International Journal of Mechanics and Materials in Design最新文献

This study presents a mixed finite element (MFE) formulation designed to efficiently determine the geometrically nonlinear behavior of laminated composite beams, ensuring rapid convergence and reduced computational cost. This is achieved by incorporating all 3D strain components into the constitutive equations while satisfying the beam theory stress-free surface conditions. Von Kármán nonlinear strains are derived from a displacement field including three displacements and three rotations per node. The governing equations, obtained from the first variation of the Hellinger–Reissner functional, are linearized via an incremental formulation and solved iteratively using the Newton–Raphson algorithm. The proposed MFE is based on Timoshenko beam theory and enhanced by the integration of the cross-sectional warping deformations over a displacement-based FE formulation. The two-noded MFE involves twelve degrees of freedom per node and achieves rapid convergence with substantially reduced computational cost. Its performance is assessed through comparison with advanced beam formulations featuring refined kinematics, as well as 3D solid element simulations for asymmetric [0°/90°] cross-ply laminated beams. It provides satisfactory convergent results via very few degrees of freedom compared to the 20-node brick finite elements and 4-node shell finite elements of ANSYS. Parametric studies discuss the influence of cross-ply lamination, material anisotropy, and geometric design on the ratio of geometrically nonlinear to linear displacements, highlighting the significance of design-induced nonlinearities in high-performance structural applications.

To clarify the micromechanical performance of Bi-containing free-cutting steels, molecular dynamics simulation was employed to investigate the nucleation process and slip mechanism of prismatic dislocation loops (PDLs) within the FeNiCr alloy matrix under nanoindentation conditions. Meanwhile, special emphasis was placed on studying the interaction between Bi inclusions of varying sizes and PDLs. The simulation results show that Bi inclusions influence the dislocation loop movement significantly through the interface between Bi inclusions and the FeNiCr alloy matrix. It is found that the dislocation loop will slide gradually from below the parallelogram indenter to the inclusion interface. Small-sized inclusions will slow down the slip velocity, while large-sized inclusions will lead to the absorption or severe distortion of dislocation loops, and simultaneously induce plastic deformation of Bi inclusions. This process is beneficial to eliminating dislocation accumulation and slowing down the initiation of fatigue cracks caused by dislocation loops generated during machining. These atomic-scale discoveries elucidate the mechanism by which inclusions coordinate local plastic deformation through unique interactions with crystal defects, thereby providing key theoretical insights for the design of high-performance Bi-containing free-cutting steels.

The demand for materials capable of reliable service at elevated temperatures is steadily increasing. Therefore, this research presents the manufacturing process of MIG-CMT linear Inconel 625 cladding onto the 16Mo3 base material to create high efficiency and corrosion resistant bimetallic material. Microstructure of the bimetallic material was examined by SEM, which revealed NbC, TiC, and MoC carbides within the structure and dendrites that were directionally solidified and aligned parallel to the thermal gradient. Dislocation in microstructure was examined by TEM analysis. The grain size and orientation were examined by EBSD analysis, which found that the grain size in heat affected zone was on average about 10 µm. Furthermore, the chemical analysis unveiled that the chemical composition of Fe decreased from the average value of 3.5–1.2% after overlapping with the second Inconel 625 layer. Micro-CT analysis showed that the bimetallic material exhibited minimum internal defects due to the appropriate welding parameters. Microhardness testing revealed that the highest value of hardness was measured between welded layers 398 HV0.1. The base 16Mo3 material exhibited a average hardness of 210 HV0.1. It was concluded that bimetallic material consisted of Inconel 625 and 16Mo3 steel offers a robust solution for industrial environments requiring high strength, corrosion resistance, and thermal stability such as the incinerating kettle.

CFRP/metal composite class origami thin-walled square tubes filled with polyurethane foam are a new energy-absorbing component. This paper uses a combination of numerical simulation and quasi-static axial compression test to study the damage modes and energy-absorbing mechanisms of metal square tubes, metal class origami square tubes, and carbon fiber square tubes. It also explores the effects of factors such as foam filling, fiber winding angle, fiber circumferential-axial winding ratio, dihedral angle degree, and number of essential pattern layers on the damage modes and energy absorption mechanisms of the components. The results show that introducing the class origami pattern into a single metal square tube can change its damage mode from non-compact crushing to compact crushing. Filling the composite tube with polyurethane foam can result in more complete destruction of the carbon fiber tube and reduce the effective length of wrinkles on the metal tube, thereby significantly improving the total energy absorption of the composite tube. The fiber winding angle has a significant impact on the components: when the fiber winding angle is less than 45°, the potential energy release of the composite tube is incomplete, with low energy absorption efficiency and poor overall stability; when the fiber winding angle is greater than 45° and less than 90°, the potential energy release of the composite tube is sufficient and it has good axial folding and buckling consistency. The appropriate increase in the fiber circumferential-axial winding ratio, dihedral angle degree, and number of essential pattern layers can all improve the energy absorption capacity of CFRP/metal composite class origami thin-walled filled members. This study demonstrates the potential of CFRP/metal composite class origami thin-walled filled members as energy absorbers, aiming to provide a reference for origami design and composite energy-absorbing structure design.

The stress–strain prediction for viscoelastic materials using integer-order thermoviscoelastic models faces challenges due to the limitations of integer-order derivatives.With the miniaturization of devices, size-dependent effects on elastic deformation become more significant. Additionally, experiments and theories indicate that thermal conductivity in materials should not be treated as a constant in practical analyses. This study develops a fractional-order thermoviscoelastic model by integrating the fractional three-phase-lag heat conduction model, the fractional strain model and the nonlocal elasticity theory. The proposed model is then applied to analyze the nonlinear electro-magneto-thermo-viscoelastic response of a polymer spherical nanoshell under ramp-type heating and an external magnetic field. Taking into account the variable thermal conductivity, the nonlinear governing equations are derived. The Laplace and Kirchhoff transformations are employed to derive and solve the governing equations. The dimensionless temperature, induced magnetic field, displacement and stress are obtained and illustrated graphically. The results show that the nonlinear thermoviscoelastic response of the polymer spherical shell can be adjusted by the suitably modified parameters, which strongly depend on the size-dependent effect, memory-dependent effect and the variable thermal conductivity.

Heat transfer between the Earth’s hydrosphere and atmosphere is influenced by density variations within water masses and thermal-jump effects in rarefied atmospheric layers. Traditional continuum-based models often neglect these coupled mechanisms, leading to inaccurate predictions of temperature transport across spherical earth regions. To address this limitation, this study investigates the combined effects of hydrospheric density variation and atmospheric thermal-jump conditions on heat transfer between two concentric spherical layers. A two-region mathematical model with temperature-dependent fluid properties is formulated in spherical coordinates, and the governing nonlinear momentum and energy equations are solved using the finite element method. The findings show that increasing hydrospheric density variation enhances thermal retention, producing up to a 14–18% reduction in temperature attenuation near the inner sphere. A reduction in the Grashof number weakens convective circulation, resulting in a 22% decrease in peak momentum intensity and a smoother thermal field. Furthermore, imposing thermal-jump conditions at the interface significantly alters heat exchange between the layers, causing a 10–15% variation in the interfacial heat flux, demonstrating the sensitivity of atmospheric–hydrospheric coupling to jump phenomena.

To explore the coupling effect of the bidirectional bistable nonlinear energy sink (BBNES), this study examines the dynamics of both BBNES and dual bistable nonlinear energy sinks (BNESs), with their application in monopile offshore wind turbines (OWTs). The research methodology involves: (1) establishing physical models of both absorbers with corresponding force and potential energy analyses; (2) developing separate dynamic analysis models for host structure (HS)-mounted and nacelle-mounted absorber configurations; (3) comparing harmonic forced vibration responses between the BBNES and dual BNESs installed on the HS to preliminarily reveal the BBNES’s coupling effect. This study culminates in evaluating both absorbers’ performance under wind-wave loads, paying attention to the emergency shutdown scenario characterized by significant tower vibrations. Under harmonic excitation, the BBNES demonstrates superior vibration mitigation with the strongly modulated response when excitations are equal in both directions, but shows complex coupling effects under asymmetric excitations. During emergency shutdown conditions with wind-wave loads, the BBNES matches the performance of the dual BNESs in the fore-aft direction but exhibits inferior side-to-side damping performance due to its bidirectional energy coupling and limited adaptability to amplitude variations. Notably, the BBNES reduces nacelle space requirements by 1.24 m, and its performance is highly sensitive to slight changes in the proportionality factors but robust against variations in the mass ratio, frequency ratio, damping ratio, and pre-compressed spring’s original length. The research reveals that while the BBNES has greater application potential than the dual BNESs, its coupling effect suggests optimization opportunities through bidirectional decoupling as well as bidirectional stiffness and damping inequality designs. This work not only provides deep insights into the dynamics of the BBNES but also lays the foundation for its future optimization design.

Compared with traditional single-decker bearings, double-decker ball bearings exhibit advantages such as higher limiting rotational speed and longer service life. However, the additional bearing stage inevitably increases the overall mass, which restricts their application in weight-sensitive fields such as aerospace. To address this issue, this study proposes a bionic design for one of the key components of the double-decker ball bearing-the adapter ring. Inspired by the three-dimensional network structure of loofah sponge, characterized by its extremely low specific density and high mechanical strength, a loofah-inspired adapter ring structure has been developed. A finite element static analysis model for the loofah-inspired double-decker ball bearing was established to perform strength analysis on various adapter ring configurations. Furthermore, the mechanical behavior of the bearing under compressive load was theoretically analyzed, and the energy transfer mechanisms in this process was elucidated. Different adapter ring structures were fabricated using additive manufacturing technology, and experimental validation was conducted. By comparing the results of multiple experimental groups, the optimal adapter ring configuration for the double-decker ball bearing was determined. Optimization results indicate that, in the case study, the mass of the adapter ring was reduced by 25.97% and the maximum equivalent stress decreased by 7.74% compared with the unoptimized design. The proposed design approach provides a theoretical foundation for subsequent structural optimization of double-decker ball bearings and their application in lightweight-demanding scenarios such as aerospace.

This study investigates the slow, steady rotation of a permeable sphere in an incompressible Jeffrey fluid under the influence of a magnetic field using an analytical approach and an artificial neural network (ANN) framework. In order to train and validate the ANN, high-quality reference data is generated by using exact analytical solutions to the governing equations. The suggested ANN reliably forecasts the swirl and external couple for a variety of controlling parameters, such as the magnetic and Jeffrey fluid characteristics. The ANN model converges quickly, maintains high accuracy, and greatly reduces the amount of computation that is required. These findings support the ANN’s efficacy as a trustworthy surrogate model for challenging non-Newtonian MHD flow issues. The governing dynamics of the flow are represented through nonlinear partial differential equations (PDEs) articulated in the form of swirl velocity, subject to the relevant boundary conditions. The conventional no-slip condition is imposed at the spherical surface, while the regularity condition for the fluid velocity is applied outside of the sphere in the far-field area. Azimuthal direction is used to apply a constant magnetic field. For both the inside and outside of the sphere, the velocity field is represented by the swirl function. A new method for estimating Navier–Stokes equation solutions has been created, based on artificial neural networks. The scheme’s performance and result correctness are assessed by comparison with established analytical methods and solutions in the literature. To create and analyze the solution for controlled fluid flow, Feed-Forward Neural Network (FFNN) approaches are used. A multilayer perceptron (MLP) neural network is used to construct the sample functions, and the adaptive moment estimation (ADAM) algorithm is applied to optimize the adjustable parameters. The mathematical calculations for both ANN and precise solutions are shown in tables and graphs for different values of physical parameters. The numerical results obtained from both the ANN and analytical solutions are presented in tabular form and further illustrated graphically for a range of physical parameter values. The accuracy of the ANN-based solution is found to improve with rise in both the amount of neurons and the volume of training data used in the network. The swirl velocity predicted by the ANN approach achieved a high coefficient of determination, with an R-Squared value of 0.99951. Additionally, the suggested ANN model shows better adaptation to more complicated mathematical frameworks than the analytical method, and it drastically reduces the amount of computation and resources needed to solve problems.

The traditional single-layer hot stamping process has a significant temperature drop during sheet metal transfer and forming, and the springback of the formed parts is relatively large. The new hot stamping forming process that adopts a triple-layer plate stacking method can effectively reduce the springback after forming. In order to predict the springback behavior of Ti-6Al-4V alloy after hot stamping of triple-layer plates, this paper studies the stress relaxation (SR) behaviors and microstructure evolution of Ti-6Al-4V alloys were investigated at different temperatures (500 °C, 550 °C, 600 °C and 650 °C) and pre-strains (2%, 4% and 8%). The SR constitutive model was also established and embedded in the simulation software to analysis the sheet springback. The prediction accuracy of the simulation model was verified by hot forming experiments. The results show that high temperature and high pre-strain jointly affect the SR process. The initial relaxation stress (IRS) difference with a pre-strain of 2% and 8% decreased from 130 MPa at 500 °C to 2 MPa at 650 °C, and the stress relaxation limit (SRL) has been reduced from 204 MPa to 4.1 MPa. By observing the microstructure of the SR samples, it was found that the content of low-angle grain boundaries (LAGBs 2°–15°) decreased from 57.3% to 49.1% with the increase of temperature. The dislocation slip and climb are the main mechanism of SR at low temperature, and mechanism of SR becomes grain boundary slip and diffusion creep under high temperature conditions. The springback angle increases with the die radius and sheet temperature increasing. In the triple-layer sheet hot stamping process, U-shaped parts experienced stress relaxation behavior during the quenching process. The springback angle decreases by 82.8% increasing by the sheet temperature. Compared with the experimental results, the simulation prediction model has a higher prediction accuracy.