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How can the working parts of your PDA or cell phone be protected if someone jars your arm while you are using it, and the device falls to the ground? Or what happens to the structure of a storage tank if the crane putting it in place should drop it? Until now, learning the results of such accidents required running physical tests that destroyed the structures under study. This is both time consuming and expensive.
COSMOS now makes it possible to run drop tests on designs easily and quickly. For how long does this test need to be run? The total duration depends on how much time elapses before the object experiences all the likely impact stress it will undergo after it bounces. If the user wants to account for any secondary impacts, that time will add to the duration. When the object under study hits the floor, a stress wave originates from the point of impact and travels through the length of the object and then travels back. This effect is similar to the ripple effect when a stone hits water in a pond. COSMOS internally calculates the time it would take this wave to travel through the length of the body few times – and assumes all major stress events would occur and be captured within that time. Ofcourse, this time can be changed by the user.
As far as input to the program is concerned, user needs to input drop height or velocity at impact, target orientation. The target could be rigid, as in a rigid floor or flexible as in a carpet type material.
 
Users can plot stress, strains, displacements plots. Besides on regions of concern or stress concentrations users can track changes here with respect to time. Thus giving a realistic understanding of impact. COSMOS drop tests simulations also support plasticity, so that engineers can determine such permanent deformations. |
