Investigation of energy absorption in a multi-body system under impact.

Abstract

This thesis investigates the energy absorption of a multi-body system impacted by a suddenly contracting pretensioned helical extension spring. The system consists of a helical extension spring and other common components used in a consumer application. Impact tests were performed on the system with varying input energies; resulting damage included plastic and brittle failure. Impact tests were also performed on individual components from the system to characterize the amount of energy each component absorbed given a specific energy input. Component models were created by carrying out regression analysis on the results from each of the components, including the helical extension spring. Through inverse prediction, component models were used to determine the amount of energy each component absorbed during system tests. System models were created, estimating the amount of energy transfered from the helical extension spring to each of the components in the system. Further analysis of the data from a prior study on the energy absorption of helical extension springs was also conducted. The energy absorption models developed in this thesis provide an understanding of the energy being absorbed in the system due to an impact event. The system models predicted energy absorption between 88 and 120 percent of the initial potential energy stored in the helical extension spring. Energy absorptions of over 100 percent indicate that the component models have over-predicted the amount of energy actually absorbed. The helical extension spring was found to absorb between 37 and 68 percent of its own potential energy during coil impact.