Advanced Materials for Electromagnetic Shielding

18Mechanical Performance Characterization of EMI Shielding Materials Using Optical Experimental Techniques

Wenfeng Hao, Can Tang, and Jianguo Zhu

Faculty of Civil Engineering and Mechanics, Jiangsu University, Zhenjiang, Jiangsu, P. R. China

18.1 Introduction

Optical testing methods include photoelastic, moiré method (including geometric moiré method and moiré interferometry, etc.), holographic interferometry, speckle method (including electronic speckle interferometry and digital image correlation method, etc.), caustics, coherent gradient sensing, and so on [1, 2]. Some optical projection methods, such as grating projection, can also be classified as optical measurement methods. The photoelastic method can be used to measure stress field of the object, and the moiré method, holographic interferometry, and speckle methods can be used to measure the displacement field of the object (including in‐plane displacement and out‐of‐plane displacement). By using differential calculation, the strain field can be obtained from the displacement field. Out‐of‐plane displacement and slope can also be separated, and shape information is obtained. The grating projection method is used for three‐dimensional topography measurement. Caustics and coherent gradient sensing, due to their characteristics, are mainly used in fracture mechanics, such as high stress concentration problems, stress intensity factor measurement, etc. However, on the whole their application is not as widespread as for ...