Behavior of thermo-acoustic emission generated from damage in composite laminates

Characteristic behavior of acoustic emission from damaged composites was studied when they were subject to a thermal heating and cooling cycle. The thermo-acoustic emission was likely to be generated on account of the friction between the crack faces by the thermal deformation mismatch and/or the internal stress relaxation during the thermal loading. The emission characteristic exhibited the degree of damages in the composites with various layups and thicknesses which had occurred during the manufacturing process and in the cryogenic liquid nitrogen immersion.