Detecting microscopic defects in aged thermoplastic using thermoelastic technique
An experimental investigation into the thermoelastic technique applied on a thermoplastic material is presented. The TSA response in PEEK polymer after it has been exposed to methane at elevated temperatures was used to establish whether microscopic defects in the PEEK material can be detected using thermoelastic measurement. Utilising a combination of high resolution lenses and sensitivity of the detectors, the TSA method was able to detect and sizing of surface damage. The size of the defect was approximately 300 μm. However the subsurface damage was untraceable by the technique.
Thermoelastic Stress Analysis of the Human Tibia
The thermoelastic stress analysis method is a non-contact technique which utilizes the thermoelastic qualities of hard tissues such as bones. It enables easy measurement and imaging of surface stress distributions. Using this approach, we performed stress analyses of human tibias in simulated loading conditions at various modes of varus valgus loading on the knee joint. In normal loading, the greatest stress image was obtained on the posterior aspect, indicating that the majority of the stress was concentrated in the posterior part of the tibia. The epiphysis of the proximal tibia, which consists predominantly of cancellous bone, showed tensile stress and the diaphysis which consists of compact bone showed compressive stress in every plane. These results indicate that the tensile stress in the epiphyseal surface indirectly reflects the impact-absorbing properties of cancellous bone. Also, results demonstrated that small changes in the alignment of the knee joint have a great influence on the stress pattern of the proximal tibia.
Quantitative stress analysis by means of the thermoelastic effect
Abstract A new non-contact, full-field, stress analysis technique based on the measurement of the intensity of infra-red radiation emitted from the surface of a cyclically loaded body is applied to series of metallic specimens (including beams in bending, the ‘Brazilian’ disc, and a simple pure-shear testpiece) and critically appraised.