed that increasing the elastic modulus of ligaments by 4 times increased the natural frequency by 77%, while increasing that of cancellous bone by 4 times only increased the natural frequency by 6%. In the axial mode, the cervical spine had not only axial deformation but also anterior-posterior deformation, with the largest deformation located at the intervertebral disc C6-C7. Decreasing the elastic modulus of a component in soft tissues by 80% increased modal displacement by up to 62%. The material properties of the intervertebral discs and ligaments had opposite effects on the modal displacement and deformation of the cervical spine. Low cervical discs were more susceptible to injury in a vertical vibration environment. Cervical spine dynamics were more sensitive to soft tissue material properties than to hard tissue material properties. Disc degeneration could reduce the range of vibratory motion of the cervical spine, thereby reducing the ability of the cervical spine to cushion head impacts. [ABSTRACT FROM AUTHOR]

In this paper, the wheel track areal distribution of a short takeoff and landing aircraft was tested by using the self-developed airport pavement wheel track test system. The transverse and longitudinal distribution regulations of the wheel track of single-aircraft takeoff, dual-aircraft takeoff and landing were statistically analyzed, and the coverage of each point on the pavement were obtained. The joint simulation of MATLAB and ABAQUS was utilised to realise the fast calculation of the stress state at each point of the pavement. The longitudinal load of the pavement calculated based on the six-degree-of-freedom aircraft taxiing model was substituted into the finite element model, and the allowable coverage at each point on the pavement was calculated combined with the fatigue equation of concrete. Furthermore, an airport pavement design method based on the cumulative damage areal distribution was proposed, which could provide damage characteristics at any point on the pavement. The case analysis shows that the thickness of pavement within 600 m at both ends of the pavement for Aircraft A can be designed as 22 cm, and that of the middle pavement can be designed as 19 cm. [ABSTRACT FROM AUTHOR]

The deployment of automated vehicles (AVs) with the gradual market penetration rate increase and different potential lateral movement patterns combined with the lane width effect would lead to different load distribution scenarios, impacting the pavement performance. This study compares pavement rutting damages induced by different load distribution scenarios by setting out different penetration rates (i.e. 0, 20, 40, 60, 80, and 100%), wander modes (i.e. zero-, normal-, uniform-time-, and uniform-frequency-wander), and lane widths (i.e. 3, 3.25, and 3.5 m). A finite element model of a full-depth flexible pavement was developed using ABAQUS software to evaluate the pavement rutting. The results showed that the significance level of differences between rutting damages induced by different wander modes and lane widths is substantially influenced by the AVs' penetration rate. For instance, in the higher penetration rates, the differences between the rutting performance of different wander modes are more significant than in the lower penetration rates. Furthermore, the lane width effect becomes more significant in the segregated scenario than in the integrated scenarios in normal- and uniform-wander modes. Accordingly, AVs' penetration rate is a decisive factor in the practical decision-making process in the wander mode determination and lane width design for AVs. [ABSTRACT FROM AUTHOR]

The cross-tensioned concrete pavement (CTCP) has good bearing capacity, anti-crack ability and convenient construction characteristics due to the cross-tenioned prestressed strands placed inside the concrete. In order to study the mechanical response of pavement in construction process, an assembled monolithic structure for CTCP has been proposed and its mechanical response was analyzed through full-scale experiments and finite element model. The results of full-scale experiments show that the longitudinal and transverse compressive strain of concrete respectively exceeds 40μϵ and 20μϵ in the area of laying cross-tensioned prestressed strands with increase of the number of cross-tensioned strands. The end of CTCP is one of the weak areas, which may produce certainly transverse tensile stress. The results of finite element model show that the transverse tensile stress in ending region is mainly affected by the angle of cross-tensioned prestressed strands and its ratio. There is transverse tensile stress at the end of the pavement when the angle of cross-tensioned prestressed strands is small and its ratio is large, which can be offset by arranging transverse prestressed strands. Furthermore, an empirical formula to calculate transverse prestressed strands ratio at the end of pavement is given based on the results of finite element simulation. [ABSTRACT FROM AUTHOR]

Lumbar intervertebral disc degeneration can induce bone hyperplasia, lumbar intervertebral disc herniation and other diseases, is one of the causes of low back pain, which seriously affects people's quality of life. And the causes of degeneration are very complex, so it is essential to understand the underlying mechanism of intervertebral disc degeneration and its influence. In this study, biomechanical effects of L4∼L5 lumbar degeneration with different degrees of degeneration were studied based on the numerical simulations. The three-dimensional finite element model of normal L2∼S1 lumbar vertebrae was established based on CT images of average adult male and verified. Several key parameters (intervertebral disc height, nucleus pulposus size, properties of different materials, etc.) of the model were modified to construct L4∼L5 models with different degrees of degeneration (grade 1, grade 2, grade 3, and grade 4). The range of motion (ROM), the intradiscal pressure of the nucleus, and the maximum Von Mises stress were determined by applying torques in different directions to simulate the four postures of flexion, extension, lateral bending, and axial rotation under compression load (500 N) to simulate the upper body weight of the human body. In different postures, with the increase of L4∼L5 degeneration degree, the ROM of the L4∼L5 degeneration segment showed a decreasing trend (Grade 4 had decrease of 41.9% to 65.2% compared to normal at different postures), while the ROM of its adjacent normal segments showed an increasing trend (L3∼L4: Grade 4 had increase of 21%–94% compared to normal at different postures; L5∼S1: Grade 4 had increase of 32%–66% compared to normal at different postures). With the increase in the degree of degeneration, nucleus pulposus pressure in the L4∼L5 degeneration segment decreased continuously under different postural conditions (Grade 4 had decrease of 25%–134.6% compared to normal at different postures), while the nucleus pulposus pressure in adjacent normal segments (L3∼L4 and L5∼S1) showed a gradually increasing trend. The maximum Von Mises stress of the three segments increased with the increasing degree of degeneration at different postures (L4∼L5: Grade 4 increased to 1.75 ∼ 4 times compared to normal at different postures). In four different models of lumbar disc degeneration, the adjacent normal segment of the disc compensates for the movement and loading pattern of the degenerated segment. At the same time, the load pattern inside the degenerated segment also changes. [ABSTRACT FROM AUTHOR]

Aiming at the reliability problem of curved steel-concrete composite box girder, this article adopts the research methods of numerical simulation and model test. A load–slip constitutive relationship suitable for simulating composite box girder shear connectors is proposed, which is introduced into ANSYS finite element program and a three-dimensional finite element analysis model is established. At the same time, a model test is established for verification. The comparison between the results of numerical simulation and model experiment verifies the correctness and applicability of the finite element analysis model. According to the mechanical characteristics of the curved steel-concrete composite box girder, the influence of different design parameters on the load-bearing capacity of the curved composite box girder bridge is studied. Based on the sensitivity index, the influence degree of the design parameters on the structural reliability of the curved composite box girder is judged. The influence of the sensitivity of the design parameters of the curved steel-concrete composite box girder bridge on the flexural reliability of the structure is discussed. The optimal measures to improve the flexural bearing capacity of curved steel-concrete composite beam bridges are proposed. It is expected to provide new ideas and analysis methods for the optimization design and reliability analysis of curved composite box girder. [ABSTRACT FROM AUTHOR]

Microneedle arrays have recently been proposed as an alternative device for delivering vaccines into the skin. In recent years, many types of microneedles, such as coated and dissolving microneedles, have been developed with a variety of array configurations. However, the study that alongside compares the vaccine delivery efficiency of different types of microneedles and optimizes their arrangements on an array has been lacking. This study aimed to evaluate the vaccine delivery efficiency of coated and dissolving microneedles as well as to optimize the microneedle arrangements by using a three-dimensional finite element modeling approach. The constructed models describe the antigen release via diffusion, the antigen-receptor binding, and the antigen internalization by antigen-presenting cells (APCs) in the skin layers. Our modeling result reveals that the coated microneedle provides higher efficiency in activating APCs than the dissolving microneedle. It also predicts that the square arrangement of microneedles is not the optimal arrangement. According to the magnitude of APC activation, the acute-angle arrangement of microneedles outperforms the square arrangement by activating more APCs in the dermis. [ABSTRACT FROM AUTHOR]

The tensile strength of the single dovetail joint was investigated by experimental, numerical, and analytical methods. First, a numerical model of the dovetail joint was constructed based on the cohesive model using the Traction Separation law. Secondly, an analytical model was proposed based on the mechanical properties of the wood and the geometric dimensions of the dovetail joint. Finally, limited experimental tests (only changing the thickness length and width of the dovetail joint) were conducted to validate the numerical and analytical models. The results showed that the numerical model was an efficient method with ratios ranging from 0.84 to 1.35. The analytical model underestimated the tensile strength with ratios ranging from 0.63 to 0.85. The numerical analysis results showed that the dovetail tenon length and thickness significantly affect the maximum tensile strength. The tail angle and thickness significantly affected the elastic stiffness of the dovetail joint. The analytical model indicated the relationships between the dimensions of the dovetail joint and the tensile strength. The proposed methods will help to rationally design and optimize the tensile strength of a single dovetail joint. [ABSTRACT FROM AUTHOR]

In this study, dynamically loaded sandwich panels with two different core materials and face sheets made of aluminum alloys (6061-T6) were investigated experimentally and numerically under low-velocity impact. Polypropylene, PP (C3H6)n honeycomb and extruded polystyrene foam, XPS (C8H8)n were preferred as core material. By using the contact force and kinetic energy changes, which were the impact test results of the sandwich panels, the contact and impact resistance was examined. As a result of the tests, damaged regions and permanent central displacement were determined and energy absorption capabilities were demonstrated for two different structures. The results obtained were compared with the results obtained by the open finite element method. In this study, it was shown that the face-sheet thickness of sandwich panels was an important parameter affecting the impact behavior. The behavior of the core material when the face-sheet loses its rigidity was investigated and it was found that polystyrene foam was more effective in preventing impact damage. However, it was found that using the PP honeycomb or XPS was affected the impact behavior in different points. [ABSTRACT FROM AUTHOR]

The longitudinal compressive properties and stress–strain relationship of original bamboo at different culm heights were studied by a uniaxial compression experiment. The experimental results show that the failure mode of bamboo is bulging failure, and its ultimate compressive strength increases linearly with the increase of height at the bamboo culm. The longitudinal compressive stress–strain curves of bamboo at different heights are normalized, and the three-stage nonlinear constitutive model and the Boltzmann constitutive model are established. The two models are close to the experimental results and can describe the main stages of bamboo compression. A finite element model of the compression specimen is established to verify the accuracy of the proposed constitutive model, and bamboo column models with different slenderness ratios are established to evaluate the feasibility of the proposed constitutive model in buckling analysis. The results show that the finite element model can well simulate the buckling capacity of the bamboo column after introducing the initial defect of L/500, while the slenderness ratio is greater than 30. This work is expected to be useful for the finite element analysis of bamboo and prediction of buckling capacity of original bamboo columns. [ABSTRACT FROM AUTHOR]

Experimental modal analysis tests were performed during the catamaran's normal operation and using only 06 accelerometers on the main deck. This work focuses on estimating and comparing modal parameters using experimental (time and frequency domain techniques) and numerical analyses. Ten (10) experimental natural frequencies and (incomplete) mode shapes were estimated, in the range of 4–50 Hz, using Balance Realisation, Frequency-Spatial Domain Decomposition and Enhanced Frequency Domain Decomposition techniques. As only 06 accelerometers had been used for modal testing, a finite element (FE) model was used to augment the spatial resolution of the experimental mode shapes. Experimental and numerical natural frequencies showed good correlation with only the 3rd bending mode shape exhibiting 13.5% deviation. It was concluded that the experimental techniques can: (i) identify natural frequencies in the presence of harmonic components and, (ii) estimate mode shapes using a limited set of accelerometers, aided by a FE model. [ABSTRACT FROM AUTHOR]

The biomechanical effects of intervertebral discs and facet joints degeneration on the cervical spine are essential to understanding the mechanisms of spinal disorders to improve pathological and clinical treatment. In this study, the biomechanical effects of a progressively degenerated C5-C6 segment on the human lower cervical spine are determined by a detailed simulation of intervertebral disc degeneration. A detailed asymmetric three-dimension intact finite element model was developed using computed tomography scan data of the human lower cervical spine (C3-C7). The intact finite element model was then modified at the C5-C6 segment to build three degenerated models, such as mild, moderate, and severe degeneration. The physiological compressive load 73.6 N, and moment 1 Nm were applied at the superior endplate of the vertebra C3, and the inferior endplate of the C7 vertebra was a constraint for all degrees of freedom. Range of motion, maximum von Mises stress in the annulus, intradiscal pressure, and facet joint force of the degenerated models were computed. With progressive degeneration in the C5-C6 segment, the range of motion of degenerated and normal segments decreases in all postures. Intradiscal pressure of the degenerated segment decreases but increases in normal segments of degenerated segment C5-C6, and facet joint forces increase at both degenerated and normal segments. This study emphasizes that the degenerated disc alters the degenerated and normal segments' motion and loading patterns. The abnormal increase in facet joint force in the degenerated models threatened to accelerate the degeneration in the normal segments. [ABSTRACT FROM AUTHOR]

To examine wavefront aberrations induced by biomechanical effects after Small Incision Lenticule Extraction (SMILE) surgery. The three-dimensional (3D) finite element models of the human eye were established. By loading the intraocular pressure (IOP), the displacement of the anterior and posterior surface of the cornea was calculated. Then the displacement was converted into the wavefront aberrations by wave-surface fitting. The results showed that the induced wavefront aberrations were noticeable from biomechanical effects after SMILE surgery. The induced higher-order aberrations from the anterior corneal surface included spherical aberration, y-Trefoil, and x-Tetrafoil. Spherical aberration was positively correlated with corrected diopter (D), but x-Tetrafoil and y-Trefoil remained stable. The induced wavefront aberrations from the posterior corneal surface were smaller than those from the anterior corneal surface, and some of the aberrations compensated each other. With IOP increased, defocus and x-Tetrafoil from the anterior corneal surface increased, while y-Trefoil and spherical aberration decreased. The IOP only affected defocus from the posterior corneal surface. In addition, the incision size also had a distinct impact on primary x-astigmatism and x-Trefoil from the anterior corneal surface, and it had a smaller effect on the aberrations from the posterior corneal surface. Therefore, the biomechanical effects increased residual wavefront aberrations after SMILE refractive surgery. [ABSTRACT FROM AUTHOR]

Low-profile angle-stable spacer Zero-P is claimed to reduce the morbidity associated with traditional plate and cage construct (PCC). Both Zero-P and PCC could achieve comparable mid- and long-term clinical and radiological outcomes in anterior cervical discectomy and fusion (ACDF). It is not clear whether Zero-P can reduce the incidence of adjacent segment degeneration (ASD), especially in multi-segmental fusion. This study aimed to test the effect of fusion level with Zero-P versus with PCC on adjacent-segment biomechanics in ACDF. A three-dimensional finite element (FE) model of an intact C2–T1 segment was built and validated. Six single- or double-level instrumented conditions were modeled from this intact FE model using Zero-P or the standard PCC. The biomechanical responses of adjacent segments at the cephalad and caudal levels of the operation level were assessed in terms of range of motion (ROM), stresses in the endplate and disc, loads in the facets. When comparing the increase of adjacent-segment motion in single-level PCC fusion versus Zero-P fusion, a significantly larger increase was found in double-level fusion condition. The fold changes of PCC versus Zero-P of intradiscal and endplate stress, and facet load at adjacent levels in the double-level fusion spine were significantly larger than that in the single-level fusion spine during the sagittal, the transverse, and the frontal plane motion. The increased value of biomechanical features was greater at above segment than that at below. The fold changes of PCC versus Zero-P at adjacent segment were most notable in flexion and extension movement. Low-profile device could decrease adjacent segment biomechanical burden compared to traditional PCC in ACDF, especially in double-level surgery. Zero-P could be a good alternative for traditional PCC in ACDF. Further clinical/in vivo studies will be necessary to explore the approaches selected for this study is warranted. [ABSTRACT FROM AUTHOR]

This paper introduces a real-time co-simulation model for the prediction of the dynamics behavior of a veneer peeling lathe machine. The real-time co-simulation model introduced is described in the framework of multi-body system dynamics. It makes use of a co-simulation procedure in which a semi-recursive multi-body approach is combined with a detailed contact description. In the employed closed-loop semi-recursive method, the constraint conditions are carried out in the system motion differential equations via the augmented Lagrangian method. A contact procedure is presented to describe the contact between the wooden log and the cutting blade and the support rollers. The results obtained by the co-simulation are compared against those experimentally measured through a peeling lathe machine in operation and an approximate finite element model of the peeling process. According to the numerical results, it is concluded that the real-time simulation model can predict dynamic performance of the complicated system of a veneer peeling lathe in real-time. Solvability of equations of motion makes the introduced model suitable to be utilized in a number of product process purposes such as marketing, training and product development projects. [ABSTRACT FROM AUTHOR]