Abstract

This work details an adaptation of the friction taper plug welding (FTPW) process to repair fatigue damage in 6.35mm AA 7050 t-7451 plate. Aircraft components experience fatigue damage around fastener holes. This damage can be mitigated by enlarging fastener holes. There is no effective repair procedure once holes reach a maximum allowable size. Damaged components must be replaced. A suitable repair process would lead to substantial savings in both time and money. A simulated repair process was developed by machining holes in 6.35mm AA 7050 t-7451 plate. These hoes were then plugged using the FTPW process. Microhardness testing and metallographic analysis were used to map the effects of thermomechanical processing in a repair. Simulated repairs were machined into a tensile sample. A 6.35mm hole was bored axially through the repair center to simulate a new fastener hole. Static tensile testing was used to measure ultimate tensile strength and yield strength in the repair. Samples were also subjected to fatigue testing at stresses ranging from 170MPa to 340MPa at a stress ration of R=0.1. The same tensile and fatigue testing was done with unaltered material. A 7.94mm hole was bored through the center of this material to simulate an enlarged fastener hole. This provides baseline level of properties. Ultimate tensile strength of the base material is reduced by 15% and yield strength by 29%. Fatigue properties at a stress of 303 MPa are reduced by 22%. Fracture surfaces of poor performing samples reveal defects on the weld interface.

Degree

MS

College and Department

Ira A. Fulton College of Engineering; Manufacturing Engineering

Rights

https://lib.byu.edu/about/copyright/

Date Submitted

2022-12-08

Document Type

Thesis

Handle

http://hdl.lib.byu.edu/1877/etd13042

Keywords

plug welding, fatigue, friction taper plug welding, AA 7050-T7451, aircraft, repair

Language

english

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