题目：Reanalysis of single-fiber pull-out test
报告人：卿海教授（南京航空航天大学航空宇航学院航空航天交叉研究院）
时间：2017年3月29日10:10
地点：A18-209会议室
主办单位：科协、航空宇航学院、航空航天交叉研究院、机械结构力学及控制国家重点实验室
报告人简介：
卿海，男，教授，博士生导师，1998年9月-2002年7月，西安交通大学，工程力学系，本科生；2002年9月-2007年7月，清华大学固体力学，博士研究生(导师杨卫院士)；2007年11月-2011年2月，丹麦技术大学，博士后；2011年3月-2014年6月，西门子风能公司(丹麦)，风机复合材料叶片高级研发工程师；2014年7月起，南京航空航天大学，教授。2013年受聘“江苏特聘教授”；2016年入选江苏省六大人才高峰。长期从事先进材料与结构的研究工作，尤其应用计算固体力学从事科学研究与工业产品研发工作。在西门子工作期间，作为项目主管、项目首席结构工程师及结构工程师参与完成西门子风能公司的多个风机复合材料叶片相关的技术攻关项目。
报告摘要：
A new theoretical model is developed in order to predict the stress transfer during the quasistatic single-fibre pullout process. The theoretical approach retains all relevant stress and strain components, and satisfies exactly the interfacial continuity conditions and all the stress boundary conditions. For both matrix and fibre, the equilibrium equations along radial direction are satisfied strictly, while the equilibrium equations along axial direction are satisfied in the integral forms. Three normal stress-strain relationships are strictly satisfied, while the radial displacement gradient with respect to the axial direction is neglected for shear stress-strain relationship. The general solutions of the axial and radial displacements in both fibre and matrix are obtained in explicit forms. In the debonded region, a modified Coulomb’s friction law, in which the frictional coefficient is a decreasing function of pullout rate, is applied to determine the interfacial frictional stress. A theoretical analysis for the single-fiber pullout with unload process is presented based on the energy-based debonding criterion and the modified analysis of stress transfer between fiber and matrix. The relationship between the applied stress and the interfacial relative displacement is expressed as a function of the radial residual thermal stress, fiber pullout rate and volume content as well as the length of reverse frictional sliding. The influence of fiber pullout rate on interfacial frictional coefficient is also taken into consideration. The theoretical results from present model agree well with the results from finite element model. The calculation results show that the applied stress result in further debonding increases with the increase of the radial residual thermal stress and the fiber volume content and the decrease of the fiber pull-out rate. There is a drop for the applied stress when the interface debonding close to the model length and the drops of short models are larger than those of long models. Under different conditions, the model length almost has no influence on the debonding and reverse sliding in unloading processes at the initial debonding region.
