Path-independent integral for the dilatation symmetry group in thermoplasticity

The aim of this study is to establish a fatigue criteria based on an energy threshold corresponding to crack initiation in the case of dilatational symmetry of a structure under thermomechanical loading. An extension of the M integral to thermoplasticity relating to the scaling symmetry is presented. Based on a discrete Lagrangian describing the thermo-inelastic system and Noether's theorem defining the conservation law, the null Lagrangian theorem is applied in order to introduce thermoplasticity. By the use of the divergence theorem, the modified M integral is obtained. Path-domain independence is discussed illustrated by a numerical example.     

弹塑性结构的动力学塑性变形的上界

本文借助于虚载荷方法讨论了弹性完全塑性结构在动载荷下塑性变形的上界问题,结出了塑性变形的上界估计式.同时,在假设分段线性加载面的情况下,将结果推广到线性强化结构.此外,本文还给出一例,将所得结果与精确解进行了比较,表明本文的结果有较大的实用价值.     

挤扩支盘桩承载变形特性的试验研究及承载力计算

根据单桩静载荷试验及桩身轴力的测试结果,深入分析了竖向荷载作用下挤扩支盘桩的荷载传递机理和变形特性;同时给出挤扩支盘桩的单桩承载力计算公式。通过分析计算,指出了支盘的承力特性具有明显的时间效应和端承性质,揭示了支盘桩高承载力和S型Q-S曲线的内涵。     

Modeling of a locking mechanism between two rough surfaces under cyclic loading

The work is motivated by experimental studies on energy dissipation due to micro-slip in mechanical joints. It has been observed that the loss of energy undergoes certain evolution under cyclic shear loading. It manifests itself in the form of the gradual decrease approaching a steady state as cycling progresses. This behavior has a repeatable character if contact is re-established and subjected to cycling again. In the present work, a simple multiple-asperity model is developed that suggests a physical hypothesis that when two rough surfaces are brought in contact and subjected to shear loads a certain locking mechanism comes into play at the interface. Such locking occurs due to the tendency of the interface to adapt its contact microstructure to the loading conditions. The adaptation mechanism is described in the present work through the contact inclination angles. The developed model is simple in application and it relates micro-characteristics of the contact to macro-behavior of the system exhibiting itself in energy dissipation.     

Influence of boron/steel/aluminium hybrid composite structure on the energy dissipation therein

The technological conditions for making polyreinforced composites by hot pressing stacks consisting of boron/aluminium monolayers and knitted nets of stainless steel have been studied. Improvement of mechanical properties, and especially behaviour under cyclic loading, was achieved as a result of introducing additional loop elements of thin steel wires into the macrostructure of the composite. It was found that the arrangement of net layers, the number of wires in a bundle and the steel content considerably affected the cyclic strength and energy dissipation factor.     

光面爆破主要参数的优选及校核

结合三峡工程右岸地下电站洞挖施工,论述了光面爆破主要爆破参数与不耦合装药系数之间的关系,提出了根据不耦合系数对爆破参数进行校核和优选的方法.     

均布荷载下钢筋混凝土梁非线性有限元分析

通过对一钢筋混凝土简支梁的分析，利用大型通用有限元软件ANSYS对其在均布荷载作用下的力学性能进行模拟，并对计算结果进行了分析比较，以促进均布荷载下钢筋混凝土简支梁的力学性能的研究。     

计算机集散监控下的机械封闭式试验台

本文对机械封闭式试验台的结构和性能以及加载方法进行了简述、较详细地叙述了集散监控微机系统的控制方式，并以一试验实例叙述了该系统的使用程序及功能，为实现室内模拟道路载荷谱试验提供借鉴手段。     

影响先期固结压力的因素

介绍了影响先期固结压力的几方面的主要因素，并结合自己的实际情况所采取的措施。     

采煤机截割部试验台监控系统的设计与实现

根据机械闭环采煤机截割部试验台的特点 ,设计并实现了以PC机为核心 ,以RS4 85总线为纽带组成采煤机截割部试验台监控系统。在设计过程中解决了通讯协议相互干扰和电子屏实时显示数据等几项关键技术。经过安装调试和对采煤机截割部的测试 ,达到了设计的要求