An experimental study of deformation modes of domes and large-angled frusta at different rates of compression

Axial compression tests were conducted on a large number of spherical domes and conical frusta of various sizes to study their modes of collapse and energy absorption capacities. The results presented here include aluminium spherical domes of R/t values ranging between 15.3 and 240.9, and large-angled conical frusta of slenderness ratio (t/d) varying from 0.00554 to 0.02152, and semi-apical cone angles from 44.5° to 67.1°. These were chosen because their mode of collapse primarily was due to the formation of rolling plastic hinges. All specimens were made from aluminium sheets of different thicknesses by the process of spinning. Quasi-static tests were conducted on an INSTRON machine at crosshead speeds of 2, 100 and 200 mm/min. Impact tests were conducted on a drop hammer, and the impact velocities varied from 2 to 9 m/s. Their various modes of collapse, load-deformation and energy-compression curves were recorded. Typical results are presented. A comparative study of the modes of collapse and load-deformation curves of the spherical domes and conical frusta, obtained from quasi-static and impact tests, is also presented.