On the dynamic radial expansion of helical springs due to longitudinal impact

Abstract An analytical and experimental programme was conducted to investigate the dynamic radial expansion of helical springs due to longitudinal impact. The basic equations of motion were normalized in such a way that terms of the same order could be retained in a systematic manner. A minimum complexity model was then developed by making suitable approximations in the resulting simplified equations of motion. Finally, an expression for the dynamic radial expansion was obtained, and it was shown to be the result of a two-wave interaction. Impact tests were made on a specially designed spring and the resulting motions recorded by using a high speed motion picture camera. The experimental results support the predictions of the theory.