How can FEA be used for Falling Impact or Collision Problems?
Falling impact or Collision problems are important for many plastics utilitarian products, and applies to falling objects, as well as those subjected to impact loads. Examples: Large 55-gallon drums, bleach bottles, milk bottles, lawn chairs, tennis rackets, Wheel Chair Wheels, automobile hoods and trunks, bumpers, helmets etc. This class of problems in FEA present a combination of at least three kinds of non-linearities – material non-linearity, geometric and boundary non-linearity, occurring together. The last-mentioned kind refers to the small increase in the area of contact, as the colliding bodies squeeze into each other, and thereby spread the stress over larger area, which in turn reduces the stress. This mechanism enables many plastics structures to withstand impact without breaking, in a large number of cases. Without considering this non-linearity, it would be hard to distinguish a rigid material from a pliable plastic. Iterative procedure is still the technique, except that
