Abstract: Through a series of drop-weight impact tests and quasi-static indentation （QSI） tests of composite laminates, three kinds of relationships are obtained between the impact energy (or the quasi-static indentation force) and the damage area, damage width or dent depth. An analysis of these relationships indicates clearly that, as compared with damage area or damage width, the dent depth is the most appropriate parameter to describe the damage. Therefore, the dent depth is selected as the damage parameter to set up the damage relationship between drop-weight impact and quasi-static indentation. Knee-point means the maximal ability of damage resistance for drop-weight impact and quasi-static indentation, and the two knee-points are very close for the two types of tests, which suggests the feasibility for setting up an equivalent relationship between them. By numerical analysis of the impact energy and static indentation force under the same dent depth, a new equivalent formula is set up, which corresponds well with the results of the tests. And it may provide theoretical support for damage tests in future.

Key words: composites, laminates, impact energy, quasi-static indentation force, dent depth, equivalent formula