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  • A fracture control plan for composite spacecraft structures

    Paper ID



    • C.K.H. Dharan


    Department of Mechanical Engineering, University of California






    Composite spacecraft structures are generally designed for high stiffness and dimensional stability. To meet these requirements, such structures have a high degree of anisotropy. Such construction results in laminates which have low transverse strength and which are susceptible to delamination. For the INTELSAT V and INTELSAT VI C-band reflectors, for example, I-beam stiffeners of high-modulus graphite fiber are employed to stiffen a thin composite sandwich shell. Such structures are usually well analyzed for in-plane loads arising from the launch vibration environment. Small out-of-plane loads, however, can cause delamination of such construction. Such loads can arise from second-order geometric effects, handling, or from supporting minor attachment brackets for thermal blankets. Incorporating fracture criteria in defining the minimum margins of safety of the entire structure will ensure that such unanticipated failures do not occur. In this paper, an approach for a fracture control plan is proposed in which delamination fracture toughness is used as a material strength parameter. Currently, no such plans exist for composite structures.