International Journal of Mechanics and Materials in Design最新文献

An optimal design study is presented for a stiffened pultruded cable tray beam manufactured from carbon fiber-reinforced epoxy with a 55% fiber volume fraction, subjected to a uniformly distributed transverse load. The objective is to determine the optimal stiffener thickness at the side sections to achieve weight-efficient structural performance. Design constraints include limits on deflection, material failure, and buckling, and the associated structural problem is solved using an 8-noded degenerated shell finite element model. First, the mechanical properties of the composite material are derived analytically, and a mesh convergence study is conducted for the unstiffened tray configuration. In the subsequent optimization phase, the optimal stiffener thicknesses are determined for selected geometries while maintaining a constant structural weight. Comparative results show that the stiffened design achieves approximately a 70% increase in load-carrying capacity relative to the unstiffened configuration of equal weight. Furthermore, the findings indicate that increasing the height of the side sections leads to more structurally efficient and economical designs.

This study presents a semi-analytical framework for the size-dependent free vibration analysis of Timoshenko nanobeams based on nonlocal elasticity theory. The Initial Value Method (IVM) combined with the Approximate Transfer Matrix (ATM) approach is employed to compute natural frequencies. The proposed method captures nanoscale effects with high accuracy and reduced computational effort, eliminating the need for closed-form symbolic expressions and offering a practical alternative to conventional numerical techniques. Convergence analyses and comparison with a benchmark solution confirm the robustness and validity of the solution method. Parametric studies reveal that increasing (mu) reduces the natural frequencies in supported, clamped–simply supported, and clamped–clamped beams, demonstrating the expected softening behavior due to nonlocal effects. For the clamped–free beam, an increase in (mu) leads to a hardening response for the fundamental mode, while higher modes retain the classical softening trend. Additionally, increasing L/h results in higher frequencies, and the influence of nonlocality becomes more pronounced for higher-order modes. The ATM–IVM framework provides a robust and efficient tool for modeling, designing, and optimizing advanced nanostructured materials, where an accurate representation of size effects is crucial.

A tube reinforced hyperelastic gradient porous sandwich structure (TRHGP) for shock isolation of gearbox is proposed based on the principles of bionics. The perfusion–moulding press integrated molding process is developed to prepare the specimens. This process is simple and conducive to industrialization. Moreover, the dynamic responses and shock isolation efficiencies of TRHGPs connected to a gearbox under different shock acceleration amplitudes are investigated experimentally and numerically. The effects of topological configuration, porosity, and impact load on the shock resistance performance of TRHGPs are also explored. The results indicate that, compared with the response under rigid impact condition, the shock isolation efficiency of TRHGPs is more than 40%. Furthermore, it is demonstrated that the TRHGP with triangular tubes exhibits better shock isolation efficiency than those with rectangular or circular tubes. The findings provide a valuable reference for the design of shock isolation structures.

Zirconium (Zr)-based alloys have great potential for orthopedic implants due to their excellent mechanical properties, corrosion resistance, and biocompatibility. However, untreated Zr-based alloys exhibit inadequate wear resistance, which limits their service life as joint prostheses. This study employed a combined surface texturing and thermal oxidation approach to enhance wear resistance. Biomimetic micro-textures were fabricated on the alloy surface via laser processing, followed by high-temperature oxidation to produce a textured ceramic coating. The influence of micro-texture diameter on anti-friction performance was systematically investigated. Surface modification treatment has significantly enhanced the hardness and roughness of the samples by several times and greatly improved the wetting performance. The contact angle decreased by approximately 56% (± 1.8%) after texturing treatment and further reduced by 16% (± 5.7%) after high-temperature oxidation. Friction test revealed that ceramic-textured specimens outperformed smooth surfaces in terms of friction reduction and wear resistance. Specifically, the friction coefficient was reduced by 25.29% (± 2.4%), with a maximum wear reduction rate of 27.7%. This study provides a novel strategy for improving the surface properties of Zr-based alloys.

In bone tissue engineering, achieving a balance between mechanical properties and mass transport capabilities is essential for designing porous scaffolds. This study proposes a dual-objective optimization design method based on triply periodic minimal surface (TPMS) structures, aiming to simultaneously satisfy the requirements for elastic modulus and permeability. Three types of TPMS structures—Diamond (D), Gyroid (G), and IWP—were constructed in both sheet and rod forms. The effects of structural parameters, including porosity and unit cell size, on the elastic modulus and permeability of the scaffolds were systematically investigated. Finite element analysis and computational fluid dynamics simulations were conducted to establish empirical formulas relating structural parameters to mechanical and transport performance, which were subsequently validated experimentally with high predictive accuracy. On this basis, orthogonal experiments and entropy weight analysis were employed to quantitatively evaluate the influence of structural parameters on the two performance indicators, and a comprehensive performance optimization strategy was proposed. The results show that porosity is the most significant factor affecting elastic modulus, while unit cell size is the dominant factor influencing permeability. Among the structures, the IWP type demonstrates superior performance in both mechanical and transport characteristics. This study provides a theoretical foundation and quantitative tools for the personalized design of TPMS bone scaffolds, offering promising potential for clinical applications.

This paper presents a novel investigation into the transient dynamic behavior of curved zigzag nanobeams using the Finite Element Doublet Mechanics (FEDM) theory. A sinusoidal shear deformation theory is employed to capture shear effects, while size-dependent behavior is introduced through a length scale parameter within the Doublet Mechanics framework. The model accounts for a range of boundary conditions, open angles, aspect ratios, and time-dependent loading profiles, including step, sinusoidal, blast, and triangular functions. Validation is performed through comparisons with molecular dynamics simulations and classical continuum beam theories. Results reveal that curvature, boundary conditions, and scale effects significantly influence the transient response. Overall, the study demonstrates the effectiveness of the FEDM theory in accurately predicting nanoscale beam dynamics and offers a robust tool for micro- and nanoscale structural analysis.

Active health monitoring and fault diagnosis methods are essential to improve the safety and reliability of rotating machineries and to prevent from catastrophic failure. The conventional fault diagnosis methods require battery-support sensors. This paper presents a novel piezoelectric smart bearing to fulfill fault detection without using battery-support sensors. An electromechanical coupling model of the unbalanced flexible rotor with piezoelectric smart bearings is established using the prominent principle of piezoelectric transducers and Lagrange equation. This model also takes in to account the nonlinearity due to the breathing transverse crack. Numerical exploration for the voltage response when the crack grows deeper is performed using the frequency response, orbit diagram, power spectrum and bifurcation diagram. Then, a test rig has been designed and built for experimental validation. The obtained results show that the voltage responses of the system contain the fault characteristic frequencies. So, the proposed smart bearing is capable of detecting the unbalance and crack faults and can be used for self-powered condition monitoring of rotating machines.

Additive manufacturing, particularly fused filament fabrication (FFF), has become an important technique for producing lightweight and geometrically complex polymer structures, yet the reliable integration of these parts into structural assemblies requires effective joining strategies. Adhesive bonding offers significant advantages over mechanical fastening by enabling uniform stress transfer and compatibility with dissimilar materials, but the mechanical integrity of bonded 3D-printed joints is strongly influenced by both adherend material and joint geometry. This study explores the effects of adherend material (PLA and PETG) and joint geometry, single lap joint (SLJ), notched SLJ (NSLJ), and curved joint (CJ) on failure loads and fracture behavior. Specimens were manufactured via fused filament fabrication (FFF) and bonded using a methacrylate-based structural adhesive. A cohesive zone model (CZM) was developed to simulate load–displacement responses and predict failure initiation and progression. The novelty of this work lies in the combined experimental and numerical investigation of how joint geometry and material selection affect the mechanical integrity of bonded 3D-printed components. Among the tested configurations, curved joints showed the highest failure loads, while notched joints performed the weakest. CZM simulations accurately predicted experimental behavior, with deviations ranging from 1.03% to 9.77%. Failure modes varied with both material and geometry, including adhesive cohesive failure and adherend fracture. These findings offer a framework for enhancing the reliability of polymer bonded joints in additive manufacturing, supporting failure prevention through informed design.

High pressure common rail pipe is mainly used for storing high pressure fuel, maintaining stable pressure in the common rail pipe, and distributing the fuel to each injector. Therefore, the stability characteristics of common rail pressure determine the stability of fuel injection and engine. This paper first analyzes the composition and working principles of the high pressure common rail injection system for diesel engines, and establishes mathematical models for its key components. Secondly, based on numerical simulation and using AMESim, the simulation model of the diesel engine high-pressure common rail system was built, and the accuracy of the established simulation model was verified based on the high-pressure common rail system test bench built. Then, a detailed study was conducted on the rail pressure fluctuation characteristics of the common rail pipe, mainly analyzing the effects of injection target rail pressure, injection pulse width, common rail pipe length, common rail pipe inner diameter, common rail pipe wall thickness, and common rail pipe material on the rail pressure characteristics. Research has shown that the maximum peak value of rail pressure fluctuation follows a linear function relationship with the length and inner diameter of the common rail pipe, while the average rail pressure fluctuation follows a polynomial function relationship with the length and inner diameter of the common rail tube. Within the range of the studied parameters, the target rail pressure has the greatest impact on the peak rail pressure fluctuation, and the common rail pipe diameter has the most significant suppression on the average rail pressure fluctuation. Finally, based on the AMESim rail pressure fluctuation curve mentioned above, Fluent were used to preliminarily study the internal flow field characteristics of the common rail pipe at different outlets during the stable pressure stage with a target rail pressure of 150 MPa. Through the research in this paper, certain references can be provided for the design and optimization of common rail tubes in high-pressure common rail injection system.

Perforated fins have been regarded as one of the most effective ways in fin optimization and are used in film cooling turbine blades. The convective heat transfer from a rectangular fin with circular perforations by considering the effect of internal heat generation, is studied in this analysis. The solution to the modelled heat transfer-perforation fin problem is explored using the Chelyshkov polynomial collocation method. The operational-matrix form of the heat transfer-perforation fin problem is established using this collocation method. The governing heat equation is developed and is transformed into a dimensionless ordinary differential equation (ODE) using appropriate dimensionless variables. This equation is solved via matrix based Chelyshkov polynomial collocation approximations (MBCPCA). The comparison with alternative approaches to solving the perforated fin equation is executed, and an error analysis is also presented. The effect of parameters, including the number of perforations and their geometrical dimensions, is considered in this analysis. The variation in thermal profiles for various parameters is illustrated through tabulated and graphical statistics. The outcomes demonstrated that the perforated fin with circular holes exhibited a lower fin temperature than the non-perforated one. The rate of heat transmission is increased by 39.83% when the Biot number is increased from 1 to 2.