THEORIES OF FAILURE UNDER STATIC LOAD

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THEORIES OF FAILURE

               For the ones who are searching for the topic of failures in life, love or game etc, I suggest they can search for some other sites. This topic is related to prediction of failure in machine members subjected to uniaxial, biaxial and triaxial stress. As we all know, the strength of all machine parts is based on the mechanical properties of materials used. These properties are determined by the tension and compression tests, which can predict failure in parts subjected to uniaxial stress.


              Ductile materials have yield strength which is common in compression and tension tests whereas brittle materials have similar ultimate tensile and compressive strengths.
              Machine parts are subjected to biaxial and triaxial stresses also but the prediction of failure cannot be done through tests in this case. Different theories have been formulated for prediction of all types of stresses. The mode of failure of ductile and brittle materials is different. The failures of members depend on various factors like type of loads, nature of material, shape and temperature of member. The values for failure predicted by the theories are similar to the ones found out by the laboratory tests, which makes the theories feasible. The principle theories of failure are as follows:-

  1.      Maximumprinciple stress theory (or Rankine’s theory)

  2.      Maximumshear stress theory (or Guest’s or Tresca’s theory)

  3.      Maximumprinciple strain theory (or Saint Venant theory)

  4.      Maximumstrain energy theory (or Haigh’s theory)

  5.      Maximumdistortion energy theory (or Hencky and Von Mises theory)

  6.      OctahedralShearing Stress theory


Note: Please click on the link to know more about the theories.        

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