Experimental analysis of the effect of discrete aggregate on the bending stability of thin-walled cylindrical shells

The effect of a discrete aggregate on the bending stability of thin-walled cylindrical shells was studied. The samples for the study were made of aluminum alloy 3004 (temper H19). The samples were cantilevered; a vertical concentrated cross force was applied to its free end. Ten empty samples and ten samples 90% filled with iron powder were tested. The samples were loaded in stages by 10N, and when approaching the moment of buckling the samples were loaded by 1N or less. The force, deflection of the free end of the sample, and axial strain were recorded at each stage of loading. Displacement of the free end of the sample versus cross force diagrams is plotted. The buckling force was determined by the inflection point of the diagrams. The samples lost the stability in elasticity. The diagrams for the empty and filled samples for each series almost coincide until the loss of stability of the empty sample. This means that when the empty sample loses its stability, the buckle directed towards the center line is formed; and for the filled samples, the formation of buckles is prevented by the discrete material, therefore the critical force increased by 18.8%. The influence of discrete aggregate is considered on the basis of approximation [24] for tank trucks manufactured at the enterprise. The critical stress is calculated using the superposition principle, since the stability is lost in the elasticity. The critical stress for the filled tank is determined by the sum of the critical stress for an empty shell with the stresses created by the weight load and the hydrostatic pressure of the discrete filler. The calculation of critical stresses showed that for the pattern samples the influence of discrete filler is 8.3%, and for the full-sized tanks the influence of discrete filler on the value of the critical voltage is significant and amounts to 62%. We studied the effect of various discrete fillers on stability, such as river sand, iron and copper powders at different filling ratios of the samples. Due to an increase in powder density and filling volume, the value of the critical force increased. For the samples filled to 90% with the river sand had the critical force increase by 13.3%, while those filled with the iron powder had their critical force increase by 40.5%, the copper powder samples had an increase of the critical force by 43.1%.