摘要
介绍一种可以用来测量曲面试件表面应变分量()的激光光栅显微图像检测技术（ＩＧＭ）．它能实现从小应变到大应变全过程的高精度定量测量．我们将这一技术成功地应用在铁基形状记忆合金（ＦＳＭＡ）管接头的结构设计中．在这项研究中，首先在管接头结构表面制作了变形的载体──位相型干涉光栅，由结构表面产生的衍射光通过光学系统后形成新的干涉光栅，我们利用数字图像系统接收了逆相变前后各自的干涉图像．采用带特殊插值的快速傅立叶变换技术和相移技术确定了结构表面在逆相交前后的应变场，进而得到了记忆合金管接头与被连接管间的接触压力分布及其它逆相变信息．
This paper presents an interferometric grating method(IGM) used in the measurementof strain field (E. I ac, E.o) on a curved surface. It can be applied to determine the small and largedeformation with the high strain sensitivity. This method has been applied successfully in Fe-baseshape memory alloy (FSMA) structure design.In this study, the crossed-line phase grating engraved on the surface of the specimen acts as adiffraction element. Some distracted orders of the incident He-Ne laser light produce a new virtualgrating through an optical information processing system. This new virtual grating representsthe state of deformation of the specimen surface. Using digital image processing techniques (fastFourier transform with special interpolation, phase shifting technique) 1 we have obtained the strainfield of outer surface of FSMA joint and contact pressure distribution on its inside surface whichhas mechanical deformation and transformation.In this research, FSMA joint firstly produces martensitic transformation by mechanical expanding. The virtual grating images from the outer surface of FSMA joint after mechanicalexpanding are received by C.C.D. camera. After heating, the inverse transformation (i.e. shapememory effect) appears. The contact pressure between joint and the pipelines is induced. Wereceive the grating images in the same manner using the optical arrangement described in Fig.1.By the processing the digital images we received above, the strain components() onthe outer surface of FSMA joint are determined by IGM (seen in Fig.6) before and after inversetransformation. Based on the results of IGM, displacement components on outer surface of FSMAjoint can be determined easily. After this procedure, the contact pressure distribution betweenFSMA joint and pipelines is calculated using hybrid iteration algorithm of elastic-plastic finite element theory. on the FSMA joint surface is very small. It is found that inverse transformationof FSMA material, with special chemical composition, is related to thermo-mechanical training(including mechanical expanding and heating) and properties of pipelines. In engineering applications, the contact pressure distribution is an important numerical value in the hydraulic system. Itcan be designed by optimizing the mechanical expanding, heating process and the shape of FSMAjoint.
出处
《力学学报》
EI
CSCD
北大核心
2000年第1期87-93,共7页
Chinese Journal of Theoretical and Applied Mechanics
关键词
干涉光栅
相变
形状记忆合金
数字图像处理
IGM
interferometric grating, transformation, shape memory alloy, digital image processing, strain, contact pressure
