Investigation of the conical type shell structure dynamics under internal axisymmetric pulse loading

Abstract

The research included analysis of theoretical aspects of the tapered structures’ stress-strain state problem and numerical calculations of the displacements and stresses of tapered shell bearing layers as function of the value of its taper angle and the corresponding length of the forming tapered structure. The taper angle effect at constant and variable lengths of the generatrix on the stress-strain state of the conical shell was considered.
 The three-layer sheared conical structure with rigidly fixed ends was used for the studies. The thickness of the sheathing layers was the same and was 10 mm. The lightweight polymer filler was reinforced with 5 discrete ribs rigidly connected to the coatings and had a thickness 20 mm.
 In first case, the length of generatrix S in the middle of shell layer was 295 mm and was constant, changing only the taper angle (from α = 10 ° to α = 20 °) and one of the diameters of the shell; in second case, the generatrix length was changed from 580 mm to 295 mm as a result of a similar taper angle change with constant diameters of elements connected by a conical structure.
 Distribution of displacements’ and stresses’ magnitudes along the spatial coordinate S was determined by the software complex Nastran through the direct transient dynamic process algorithm within the time interval 0 ≤ t ≤ 10T. The time interval step duration was 0.25*10-6 s and the total number of steps was 200. The detailed and accurate calculation results have determined the choice of the solid finite element type.
 In addition to the horizontal displacements (deflections) and stresses of the bearing layers of the analyzed conical structures, their first natural frequency (f1) was also calculated.