Ram Ranjan Sahu

Geometrical metallic shell behavior study under compression

The loading response of shell structures depends on their shapes. The individual shape behaves uniquely to the loading, and different shapes give different load displacement graphs. If these geometries are combined, then their load displacement graphs can be different. It may happen that their combined behavior can be harnessed to be used as better energy absorber in a controlled manner, which they cannot if they are used individually. Experiments were conducted on two separate geometries as well by joining them with weld. The first geometry was the top cylindrical and frusta bottom. The second geometry was the shape of inverted bell crater and half-spherical shells. Combining these two shapes produced the third geometrical shape. The large deformation was obtained by crushing these geometrical shells between two flat plates. The finite element analysis was used to simulate the crush phenomenon. The behavior of the geometrical shell to large deformation was understood with load displacement graph for different samples. The energy absorbed by the different samples was calculated and compared. The parameters, like material and thickness, were varied for the samples to see their effect on the large deformation behavior. Moreover, friction role is discussed on the crush phenomenon. This paper also gives an idea on the different parameters which can affect the energy-absorbing capacity of the combined geometrical shells.

Experimental and numerical studies on the tube contraction using a conical–cylindrical die

This article describes the plastic contraction phenomenon and energy absorption of aluminum tubes, under axial compression by conical entry dies. Experiments were carried out on aluminum tubes machined from commercially available tubes. All tubes had outer diameter of 30 mm and inner diameter was made such that the tubes were obtained in the thickness range of 1–5 mm. The dies were made with semiangles of 5°, 10°, 15°, and 20°. The straight portion of die had inner diameter of 28.5 mm; hence, the diametric interference of 1.5 mm was obtained at straight portion. These dies were made with steel with sufficient thickness to treat them as rigid. The numerical simulation was done for the experiments using LS-DYNA software. Based on numerical and experimental results, the force–displacement graph characteristics for different deformations modes were discussed in detail. Effects of tube thickness and its interference with die were studied. The effect of material property on energy absorption was studied. The effect of friction on overall energy was also studied. The various associated characteristics such as tube deformation at tip and stress pattern were also studied.

Improvement of crush can configuration

Crush can is an automotive part located behind the bumper of automobiles like cars, trucks, jeeps, buses, etc. on each side. The purpose of crush can is to absorb impact energy in smooth way. The ideal requirement for crush can is that it should give a rectangular shape of force–displacement graphs on crush event. In this paper, it is described that the finite element analysis can be taken to assess the performance of conventional crush can. If required, the other large shell deformation mechanism can be plugged into it for improving its performance. Hence individual performance of crush and its combination with mechanism can assess through finite element analysis, which is cheaper than the physical test. The best mechanism of crush can lead towards the ideal requirements that can be chosen from finite element analysis iterations. The experimental verification is done for finite element analysis of individual and mechanism plugged in crush cans.

Inward Inversion Studies on the Stepped Shape Frusta

This paper describes the plastic deformation and energy absorption of aluminum stepped geometry frusta, under axial compression between two flat plates. Experiments were carried out on aluminum frusta having stepped geometry. Geometrically these frusta were made with different diameter to thickness ratio at a height, different angle of steps & the thickness of frusta were also varied. Finite element (FE) analysis was carried out for experimental simulation. Deformation results and correlation from experiment and numerical simulations are discussed. Effect of various ratios like height to diameter, height to thickness, step geometry etc on deformation behavior, has been discussed in details, in this paper.