HOLOGRAPHIC EVALUATION OF WARP IN THE TORSION OF A BAR OF CELLULAR SOLID

Holographic methods are utilized to examine deformations in a cellular solid, polymethacrylamide closed cell foam. A square cross section ba r is subjected to static torsional deformation. The warp deformation i s observed to be less in a foam bar than in a homogeneous polymeric ba r used as a control. The homogeneous bar obeys the predictions of clas sical elasticity. Behaviour of the foam bar is consistent with Cossera t elasticity. In a Cosserat solid, points in the continuum rotate as w ell as translate, and the material supports couple per unit area as we ll as force per unit area. Cosserat effects are important since they c an lead to enhanced toughness.