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The yield strength or yield stress is a material property and is the stress corresponding to the yield point at which the material begins to deform plastically. The yield strength is often used to determine the maximum allowable load in a mechanical component, since it represents the upper limit to forces that can be applied without producing ...
The stress is proportional to the strain, that is, obeys the general Hooke's law, and the slope is Young's modulus. In this region, the material undergoes only elastic deformation. The end of the stage is the initiation point of plastic deformation. The stress component of this point is defined as yield strength (or upper yield point, UYP for ...
The strength of materials is determined using various methods of calculating the stresses and strains in structural members, such as beams, columns, and shafts. The methods employed to predict the response of a structure under loading and its susceptibility to various failure modes takes into account the properties of the materials such as its yield strength, ultimate strength, Young's modulus ...
Ludwik's equation is similar but includes the yield stress: [11] σ = σ y + K ϵ p n {\displaystyle \sigma =\sigma _{y}+K\epsilon _{p}^{n}\,\!} If a material has been subjected to prior deformation (at low temperature) then the yield stress will be increased by a factor depending on the amount of prior plastic strain ε 0 :
The exact equation to represent flow stress depends on the particular material and plasticity model being used. Hollomon's equation is commonly used to represent the behavior seen in a stress-strain plot during work hardening: [2] =
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.
This assumes that yield occurs when the shear stress exceeds the shear yield strength τ = σ 1 − σ 3 2 ≤ τ y . {\displaystyle \tau ={\frac {\sigma _{1}-\sigma _{3}}{2}}\leq \tau _{y}.\,\!} Total strain energy theory – This theory assumes that the stored energy associated with elastic deformation at the point of yield is independent of ...
Alternatively, if the yield stress, , is assumed to be at the 0.2% offset strain, the following relationship can be derived. [5] Note that is again as defined in the original Ramberg-Osgood equation and is the inverse of the Hollomon's strain hardening coefficient.