土工膜筒状双向拉伸试验非接触式应力应变量测方法

Non-contact Measurement of Stress and Strain for Geomembranes Cylinder Biaxial Tensile Test

土工膜是一种新型高分子防渗材料,由筒状双向拉伸试验研究材料的力学性能相对简单易行,但是其环向应力应变以及轴向应变却很难直接测得.通过高清相机拍摄筒状土工膜双向受拉变形过程,使用Matlab对拍摄图片进行预处理、增强图像、提取特征边缘,并使用Matlab编写脚本文件批量计算试验过程中每个时间点的轴向应变、环向应变、轴向和环向的应力,可以实现实时精确测量试验过程中的应力应变值,进而得到土工膜在筒状双向拉伸的极限延伸率、屈服强度、弹性模量等重要指标参数,为后续探索土工膜的本构关系提供数据基础.

Geomembrane is a new polymer material for anti-seepage;the cylinder biaxial tensile test is very important to know its mechanical property;and it is very easy to be performed.However,it is difficult to measure its axial strain and hoop strain.This paper can get the stress and strain during the text by the means of taking pictures of the deformed geomembranes.These pictures must be pretreated,enhanced to improve contrast,and extracted its edge.Then we can batch calculate axial stress and strain,hoop stress and strain after the code read in these pictures,which is very important to get the important parameters such as ultimate elongation,yield strength,modulus of elasticity;and then we can get the constitutive relation of geomembranes.