Reflectance difference laser measurements applied to the study of the stress/strain state in materials

Development of experimental setup to study strain/stress state in materials emerges from a need to evaluate by a nondestructive and non-invasive technique the performance in new materials like semiconductor heterostructures, composite materials and alloys. The system was designed and built to be used as a multi-functional experimental setup. The main purpose is to characterize materials in elastic and plastic regime by reflectance difference laser measurements and strain gages. This system allows the generalization of results obtained from a theoretical model based in Finite Element Model and experimental measurements taken in finite specific points with strain gages. A NI™ platform is used for signal conditioning and processing. System built is described which includes an optical setup to measure reflectance difference laser (RDL), and a flexor which applies deformation in a link, with a micrometer. A correlation bigger than 0.95 was found between optical signal, strain gage signal, and finite element modeling.