Title: Design and Analysis of a Large Multi-Axial Loading Test Fixture for Structural Repair of Configured Composite Panels

Authors: Lillian Owen, John Lin, Erick Espinar-Mick, Michael Fleming, Reewanshu Chadha, Yongzhe Tian, Ahmet Oztekin

DOI:

Abstract: Under a multi-year Collaborative Research and Development Agreement (CRADA), The Boeing Company and the Federal Aviation Administration (FAA) have been investigating the safety and structural integrity of bonded repairs since 2007. Recent efforts have been focused on developing a large panel test fixture with combined shear, bending and torsion loading capability to test bonded repairs to configured carbon fiber reinforced composite panels representative of transport category aircraft structure. This novel test fixture is designed for 152” by 60” (3.86m by 1.52m) configured panels and will be the largest self-reacting, multi-axial test fixture capable of high residual strength and repair static and fatigue testing, with applied axial strain significantly more than 6,000 microstrain for a typical mid-span wing skin panel. This paper will cover the complex design and analysis of this test fixture. Various finite element and fracture mechanics based analysis techniques are used to guide the fixture design, especially the highly loaded bonded and bolted load introduction joint, including discrete fastener modeling, Virtual Crack Closure Technique (VCCT) and cohesive interface modeling. The hybrid bonded and bolted joint enables high load configured composite panels testing and repair design. This joint design is an innovative way of sustaining a high load introduction to configured composite panels. Without the load transferred through the extended bond region of the stainless steel blocks the high load is unsustainable in a typical test fixture without premature failure of the composite test article. These analysis techniques have been proven successful and show the design meets all requirements. The fabrication of the fixture is underway. Future work on this fixture and potential usages for further composite repair research will be presented.

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Conference: SAMPE 2026

Publication Date: 2026/04/27

SKU: 164

Pages: 14

Price: $28.00