A Perspective on Damage and Failure of Composite Structures based on Innovative Analytical and Testing Methods

The extensive use of composite materials in new airplane design has many advantages to both the airlines and the passengers compared to traditional metallic airframes. Besides having a considerably higher strength-to-density ratio, composite structures can be highly unitized and are superior in their fatigue and corrosion performance. These advantages lead to significant weight savings, reduction in maintenance costs and innovative repair techniques. One of the challenges in using composite materials lies in understanding the failure mechanisms which are considerably more complex than those in metals. In order to reduce the number of configurations required for testing, we are looking at both traditional and innovative modeling tools. The peridynamics theory is a reformulation of the classical equations of continuum mechanics based on integro-differential equations [1]. The primary advantage of the peridynamic theory is that the same equations of motion with an integral formulation of interior forces apply across any damage sites, discontinuities, or dislocations. At Boeing the peridynamic model has been successfully utilized to predict the impact damage of both un-conflgured and stiffened composite components and determine the residual strength through compression after impact (CAI) analysis [2]. The simulation results are correlated with the scarcely available experimental data to guide the further experimental tests and analyses. One example of simulation results is shown in Figure.