Measurement of uniform and localized heat dissipation induced by cyclic loading

An experimental technique is presented for measuring the heat dissipation and localization during cyclic loading of materials. The temperature field is measured by a number of thermistors and an infrared camera, which scans the specimen surface continuously. The specimen is mounted 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 discussed using a onedimensional model for the heat loss under steady-state conditions. Applications of the technique are demonstrated for specimens made of fiber-reinforced ceramic and polymer matrix composites (PMCs). A methodology is proposed for measuring changes in damping and stiffness properties of viscoelastic polymer matrix composites using the temperature rise of a cyclic loaded specimen. It is demonstrated that for a ceramic matrix composite, where interfacial frictional sliding gives rise to heat dissipation, the temperature resolution can be used for detection of stress-strain hysteresis with an accuracy better than that of the stress-strain data.