STP981: Understanding Effects of Adhesive Ductility and Bondline Geometry on Tube-and-Socket Joint Performance

    Miller, JM
    Senior Engineer, Senior Engineer, and Technical Specialist, Aluminum Company of America, Product Engineering Division, Alcoa Technical Center, Alcoa Center, PA

    Hammill, JL
    Senior Engineer, Senior Engineer, and Technical Specialist, Aluminum Company of America, Product Engineering Division, Alcoa Technical Center, Alcoa Center, PA

    Luyk, KE
    Senior Engineer, Senior Engineer, and Technical Specialist, Aluminum Company of America, Product Engineering Division, Alcoa Technical Center, Alcoa Center, PA

    Pages: 12    Published: Jan 1988


    Abstract

    Tube-and-socket joints are commonly used in adhesively bonded structural assemblies. Three parameters which can affect the structural performance of bonded tube-and-socket joints are overlap length, bondline thickness, and adhesive properties. Adhesive shear behavior and the effects of overlap length and bondline thickness on tensile failures and stress distributions in a round tube-and-socket joint are evaluated. Bondline thickness is varied using finite element models to determine its effect on maximum radial and shear stresses and stress variations through the adhesive thickness. Measured tensile failure loads are compared with predictions from a fully plastic closed-form analytical model.

    Results show the measured tensile failure loads of tube-and-socket joints to be dependent on bondline thickness and adhesive ductility. Joints with thin bondlines develop higher tensile failure loads than joints with thick bondlines. The combination of thick bondlines and the brittle adhesive resulted in the lowest tensile failure loads. Predicted stress distributions from finite element analyses show the magnitude of the maximum radial stresses in tube-and-socket joints to be strongly dependent on bondline thickness. Maximum radial stresses are higher in thick bondlines than in thin bondlines. The brittle adhesive is sensitive to the high radial stresses occurring in thick bondlines, as evidenced by tensile failure loads and predicted stress distributions. The ductile adhesive is not as sensitive to the magnitude of the radial stresses.

    Keywords:

    structural adhesives, stress analysis, aluminum, joining, joint geometry, shear strength, epoxy, paste adhesives, overlap length, bondline thickness, stress-strain curve, finite element analysis


    Paper ID: STP30340S

    Committee/Subcommittee: D14.03

    DOI: 10.1520/STP30340S


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