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The yield calculation will determine the safety factor until the part starts to deform plastically. The ultimate calculation will determine the safety factor until failure. In brittle materials the yield and ultimate strengths are often so close as to be indistinguishable, so it is usually acceptable to only calculate the ultimate safety factor.
The maximum stress criterion assumes that a material fails when the maximum principal stress in a material element exceeds the uniaxial tensile strength of the material. Alternatively, the material will fail if the minimum principal stress σ 3 {\displaystyle \sigma _{3}} is less than the uniaxial compressive strength of the material.
As shown later in this article, at the onset of yielding, the magnitude of the shear yield stress in pure shear is √3 times lower than the tensile yield stress in the case of simple tension. Thus, we have: = where is tensile yield strength of the material. If we set the von Mises stress equal to the yield strength and combine the above ...
The first equation determines the magnitude of the deviatoric stress needed to keep the soil flowing continuously as the product of a frictional constant (capital ) and the mean effective stress ′. The second equation states that the specific volume ν {\displaystyle \ \nu } occupied by unit volume of flowing particles will decrease as the ...
The Herschel–Bulkley fluid is a generalized model of a non-Newtonian fluid, in which the strain experienced by the fluid is related to the stress in a complicated, non-linear way. Three parameters characterize this relationship: the consistency k, the flow index n, and the yield shear stress . The consistency is a simple constant of ...
The plasticity index of a particular soil specimen is defined as the difference between the liquid limit and the plastic limit of the specimen; it is an indicator of how much water the soil particles in the specimen can absorb, and correlates with many engineering properties like permeability, compressibility, shear strength and others ...
Figure 1: View of Drucker–Prager yield surface in 3D space of principal stresses for =, = The Drucker–Prager yield criterion [1] is a pressure-dependent model for determining whether a material has failed or undergone plastic yielding. The criterion was introduced to deal with the plastic deformation of soils.
Within the branch of materials science known as material failure theory, the Goodman relation (also called a Goodman diagram, a Goodman-Haigh diagram, a Haigh diagram or a Haigh-Soderberg diagram) is an equation used to quantify the interaction of mean and alternating stresses on the fatigue life of a material. [1]