Scope:

Structures made using sandwich constructions are susceptible to damage by concentrated out-of-plane forces. Such primary design concerns can be taken care of by knowing the damage resistance properties of a sandwich panel. The ASTM D7766 test calculates damage after a quasi-static indentation or a drop-weight impact of sandwich cores (including continuous (foams) and discontinuous bonding surfaces (honeycomb). The properties obtained using ASTM D7766 are helpful in product development and material selection while considering the damage resistance capability of sandwich structures concerning thickness, stiffness, geometry, stacking sequence, and other processing and environmental variables.

Test Procedure:

For the ASTM D7766 test method there are three procedures A, B, and C in this test. Procedure A (in-plane damage, face) and Procedure B (out-of-plane damage, edge-supported) are carried out for indentation by ASTM D6264. Procedure C takes care of impact and is done using ASTM D7136 (drop weight impact, edge supported). Surface and through-thickness damage after impact or indentation for each specimen is measured and recorded. Damage resistance is then calculated.

Data:

Results of damage resistance of sandwich constructions by ASTM D7766 test is given in terms of Impact energy and Failure type/mode

Conclusion:

Hence, ASTM D7766 is a standard test method that determines damage resistance of cores to indentation or impact on composites.