Elastic behavior of uniformly loaded circular corrugated plate with sine-shaped shallow waves in large deflection

By means of modified iteration method, this paper gives approximate solution of the large deflection equations of circular corrugated plate with sine-shaped shallow waves having a central platform under uniform lateral load. A formula of initial modification coefficient is given, and an integral is obtained for the simplification of modified iteration calculations. The results of present paper show better agreement with experimental data and larger applicable range than all other existing solutions of corrugated plates.     

用激光三角法重构混凝土断裂面三维轮廓与断裂能分析

采用基于激光三角法的测试方法对混凝土断面表面轮廓进行了三维重构,初步的断面分析结果表明,相对于传统断面分析方法,本试验方法实现了断面的无损、快速和准确的测量分析,在测量到的断面基础上,给出了本试验所得到的混凝土材料断裂能与分维的关系。     

Geometric Characteristics of Fracture‐Associated Space and Crack Propagation in a Material

It is shown that fracture can be treated as a process occurring in the Finsler space. The use of the Finsler space allows one to construct a delaminated manifold whose characteristics are related to the defect structure of the medium. A method of determining the fractal dimension of fracture is developed using the concept of crack propagation along geodesics.     

多簇压裂干扰应力变化规律及对裂纹扩展的影响

为研究水平井分段多簇压裂缝间的干扰应力及其对裂纹扩展的影响,在现有二维未考虑地应力的单裂缝干扰应力解析解的基础上,利用双平面复变函数保角变换得到了包含地应力项的三维干扰应力解析解。基于扩展有限元法建立三维多裂缝扩展力学模型,利用Python脚本二次开发平台实现了三维多裂缝水力压裂参数化建模,通过解析解与数值计算对比分析,得到如下结论。裂纹两侧裂纹面法向和走向干扰正应力分别为压应力和拉应力,均呈纺锤形,法向干扰应力影响范围大约为走向干扰应力的5倍;裂纹尖端裂纹面法向和走向干扰正应力分别为拉应力和压应力;裂纹尖端两侧存在干扰剪应力;考虑初始地应力对干扰应力解析解进行修正后的干扰应力值均变小;多簇压裂中裂缝间的干扰应力叠加,簇间距越小,叠加效果越强;多簇压裂的干扰应力使裂缝间裂纹面法向压应力增大,走向压应力减小,导致裂纹扩展注水压力升高,裂缝张开的宽度降低,不利于单裂缝的扩展;干扰应力使裂缝间应力差降低,甚至局部最小地应力方向发生改变,有利于形成复杂缝网。     

聚醚醚酮基复合材料的热性质和物理性质预测及其摩擦销三维温度场的数值模拟

通过研究填料含量对聚醚醚酮(PEEK)基复合材料密度、比热和导热系数等热学和物性参数影响的规律,提出了三相PEEK基复合材料热学和物理性质的计算模型;以销/盘摩擦副作为研究对象,采用有限元分析法计算模拟了复合材料摩擦销的温度分布,给出了销的三维稳态和瞬态温度场,并讨论了填料含量对摩擦销端面温升的影响规律.结果表明,计算结果与试验结果吻合较好.     

Analysis to the stress and strain structures of mode I 3-D crack in elastic-plastic state

In this paper, the stress and strain structures of Mode I 3-D crack in power hardening material are studied by analyzing the fundamental equations of elastic-plastic mechanics. It is shown that three regions, Z1,Z2 and Z3 can be divided in the thickness direction according to the stress characteristic. In region Z1, the stress components in the plane Perpendicular to z axis (thickness direction) can be solved first using the fundamental equations of plane strain state; in region Z3, they can be solved first by the equations of plane stress state. The region Z2 is defined as a transition layer. It is shown that the transition layer is the characteristic of Mode I 3-D crack in elastic-plastic state, and it is significant to the research on 3-D fracture. The crack tip opening displacement CTOD is chosen to describe the amplitude coefficient of the local stress field, and the distribution of CTOD in 3-D state is investigated.The project supported by National Natural Science Foundation of China.