低碳钢试件弹塑性边界的白光相关检测

金属试件的弹塑性边界检测对判断该试件是否失效有着重要意义,因此一直是研究人员较感兴趣的研究课题。利用激光和白光作为照明光源的方法都曾被提出以检测金属试件的弹塑性边界以及塑性变形。为避免激光测量的诸多缺点,本文提出一种用白光作为照明光源并结合数字图像处理来检测低碳钢试件弹塑性边界的方法。该方法将数字图像相关和低碳钢试件表面弹塑性变形前后对照明光强的反射特性结合起来以判断试件是否进入塑性屈服。文中通过对加载过程中低碳钢试件表面序列图像的处理,准确地判断了该试件是否进入塑性屈服,验证了该方法的可行性。

Determination of Low-carbon Steel Specimen Elastic-Plastic Boundary Using Improved White-light Correlation Method

Determination of elastic-plastic boundary and plastic strains on the surface of metal specimen has long been an attracting and challenging research topic and also is meaningful in determining whether the specimen is in the failure state or not.Both laser speckle and white-light methods have been presented to measure the elastic-plastic boundary and plastic strains of the specimen.To avoid the shortcomings accompanying the laser method,an improved and simple optical method is proposed to determine the elastic-plastic boundary of low-carbon steel specimen in this paper,which using white-light scattering generated by plastically induced surface roughness on the metal specimen polished surface.By digital processing of consecutive images acquired during load, it is possible for us to accurately determine the initiation of the plastic strain.