An adaptive finite element procedure for crack propagation analysis

INTRODUCTION The finite element method (FEM) has proved to be very well suited for the study of fracture mechanics. Nevertheless, modelling the propagation of a crack through a finite element mesh turns out to be difficult because of the modification of the mesh topology. Use of crack propagation laws based on stress inten-sity factor range is the most successful engineering application of fracture mechanics. The stress intensity factors are a very important parameter in fracture analys…     

利用认知技术有效地克服体育运动中的应激现象

体育运动中，不良的应激反应会使运动中或参加体育锻炼的人过多地消耗身体能量，人际关系紧张，并导致运动损伤，最终导致比赛的失利和运动乐趣的丧失。本文主要从认知的角度阐述了克服体育运动中不良应激的几种方法。     

锥形杆应力公式的讨论

锥形杆在拉(压)、扭、弯时,平面假设不成立,严格地说,用材料力学的方法给出的应力公式不能用,而应该根据弹性理论给出其应力的计算公式.本文就锥形杆在拉压与扭转以及锥形梁在集中力作用下弯曲时,分别用材料力学和弹性力学的方法给出应力公式并加以讨论,同时对材料力学给出的结果及误差进行分析.     

矩形板的杂交有限条解法

本文建立一种板的应力杂交有限条,用于求解简支矩形板。在有限条列式中,条内假设应力场,并使其满足平衡方程。在条间假设位移场。对简支矩形板的数字算例表明,这种方法是可行的,并能较快地逼近准确解。     

焊接接头的应力腐蚀开裂及防护

应力腐蚀断裂是焊接结构断裂失效的重要原因之一,这种断裂失效呈脆断特点,易导致灾难性后果.探讨应力腐蚀裂纹的产生、开裂的机理及其影响因素,并提出控制焊接结构发生应力腐蚀断裂的措施.     

Finite element model for linear-elastic mixed mode loading using adaptive mesh strategy

An adaptive mesh finite element model has been developed to predict the crack propagation direction as well as to calculate the stress intensity factors （SIFs）, under linear-elastic assumption for mixed mode loading application. The finite element mesh is generated using the advancing front method. In order to suit the requirements of the fracture analysis, the generation of the background mesh and the construction of singular elements have been added to the developed program. The adaptive remeshing process is carried out based on the posteriori stress error norm scheme to obtain an optimal mesh. Previous works of the authors have proposed techniques for adaptive mesh generation of 2D cracked models. Facilitated by the singular elements, the displacement extrapolation technique is employed to calculate the SIK The fracture is modeled by the splitting node approach and the trajectory follows the successive linear extensions of each crack increment. The SlFs values for two different case studies were estimated and validated by direct comparisons with other researchers work.     

锥杆中应力波传播的放大特性

从变截面杆中一维应力平面波的无量纲控制方程组出发,采用特征线数值解法分析了应力波在锥形杆段中的传播特性,讨论了无量纲参数λ、τ_r和R对透射波放大系数和波形的影响,为应力波放大器的合理设计提供了理论依据。在Hopkinson压杆装置上对锥杆中的应力波传播进行了实验研究。理论分析计算和实验研究结果一致地表明原先由Leftheris提出的计算公式和有关结论是错误的。     

A first order system model of fracture healing

INTRODUCTION Fracture healing is an important research subject in biomechanics. During the last years, many theories and simulation models have been proposed for de- veloping a comprehensive view of the mechanisms controlling bone morphogenesis. Pauwels (1960) was one of the first authors to propose a theory of tissue differentiation in response to local mechanical stress and strain. He assumed that deviatoric stresses com- prise the specific stimulus for the formation of fibrous connecti…     

应用网络虚拟实验技术实现压力容器应力测试实验

随着计算机技术的发展,网络虚拟实验室技术正在悄然兴起,能够实现跨时空、跨学科的仪器设备远程共享,甚至远程控制,满足科研教学对分布式实验系统的要求,本文介绍了压力容器应力测试虚拟实验的实现技术,通过计算机网络系统,研究人员或学生将不受时空的限制,随时随地与同行协作,共享仪器设备,共享数据和计算资源。