Assessment of Hygrothermal Ageing and Damage in Sandwich Foam Using Tsa.

Abstract

This work deals with the experimental measurement and characterisation of damage to PVC closed-cell sandwich core foams. The damage to the foam is introduced in the form of moisture effects after immersion in a controlled hygrothermal environment and later, by the insertion of a crack. The non contact technique of Thermoelastic Stress Analysis (TSA) is detailed by Dulieu-Barton and Stanley [1], is used to assess and evaluate the effects of these damage conditions upon the foam. The TSA system used in this work is the ‘Silver’ model manufactured by Cedip Infrared Systems and comprises of a 320x240 array of infra-red detectors to register the thermal changes in a material subjected to an excitation. One advantage of the TSA technique is the option of a zoom lens attachment which permits the transformation from a full-field to a high resolution assessment of localised effects in individual foam cells. TSA thus provides the scope for validating theoretical models presented in the literature for foam cell behaviour under load.