A Building Block Method for Damage Tolerance Evaluation of Impacted Composite Stringer Panel

Integrally stiffened composite panels are a typical design feature used in aircraft and rotorcraft wing and fuselage structures. These structures are exposed to possible low-energy impacts from various sources and, as such, are subjected to durability and damage tolerance requirements. The focus of this paper is to present an analytical method to comprehensively simulate several defects and damage modes that have been identified as primary failure patterns for laminated stiffened panels. The methodology employs analyses that include fracture-mechanics-based failure prediction and strength-based failure analysis by using a building block approach. In addition, a probabilistic approach was taken to perform a risk assessment. The methodology allows for initial defects to be located at any appropriate area in the panel, allowing for multi-site damage analysis. The risk assessment can thus be evaluated for multiple failure modes. The methodology has been demonstrated using a three-stringer panel.