Reliability analysis based material and process selection for aircraft landing gear

Abstract

Functional and constraints optimized materials selection procedures using normalized property maps is a notable advancement in the area of materials development. Advances in manufacturing include techniques such as Dynamic Materials Modeling (DMM), that enables prediction of suitable processing conditions applied during bulk forming operations to obtain designed microstructures. Design of components for safety-critical applications is best done by combining these advancements in materials and manufacturing with reliability analysis. The present work examines the influence of processing history on the strength of 4340 steel which is used in the aircraft landing gear, estimated using Weibull Reliability Analysis (WRA). From strength data compiled for different processing routes, the Weibull scale, shape and location parameters indicating respectively spread, characteristics and minimum strength are estimated and ranked. These rankings guide designers to recommend appropriate processing routes for reliable performance. Weibull analysis of strength data of 4340 steel derived from various processing routes, including that of as-cast and wrought conditions, indicate that better ranking is obtained in wrought condition than the as-cast condition. The high Weibull modulus is indicative of better reliability of the wrought material. It is concluded that processing history significantly influences the reliability of safety-critical components.