Accession Number : AD0769351

Title :   Heat Generation in Composite Materials During Fatigue Loading.

Descriptive Note : Technical rept.,

Corporate Author : VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG COLL OF ENGINEERING

Personal Author(s) : Reifsnider,Kenneth L. ; Stinchcomb,Wayne W. ; Williams,Richard S. ; Marcus,Larry A.

Report Date : MAY 1973

Pagination or Media Count : 37

Abstract : Two composite materials, boron-epoxy (B/Ep) AND BORON-ALUMINUM (B/Al) are monitored during cyclic loading to establish the amount of heat generated by dissipative internal deformation processes. Both the magnitudes and distributions of heat generation are recorded in real time so that heat build up can be correlated with load amplitude, frequency of load oscillation, and damage development. The study of heat generation is carried out with three measurement techniques, liquid crystals thermocouples, and video-thermography. Liquid crystals are the most sensitive to temperature changes on the specimen surfaces, with the capability to resolve less than a 0.01 F temperature difference from point to point. The thermocouples serve the purpose of determining the exact value of temperature at chosen points of special interest, as well as serving as a calibration position for the liquid crystal and video-thermography methods. An AGA THERMOGRAPHIC VIDEO-CAMERA WITH TEN-COLOR ISOTHERM DISPLAY IS USED TO RECORD THE BULK OF THE DATA. That device provides a calibrated determination of surface temperature over the entire imaged surface with a resolution of 0.2 C. Since it is a video-camera, the data are time-resolved. Temperature increases of 20 F in B/Al and 70 F in B/Ep near stress concentration positions are found to be common. Correlations of heat generation with mechanical hysteresis, frequency of load oscillation and development of damage are established. (Author-PL)

Descriptors :   (*Composite materials, Fatigue(Mechanics)), Heating, Fiber reinforcement, Heat, Epoxy resins, Boron, Aluminum alloys, Damage, Temperature

Subject Categories : Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE