An explanation for a feature found in several experiments in the general picture of the destruction of non-brittle polymers under the influence of a shock wave initiated by a powerful electron beam is proposed. The distance of the cracking region from the surface of the material affected by the beam to a finite length in depth is associated with the three-dimensional nature of the propagation of elastic waves. The universality of the effect is demonstrated by the simplest isotropic model, which shows that large tensile stresses are effectively generated inside the target at its sufficiently large transverse and longitudinal size, even without taking into account nonlinear and shear processes.