复杂边界支承的钢筋混凝土板的试验研究

对复杂边界支承条件下的钢筋混凝土矩形板进行了试验 ,重点研究不同支承条件以及不同板内配筋对板的性能的影响 ,对板的屈服线模式、板的强度及变形等方面作了分析     

考虑土与结构相互作用的钢筋混凝土框架子结构抗震性能试验研究

独立基础-钢筋混凝土框架结构在遭遇地震时会出现底层柱破坏严重并且柱端出现大量塑性铰的破坏形态,同时考虑到独立基础对底层柱的约束能力会影响上部结构塑性铰的发展顺序,应对土与结构相互作用对混凝土框架抗震性能的影响进行研究.为此,对一榀独立基础-框架子结构开展低周反复荷载试验,分析考虑土与结构相互作用下结构的抗震性能.结果 ...     

新型屈服锚杆发展现状综述

介绍了屈服锚杆的工程应用背景和作用机理;综述了国内外近期研制的几种新型屈服锚杆结构、工作原理及其相关试验研究成果,包括国外的Garford锚杆、Yield-Lok锚杆、Roofex锚杆、新型吸能锚杆和D锚杆以及我国的.CRLD锚杆和新型高强预应力让压锚杆;在此基础上分析了当前屈服锚杆研制中存在的问题,指出了屈服锚杆今后的研究方向.     

基于ABAQUS的45钢切削有限元仿真研究

基于大型通用有限元软件ABAQUS,通过建立有限元模型,分别模拟了45钢带状切屑形成的动态过程,并分析了切削过程中切削速度、进给率、背吃刀量三要素对切削力的影响规律。     

动压软岩巷道用让压锚杆的设计与性能分析

根据弹簧恒力支撑装置的原理,设计了一种动压软岩巷道用让压锚杆,介绍了动压软岩巷道用让压锚杆的总体结构及让压机理,并对锚固头进行了受力分析,推导了刀形凸轮方程,通过Matlab编程求解了刀形凸轮轮廓曲线.该锚杆具有3级伸长性能,变形量大,能在保持一定锚固力的条件下,使锚固头沿锚杆体产生大位移让压,且在围岩卸压后锚固头可回移补强,形成柔性支护.     

室温下20钢高周次单轴棘轮行为的实验研究

通过对20钢的单轴应变控制循环和应力控制循环实验研究, 揭示了20钢在室温下的循环变形特性, 讨论了材料的循环软/硬化特性和材料的屈服平台以及平均应力、应力幅值和应力比对材料高周次棘轮行为的影响. 研究表明: 20钢表现出弱的、与应变幅值相关的循环硬化特性; 其棘轮行为依赖于平均应力、应力幅值和应力比的大小, 在高应力水平时的高周次循环后期, 棘轮变形会出现<再次增长的现象; 材料的屈服平台对棘轮行为有明显的影响, 在对20钢的棘轮行为进行本构描述时需要加以合理考虑.     

Molecular dynamics study on the nano-void growth in face-centered cubic single crystal copper

Cylindrical nano-void growth in face-centered cubic single crystal copper is studied by mean of molecular dynamics with the Embedded Atom Method. The problem is modeled by a periodic unit cell containing a centered nano-sized cylindrical hole subject to uniaxial tension. The effects of the cell size, crystalline orientation, and initial void volume fraction on the macroscopic stress–strain curve, incipient yield strength, and macroscopic effective Young’s modulus are quantified. Defect evolution in terms of dislocation emission immediately after incipient yielding is also investigated. Obtained results show that, for a given void volume fraction, cell size has apparent effects on the incipient yield strength but negligible effects on the macroscopic effective Young’s modulus. Moreover, the macroscopic effective Young’s modulus and incipient yield strength of the [ 1 0]–[1 1 1]–[1 1 ] orientated system are found to be much more sensitive to the presence of void than those of the [1 0 0]–[0 1 0]–[0 0 1] system.     

Anomalous temperature dependence and tension–compression asymmetry of Fe3Al intermetallics—an internal variable approach

Tension/compression asymmetry in the high-temperature flow and anomalous yield/flow stress of Fe–28 at% Al–5 at% Cr alloy has been investigated. Flow curves were obtained from a series of tensile and compressive load relaxation tests. Constitutive relations at each deformation conditions were formulated using the internal variable theory based on dislocation dynamics. In this study, high-temperature flow stress of selected material was to be safely described as the sum of internal stress and frictional stress. The anomaly and peak temperature of yield strength seem to be controlled by the anomaly of internal stress and the relative portion of internal and frictional stress in total flow stress, respectively. Asymmetric flow stress was observed in analogy with yield strength. In terms of constitutive parameters, critical stress for frictional flow (Σ₀) exhibited considerably higher value in compression, which physically postulates increased critical resolved shear stress (CRSS). Considering the crystallography and microstructure, it is presumably due to the ‘extrinsic’ effect of non-deviatoric stress tensor, as proposed in other studies.     

铲齿齿背曲线的自动生成方法

在VisualLisp二次开发环境中 ,利用VisualLisp的图形处理函数 ,针对铣刀、滚刀等典型复杂刀具工作图中端面齿形的绘制特点 ,提出了一套简单实用的弧线求交和弧弧求交特殊算法 ,实现了铣刀、滚刀等端面齿形图中铲磨齿背曲线的自动生成。     

复合型裂纹小范围屈服下裂尖塑性区统一解

采用俞茂宏统一强度理论,推导Ⅰ、Ⅱ复合型裂纹在小范围屈服条件下裂尖塑性区尺寸的统一解析解.给出材料参数在不同拉压比α、泊松比v和中间主应力影响参数b下的一族裂尖塑性区形状与大小的轨迹.讨论以上参数对裂尖塑性区变化的影响,其中拉压比α对塑性区影响较大,α≠1导致塑性区在裂纹上下表面处不连续,b=0和b=1分别对应裂尖塑性区的上限、下限边界.同Tresca准则、Mises准则的解进行比较分析,已有解均是它的特例或线性逼近,该理论解具有理论的统一性和对不同材料的普适性.