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Design and Stress Analysis for Aircraft Structure Repair Beyond Specification

Conference paper
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Part of the Lecture Notes in Electrical Engineering book series (LNEE, volume 622)

Abstract

The airline structure design engineers often need to design repairs to restore structural integrity for conditions not covered in the Structural Repair Manuals (SRM) provided by the OEM. This is normally called repair beyond specification. Reasons for having to modify SRM repair include: variations in local structural configuration, limitations on space and variations in fastener usage or availability, and so on. As the local design loads are always unavailable for airline design engineers, the principle for repair design is to restore the ultimate static strength and the equivalent fatigue life. Through an example of a chord structure repair design, this paper provides an integrated methodology to design aircraft structure repairs beyond specification. The repair design is based on static analysis. In order to determine the minimum number of fasteners to fulfill the ultimate static strength requirement, the general failure modes for the joint structure and the approach to get its allowable is described. Since the end fasteners transfer more load than the center fasteners when parts are below yield, a joint modeling method is used to calculate the joint load distribution for the operating fatigue load. Based on the load distribution of the critical end fasteners and their geometry properties, the fatigue life could be calculated with a professional Damage Tolerance Analysis (DTA) software AFGROW. The results would be compared to the recommended SRM repair to check whether the fatigue life could be restored. Following the method provided in this paper, engineers could design repairs which can restore the integrity of the damaged aircraft structures.

Keywords

Repairs beyond specification Fatigue life Damage Tolerance Analysis 

Abbreviations

DTA

Damage Tolerance Analysis

SRM

Structural Repair Manuals

MMPDS

Metallic Materials Properties Development and Standardization

References

  1. 1.
    MMPDS, Metallic materials properties development and standardization handbook, FAAGoogle Scholar
  2. 2.
    Michael C Y NIU (1997) Airframe stress analysis and sizingGoogle Scholar
  3. 3.
    Swift T (1990) Repairs to damage tolerant aircraft, FAA-AIR-90-01Google Scholar
  4. 4.
    Stress severity factors for axially loaded mechanically fastened joints, BoeingGoogle Scholar
  5. 5.
    737–800 SRM, structural repair manual, BoeingGoogle Scholar

Copyright information

© Springer Nature Singapore Pte Ltd. 2020

Authors and Affiliations

  1. 1.AmecoChaoyangPeople’s Republic of China

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