Time–temperature equivalence and adiabatic heating at large strains in high density polyethylene and ultrahigh molecular weight polyethylene

High Strain Rate Mechanics of Polymers: A Review

“…where A quantifies the interaction between rate and temperature and maps from a temperature T to a new temperature T 0 and mapping the strain rate from _ e 0 to a new strain rate _ e. The mapping parameter, A, may be considered as the temperature-strain rate equivalence parameter, which relates equivalent stress states in the material and is agnostic to the underlying deformation mechanisms [185] and it is typically found by fitting temperature dependent and rate dependent yield data but, in principle, should be obtainable from Dynamic Mechanical Analysis (DMA) data, and is certainly consistent with these data [153]. Siviour's formula was able to capture several changes deformation mechanisms which govern changes in yield stress, including the inflection in data which involves the glass transition PVDF, and that which is understood as the beginning of the b-transition in PC.…”

“…Furthermore, they also discussed the difficulties in accurately extrapolating glass transition temperatures to high strain rates, where small uncertainties in T g can lead to relatively large changes in the strain rate at which its effects can be seen in rate dependent data. One issue that must be considered when implementing time-temperature superposition in polymers is the effect of adiabatic heating, particularly at high strain rates [185]. At elevated strain rates, the conversion of plastic work to heat in the specimen can occur much faster than the heat can be dissipated away through the platens or other loading device.…”

“…a point-wise mapping, usually of the yield stress. The work of Furmanski, Cady, and Brown [185] considered the full deformation response using a strain-rate jump technique to eliminate the adiabatic effects that can be seen in polymers at strain rates greater than 0.01 s -1 and 15 % strain. The experiments involved rapidly increasing from low to intermediate (1 s -1 ) strain rates, deforming the specimen, and then allowing it to cool.…”

Experimentally Simulating High Rate Composite Deformation in Tension and Compression: Polymer Bonded Explosive Simulant

“…This has been used by a number of authors [1][2][3][4][5] to understand the yield stress of polymers at rates up to ca. 10 4 s -1 ; however, Kendall and Siviour [6] were the first to apply this technique to simulating the large-strain true stress-true strain behaviour of a polymer at high rates.before using temperature profiles to account for the adiabatic heating effect in high rate deformation.…”

Specimen Geometry Effect on the Deformation Mechanisms of Polypropylene-Based Composites Under Impact Loading at Different Temperatures

“…Indeed, when polymers are subjected to high loading rates, the effects of strain hardening, strain rate and temperature sensitivity play important roles in the behavior of materials [47]. The dynamic behavior of materials is based on the opposing tendency of materials to strengthen at high strain rates and to soften with the temperature increase produced by adiabatic loading conditions [48,49]. The ratio b (the fraction of plastic work converted to heat for plastic materials during high strain rate deformation) ranges from 0.4 to 1 [50][51][52].…”