Difference between yield stress and ultimate stress [with Pdf]

The difference between yield stress and ultimate stress is that the yield stress is the minimum stress at which the material starts to deform plastically and the ultimate stress is the maximum value of stress that material can withstand before undergoing failure.

Before comparing ultimate stress vs yield stress, let’s know in brief about yield stress and ultimate stress.

Yield stress:

yield stress

The yield stress of a material is the point at which the elastic behavior of the material ends and if the stress is more than the yield stress then the material undergoes plastic deformation.

The yield stress is observed in the ductile material and it is the point where the ductile materials start to show the plastic deformation.

Ultimate stress:

ultimate stress

The ultimate stress is the maximum value of stress, that material can withstand before undergoing fracture.

After the ultimate stress point, the material loses its strength and undergoes fracture.

Depending on the type of loading, the ultimate stress can be classified as ultimate tensile stress, ultimate shear stress, and ultimate compressive stress.

Difference between yield stress and ultimate stress:

Sr. No.Yield stressUltimate stress
1]It is the value of stress at which the elastic nature of the material ends.It is the maximum value of stress that material can withstand.
2]From the yield stress, the material starts to deform plastically.After reaching the ultimate stress, the material loses its strength and undergoes fracture.
3]The value of yield stress is generally lower than the ultimate stress.The ultimate stress is higher than the yield stress.
4]The yield stress is used as a criterion for the design of ductile material.Ultimate stress is the criteria for the design of brittle material.
5]The brittle material doesn’t have yield stress.The brittle as well as ductile material has ultimate stress.
The above table compares the yield stress vs ultimate stress.

FAQs:

  1. What is the difference between yield stress and ultimate tensile strength?

    The yield stress is the minimum value of stress at which the material shows the plastic deformation and ultimate tensile strength is the maximum value of stress, that material can withstand when it is stretched.

  2. Is ultimate stress greater than the yield stress?

    Yes, in the case of ductile material, the ultimate stress is always greater than the yield stress.

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