STUDY ON IMPACT COMPRESSIVE AND TENSILE MECHANICAL PROPERTIES OF HTPB COMPOSITE BASE BLEED GRAIN AT VARIOUS TEMPERATURES

摘要

In order to investigate compressive and tensile mechanical properties of HTPB CBBG, split Hopkinson bar experiments were conducted. The strain rate varied from 1100 to 8000 s~(-1) at temperatures of 323 to 233 K. Non-linear true stress-true strain curves show that yielding is more significant at high strain rates or low temperatures. All true stress-true strain curves under compression have characteristics of strain hardening after yield point. The obvious stress drop after yield point of true stress-true strain curves under tension at high strain rates and low temperatures indicates that serious damage occurs and evolves. Based on the sensitivity analysis of yield stress to temperature and strain rate, it is found that the former has a more significant influence on compressive mechanical behaviors while temperature and strain rate have an evenly effect on tensile mechanical behaviors. According to the time-temperature superposition principle, the master curve of compressive initial modulus was built at reference temperature of 301 K and it matches well with experimental data.