Experimental and Numerical Study on Softened Inclusions Equivalent Method for Impacted Stiffened Panel Skin

This paper presented and validated a method of softened inclusions for impact damage of stiffened panel skin. The impacted laminates with different impact energy were cut into strips according to the damage area from C-scan results. Then, the stiffness distribution in the impact damage area was obtained by testing the tensile and compressive stiffness of the strip specimens. The results showed that the stiffness reduction in some delamination was independent of the impact energy. The testing results also suggest that the damaged area was divided into three regions with different degrees of reduced stiffness. An equivalent method was proposed to replace the damage area with softened inclusions in impacted laminates. To validate the effectiveness and accuracy of the method, softened inclusions was introduced into the finite element models of stiffened panels with impacted skin. And the strain distribution of the models were compared with the test results under the same conditions. The results showed good agreement between the models and experiments.