| Grain porosity is due to the presence of a space between the grains caused by the percentage of pores is called porosity. Porosity is one of the basic physical and mechanical parameters of the grain bulk, but for experimental research grain bulk porosity test less.The key parameters when unloading grain storage and grain bulk porosity will change, thus affecting the silo wall side pressure, grain porosity is the key parameter for storage, affecting the value of its warehouse wall side pressure generating mechanism is grain storage ventilation.Therefore, in particular the maximum and minimum has important practical significance through experiments to explore the distribution of positions within the grain bulk porosity.In this paper, calculation formula and pressure test, and to study the porosity size of the heap of grain combine PFC3D discrete element numerical simulation stress test. The proportion of wheat when using the formula method is an important parameter, but has significant limitations when existing norms proportion test, we studied the proportion of experimental methods, and on this basis to calculate the porosity of the heap of grain. The improved pressure test equipment, application range of different stress tests porosity. Referring soil test method to obtain the heap of grain loosest state, that maximum porosity. Numerical experiments using PFC3D reproduced pressure test procedure, analysis of different factors porosity distribution, and analysis of spatial distribution of porosity. The main results of this paper are the following:â‘ According to existing norms defect in the proportion of grain testing, testing methods to explore the proportion of wheat to study the test solution, testing the impact gravity of wheat quality wheat, to obtain experimental method to test the specific gravity of wheat.Calculated using the formula method and direct grain bulk porosity.â‘¡ Referring soil test specification, test method using rain wheat heap maximum void ratio, and repeat the test averaged five groups get maximum grain bulk porosity.â‘¢ The improved compression test equipment, performed with pressure variation wheat stack compression test for each grade under pressure to obtain porosity ratio analysis, to make e-p curve, e-lgp curve, analysis of porosity.â‘£ Due to the limited test pressure, porosity may not tend to balance, using PFC3D discrete element numerical simulation to simulate the compression test on wheat, increase the pressure applied to obtain a heap of wheat porosity variation at a greater range of pressure and porosity analysis spatial distribution of degree. |
