深部土高压卸载变形结构性量化参数确定及本构模型

用取自山东巨野矿区埋深300～600m的深部粘土样,在三轴伺服仪上进行原状和重塑土的高压三轴卸载试验,对比分析其变形特点;提出一种描述深部土高压卸载变形与强度连续变化的土结构性参数的方法,并根据三轴卸载试验结果,确定了巨野矿区深部土高压卸载变形结构性参数,建立了描述巨野矿区深部土高压卸载结构性本构模型。     

功能铁磁材料的变形与断裂的研究进展

综述了近几十年, 特别是近十几年来铁磁材料的力磁耦合变形与断裂行为的研究概况. 传统铁磁弹性问题的研究已经有较长时间的积累, 文献中已有大量的研究结果发表. 近些年 来, 随着智能材料及结构应用与研究的兴起, 功能铁磁材料如稀土超磁致伸缩材料、铁磁相 变材料以及铁磁复合材料等的力学行为越来越受到重视, 人们在功能铁磁材料的变形与断裂 以及铁磁复合材料的有效性质等方面开展了大量的研究工作. 本文在简单介绍了经典铁磁弹 性和传统铁磁结构的力磁性能的研究背景基础上, 结合作者近年来在铁磁材料变形与断裂方 面所开展的工作, 着重评述了功能软铁磁材料在变形与断裂的实验研究,如实验设备和技术, 以及铁磁复合材料细观力学、软铁磁材料、铁磁功能材料的变形与断裂理论等方面的研究进 展, 并指出了需要进一步研究的方向.     

消减舰船变形的影响和为全舰提供高精度姿态基准

引用国内外一些文献列举的现代舰船船体变形的数据，论证了消减船体变形的影响和为全舰提供精确的姿态基准的重要意义。对舰载航向姿态基准的功能、性能与特点进行了综述。介绍了基于激光陀螺和光纤Bragg光栅传感器测量船体变形的新方法。最后，探讨了分布式姿态基准系统的技术方案。     

弹塑性有限变形的拟流动理论

本文提出一种弹塑性有限变形的拟流动理论。该理论从正交性法则出发，通过引入“拟弹性模量”和模量衰减函数并改进应变率的弹塑性分解，实现了由有限变形Ｐｒａｎｄｔｌ－Ｒｅｕｓｓ流动理论（Ｊ２Ｆ）向基于非正交法则的率形式形变理论（Ｊ２Ｄ）的合理的光滑过渡；并适用于初始及后继各向异性变形分析。在特殊条件下，可退化为Ｊ２Ｆ、Ｊ２Ｄ理论以及由任意各向异性屈服函数描述的流动理论。将该理论用于韧性金属平面应力／应变拉伸失稳与变形局部化的有限元模拟，并与理论分析及实验结果相比较，表明了本文理论的正确性。     

脆性固体变形响应与裂纹扩展的同步试验观测及其定量分析

通过对砂浆试样的材料变形响应和表面裂纹图象的同步观测实验研究、试样表面细观裂纹萌生和裂纹扩展图象信息的采集和量化方法的研究，探讨脆性固体材料的损伤状态与其宏观力学响应之间的关联。用本文提出的实验及其分析处理方法，可以得到砂浆、混凝土、岩石一类脆性固体材料在承载和变形过程中，表面裂纹扩展的定量结果。试样的表面裂损度代表了砂浆试样在承载和变形过程中表面裂纹扩展的情况，也在一定程度上反映了试样内部的损伤情况。     

粘塑性损伤模型模拟准超塑性单轴拉伸行为

发展了Chaboche粘塑性本构模型的大变形隐式算法，用损伤(DM)和无损伤(NDM)模型模拟准超塑性单轴拉伸。发现变形过程可分为三个阶段：均匀变形、颈缩发展、断裂破坏阶段。DM可准确模拟前两个阶段变形，NDM只能较好地模拟均匀变形阶段，表明DM可以较精确地描述稳定发展的动态过程。由于有限元方法只能描述连续介质，因此对于断裂破坏阶段，NDM模拟载荷大于试验结果，DM的载荷小于试验结果，这是由高应变速率敏感性造成。DM能够描述试验中出现地多处颈缩现象，局部应变速率分布随时间演化反映了颈缩发展程度。严重颈缩部位的距离代表着超塑性变形能力，距离越大，抗颈缩能力越好。     

Experimental and theoretical study of the nonlinear response of agiant magnetostrictive rod

In this paper, a magnetomechanical coupling constitutive relation of the giant magnetostrictive material was investigated experimentally and theoretically. A grain-oriented magnetostrictive rod of iron and rare earth was tested under a combined magnetomechanical loading. Two types of experimental curves were obtained, i.e., the magnetostrictive curve of the extensional strain vs the magnetic field, and the curve of the magnetic polarization intensity vs the pre-stress. A new theoretical constitutive model, based on the density of domain switching, is developed. Comparison of the theoretical predictions with the experimental results indicates that this model can capture the main characteristics of the magnetoelastic coupling deformation of a giant magnetostrictive rod. The project supported by the National Natural Science Foundation of China (10025209, 10132010, 10102007)     

ANALYSIS OF THE LOCALIZATION OF DAMAGE AND THE COMPLETE STRESS-STRAIN RELATION FOR MESOSCOPIC HETEROGENEOUS ROCK UNDER UNIAXIAL TENSILE LOADING

The mechanical behavior of rock under uniaxial tensile loading is different from that of rock under compressive loads. A micromechanics-based model was proposed for mesoscopic heterogeneous brittle rock undergoing irreversible changes of their microscopic structures due to microcrack growth. The complete stress-strain relation including linear elasticity, nonlinear hardening, rapid stress drop and strain softening was obtained. The influence of all microcracks with different sizes and orientations were introduced into the constitutive relation by using the probability density function describing the distribution of orientations and the probability density function describing the distribution of sizes. The influence of Weibull distribution describing the distribution of orientations and Rayleigh function describing the distribution of sizes on the constitutive relation were researched. Theoretical predictions have shown to be consistent with the experimental results.     

Study of thermal deformation of microelectronics packaging product by interferometric technique

In this paper, the out-of-plane deformation of silicon surface of Direct Chip Attachment (DCA) assembly, under thermal loading, was measured in real-time by Twyman/Green interferometry. The contour maps of the out-of-plane displacement fields of silicon surface under thermal loading and cycling of various temperature were obtained. Experimental results show that the relation between the out-of-plane displacement and temperature is nonlinear and varies with temperature cycling, due to nonlinear mechanical behavior of the materials used in electronic packaging. A comparison of the out-of-plane displacement fields of silicon surface measured by T/G interferometry in real-time and replicating technique of high temperature specimen grating of moire interferometry was made.     

钢框架中组合楼盖的面内变形

为了研究影响钢-混凝土组合框架中组合楼盖隔板性能的因素,以楼板厚度、框架侧移刚度以及结构平面刚度布置为参数对钢框架中的组合楼盖进行了弹性有限元分析．分析结果表明,除长宽比外,组合楼盖的隔板性能还与其面内刚度以及支撑体系的特性有关．根据分析结果提出了组合楼盖隔板性能的评价方法, 并与试验结果进行了验证．该方法可以为工程实践中评价组合楼盖的隔板性能作参考．