用图3-13所示板状试件进行拉伸试验时, 在试件表面沿轴向和横向贴电匹应变片来测量其应变。已知<img src='https://fb.fenbike.cn/api/planet/accessories/formulas?fontSize=18&latex=1AnfiN0v7qz8UtJgbQUzz98jck2RY1jaitTOMMgO9gU' />;每增加3kN的拉力,试件的轴向线应变增量<img src='https://fb.fenbike.cn/api/planet/accessories/formulas?fontSize=18&latex=cdHJFO0FUqeLufAOFEluB5V2EP8Rxuwgo1rk4JOWnGXuBHb64FQrWx8bf6IotLZAcEHss8p993j5BK4hyYaxKw' /> ,横向线应变增量<img src='https://fb.fenbike.cn/api/planet/accessories/formulas?fontSize=18&latex=5yAhSI3MofMpYnHYvhVHMzhvIJHyFB-ieCOCJQv-XKS7IRV806F-cOMGaGmNTZJH' />求试件材料的弹性模量E和泊松比<img src='https://fb.fenbike.cn/api/planet/accessories/formulas?fontSize=18&latex=rR3dilaQ9VopkNk1C1MR_g' />。<img src='https://fb.fbstatic.cn/api/ape-images/17cff1518eabd28.png' />