Measurement of residual strains and uniaxial tension states of shock-loaded polymethylmethacrylate with the longitudinal strain-gauge technique

The authors present a series of planar shock-wave experiments in which the longitudinal strain-gauge technique is extended to measure residual strains and tension strains in shocked polymethylmethacrylate (PMMA). They also show that the residual strains can be simply related to residual temperatures which prevail in the specimen after complete release, through the thermal expansion coefficient. Uniaxial tension can be created if two rarefactions interact and they use the impedance mismatch of the copper impactors and PMMA to cause controlled tensions in it. They also obtained the maximum tensile strain in the uniaxial configuration which PMMA withstands, from which we get a value of 0.18+or-0.02 GPa for the spall strength of this material.