The concept of a “good impact test” has two aspects: the quality of the test results and the applicability of the test results. The quality of output from various impact tests is the subject of a companion paper. This paper presents a methodology for selection and interpretation of impact tests for automotive composites. Proper selection and interpretation can provide good correlation between test results and performance in application.
A necessary condition for obtaining correlation between test results and service performance is that the key impact parameters in an end-use impact event are identified and duplicated in the test method. The key impact parameters—stress state, controlling variable, and failure limit—are defined and developed from the special characteristics of composite materials.
The starting point of the methodology is a set of simple statements of the impact-related functional requirements of the application. A procedure is presented for systematically transforming these statements into a characterization of the application in terms of key impact parameters. Test methods that match this characterization are specified.
As an example, the methodology is applied to an automobile fender. A set of test methods is specified. Characterizations of six additional automotive applications are summarized, and implications for future test method development are discussed.