Narrow Results

The study aims to provide firsthand knowledge on finite element simulation (FES) of double-side laser welded (LW) stainless steel 304 (SS-304) thick plates used for automobile application. Double-side welding technique is an idea of achieving complete penetration with minimal heat input. The microstructural evaluation revealed the presence of dendritic growth that results in the enhancement of tensile strength (TS) for the welded sample. There is a slight increase in the delta ferrite content in weldment. The change in microstructure is due to thermal history during solidification. The TS of base metal (BM) was $542\pm 5.1$MPa whereas the welded sample exhibited strength of $554\pm 2.3$MPa. FES was successfully employed to simulate TS with error percentage less than 1.

This study explored the dynamic response and impact resistance of 3D-printed honeycomb-like structured elastomers in drop tests. Using triangles as the impact-resistant units, honeycomb-like structured elastomers were designed and fabricated. Based on the drop weight impact test and FEA analysis, the dynamic response of the honeycomb-like structured elastomers during the drop impact process was investigated. Subsequently, the effects of the angle of the base angle of the triangular cells, the thickness of the sample, and the number of internal layers on the impact resistance of the honeycomb-like structured elastomers were discussed. The results indicated that an increase in the base angle would enhance structural density and impact resistance. Among these, sample T10L1A75 exhibited the best impact resistance with a peak force of 1.71kN, which is 74.96% lower compared to the solid sample of the same thickness. Thicker elastomers provided more deformation space, thereby enhancing impact resistance. However, surpassing a certain threshold in the arrangement density of the samples could limit the buckling deformation of the internal fill walls, consequently weakening the impact resistance. Furthermore, extending the effective impact duration could offer insights for developing high-performance impact-resistant materials.

Ground settlement prediction for shield construction is highly important and challenging. This study introduces a machine learning algorithm combined with finite element numerical simulation, i.e., machine learning–finite element mesh optimization. For surface subsidence prediction, 16 combination models of ANN, KNN, RF and SVR were optimized by PSO, GA, BT and BO, involving raw data preprocessing, principal component analysis, hyperparameter selection and prediction accuracy evaluation. A subway shield tunneling project was analyzed, in which the meshes of finite element numerical models were discretized into different sizes from 1.0m to 2.0m. In total, 360 sets of data points were extracted from the simulation results, including stress, strain, shield jacking force, internal friction angle, cohesion force, and settlement, of which 252 data points were used as the input parameters of machine learning model. Analysis of average error rate of finite element–machine learning coupling models showed that the finite element model had the highest accuracy of settlement prediction when the mesh size of the finite element model was 1.4m, and the GA-SVR model had the highest accuracy and generalization ability in ground settlement prediction. This study highlights the uniqueness of machine learning–finite element mesh optimization model in application.

The objective of current communication is to study heat transfer phenomenon for slip flow of viscous fluid due to wavy channel with general cosine function boundaries and fixed amplitude. The walls along with slip boundary constraints are kept at different temperatures. The flow is incompressible and Newtonian with AIS as a predicting material being used to check the fluids and thermal properties. The Navier–Stokes expressions with 2D flow regime subject to heat transfer due to convection are used to develop the simulations. A parametric theoretical assumptions analysis is performed for specified range of Reynolds number (100–1000) with upper and lower surface vibration periods of 1 to 6. The results are displayed with graphs, surface and contours plots and first, ever a novel work was done to represent the percentage change in velocity magnitude and local Nusselt number as surface plots and contours, respectively. The results are authentic due to mesh independent study and verification with the experimental correlation. A periodic flow at the lower wall was deducted. The maximum and average rotation rates attain a linear relationship with Reynolds number and their correlation was found. The simulations show the strict relationship of Reynolds number and the geometry of the channel with shear rate. The pressure gradient in $y$-direction was found minimum in trough and maximum in the crest region. It has been observed that the boundary friction is reduced due to periodic variation of walls surface.

In various applications of ultrasonic waves, the ultrasonic transducer is the key device of ultrasonic testing and ultrasonic imaging. Compared with the traditional piezoelectric transducer, the capacitive micromachined ultrasonic transducer (CMUT) has many striking advantages, such as low impedance, high bandwidth, easy integration and low cost, and it is expected to become a next generation of mainstream products. In this paper, a CMUT structure for underwater-imaging applications is designed, and the finite element model is established by using COMSOL software, then the modal analysis, harmonic response analysis, electromechanical coupling analysis and transient analysis are carried out. As a consequence, the key parameters of CMUT are obtained, namely resonance frequency, voltage collapse and electromechanical coupling coefficient. For the processed CMUT line array consisting of 16 elements, a test system is built and the emission performance, receiving performance, directivity, bandwidth and preliminary imaging of the designed transducer are tested and analyzed. The results show that the designed CMUT array can meet the requirements of underwater-imaging applications.

An energy-balance-based analytical method and finite element (FE) simulations were developed in this paper to study the dynamic response of metallic sandwich panels subject to blast loadings. The analytical model can be used to predict approximately the deflection of the panels, while the FE model can take into account fluid–structure interactions and the effect of strain rate. Both models were validated by comparing their predictions with the test results available in the literature. Parametric studies were then carried out to assess various factors that are influential in characterizing the dynamic behavior of sandwich panels subject to blast loads.

Some types of rigid origami possess specific geometric properties. They have a single degree of freedom, and can experience large configuration changes without cut or being stretched. This study presents a numerical analysis and finite element simulation on the folding behavior of deployable origami structures. Equivalent pin-jointed structures were established, and a Jacobian matrix was formed to constrain the internal mechanisms in each rigid plane. A nonlinear iterative algorithm was formulated for predicting the folding behavior. The augmented compatibility matrix was updated at each step for correcting the incompatible strains. Subsequently, finite element simulations on the deployable origami structures were carried out. Specifically, two types of generalized deployable origami structures combined by basic parts were studied, with some key parameters considered. It is concluded that, compared with the theoretical values, both the solutions obtained by the nonlinear algorithm and finite element analysis are in good agreement, the proposed method can well predict the folding behavior of the origami structures, and the error of the numerical results increases with the increase of the primary angle.

The use of fiber-reinforced polymer (FRP) has been widely recognized to be an effective and economical way to strengthen existing structures or repair damaged structures for extending their service life. This study investigates the feasibility of using nonlinear guided wave to monitor crack-induced debonding in FRP-strengthened metallic plates. The study focusses on investigating the nonlinear guided wave interaction with the crack-induced debonding. A three-dimensional (3D) finite element (FE) model is developed to simulate the crack-induced debonding in the FRP-strengthened metallic plates. The performance of using fundamental symmetric ($S_0)$ and anti-symmetric ($A_0)$ modes of guided wave as incident wave in the second harmonic generation at the crack-induced debonding is investigated in detail. It is found that the amplitude of the second harmonic and its variation with different damage sizes are very different when using $S_0$ and $A_0$ guided wave as the incident wave, respectively. The results suggest that it is possible to detect potential damage and distinguish its type based on the features of the generated second harmonic.

A conventional plate-type viscoelastic damper (VED) can easily crack at the interfaces of steel plates and viscoelastic components. In the present work, grooved VEDs, which are a new type of interfacial enhanced VEDs with interfacial grooves, are designed to improve the damping capacity and anti-cracking ability of conventional dampers. The dynamic property experiments of the normal and grooved VEDs are carried out and the interfacial cracking failure of the VEDs are simulated and analyzed by using bilayer cohesive constitutive model with ABAQUS. The grooved VED exhibits excellent dynamic performance and energy dissipation capacity at different temperatures, frequencies, and displacement amplitudes. Experiments and finite element analysis prove that the energy dissipation performance and interfacial bonding strength of the grooved VED are effectively improved. A modified fractional standard linear solid model, in which the Payne effect and temperature–frequency equivalent principle are combined and implemented, is proposed. This model can portray the influence of the excitation displacement, surrounding temperature and external excitation frequency on damper properties at the same time. The fillers and molecular chains affections at micro- and meso-scale are also taken into account. The model’s numerical calculations and experimental results comparisons present that the modified fractional standard linear solid model has sufficient accuracy and performs well in depicting the dynamic properties of the interfacial grooved VED. The errors between the theoretical and experimental values of $G_1$ and $G_2$ for the grooved VED are mostly within 20% at representative conditions. The interfacial groove structures can well enhance the interfacial bonding and improve the service life of conventional dampers. The modified fractional standard linear solid model is simple and has clear physical meanings for each macro/micro parameters, making it convenient for application in engineering practice. The present research is of great significance in improving the work stability of VEDs and promoting the application of viscoelastic damping technology.

Circular steel-tube members are extensively used in various large-scale steel structures. The detrimental effects of corrosion on the ultimate bearing capacities of these structures require urgent attention. This study designed six circular steel tube specimens to explore the degradation pattern of the ultimate bearing capacity of corroded circular steel tubes under axial compression; three were subjected to accelerated corrosion by electrification, and the other three were used as the control group. Following the accelerated corrosion test, both groups of specimens were subjected to material-property and axial-compression tests. These tests provided data on the bearing capacity and midspan displacement of the corroded circular steel tubes, allowing for the construction of load–displacement relationship curves. The test results demonstrate that corrosion significantly affects the bearing capacity of circular steel tubes. As the severity of the corrosion increased, the bearing capacity and stiffness of the corroded circular steel tubes progressively weakened. To simulate the behavior of circular steel tubes, a numerical model was established that provided the ultimate bearing capacity under axial compression and generated load–displacement curves. The simulation results closely aligned with the test results. This study introduced a novel approach for accurately computing the stability-bearing capacity of circular steel tubes subjected to corrosion and axial compression. Comparative analyzes with test results validated the superior performance of the proposed method in accurately predicting the ultimate bearing capacity.

This study used biomechanical models of soft tissues based on combined exponential and polynomial models. Finite element methods were used to solve material nonlinear and geometrically nonlinear problems of soft tissue models. This involved assigning a screening coefficient in the model-accelerated computing process to filter the units involved in the calculation. The screening coefficient controlled both the accuracy of the results of simulation and the computing speed through setting up a subset of finite elements. The fast computer method based on the screening coefficient was applied to the rectus femoris simulation.

This study selected the maxillary labial impacted canine as the research object to build the model of periodontal ligament (PDL) and simulate the process of orthodontic treatment. This paper obtained stress–strain curve by calculating and analyzing the data of nanoindentation experiments. The parameters were identified through curve fittings by ABAQUS. The fitting results show that the third-order Ogden model is in good agreement with the experimental data which demonstrate that the third-order Ogden model is able to reflect the material properties of the PDL. In this paper, orthodontic process of the maxillary labial impacted canine was simulated. The results show that inside and outside surfaces of PDL all have stress variation, the stress on the root apex and dental cervix of PDL is relatively large, the maximum appears at dental cervix and the minimum appears close to tooth impedance center.

This study investigates the effect of different unit cells on the mechanical performance of porous implant. Three shapes of unit cells (Diamond 30(DO30), Octet truss 30(OT30), and Rhombic dodecahedron 30(RD30)) were selected, which have the same relative density. Corresponding models of single pore (SP), repeating pores (RP) and porous implant (PI) were created. Using finite element methodology, mechanical performances of three classes of models under the conditions of pressure and torsion were simulated based on the same static load (SP: 50N, 0.125N$\cdot$m; RP: 200N, 0.5N$\cdot$m; PI: 200N, 0.5N$\cdot$m), respectively. Results demonstrated that RP showed consistent mechanical performances with SP: OT30 displayed the lowest stresses, displacements, and strains under the conditions of pressure and torsion, and conversely DO30 always resulted in the highest magnitudes. For the case of PI, mechanical performances were different from SP and RP: implant with shape of RD30 resulted in the lowest stress (275.2MPa) under the condition of pressure, but displacement (2.236e$-$002mm) and strain (3.050e$-$003) of OT30 were the largest; under the condition of torsion, stress sequence was same as SP and RP, but DO30 provided the highest strain (2.437e$-$003), RD30 displayed the largest displacement (1.508e$-$002mm). Unit cell influences mechanical performance of porous implant directly, and the implant outline and incomplete structure may also affect it. It could not select pore simply by the right type of unit cell, and surface area is an important parameter as well as pore size.

With its good flexibility and adaptability to the environment, soft robot has been attached great importance by the majority of researchers in recent years, and is widely used in rehabilitation treatment, flexible grasping and other fields. However, the existing actuators have disadvantages such as single deformation mode, poor flexibility and insufficient environmental adaptability. The reason is that the actuator structure is too simple to meet the complex application scenarios. In this paper, an omnidirectional bending multi-segment soft actuator is proposed, and the parameter analysis and dynamic analysis models are given. Meanwhile, the prestressed modal analysis of the proposed model is carried out to better characterize the dynamic behavior. A numerical study of a climbing motion verifies the novelty and validity of the proposed structure.

The Johnson–Cook model is the popular constitutive relation for the simulation of metal cutting process because of the availability of various sets of parameters for different materials. Different sets of Johnson–Cook parameters are observed to be available for a particular material due to dissimilarity in the initial condition of the material and experimental methods utilized for the calibration. Hence, it is difficult to choose an accurate parameter set for modeling the behavior of a material for the finite element simulation of its cutting process. In this regard, a strategy is proposed and validated in this study for choosing an accurate Johnson–Cook parameter set for Inconel 718. Twelve sets of Johnson–Cook parameters were collected from the literature for Inconel 718 and their flow stress predictions were investigated by comparing with experimental flow stress values for wide ranges of strain rates and temperatures as encountered during the cutting process. The Johnson–Cook parameter sets corresponding to the predicted flow stress curves that agree with the experimental values are chosen for modeling the behavior of Inconel 718. This comparison also helps in indexing the parameter sets according to the initial condition of the material since it is not reported mostly in the literature. The chosen material parameter sets are validated further for the orthogonal cutting simulation of Inconel 718 for a wide range of cutting conditions by comparing the cutting force and chip thickness predictions with the experimental values. Thus, the analysis of predicted flow stress values helps in choosing the accurate Johnson–Cook parameters for an Inconel 718 specimen which in turn helps in conducting accurate orthogonal cutting simulations. The finite element simulation of metal cutting helps in identifying the optimum cutting parameters which would help to reduce energy consumption and thus make the process more efficient and sustainable.

Laser forming is a flexible sheet metal manufacturing technique capable of producing various shapes, without hard tools and external forces, by irradiation across the surface of the metal piece. A three-dimensional thermal-elasto-plastic (TEP) finite element model for a straight line laser forming process has been developed during the course of this study, which simulates bend angles and temperature distributions. Laser forming process optimization and material sensitivity are investigated. In order to seek the optimal process conditions to generate a desired bend angle in the multi-scan laser bending process, an optimization algorithm based on the approximation of objective function and state variables is integrated into the numerical model. An optimal set of process parameters such as laser power, scan speed, beam diameter and the number of scans are obtained with optimization procedure. In order to assess process sensitivity to material roperties, associations between bend angle and material properties are statistically determined using the Pearson product-moment correlation coefficient via Monte Carlo simulations, for which a large number of the finite element simulations are carried out. The material properties of interest include the coefficient of thermal expansion, thermal conductivity, specific heat, modulus of elasticity, and Poisson's ratio. Results show that the process optimization coupled with finite element analysis can be used to determine processing parameters, and that the material properties of primary importance are the coefficient of thermal expansion, thermal conductivity and specific heat.

Optical tweezers are widely used to study the mechanical properties of human red blood cells. This paper examines the inverse problem of computing constitutive parameters from the experimental loading-response data. Hyperelastic constitutive models are employed to characterize the stress–strain relationship of red blood cells. The large deformation and evolution of stress in red blood cells under different tensile loadings are investigated using finite element simulations. The results show that the Yeoh model provides a better characterization of human red blood cells. A nonlinear regression analysis method is presented to derive hyperelastic parameters from the experimental results. The obtained constitutive model and parameters are validated by comparing the force–displacement curves from finite element simulations and from experimental data.

A sequential model of multiple-shot impacts has been established to investigate the shot peening process. Shot groups are proposed and designed with different patterns to obtain full surface coverage in the impacted region and a satisfactory computational efficiency. The sequential model was applied for the prediction of residual stress on a GH4169 alloy specimen. The results showed that uniform and saturated states of residual stress along the surface and depth profile were obtained in the impacted region when the numerical order of shot patterns reached 4. Furthermore, the numerical results of compressive residual stress in the subsurface were compared with the experimental results obtained using the X-ray diffraction (XRD) analysis and the incremental hole drilling method. The maximum relative error between the numerical results and XRD measurement was 11.6%. Furthermore, the stress profile measured using the incremental hole drilling method was consistent with the numerical results. The established finite element model demonstrated its robustness and effectiveness for the evaluation of residual stress in the shot-peened GH4169 alloy, and it may be applied to other metallic materials with simple modifications.

A simplified model for calculating the seismic responses of the shaft is proposed in this paper. Based on the theory of Winkler elastic foundation beam, the urban shaft is simplified as a vertical beam. The horizontal soil reaction and vertical shear tractions between the shaft circumference and the surrounding soils are considered through horizontal springs and rotating springs on the sidewall of the shaft. The translation and rocking motion of the shaft are considered through horizontal springs and rotating springs at the bottom of the shaft. Then, the dynamic analysis model of the shafts under seismic motion is established, and the control equation of the dynamic response of the shaft in frequency domain is deduced. The analytical solution of the steady state response of the shaft is obtained. Considering the randomness of the earthquake motion, this method can get the shaft kinematic responses under different ground motions efficiently in conceptual design process.

When mentioning multidisciplinary design optimization methods, the deterministic optimum design is frequently applied to set the constraint boundary. Furthermore, only a small amount of space tolerances (or uncertainty) is available in the process of design, manufacture and operation. Therefore, deterministic optimum design lacking uncertainty cannot meet the needs of reliability-based design optimization. In this paper, reliability optimization design method, finite element (FE) analysis, optimal Latin hypercube test design and response surface approximation model are combined to optimize the side structure of electric vehicles and improve its crashworthiness. Firstly, a side impact FE model of the electric vehicle is established and verified in this paper. Then, the dimensions and the material yield strength of the force-bearing structure in the vehicle are selected as design variables, and the impact speed in the actual collision is selected as a random variable to optimize the car crashworthiness in the side impact using the 95% reliability optimization method. The results show that the 95% reliability optimization design increases the total energy absorption of the side components by 9.45%, the intrusion of the B-pillar and the vehicle door inner panel decreased by 10.42% and 14.75%, respectively. The intrusion speed of the B-pillar and the inner panel of the vehicle door decreases by 10.35% and 17.78%, respectively. By comparing the results of traditional deterministic optimization and reliability optimization methods, the latter can better satisfy the crash safety objectives, and improve the reliability of vehicle body design.