MEASUREMENT OF UNIFORM AND LOCALIZED HEAT DISSIPATION INDUCED BY CYCLIC LOADING

An experimental technique is presented for measuring the heat dissipat ion and localization during cyclic loading of materials. The temperatu re field is measured by a number of thermistors and an infrared camera , which scans the specimen surface continuously. The specimen is mount ed inside an isothermal chamber. The measured whole-field temperature can be used for detection of damage propagation and localization. The resolution of the technique under various boundary conditions is discu ssed using a one-dimensional model for the heat loss under steady-stat e conditions. Applications of the technique are demonstrated for speci mens made of fiber-reinforced ceramic and polymer matrix composites (P MCs). A methodology is proposed for measuring changes in damping and s tiffness properties of viscoelastic polymer matrix composites using th e temperature rise of a cyclic loaded specimen. It is demonstrated tha t for a ceramic matrix composite, where interfacial frictional sliding gives rise to heat dissipation, the temperature resolution can be use d for detection of stress-strain hysteresis with an accuracy better th an that of the stress-strain data.