Advances in Engineering Software最新文献

This paper presents a user-friendly software to assign spatially distributed material properties to nonlinear finite element models in LS-DYNA using discretized three dimensional random fields and random variables. The purpose of the software is to enable probabilistic analysis frameworks that incorporate results from LS-DYNA simulations with random material properties. The software leverages the existing well-established deterministic formulation of LS-DYNA by utilizing inbuilt material constitutive laws. K-nearest neighbors spatial interpolation and k-means clustering are implemented to streamline the generation and assignment of random fields to parts in LS-DYNA models. The functionality of the software is demonstrated through real-life safety assessments of two marine structural elements composed of steel-reinforced concrete. Analysis results demonstrated the robustness and efficiency of the software where it can be successfully integrated into analysis frameworks to evaluate the safety of structural members.

The aim of this work is modeling processes of field electron emission in strong electromagnetic fields. This problem is relevant for many technical and medical applications. At present time, electrical devices that combine a large value of field, a powerful relativistic effect and an ultra-short time interval of action are in demand. They find their application in the treatment of the surfaces with inorganic, organic and mixed structures. Modeling of such devices encounters certain difficulties due to the complexity of the mathematical description of the emission processes. In this paper, an approach using the method of large smoothed particles in combination with grid calculation of fields based on Maxwell's equations is proposed. The study was carried out within the framework of the problem of calculating the field emission of electrons from the surface of axisymmetric metal cathodes on Cartesian and unstructured curved meshes. To implement the approach, a complex mathematical model, a parallel numerical algorithm and its software realization have been developed. The elaborated software is focused on the use of multiprocessor computing systems with a central architecture. Test calculations confirmed the correctness of the proposed approach and the high efficiency of its software implementation.

This paper presents a novel algebraic workflow for topological voxelization of spatial objects, construction of voxel connectivity graphs & hyper-graphs, and derivation of partial differential and multiple integral operators. Discretization of models of spatial domains is central to many analytic applications in such application areas as medical imaging, geometric modelling, computer graphics, engineering optimization, geospatial analysis, and scientific simulations. Whilst in some medical applications raster data models of spatial objects based on voxels arise naturally, e.g. in CT Scan and MRI imaging, in engineering applications the so-called boundary representations or vector data models based on points are far more common. The presented methodology puts forward a complete alternative geometry processing pipeline on par with the conventional vector-based geometry processing pipelines but far more elegant and advantageous for parallelization due to its explicit algebraic nature: effectively, by creating a mapping of geometric models from $R^3$ to $Z^3$ to $N^3$ and eventually to an index space created by Morton Codes in $N$ while ensuring the topological validity of the voxel models; namely their topological thinness and their geometrical consistency. The set of differential and integral operators presented in this paper generalizes beyond graphs and hyper-graphs constructed out of voxel models and provides an unprecedented complete set of algebraic differential operators for the discretization of digital simulations based on PDEs and advanced analyses using Spectral Graph Theory and Spectral Mesh Processing.

We present an open-source parallel shared-memory C++ software for simulations of transient phenomena on tensor product grids, with the following features: (1) it supports isogeometric finite element method discretizations; (2) it employs alternating-directions (ADS) linear cost $O\left(N\right)$ solver; (3) it uses implicit time-integration schemes suitable for ADS, including Peaceman–Rachford, Douglass-Gunn, Adams–Moulton, generalized alpha, and BDF; (4) it works for 2D/3D problems; (5) it enables residual minimization stabilization; (6) it supports scalar, vector fields, and systems of PDEs; (7) it provides a ParaView interface; (8) it supports an interface to parallel MUMPS direct solver for problems not suitable for ADS solver; (9) it also supports interface to Preconditioned Conjugate Gradients (PCG) solver; (10) it includes a large library of problems: (a) non-stationary heat transfer (2D/3D); (b) stationary advection–diffusion (2D); (c) non-stationary advection–diffusion (2D/3D); (d) laminar flow (Stokes equations) (2D/3D); (e) Navier–Stokes (2D); (f) pollution propagation (2D/3D); (g) pathogen propagation (3D).

Due to forest soil environment being short of structured terrain, research of tire-soil interaction is critical to enhance the performance for small wheeled mobile platform in forest. A novel model coupled finite element method (FEM) and discrete element method (DEM), which can be used to investigate the interaction behavior between the small wheeled mobile platform tire and forest soil, was proposed in this paper. In particular, the tire model based on rubber parameters that were obtained by uniaxial tensile tests is established in ABAQUS. The mechanical parameters of the soil in forest were obtained by the standard of geotechnical test and the triaxial compression test. The soil model was established in PFC3D. Significantly, the novel tire-soil interaction model based on the coupling ABAQUS and PFC3D was proposed accurately. The drawbar pull, the sinkage and the soil vertical stress were obtained through the proposed tire-soil interaction model. Meanwhile, soil-bin tests for tire-soil interaction were established. The drawbar pull, the sinkage and the soil vertical stress were obtained in soil-bin tests, which were consistent with the results from the proposed tire-soil interaction model. The results validated the effectiveness of the coupling method and the accuracy of the proposed tire-soil interaction model. Moreover, the flow state of soil particles was described by the proposed tire-soil interaction model, which analyzed the forces evolution in the area where the tire was in contact with the soil.

An essential task in the oil and gas industry is establishing an efficient way to assess corroded pipeline integrity. The literature shows that integrity analysis with Finite Elements simulations is the most effective. However, when faced with solving practical problems, the inconvenience of the high computational cost arises. This work aims to develop an efficient system to accurately predict the burst pressure of corroded pipelines with complex corrosion profiles through hybrid models combining multiresolution analysis, numerical simulations, and metamodels. The corroded region will be captured from ultrasonic inspections. Subsequently, the representation of corroded zones is parameterized with a discrete wavelet transform to reduce the amount of data representing the defect. The metamodel is built by training a neural network with the coefficients obtained from the wavelet transform and the pipeline material properties. The training data for the neural network are the failure pressures computed with non-linear finite element analysis of three-dimensional synthetic models with similar statistics to real corrosion profiles. The results obtained with the neural networks are accurate for all the test cases presented in this work.

The classic Kresling origami structure has been widely studied in the past two decades because of its interesting mechanical properties, including compressive-twist coupling deformation and bistability. It is also known that the conical derivative of Kresling origami can achieve a wider range of structural configurations while preserving the bistability of the original design. Moreover, different origami structures exhibit different responses to local geometric or material imperfections which are often inevitable in practical applications. In this study, we utilize the bar-and-hinge model to convert local imperfections to corresponding variations in nodal coordinates and equivalent stiffness values. Subsequently, we examine the response of conical Kresling origami structures to certain local imperfections. It is demonstrated that the effect of geometric imperfections on the folding properties of such structures is more substantial than that of material imperfections. We show that the multistability of conical Kresling origami structures may undergo a radical transformation when the value of the imperfection exceeds a certain threshold. Furthermore, based on responses to local imperfections, a derivative of the conical Kresling origami structure is designed which manifests tristability. This work develops a strategy for the form-finding of origami structures with tunable multistability, and can be generalized to analyze combined results from multiple local imperfections.

The efficiency of solving sparse linear equations in isogeometric topology optimization (ITO) can be improved by the multigrid algorithm due to its excellent convergence rate. However, its convergence rate heavily relies on the smoother's parameters. To address this problem, a new h-refinement multigrid conjugate gradient method with adaptive damped Jacobi (ADJ-hMGCG) has been developed. By analyzing the eigenvalues of the stiffness matrix, the damping coefficient of the smoother that achieves the fastest convergence rate has been determined. Due to the significant computational resources required to compute eigenvalues in the stiffness matrix, this paper also presents a preconditioned power method based on ITO and geometric multigrid characteristics to improve the efficiency of adaptive damping solutions. The results of 2D and 3D numerical examples show that the ADJ-hMGCG method successfully improves the solution speed and robustness while meeting the accuracy requirements of topology optimization, and the total computational cost can be reduced by up to 59 % compared to traditional solvers for large-scale problems.

An adaptive dimension-reduction Chebyshev metamodel (ADC) is proposed to balance the accuracy and efficiency of dimension-reduction Chebyshev metamodels. A univariate dimension-reduction Chebyshev metamodel (UDC) is constructed by the dimension-reduction method and the Chebyshev metamodel. Based on the UDC, the bivariate terms largely impacting the metamodel are selected using an adaptive selection method, and are combined with the UDC to construct the ADC. The ADC has higher accuracy than the UDC because more calculated sample points are added. Compared with the bivariate dimension-reduction Chebyshev metamodel, the ADC needs fewer sample points and has higher efficiency. The result of numerical examples illustrate that ADC has higher accuracy compared with other commonly-used metamodels and is more suitable for approximating high-dimensional complex models.

Parallel computing is essential for enhancing computational efficiency and advancing computational mechanics. To reduce the computational cost, peridynamics, a nonlocal numerical method, has been coupled with the finite element method (FEM). However, the accurate modeling of plastic deformation within the coupling framework of the FEM and non-ordinary state-based peridynamics (NOSB-PD) requires further investigation and might add to the computational expense. In this study, the open multi-processing application interface (OpenMP) is implemented for the plastic coupling of the FEM and stabilized NOSB-PD. The framework for the plastic coupling model using OpenMP is described in detail. The implemented code is used to investigate the coupling boundary effect on plastic deformation depending on the size of the coupling zone. After verifying the plastic coupling, the parallelization performance of the coupling model is examined. The efficient coupling model is applied to simulate plastic deformation on a plate with a circular hole, and the displacement results show good agreement with the reference solution. The proposed coupling model can be applied to efficiently solve the plastic deformation and fracture in future studies.