Calibration of infrared stress measurement technique for CFRP composites and its application

摘要

Infrared stress measurement technique is applied as a method of nondestructive evaluation of composites with advantages of in-situ and non-contact nature. Thermo-elastic constants of unidirectional carbon fiber reinforced plastics (UD-CFRP) needed for quantitative measurements are obtained through the infrared stress graphic system. The theoretical thermo-elastic constants are derived through the basic equations and physical properties of constituent materials, which are compared with theexperimental values. As a consequence, a reliability of the measured thermo-elastic constants is established and capability of this system for quantitative stress measurement is shown. It is also demonstrated that temperature dependency of a transversecoefficient of thermal expansion and a specific heat at constant stress of UD-CFRP cancel each other so as to decrease temperature dependency of the thermo-elastic constant. Other influential factors on measurements like a frequency effect are alsoexamined.