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This paper describes the initial development of methods for predicting the fatigue life of bonded composite repairs applied to cracked aluminum aircraft structures. Bonded repairs offer great potential in stopping or slowing crack growth. The benefits of bonded repairs when compared to riveted repairs are significant, and include improvements in fatigue life, inspectability, and cost. The main barrier to the widespread use of this technology is the lack of methods for ensuring damage tolerance and durability [1–3]. In this paper, approximate analytical equations are developed to characterize both disbonding and crack growth in a repair applied to a center-cracked plate. The equations are in a form suitable for use in probabilistic risk assessments and inclusion in industry codes and standards, and have been validated against a boundary element model.

Accident investigations and empirical information are used to evaluate the performance of the occupant's seatback for frontal and rear impact collisions. The role of the seatback is to prevent rear seat objects from intruding into the occupant's space (frontal impacts) and to keep the occupant from moving rearward out of this zone (rear impacts). Trends in the dynamic performance of the seatback are identified and are discussed relative to the current government safety standards. The results indicate that bucket seats could be improved to better protect the occupant during collisions. The strength requirements in present standards appears to be inadequate to protect the occupant from seatback collapse during a modest collision. These standards only consider the effects of the seat's mass and do not account for inertial loading of the occupant or any other externally applied impulsive loads.

In this paper, the authors review damage mechanisms and failure modes of bonded composite repairs applied to aluminum aircraft structures, with a focus on the effects of bending on the performance of asymmetric or one-sided repairs. Failure mechanisms are elucidated using results from testing carried out during the course of the University of British Columbia Bonded Composite Repair Program (UBC-BCRP). The authors then outline the regulatory requirements for damage tolerance and describe the new methods and test data developed under the UBC-BCRP to improve the analysis of bending repairs.