High strain-rate hardening

Besides frequency effects due to strain-rate hardening and/or specific cyclic damage of the fibrils, there is another typical effect in the case of cyclic loading at high frequencies, namely hysteretic heating. The increase of temperature T near the crack tip, in that case, scales as in Eq. (5)" ... 

However, many polymers show strain hardening, that is, an increase in beyond this asymptotic value at high strain rates (Figure 13.27). Such behavior of high molecular weight polymers is responsible for stabilizing stretching processes involved in the production of films and fibers. 

Figure 16.25 The effect of shear or strain rate on the elastic viscosity of semicrystalline high-density polyethylene. (Note the upsweep in viscosity is often referred to as strain rate hardening).

The effort is complicated by the high strain-rate sensitivity (strain hardening), and the temperature sensitivity of the Sn-Ag-Cu alloy (Ref... 

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