International Journal for Numerical Methods in Engineering最新文献

The explicit moving particle simulation (EMPS) method, due to its pressure calculation through the equation of state, has high computational efficiency and broad prospects for engineering applications. However, the conventional EMPS method has issues of numerical instability such as high-frequency oscillations and discontinuous distributions of pressure. In this paper, to improve the accuracy and stability of numerical simulations, an enhanced δ_MPS-EMPS method was proposed, in which a new enhanced equation of state and a diffusion term of particle number density were developed. The new enhanced equation of state includes the terms of the velocity divergence and the particle number density. It describes the relationship between pressure and fluid density through the changes in the velocity field and the particle number density field, resulting in a smooth pressure. It is worth noting that the artificial bulk modulus K in this equation is accurately calibrated using the specified pressure field calculated by the MPS method at the first time step. Additionally, the particle number density is corrected by introducing a diffusion term into the mass conservation equation. This approach can reduce high-frequency pressure oscillations by filtering out non-physical density fluctuations. The proposed method was evaluated and validated through simulations of four benchmark cases, including a hydrostatic pressure tank, the deformation of an elliptical droplet, the Taylor-Green vortex flow, the 2D water dam-break flow, and the evolution of a square patch of fluid. The simulation results proved the effectiveness and robustness of the enhanced δ_MPS-EMPS method.

Engineers can accomplish customised thermal properties that maximise fluid performance in various operating scenarios by hybridising alloy nanoparticles. The present study provides new insights into the heat and mass transfer of the squeezing flow of hybrid nanofluid between the parallel Riga plates under the impacts of shape effects, non-uniform heat generation/absorption and activation energy. A suitable similarity approach is implemented to transform governing equations into non-linear systems of ordinary differential equations and is solved numerically using the bvp-5c technique. The results show that the velocity profile increases near the lower plate and decreases near the upper plate. In contrast, both the temperature and concentration profiles rise for growing values of the squeezing number. It is found that both temperature and concentration profile rise for augmented values of the Biot number parameters. Also, engineering factors are discussed graphically with specific parameters. Further, properly aligned residual plots and less variance in fitted values reveal the response surface methodology's great accuracy and validity. And from the sensitivity analysis, it is observed that the Skin friction has a positive influence for Hartman and porosity parameters and negative influence for squeezing parameter also the Nusselt number has a negative sensitivity for both squeezing and Biot number and less positive sensitive to the Hartman number.

This study introduces a microstructure-temperature coupled framework to analyze the collapse behavior of non-API high-toughness casings (BG110V/BG140V), addressing a 16%–18% prediction error in conventional API standards through experimental validation, 3D modeling, and a novel multifactor correction formula. Full-scale collapse tests at 50°C and 85°C revealed temperature-dependent elastoplastic behavior. BG140V showed higher-pressure resistance (75.89 MPa at 50°C vs. 59.47 MPa for BG110V), attributed to its finer grain structure (ASTM 10.0 vs. BG110V's 6.5). Thermal softening reduced yield strength by 4.3% (BG110V) and 2.4% (BG140V) at 85°C, correlating with accelerated dislocation mobility (1.5 × 10⁸/cm² vs. 10⁸/cm² at 50°C). Finite element simulations (mesh size: 5 mm global/2 mm local) replicated collapse pressures with ≤ 3% error, validated against experimental data. Microstructural analysis identified dual failure mechanisms: axial collapse initiated at stress-concentrated zones (100–150 mm from ends, 30% above average stress), while radial failure originated from surface defects (0.1 mm scratches amplifying strain by 40%). A novel multifactor correction formula integrating API standards with microstructure-aware terms (grain size: n = 0.5 Hall–Petch exponent; defect tolerance: ovality ≤ 2%) reduced collapse pressure prediction errors from 16% to 18% (API) to ≤ 6.7%. The model quantifies temperature effects via Arrhenius-type decay (α_T = 0.0032 for BG110V) and inclusion-driven microcrack thresholds (C_inclusion ≤ 1.2 vol%). These findings establish a microstructure-property-performance framework for optimizing casing design in ultra-deep reservoirs, balancing computational efficiency with industrial reliability. Recommendations include expanding validation to cyclic fatigue scenarios and hydrogen embrittlement environments to advance next-generation well integrity protocols.

New triangular elements incorporating an interior node are developed based on barycentric coordinates and implemented in the Element Differential Method. Shape functions for four- and seven-node triangular elements are constructed following a serendipity-inspired approach, with explicit expressions for their first- and second-order derivatives. Numerical validation is performed through steady-state and transient heat conduction, as well as solid mechanics problems involving both regular and complex geometries. Results demonstrate that the seven-node barycentric element (T7B3) achieves second-order convergence, exhibits superior numerical stability, and outperforms its Cartesian counterpart (T7C3) and conventional elements in both accuracy and robustness. Notably, proper placement of the interior node at the centroid markedly enhances performance, whereas deviation leads to numerical oscillations and instability. The proposed T7B3 element demonstrates excellent performance for high-fidelity simulations in complex geometries and offers an effective alternative to traditional triangular and quadrilateral elements.

A novel Adaptive Mesh Refinement (AMR) strategy is developed and evaluated for transonic high-speed flows using Ansys Fluent. The algorithm for marking cells for adaptation is designed to systematically reduce local truncation errors based on the curvature of the primitive vector field. The algorithm for marking cells for adaptation is described in sufficient detail to be portable to other flow solvers that offer AMR. The relative importance of each primitive vector variable within the scheme is evaluated using both equal-weighting and optimized-weighting approaches. Variations of the proposed algorithm that use flow gradients or limit adaptation regionally are also investigated. The negative consequences of adaptation without enforcing the original smooth surface shape are demonstrated. An equal-weighted, primitive vector curvature-based strategy is shown to typically produce near-grid-independent results with an order of magnitude less grid required than classic grid refinement.

The proposed study presents a finite element direct formulation of limit analysis, allowing the application of the classical method of limit design to complex structures in two and three-dimensional environments. The main result of the proposed method is to recognize the admissible stress in a structure as a function of a finite number of nodal parameters that allow defining the optimal program to implement the lower bound theorem in the Melàn form. Direct limit analysis, devoted to calculating the collapse load, does not depend on the detailed knowledge of the load time history that is generally unknown. Specific formulation for masonry structure is described, focusing on the two-step approach at the constituent scale, mortar and brick fabric, and at the structural scale. Namely, at first, limit analysis has been applied to Representative Volume Elements describing the masonry fabric and has been used to calculate the limit strength along the principal axes of the material anisotropy. A second step involves applying the procedure to a structure composed of the material obtained from the previous analysis. The proposed examples describe a typical masonry building where the anisotropic behavior of the material, both in the elastic and plastic ranges, has been considered, highlighting the feasibility of the method and the accuracy of the obtained results. Finally, a literature case, the Prestwood bridge, whose experimental collapse load is obtained from a full-scale test by Page, has been analyzed to compare the method with experiment and different numerical approaches, confirming its feasibility and robustness.

A novel finite element particle method (FEPM) is proposed in this paper for modeling extreme deformation problems. In a material domain, regions undergoing small deformation are discretized using elements of the finite element method (FEM), while zones subject to extreme deformation are represented with particles of the material point method (MPM). A background grid, covering the entire computational domain, is employed to solve the momentum equations. To circumvent mesh distortion, distorted elements under extreme deformation are adaptively converted into particles during the simulation. The seamless coupling between elements and particles is naturally achieved through the background grid's single-valued velocity field. Furthermore, a contact method is introduced to handle interactions between distinct material domains. Several numerical examples, including symmetric rod impact, soil collapse, soil collapse with a base, penetration of a plate by a long rod projectile, and penetration of a plate by an explosively formed projectile, are studied using the proposed FEPM. The numerical results exhibit good agreement with published literature data and experimental results, demonstrating the effectiveness of FEPM in simulating extreme deformation scenarios.

The initial value problem under dense initial conditions (D-IVP) is a critical challenge in aerospace engineering, such as debris tracking and orbital uncertainty propagation. Finite-difference-based methods are the most commonly used methods for solving this type of problem; however, they suffer from low computational efficiency when dealing with large-scale D-IVPs due to their reliance on small integration step sizes to maintain accuracy. To address this issue, this paper proposes an efficient semi-analytical method that combines polynomial approximation with parallel large-step computation. Using Taylor expansion in the spatial domain, the proposed method expresses the solutions of the D-IVP as a polynomial with temporally varying coefficients, whose computational cost is independent of the problem's scale. In particular, these coefficients are efficiently derived through parallel integral iteration in large steps, bypassing the limitations of finite-difference methods. The method's performance is validated through three classical dynamic problems, and the computational results demonstrate that its efficiency advantage over conventional methods increases with the scale of the D-IVP.

This study presents a numerical investigation into the fracture behaviour of composite materials—an essential consideration for the reliable and sustainable design of lightweight structural components. To accurately capture their complex failure mechanisms, a phase-field approach integrated with an elasto-plastic material model was employed. The numerical framework utilised user-defined subroutines (UMAT and UEL) within ABAQUS, complemented by additional simulations performed on the open-source FEniCS platform. Deep Neural Network (DNN) is used to solve the phase field equations, and the results are compared to the standard FEA framework. Characteristic composite fracture features like crack deflection, kinking and nonlinearity are well presented. Given the inherent anisotropy and heterogeneity of composite materials, modelling their fracture behaviour remains challenging. Benchmark simulations, including force–displacement responses, were validated against published literature and demonstrated strong agreement. The diffuse nature of crack propagation—characteristic of the length-scale-dependent, nonlocal continuum mechanics underpinning the phase-field method—was effectively captured and illustrated through plots showing phase-field evolution relative to the distance from the crack centre.