Tensile Strength of the Brittle Materials, Probabilistic or Deterministic Approach

摘要

For various loading rates we estimated the activated defect localization in Modified Brazilian Disk (MBD) type glass specimens in comparison with standard spherical glass specimens. Specimen geometry can considerably affect the mechanical response of material, especially brittle ones, which are very sensitive to the distribution of defects. High and low loading rates of MBD lead glass specimens have been investigated using universal Instron test machine and compressive Hopkinson pressure bars. The experimental results obtained have been compared using the Weibull distribution for scatter strength variation. Stress distribution in the above specimens was calculated using the finite element method, which provided detailed analysis of the macromechanical brittle fracture mechanism. In static tests of spherical glass specimens, we observed generation of contact stresses, which result in activation of defects in the working parts of specimens, whereas no activated defects were observed in MBD specimens neither under static, nor under dynamic loading conditions. For specimens of various geometries and type of load application it is recommended to apply probabilistic approaches, e.g.,Weibull's approach, insofar as contact stresses in brittle materials induce activation of defects, location of which depends on the specimen geometry and loading type.