A new method to determine the characteristic lengths of composite joints without testing

A numerical method is presented to determine the characteristic lengths for the failure analysis of composite joints without characteristic length tests. In the conventional methods, compressive characteristic length was determined from the result of a combined bearing test and finite element analysis. The present study, however, shows that the same compressive characteristic length can be obtained by numerical calculation without the bearing test. A new method to define the tensile characteristic length is also introduced so that the tensile characteristic length is numerically determined without the tensile test. Failure loads and modes based on the numerically calculated characteristic lengths are validated by the test results for composite joints with nine different geometries. Good agreement was found among the results of the present numerical method, the conventional method, and the test.