Reworking welded tubular aeronautical structures - steel ABNT (Brazilian Association of Technical Rules) 4130

• Grant number: 99/06549-5
• Support Opportunities: Research Grants - Innovative Research in Small Business - PIPE
• Start date: January 01, 2000
• End date: July 31, 2005
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Physical Metallurgy
• Principal Investigator: Sidiney Peruchi de Godoy
• Grantee: Sidiney Peruchi de Godoy
• Company: Esra Engenharia Serviços e Representação Aeronáutica Ltda
• City: São José dos Campos

Abstract

The purpose of the present project is to establish parameters for reworking welded tubes in ABNT (Brazilian Association of Technical Rules) 4130 steel used in the manufacturing of aircraft engine cradles indicating the amount of reworking and its influence on the mechanical properties of the material (resistance to metal fatigue along with changes to the microstructure because of reworking the welds). Information may result from this project to support the preparation of a guideline on the quality of the number of welds that can be reworked in the sector and still ensure the same level of safety of the equipment. During flight, an aircraft is subject to repeated loads of highly varying size and frequency. It is estimated that 90 per cent of failures, in service, of components that undergo movement of one sort or another, can be attributed to material fatigue. The aircraft engine cradle is a critical aeronautical component that undergoes complex loads, and fractures caused by fatigue are constantly found. This component, manufactured in ABNT 4130 steel, includes welding operations during manufacturing, or even reworking, and the process requires considerable analysis and care. A study of fractures in aircraft engine cradles suggests that the welds are the parts most subject to metal fatigue failure. For this reason, the standards in respect of the manufacture of these components are extremely strict and careful, particularly in the case of welding operations, where a zero failure rate is demanded. What we do not have, however, are guidelines on the number of reworkings permitted and their consequent influence on the fatigue of the joint. (AU)