Finite element model prediction of cyclic thermally induced loads in a scaled bin using elastic-viscoplastic constitutive equation

Capability of the finite element model (FEM) developed by Zhang et al. (1987) was enhanced to predict cyclic thermally induced loads in bulk solids storages. The FEM enhancement comprised a rate-dependent elastic-viscoplastic (EVP) constitutive equation for wheat en masse and inclusion of cyclically varying ambient temperature profiles. The predicted static and cyclically varying, thermally induced, lateral over- and under-pressures were compared with the measured data from a model bin filled with wheat (Li et al., 1990a). The test bin 0.9 m (diameter) × 1.2 m (high) was subjected to three ramp-type (constant slope) ambient temperature cycles with time period of 2 h and amplitude of 10° C. The FEM's thermal pressure coefficient (C_p) values were larger than the measured values by 31.8% for the temperature decreasing mode in the first cycle, and 2.4% to 13.8% for the rest of the temperature decreasing and increasing modes in all cycles. The FEM's maximum, thermally induced, lateral over-pressures (minimum temperature value) were 32%, 55%, and 78% larger than the measured values in the first, second, and third cycles, respectively; whereas, the minimum thermal lateral under-pressures (maximum temperature value) were 38%, 45% and 52% larger in the first, second, and third cycles, respectively. At the 0.05 level of significance, the X² test showed that there was no statistical difference between the FEM and measured thermal lateral over- and under-pressures for the first two cycles.