The Evaluation of Thermally Induced Damage in Polymer Matrix Composites via a Design of Experiments Approach

Abstract : As of the date of this report overheat damage is an area of concern for the supportability of polymeric matrix composites, since a significant amount of strength is lost, up to 30% in shear, before this a damage is detectable by standard ultrasonic inspections techniques. This report takes the approach of using a design of experiments to determine which factors and interactions significantly affect the heat damage behavior of polymeric matrix composites. A 64-run design was developed which could rank all the identified factors and interaction. A quartz lamp bank is used to provide one-sided radiant heating. Mechanical testing includes four-point shear, and 24:1 four point flexure. The factors were analyzed and ranked for both test methods. Also, the data was entered two different ways (1) as five replicates of the same exposure conditions, and (2) as average values. The data entered as replicates showed many more of the factors and interactions to be significant than when the data was entered as averages. The work has identified the significant factors and two-level interactions affecting the heat damage behavior of polymeric matrix composites. Follow-on efforts should be orientated at identification of heat damage failure mechanisms and nondestructive methods to detect these identified mechanisms.