Advances in Engineering Software最新文献

This paper describes the design and implementation of a digital twin model in the open-source MuPIF simulation platform. MuPIF enables a user-defined data model based on an ontology or schema to be created. A representation of the data model is generated in a target data management system. The data model, integrated with MuPIF, lets model entities to be linked, and model attributes can be assigned to simulation workflows inputs and outputs. The model is semantically-defined, provides full traceability, and has a web-based API for data discovery.

The existing data indicate that two-thirds of engineering accidents occur during construction among which engineering accidents caused by scaffold collapse account for a large proportion. Due to the complex mechanical behavior of connection and random nature of scaffold system caused by random geometrical imperfection, the reliability of scaffold system is lower than other kinds of building structures. However, the method considering the random geometrical imperfection is limited. To facilitate the analysis of random geometrical imperfection, the original numerical algorithm is proposed based on ANSYS Parametric Design Language. Through proposed method, two types of geometrical imperfections, i.e., the nodal location error and initial curvature can be automatically considered. The randomness in initial curvature includes random magnitude and random direction. The established numerical model is as close to reality as possible and the process of establishing stochastic numerical model can be automatically finished. The only work that needs to be done is to enter the dimensions of the scaffold. Except the propose of numerical algorithm, the objective of this study is to reveal the influence of geometrical imperfection on random distribution of loading capacity of scaffold system under different load conditions. The influence of random geometrical imperfection on probabilistic distribution of loading capacity is systematically investigated. The results indicated that there may be several buckling modes exist and the buckling mode occurred in actual condition is closely related to the random distribution of geometrical imperfection. The load factor of internal post (point 3) is 8 %–12 % larger than that of corner post. The load factor of side post is 4.7 %–7.2 % larger than that of corner post. The ultimate bending capacity M_u has little influence on the loading capacity of scaffold system when the initial bending stiffness k_o is small enough.

This paper provides an insight into the development of a state-of-the-art video processing system to address limitations within Durham University’s ‘Encore’ lecture capture solution. The aim of the research described in this paper is to digitally remove the persons presenting from the view of a whiteboard to provide students with a more effective online learning experience. This work enlists a ‘human entity detection module’, which uses a remodelled version of the Fast Segmentation Neural Network to perform efficient binary image segmentation, and a ‘background restoration module’, which introduces a novel procedure to retain only background pixels in consecutive video frames. The segmentation network is trained from the outset with a Tversky loss function on a dataset of images extracted from various Tik-Tok dance videos. The most effective training techniques are described in detail, and it is found that these produce asymptotic convergence to within 5% of the final loss in only 40 training epochs. A cross-validation study then concludes that a Tversky parameter of 0.9 is optimal for balancing recall and precision in the context of this work. Finally, it is demonstrated that the system successfully removes the human form from the view of the whiteboard in a real lecture video. Whilst the system is believed to have the potential for real-time usage, it is not possible to prove this owing to hardware limitations. In the conclusions, wider application of this work is also suggested.

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.