Shear stresses in polymers under shock compression

The deviatoric response of polymethylmethacrylate to one-dimensional shock loading

“…Also, observe that the agreement between our data and that of Bat'kov et al 10 is very close, although small differences between the data sets can probably be explained in terms of differences between properties of differently sourced materials. Also, observe that the agreement between our data and that of Bat'kov et al 10 is very close, although small differences between the data sets can probably be explained in terms of differences between properties of differently sourced materials.…”

“…It is interesting to observe that there is no observed change in mechanical response at ϳ2.0 GPa, even though significant changes in thermal 12,13 and electrical behavior 14 have been noted at this stress. They themselves observe no such reduction in shear strength, in agreement both with ourselves and Bat'kov et al 10 Thus, it would appear that the thermal and electrical effects discussed above have no corresponding mechanical counterpart during the shock loading of PMMA. However, Gupta and Gupta 8 have pointed out that by using the same gauge calibration for both longitudinal and lateral orientations, significant errors could be introduced into the final result.…”

“…The slight overshoot seen at 4.06 GPa is most likely a gauge artifact, and does not reflect the true mechanical response of PMMA. As a comparison, we have also included values of shear strength calculated in the same way from the work of Bat'kov et al 10 The solid line represents the elastic behavior according to This is shown more clearly in Fig.…”

“…9 The advantage of this method is that now shear strength is deduced from two measured values. Such measurements performed in PMMA 10 show an initial increase in shear strength to ϳ7.5 GPa before dropping to near zero. Gupta 11 has also detected a drop in shear strength, although he has placed it somewhat lower, around the HEL.…”

Shock Response of Polymethylmethacrylate

“…However, more recently, the shear strength has been determined by measuring the lateral stress, r y , in the sample [3][4][5][6][7]: In PMMA, the lateral stress has been observed to decrease following the shock front indicating a strengthening of the material, possibly due to the viscoelastic/viscoplastic response of PMMA [6]. Experiments at higher pressures have indicated a dramatic decrease in shear strength, which the authors attributed to rising temperature behind the shock front [7]. Since the temperature in PMMA has been shown to rise dramatically above 2 GPa [8,9], this may be responsible for the deviation from elastic behavior and subsequent dramatic drop in shear stress above 7.5 GPa [7].…”