Engineering Analysis with Boundary Elements最新文献

The bifurcation stability of sandwich sector plates, primarily constructed from lead halide perovskite skins known for their significant photostrictive and electrostrictive properties, is explored. These properties render them highly relevant for multiphysics applications. The influence of a photo-induced thermal environment on the behavior of these plates is also examined. A notable challenge, the inherent stiffness of these structures, is addressed by integrating a nanocomposite laminated core composed of a polymer matrix and graphene platelet (GPL) reinforcers. The GPLs are distributed throughout the core layers according to functionally graded models, significantly enhancing structural integrity. To effectively model the core environment, the Halpin-Tsai micromechanical rule is employed. The structural displacement field is modeled using the first-order shear deformation theory. Moreover, the von-Kármán geometrically nonlinear strain-displacement relations are applied. The constitutive relationships are governed by the theory of linear photo-thermo-electro-elasticity, providing a framework for the analysis of perovskite-based structures. The reorganization of bifurcation points from the pre-buckling route and the linearization of stability equations are performed using the adjacent-equilibrium criterion. The generalized differential quadrature (GDQ) method is utilized to solve the equilibrium equations of pre-buckling and the stability equations of buckling. This comprehensive investigation reveals the critical influence of photonic, electrical, and rotational stimuli on the stability characteristics of advanced perovskite-based sandwich sector plates, demonstrating potential advancements in multiphysics applications.

This study innovatively combines Isogeometric Analysis (IGA) with Machine Learning (ML) to assess strip footing bearing capacity on dual clayey layers. Overcoming limitations of conventional methods with small sample sizes, our research generates a dataset of 10,000 samples, allowing a thorough exploration of diverse soil profiles. Facilitated by ML, 10,000 IGA analyses using upper bound limit analysis unveil intricate patterns and relationships previously obscured. The key innovation lies in harnessing big data and employing advanced data visualization, particularly 2D and 3D Partial Dependency Plots (PDPs). These PDPs visually showcase the impact of factors such as upper layer thickness, cohesion ratios, shear strength profiles, footing depth, and foundation roughness on bearing capacity. Offering intuitive insights, these visualization tools enhance comprehension, aiding informed decision-making in design and construction. Engineers and geotechnical experts receive a precise predictive tool, optimizing strip footing performance on clayey soil layers. Moreover, this research contributes to advancing geotechnical engineering by enriching fundamental knowledge of load-bearing characteristics. In summary, the fusion of big data, advanced visualization, and upper bound limit analysis, exemplified by PDPs, signifies a substantial leap in geotechnical engineering, impacting design, construction, and infrastructure development.

Lots of experiments observe the size-dependent phenomena of concrete mechanical behaviors. In this paper, the micropolar theory is adopted to describe the size effects by introducing two size-related parameters into their constitutive equations, named coupling number N and characteristic length l. A micropolar damage model is built for size-dependent concrete fracture problems utilizing the bond-based peridynamic (PD) idea. That is, the material damage and fracture behaviors are determined by the local damage factors of the PD bonds. Then, the tensile strength of a concrete specimen is numerically estimated by the PD differential operator (PDDO) method. The influences of the size parameters N and l on the tensile strength are studied. By comparing with the transformed Bažant size-effect law and the fitting error analysis, the reasonable values of N and l are determined for a certain reinforced concrete composite. Finally, by using the determined micropolar damage model, the crack propagation paths in concrete members are numerically simulated.

A general modeling approach is presented to analyze the free vibration behavior of the spatially coupled shell-plate system (SCSPS) with complex geometric shapes. The coupling mechanism established by the penalty function method can be applied not only to the SCSPS but also to other extensively studied shell-plate structures. The conventional method for irregularly-shaped plates involves the utilization of one-to-one mapping technology (OTOMT) to transform the two-dimensional plane domain of the plate into a square domain, aiming to fulfill the numerical solution requirement for integral calculation. However, since the OTOMT is a planar mapping technique that cannot be applied to shells, in this paper, we propose a coordinate transformation strategy to convert two-dimensional shells into plane geometry in order to address this limitation. The vibration problem is simultaneously resolved numerically using the Hamilton's principle and the Jacobi spectral method. The current method is validated for several key capabilities based on three case studies, as well as modal experiments and the commercial finite element software. Additionally, a series of model evaluations are employed to demonstrate the advantages of the current method. Moreover, the results of the parametric study illustrate the impact of several variables on the natural frequency of the structure.

In this paper, a novel semi-analytical numerical model based on the scaled boundary finite element method (SBFEM) is developed for the static and free vibration analyses of the stiffened cylindrical shells. The SBFEM is a numerical technique in which only the surfaces or boundaries of the computational domain need to be discretized, while an analytical formulation can be derived in the radial direction of the surrounding area. These advanced features enable the spatial dimension to be reduced by one, while the accuracy of the proposed algorithm is maintained. The stiffened shell structure is divided into the shell and stiffeners (curved beam and straight beam), and the basic physical equations as well as the associated boundary conditions of each part are described according to the elasticity theory. The surface of shell and the axis of stiffener are discretized, then the ordinary differential governing equations of shell and stiffeners are derived in the scaled boundary coordinate system using the virtual work principle. Based on the continuity conditions of displacement, the shell and stiffeners are assembled together, and the coupling stiffness and mass matrices are derived. Furthermore, the semi-analytical solutions are obtained by using Padé series expansion method, and the natural frequencies of the stiffened shell are determined through generalized eigenvalue analysis. Comparisons between the present numerical results and solutions available in the published work have been carried out to demonstrate the convergence and accuracy of this approach. At the same time, the influences of the geometric parameters and stiffener configuration on the static and free vibration behaviors of the stiffened cylindrical shells are studied in detail.

The problem of hydraulic fracturing is of great relevance to various areas and is characterised by the occurrence of complex crack patterns with bifurcations and branches. For this reason, an interesting approach is the modelling of hydraulic fracture using a phase-field model. In addition to the discretisation using the Finite Element Method (FEM), some works have already explored the discretisation of the phase-field model with meshfree methods, including the Smoothed Point Interpolation Methods (SPIM) family. Seeking to take advantage of the good convergence results of SPIM for phase-field modelling of brittle fractures, this paper proposes the use of SPIM for phase-field modelling of pressurised fractures. In order to limit the computational cost, a prescribed SPIM-FEM coupling is employed, with the purpose of concentrating the meshless discretisation only in the regions of expected crack propagation. The model is characterised by a constant internal pressure load along the fracture that is applied indirectly from the formulation of the phase-field model. A series of numerical simulations is presented. The aim is to evaluate the proposed model, verify the results and point out characteristics of the phase-field model with internal pressure.

Computational analysis of debris flow dynamics and its impact on structures, including check dams, is a long-standing problem for hazard prevention. It's a complex issue involving two-phase interaction between fluid mass and solid structure, as well as the large deformation failure of check dams, therefore, three-dimensional simulation of this process remains a scientific challenge. In this paper, a 3D-SPH-DEM coupling model is proposed by incorporating a nonlinear collision-constraint bond model. The model first builds upon our previous 3D-SPH model based on Herschel-Bulkley-Papanastasiou (HBP) rheology to describe the fluid behavior within the debris flow process. Secondly, a constituent particle-based DEM block representation method is integrated to model check dams, and the fluid-solid interaction force between debris flow particles and DEM blocks is obtained. Additionally, a nonlinear collision-constraint bond model with a predefined coefficient α is incorporated to simulate the solid interaction between DEM blocks and characterize the different strength levels of check dams. To verify the proposed model, a well-documented pier cubes failure experiment in a previous study is used, wherein the simulation results well reproduce the failure process as observed in the experiment from the quantitative perspective. The 2010 Yohutagawa debris flow event is selected as the case study. Results show that the proposed model well simulates the fluid-solid interaction phenomenon and can effectively explore the large deformation failure process of check dams under debris flow impact.

Selective laser melting (SLM) is an advanced additive manufacturing technology related to the powder bed fusion (PBF) process. Numerical simulation is the key means of realizing the shape and property control of components for additive manufacturing. In this paper, an improved smoothed particle hydrodynamics (SPH) method is proposed for the numerical simulation of the SLM process, focusing on the melt pool flow. The accuracy of calculations at the free surface is significant for modeling the SLM process and there are kernel function truncation errors of the SPH method at the free surface. Therefore, an improved kernel gradient correction (KGC) technique and an improved continuous surface tension model are proposed to improve the accuracy of calculations at the free surface. The KGC technique can improve the accuracy of the kernel gradient in SPH approximation, however, the accuracy of KGC will decrease on the free surface. To improve the computational accuracy on the free surface, an improved KGC is developed. The surface tension model is significant for the numerical simulation of the SLM process, and an improved continuous surface tension (CSF) model is developed to enhance the stability and accuracy of surface tension modeling. In addition, a Gaussian heat source model and a latent heat model are introduced in the improved SPH model. The accuracy and effectiveness of the present SPH method for simulating the melting and melt pool flow of the SLM process are also verified by four numerical examples.

Potential flow theory-based solvers are commonly used in ocean engineering to investigate the interactions between ocean waves and floating bodies. Depending on assumptions, several methods have been proposed. Among them, the Weak-Scatterer method is an interesting trade-off in the sense that this approach is not limited in theory by the small wave amplitudes and small body motions assumptions of linear methods. Moreover, this approach is in practice more stable than the fully non-linear methods. An implementation of the Weak-Scatterer method is the WS-CN code (Letournel, 2015; Chauvigné, 2016; Wuillaume, 2019).

The computational time of the WS-CN code which is considered in the present study is relatively long for engineering purposes. In order to reduce it, the present paper presents an implementation of the Parareal method in the WS-CN code. The Parareal method is an algorithm for parallelizing a simulation in time that can accelerate the complete simulation (Lions, 2001) . This is a key difference in comparison to other acceleration techniques which have been studied in the literature (e.g. the Fast Multipole Method (FMM), the precorrected Fast Fourier Transform (pFFT) method, $\dots$ ). To the authors’ knowledge, the present study is the first to couple the Parareal method to a potential flow theory-based wave-structure interaction solver. It is shown that the method can significantly reduce the computational time for small wave steepness, but that the performance decreases rapidly with increasing steepness.

Promising algorithm of alternating generalized projection method (AGP) is proposed for phase-only synthesis process of satellite reflectarray antennas under intersection approach. This promising algorithm is a hybridized algorithm of two specialized algorithms for non-convex sets rescued in the literature: algorithm based on separating hyperplanes and algorithm based on decomposition method in polar cones. Since the sets involved in phase-only synthesis process of satellite reflectarray antennas are non-convex, the conventional von Neumann alternating projection method proposed in the literature does not guarantee convergence to the point in the intersection of the involved sets. In addition, the results of the phase-only synthesis obtained by the different algorithms were compared and promising improvements produced by the proposed hybridized algorithm were shown.