Comparisons of the Ballistic Impact Response of Metals and Composites for Military Aircraft Applications

Abstract

This paper compares the ballistic impact response of advanced fiber composites and metals. These comparisons are made within the framework of a methodology that defines the necessary data and analysis requirements for evaluating the survivability of combat aircraft designs. A side-by-side comparison was made of the available residual strength and damage size test data for metals and fiber composites damaged by small arms projectiles. In addition, the available composite data was used to extend a model for predicting the ultimate strength of composite tension panels damaged by bullets. This model was used in conjunction with an existing model for metals to extend the comparisons to equal strength, equal stiffness, or equal weight structural panels. The results show that both metal and fiber composite panels lose a significant percent of their undamaged strength (50 percent or more) when impacted with small arms projectiles. For the cases considered, the percent reduction in the fiber composite panels was greater than in the metal panels. These results are considered to be preliminary for structural evaluations, however, because only simple panel data were used in the comparison.