'FAST': A Leading Edge Experimental Stress Analysis System

FAST (Focal-plane Array for Synchronous Thermography) is a global, non-intrusive system for measuring stress. The system exploits a phenomenon known as the thermoelastic effect, viz, if an isotropic body is subjected to a dynamic load then the body emits an infra-red signal having a spatial variation which is proportional to the sum of the principal stresses. Since the variations in temperature sought after are of the order of 0.01 C, sophisticated means of extracting these small temperatures is required. This paper gives a brief description on the hardware (ie Digital Signal Processing (DSP) boards, image-processing boards, infra-red video camera and real-time disk) as well as the innovative software (digital signal processing) in the FAST system. Some of the problems encountered along the way in the design are mentioned as well as their solutions. Some practical applications of the system, as well as its advantages, are discussed.