SOLID PROPELLANT MECHANICAL PROPERTIES INVESTIGATIONS.
Quarterly progress rept. no. 3 (Rept. no 9), 1 Apr-1 Jul 64,
STANFORD RESEARCH INST MENLO PARK CALIF
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Equations of finite elastic theory based on Rivlins I-invariants were developed and used to analyze propellant test results See AD-439 403. A path-independent equation was developed interrelating volume ratio, strain energy, and time for each propellant composition. Futher, by using a reduced time expression, as adjusted by empirically determined shift factors, this dilatational state equation can be used to calculate dilatation from results of tests conducted at various temperatures and humidities. Interpolation can provide factors which will enable the prediction of dilatational behavior over the entire range of temperature and humidity studied. Constant volume envelopes were prepared from data of tests of both compositions conditioned at 42 RH. It was found that these envelopes could be superposed on the envelopes drawn for 0 RH data by performing a vertical shift, i.e., a shift along the stress axis. Further, we found that the same shift, 0.16 log unit, was required to superpose the envelopes for either propellant.