ABSTRACT:This paper focuses on the development of full-field experimental methods for validating computational models of needle insertion, and specifically the development of suitable tissue surrogate materials. Gelatine also known as "ballistic gel" is commonly used as a tissue surrogate since the modulus of elasticity matches that of tissue. Its birefringent properties also allow the visualisation of strains in polarised light. However, other characteristics of tissue are not well emulated by gelatine, for example the fibrous network of cells of tissue is not well represented by the granular microstructure of gelatine, which tears easily. A range of birefringent flexible materials were developed and calibrated for photoelastic analysis. The most suitable were then used to explore quantitatively the different strain distributions in tissue when subjected to a range of needles with different tip profiles.

The application of high speed moire' photography to the measurement of the dynamic strains of the points in a surface is presented. This method has been used to measure the dynamic strain distribution along the axis of different bars, and the process of stress concentration of an aluminium bar with two circular holes at the high rates of the loading. AbstractThe application of high speed rnoire' photography to the measurement of the dynamic strains of the points in a surface is presented. This method has been used to measure the dynamic strain distribution along the axis of different bars, and the process of stress concentration of an aluminium bar with two circular holes at the high rates of the loading.