Thermal Residual Stresses in the Analysis of Fiber-Bridged Matrix Crack Growth in Titanium Matrix Composites

    Volume 18, Issue 2 (April 1996)

    ISSN: 0884-6804

    CODEN: CTROAD

    Page Count: 13


    Bakuckas, JG
    Senior research engineer, Galaxy Scientific Corporation, Pleasantville, NJ

    Johnson, WS
    Professor, Georgia Institute of Technology, Atlanta, GA

    Abstract

    In this research, thermal residual stresses were incorporated in an analysis of fiber-bridged matrix cracks in unidirectional and cross-ply titanium matrix composites (TMC) containing center holes or center notches. Two TMCs were investigated, namely, SCS-6/Ti-15-3 and SCS-6/Timetal-21S laminates. Experimentally, matrix crack initiation and growth were monitored during tension-tension fatigue tests conducted at room temperature and at an elevated temperature of 200°C. Analytically, thermal residual stresses were included in a fiber bridging (FB) model. The local R-ratio and stress-intensity factor in the matrix due to thermal and mechanical loadings were calculated and used to evaluate the matrix crack growth behavior in the two materials studied. The frictional shear stress term τ assumed in this model was used as a curve-fitting parameter to matrix crack growth data. The scatter band in the values of τ used to fit the matrix crack growth data was significantly reduced when thermal residual stresses were included in the fiber-bridging analysis. For a given material system, lay-up and temperature, a single value of τ was sufficient to analyze the crack growth data. It was revealed in this study that thermal residual stresses are an important factor overlooked in the original FB models.


    Paper ID: CTR10517J

    DOI: 10.1520/CTR10517J

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    Author
    Title Thermal Residual Stresses in the Analysis of Fiber-Bridged Matrix Crack Growth in Titanium Matrix Composites
    Symposium , 0000-00-00
    Committee D30