Welcome to the Impact Finite Element Program.
This program was designed to be a free and SIMPLE alternative to the advanced commercial Finite Element codes available today. The guideline during the development of the program has been to keep things clear and simple in design.
Impact has been designed to be easily extendible and modular to enable programmers a way to easy add features to the program without having to enter other parts of the code. Impact has been written in Java. This choice of language may seem strange at first, but with the recent development of Java engines, speed penalty is not that significant. On the other hand, the Object Oriented features and the high portability of Java is a clear advantage for the future.
Impact is a Finite Element Code which is based on an Explicit Time stepping algorithm. These kind of codes are used to simulate dynamic phenomena such as car crashes and similar, usually involving large deformations.
There are quite few explicit codes around which might seem strange since the other cousin (implicit finite element) are quite common. The implicit codes are used to simulate static loads in structures. Something that explicit codes does not manage very well.