Thermal emission is the phenomenon of heat dissipation in crystalline materials
undergoing deformation. Analysis of the thermal emission from materials subject to
strain in the form of mechanical tests is possible by measuring the specimen
temperature locally with high resolution temperature sensors.
The mechanism of heat dissipation depends intrinsically on a material's mechanical
properties and stress history. It is shown that analysis of the thermal emission
response to deformation can quantify these properties and provide evidence of
A number of different materials have been studied, including steels, aluminium and
nickel alloys, and a carbon/epoxy composite. Simple stress regimes were imposed on
the specimens, e.g. creep, fatigue and impact damage, and their thermal emission
characteristics were analysed during a following tensile test. It was found that the
thermoelastic response of the materials was in some cases sensitive to the level of pre-stressing
or damage. In addition information was often contained in the thermal
emission responses which was not present or unclear in the stress and strain data.
It is concluded that deformation mechanisms cannot be fully understood unless the
complete thermomechanical process is examined, involving the measurement of
temperature as well as the usual stress and strain. It is envisaged that thermal emission
could be developed into a tool for non-destructive damage assessment operating as a
complement for established techniques.
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy at Loughborough University.