Computer-Assisted Cure Cycle Design, Monitoring, Control and Post-Fabrication Damage Assessment in Thermoset Composites

Abstract

A computer aided design and manufacturing methodology, in conjunction with a multi-functional intelligent sensor, has been developed that can be used throughout the manufacturing and service-life cycles of thermoset composite materials. The concept of the sensor, called mechanical impedance analysis (MIA), involves measuring the relation between a force input (excitation) and a motion output (response) between various points in the material and therefore can provide a quantitative indication of the resin cure state and the structural health of the composite. Rapid measurements and analysis of the dynamic mechanical properties such as G’, Gil”, and tan δ of a composite can be obtained in real-time by using a multi-channel Fast Fourier Transform (FFT) spectrum analyzer interfaced with a microcomputer. This methodology, including the MIA concept, has proven to be effective in (1) the cure cycle design and optimization, (2) serving as a real time monitor for resin/prepreg aging/shelf life, (3) determining the processability of a resin/prepreg, (4) acting as an in-situ cure monitor for press curing and autoclaving of composites and (5) providing structural health state or condition monitoring of composites when subjected to various stressing conditions. In the present report, we will discuss the feasibility, advantages, and limitations of applying the computer-assisted MIA methodology for quality assurance, control and management before, during and after composite manufacturing.