Aerospace structures utilize fiber reinforced matrix composites because these offer high strength and stiffness to weight ratios. In these structural designs, members often require a combination of mechanical joining and adhesive bonding. Adhesive bonding is preferred because of the increased weight and quasi-brittle nature of mechanical attachments along with the introduction of stress concentration areas at the joint. However, adhesive joining requires a complex and delicate manufacturing assembly process in order to ensure the adhered members maintain the designed joint strength. In the space industry, where low weight is critical and high thermal and structural loads are the norm, structural members are often bonded sandwich composite materials that require adequate strength prediction at the structural joints. Insufficient adhesive joint strength can be catastrophic and costly, and as such there is intense focus in proper design for manufacturing and analysis of adhesively bonded structures. Although structural testing is necessary to verify space structure integrity, it cannot address the structural integrity of all the spacecraft joints at 100% of proof loading. That is why it is very important to be able to accurately predict the structural capability of bonded joints in a space structure. A typical method for analytical strength predictions is the finite element method. Finite element modeling of these structures is challenging since one often must address the modeling of the interface of thick sandwich composite panels to relatively thin bonded joints and properly address the discontinuity at the materials interface. Additionally, the analysis results shall be validated through test-correlated models. In this paper, the accuracy of two space structure bonded joint's strength prediction are demonstrated by improving the fidelity of the joint modeling and test correlation techniques. Also described are the steps taken to predict the failure modes of the joint. The model fidelity of the space structure joints will focus on adhesively bonded joints detail that allows prediction of not only the failure load but also the failure mode.
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