Is volume constant in plastic deformation?

In the region of uniform plastic deformation, sample volume is conserved: Α0L0 = A1L1 .and a power law links stress and strain : σ = K εn , where K = Strength Coefficient n = Strain Hardening Exponent.

What is the plastic region on a stress-strain curve?

The linear portion of the curve is the elastic region and the slope is the modulus of elasticity or Young’s modulus . Many ductile materials including some metals, polymers and ceramics exhibit a yield point. Plastic flow initiates at the upper yield point and continues at the lower one.

What is the plastic deformation region?

Plastic deformation is the permanent distortion that occurs when a material is subjected to tensile, compressive, bending, or torsion stresses that exceed its yield strength and cause it to elongate, compress, buckle, bend, or twist.

Is plastic strain linearly proportional to stress?

Many unreinforced and reinforced plastics have a definite tensile modulus of elasticity where deformation is directly proportional to their loads below the proportional limits. Since stress is proportional to load and strain to deformation, stress is proportional to strain. Fig. 2.4 shows this relationship.

When looking at the stress strain curve what occurs when stress on the bone exceeds the yield point?

1)Elastic deformation. When stress is removed, material returns to original dimension. Deformation is reversible, non permanent. 2) Plastic deformation.

What happens when stress exceeds the strength of material?

If the stress is greater than the yield stress, the material will deform plastically, but not break. Ultimate tensile strength (UTS), Sut , is the amount of stress a material can take before breaking.

What happen in plastic region?

An object or material has plastic behavior when stress is larger than the elastic limit. In the plastic region, the object or material does not come back to its original size or shape when stress vanishes but acquires a permanent deformation. Plastic behavior ends at the breaking point.

Why stress is directly proportional to strain?

So, a metal wire exhibits elastic behavior because according to Hooke’s law the small increase in its length when stretched by an applied force doubles each time the force is doubled. According to Hooke’s law within the elastic limit, the stress is directly proportional to the strain on the body.

What is the stress-strain curve for perfectly plastic materials?

Stress-Strain Curve for Perfectly Plastic Materials 1 There will not be any work hardening during plastic deformation. 2 It shows linear elastic properties in the curve up to the yield stress. 3 After yield stress, it exhibits ideal plastic properties. More

What is the stress-strain relationship for a material?

The stress-strain relationship for a material is given by that material’s stress-strain curve. Under different loads, the stress and corresponding strain values are plotted. An example of a stress-strain curve is given below.

What is the maximum ordinate in the stress-strain diagram?

The maximum ordinate in the stress-strain diagram is the ultimate strength or tensile strength. Rapture strength is the strength of the material at rupture. This is also known as the breaking strength.

Which region of the stress–strain curve is linear?

This region of the stress–strain curve is linear. In this region, ideally, if the stress is removed, the strain returns back to zero. The deformation is completely reversible. The modulus of elasticity or Young’s modulus is defined by the slope of the stress–strain curve in the elastic region.