微小缺口/孔洞的激光衍射无损检测

基于裂纹和孔洞的小尺寸特征,提出了微小缺口/孔洞的激光衍射无损探测技术,给出了解析表达式.通过这一技术,对单向拉伸试件中所含单边缺口和中心孔洞在外载作用下的演化过程进行了实时原位检测,获得了缺口/孔洞孔径随载荷的变化曲线及模拟裂纹时裂纹的张开位移、裂纹开裂长度及应力强度因子等一系列断裂参数.

NONDESTRUCTIVE TESTING OF SMALL CRACKS/CAVITIES USING FAR-FIELD LASER DIFFRACTION

A good knowledge of the evolution process of a crack/cavity is important for a better understanding the mechanical behavior of the damage and failure of materials and structural components. Based on the small size of the initial or prescribed cracks/cavities before damage beginning, the far-field laser diffraction technique has been introduced here to characterize the evolution process of a crack/cavity subjected to load. The analytical solutions were presented for the simple geometrical shape crack/cavity. Two uniaxial tension experiments, a single edge crack and a central circular cavity, were conducted in situ at original testing position to demonstrate the ability of the proposed technique. By analyzing the diffraction fields the evolution curves of the crack aperture versus the applied load was obtained, and the important fracture parameters, such as crack opening displacement, stress intensity factor, crack growth length, crack opening angle and crack tip opening angle can be easily estimated using these evolution curves. Finally, the retrieval problem about the complex crack/cavity aperture has also been discussed in this paper.