Accession Number : ADA303076

Title :   Prediction of Crack Extension Direction in Unidirectional Composites,

Corporate Author : VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF ENGINEERING SCIEN CE AND MECHANICS

Personal Author(s) : Gregory, M. A. ; Herakovich, C. T.

PDF Url : ADA303076

Report Date : AUG 1984

Pagination or Media Count : 134

Abstract : The purpose of this study was to gain a better understanding of the parameters affecting crack growth direction in unidirectional composite materials. To achieve this, the effect of anisotropy and biaxial loading on the direction of crack growth in unidirectional off-axis composite materials were investigated. Specific emphasis was placed on defining the crack tip stress field and finding a consistent criterion for predicting the direction of crack growth. Two models are presented to predict the crack tip stress field, an anisotr6pic elasticity solution and a singular isoparametric finite element formulation. After defining the crack tip stress field, three crack extension direction criteria, thr normal stress ratio, the tensor polynomial and the strain energy density criterion, were applied to predict the direction of crack extensiufl. The theoretically predicted crack extension directions were then compared with experimental results. After comparison, it was determined that only the normal stress ratio criterion correctly predicts the direction of crack extension. (MM)

Descriptors :   *COMPOSITE MATERIALS, *CRACK PROPAGATION, *GRAPHITE EPOXY COMPOSITES, STRESS ANALYSIS, FINITE ELEMENT ANALYSIS, ELASTIC PROPERTIES, ORIENTATION(DIRECTION), STRAIN(MECHANICS), ANISOTROPY, TENSORS, FAILURE(MECHANICS), UNIDIRECTIONAL.

Subject Categories : Laminates and Composite Materials
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE