Elastic Strain - Plastic Strain
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Elastic Strain - Plastic Strain

The proportional limit of a member made of a type of steel is 30,000 psi. Modulus of elasticity of member is 30 x 106 psi. When this member is subjected to a tensile load of 45,000 psi, the strain is 0.0615 in./in. When this member is subjected to a tensile load of 60,000 psi, the strain is 0.2020 in./in.

What is the ratio of elastic strain to plastic strain?

The strings: S7P3A31 (Force - Pull).

The math:
Pj Problem of Interest is of type force (pull).

Formula of interest:
Stress = (modulus of elasticity)(strain)
Strain = Stress/Modulus of Elasticity

The plastic range in a stress-strain relationship is the region in which yielding and strain-hardening takes place. The strain from this yielding is permanent.

Elastic strain, εe = 30,000/(30 x 106) = 0.0010 in./in.
No plastic strain since this is the proportional limit stress.

Elastic strain, εe = 45,000/(30 x 106) = 0.0015 in./in
plastic strain, εp = 0.0615 - 0.0015 = 0.0600 in./in.
So, εep = 1/40
So, εe = 2.5% of εp