In collapse analysis of mechanical or structural components made of ductile materials and subjected to impact loads, it is necessary to consider material tearing (cracking and crack propagation). Traditional methods that focus on material behavior at crack tip require very fine FE meshes and are not suitable for impact analysis where explicit integration codes, for very good reasons, are used. On the other hand, in methods which utilize surface separation such as the interface element approach or node break approach, crack propagation route needs to be known beforehand.
In this paper, the development of an efficient 3-D Finite element for such collapse analysis is reported. This element utilizes the ISUM concept and may be used in relatively coarse meshes at crack tips. Stress-strain relationship takes account of element size and strain rate effects. Crack propagation through the element (tearing of the element) is based on the sum of the strain energy and surface creation energy, and takes account of the effects of element size and strain rate on the tearing energy. Comparison of test and analysis results of a conical impactor dropped on a circular steel plate is utilized to confirm the validity of the element.
