BEHAVIOUR OF THE MATERIAL TELLS THE FRACTURE INDICATION AND ITS THEORY FOR EXAMINATION

FRACTURE MECHANICS :-- The post fracture examination of the fracture surfaces generally tells a great deal about the material behaviour .This is true not only of the fracture of a precracked body but of an intact structure for example,ina tensile test .A postmortem investigation of a fracture face can tell much about the nature of the stress state ,as well as identify the possible failure mechanism.In fatigue , the appearance of the fracture surface can provide clues to the investigator as to the prior stress history .In fracture , a macroscopic view of the fracture surface can supply Information as to the prior state of stress too .If a thorough the thickness crack has developed , the preference for crack progression during fracture can be associated with the plain stress ,plain strain or mixed mode regions . Therefore,fractures under plane stress conditions usually lead to thorough the thickness,45 degree slant or V slant cross sections .The development of the slant fractures at the fracture faces are referred to as shear lips and provide one of the many indications as to the validity of plane strain fracture toughness tests .