共查询到16条相似文献,搜索用时 193 毫秒
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基于非局部近场动力学(Peridynamics,PD)理论,对含预置裂纹的混凝土巴西圆盘劈裂破坏问题进行建模分析.将结构离散为包含混凝土材料信息的粒子,引入动态松弛、分级加载和失衡力守恒等粒子系统数值算法,构建可以自然模拟脆性裂纹扩展的PD算法体系.对含不同角度单预置中心裂纹巴西圆盘的裂纹扩展过程进行数值模拟,所得结果与试验结果吻合较好,验证所提出的模型和算法正确.进一步采用该方法模拟双预置裂纹巴西圆盘劈裂破坏过程中的裂纹扩展、交汇、贯通过程,通过将所得模拟结果与试验结果进行比较分析,探究该方法处理多裂纹扩展问题的可行性. 相似文献
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提出基于神经网络的裂纹扩展过程实时预测方法,其计算效率比近场动力学(peridynamic,PD)模型提高.使用PD算法获取裂纹扩展过程中的损伤云图,构建裂纹扩展数据集.基于数据集构建生成对抗网络(generative adversarial networks,GAN)模型,根据不同加载条件实时生成损伤云图,从而快速预测裂纹的扩展过程.将PD模型计算得到的损伤云图中的RGB值与相应位置处的损伤值结合,构建多层前馈神经网络模型的数据库,并使用多层前馈神经网络模型分析GAN模型产生的损伤云图,得到相应的损伤值.通过数值算例证明该方法的效率和准确性. 相似文献
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提出适用于壳结构裂纹扩展仿真的等几何分析(isogeometric analysis, IGA)与近场动力学(peridynamic, PD)耦合模型,采用非均匀有理B样条(non-uniform rational B-spline, NURBS)函数精确描述几何模型,将整个模型分为裂纹扩展区域和非扩展区域。将裂纹扩展区域设置为近场动力学区域,基于非连续伽辽金(discontinuous Galerkin, DG)有限元离散的PD Reissner-Mindlin(R-M)壳模型进行计算;在非扩展区域采用等几何分析R-M壳模型进行计算。基于力和力矩平衡原理,进行2个区域的耦合。IGA-PD壳耦合模型可以准确模拟壳结构中的裂纹扩展、分叉和合并过程,可提高计算效率。采用标准算例验证所提出算法的效率和准确性。 相似文献
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使用近场动力学常规态理论对于弹体高速侵彻陶瓷/金属复合靶板进行了数值仿真,并讨论了态理论中的适用性问题.分别采用弹性和J2率无关弹塑性本构模型进行了陶瓷/金属靶板的PD建模,模拟了刚性弹体高速侵彻陶瓷复合靶板的过程,获得了弹体的速度时程曲线、靶板的破坏模式及靶板飞溅的情况,并将仿真结果与有限元结果及实验对比.采用不同的影响函数及近场作用范围计算得到靶板的裂纹扩展模式.结果表明通过采用合适的本构模型PD方法可以有效准确地模拟复合靶板受弹体高速侵彻的全过程,存在较优的影响函数与近场作用范围使得计算结果准确. 相似文献
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基于二次插值重构有限元法(Twice interpolation Finite Element Method, TFEM)分析动态断裂力学问题并进行数值实验,考察TFEM在裂纹动态扩展模拟中的准确性和可靠性.由于TFEM保证节点处梯度场的连续性,因此裂尖附近的应力场可以得到较好的逼近.把该算法成功移植到自主开发的三维裂纹扩展仿真软件(ZonCrack)中.利用ZonCrack进行的裂纹扩展,分析结果表明:TFEM得到裂尖应力强度因子(Stress Intensity Factor, SIF)与解析解基本一致;裂纹扩展的模拟结果与实验值吻合良好. 相似文献
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给出了一种利用有限元技术模拟周期性张力载荷作用下孔边角裂纹扩展过程的方法。首先利用一系列点定义裂纹前沿,据此形成包含奇异单元的二维有限元网格,再扩展为三维网格.然后利用有限元法进行应力应变分析,最后使用Paris定律计算局部扩展增量.以此来更新裂纹的形状和尺寸。该方法还能够自动地重复执行扩展仿真。文中还对三个不同半径的四分之一椭圆形边角裂纹扩展过程进行了仿真和分析比较,以此来取得裂纹在扩展过程中的形状变化特征和不同方向上扩展的特征。 相似文献
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《Advances in Engineering Software》2002,33(7-10):577-587
The FRANC3D/BES software system has been used to simulate the reorientation and link-up of hydraulic fractures in three-dimensional (3D) problems. The adopted technique only needs to discretize the body surface and the crack surface. The crack propagation direction is determined using the minimum strain energy criterion. Crack propagation amount is calculated using the mode I stress intensity factor. In hydraulic fracturing, the number of multiple cracks for a given number of perforations depends on the resulting interaction of the cracks. The interaction may be expressed by the fracture stiffness which has been obtained for 3D problems in this paper. 相似文献
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In this paper, we exploit the use of peridynamics theory for graphical animation of material deformation and fracture. We present a new meshless framework for elastoplastic constitutive modelling that contrasts with previous approaches in graphics. Our peridynamics‐based elastoplasticity model represents deformation behaviours of materials with high realism. We validate the model by varying the material properties and performing comparisons with finite element method (FEM) simulations. The integral‐based nature of peridynamics makes it trivial to model material discontinuities, which outweighs differential‐based methods in both accuracy and ease of implementation. We propose a simple strategy to model fracture in the setting of peridynamics discretization. We demonstrate that the fracture criterion combined with our elastoplasticity model could realistically produce ductile fracture as well as brittle fracture. Our work is the first application of peridynamics in graphics that could create a wide range of material phenomena including elasticity, plasticity, and fracture. The complete framework provides an attractive alternative to existing methods for producing modern visual effects. 相似文献
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Min-Yeong Moon Jae-Hyun Kim Youn Doh Ha Seonho Cho 《Structural and Multidisciplinary Optimization》2015,51(3):585-598
Based on the peridynamics of the reformulated continuum theory, an adjoint design sensitivity analysis (DSA) method is developed for the solution of dynamic crack propagation problems using the explicit scheme of time integration. Non-shape DSA problems are considered for the dynamic crack propagation including the successive branching of cracks. The adjoint variable method is generally suitable for path-independent problems but employed in this bond-based peridynamics since its path is readily available. Since both original and adjoint systems possess time-reversal symmetry, the trajectories of systems are symmetric about the u-axis. We take advantage of the time-reversal symmetry for the efficient and concurrent computation of original and adjoint systems. Also, to improve the numerical efficiency of large scale problems, a parallel computation scheme is employed using a binary space decomposition method. The accuracy of analytical design sensitivity is verified by comparing it with the finite difference one. The finite difference method is susceptible to the amount of design perturbations and could result in inaccurate design sensitivity for highly nonlinear peridynamics problems with respect to the design. It is demonstrated that the peridynamic adjoint sensitivity involving history-dependent variables can be accurate only if the path of the adjoint response analysis is identical to that of the original response. 相似文献
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This study develops a novel hybrid method that combines the finite element method (FEM) and the scaled boundary finite element method (SBFEM) for crack propagation modelling in brittle and quasi-brittle materials. A very simple yet flexible local remeshing procedure, solely based on the FE mesh, is used to accommodate crack propagation. The crack-tip FE mesh is then replaced by a SBFEM rosette. This enables direct extraction of accurate stress intensity factors (SIFs) from the semi-analytical displacement or stress solutions of the SBFEM, which are then used to evaluate the crack propagation criterion. The fracture process zones are modelled using nonlinear cohesive interface elements that are automatically inserted into the FE mesh as the cracks propagate. Both the FEM’s flexibility in remeshing multiple cracks and the SBFEM’s high accuracy in calculating SIFs are exploited. The efficiency of the hybrid method in calculating SIFs is first demonstrated in two problems with stationary cracks. Nonlinear cohesive crack propagation in three notched concrete beams is then modelled. The results compare well with experimental and numerical results available in the literature. 相似文献
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针对现有顶板定向水力压裂技术中缝槽预制工序繁琐、成缝质量差的问题,提出钻孔、高压水射流切缝、高压水力压裂(钻-切-压)一体化预裂顶板防冲技术,并在葫芦素煤矿进行了试验研究。试验结果表明:“钻-切-压”一体化技术与装备在不退钻杆的前提下能够进行人工切槽,并采用单孔后退式多次压裂,提高了施工效率;使用的对称双孔型高压射流器能够高效形成4~5 mm宽度的人工缝槽,增大了切缝效果,并降低了压裂时裂缝起裂压力,扩展了压裂半径,单轴抗压强度为50~60 MPa的顶板岩层,单次压裂半径最大可达15 m;“钻-切-压”技术弱化顶板使得巷道围岩应力水平降低,临空巷道附近高能微震事件数量大幅减少,微震频次和能量无急剧变化,保证了工作面顺利回采。 相似文献