What happens when strain increases?

1. In the case of thin plates, as the strain rate increases, the polymer hardens significantly, and thus reduces the plastic deformation, delaying necking instability.

What is load strain?

 A mass, with a known velocity, hitting an object and thereby causing a suddenly applied impact load. Strain When a body is subjected to some external force, there is some change of dimension of the body. The ratio of change of dimension of the body to its original dimension is known as strain.

Why strength increases with increase in strain rate?

Thus, the yield strength, the ultimate strength and the tensile toughness are all observed to increase with increasing strain rate, which indicates both higher strength and higher toughness under tension at higher strain rates.

What does higher strain mean?

Strain rate is the change in strain (deformation) of a material with respect to time. In solids, higher strain rates can often cause normally ductile materials to fail in a brittle manner.

What is high strain rate?

During high-strain-rate deformation, especially shock loading, where the rate sensitivity can lead to high stresses, jog movement is enhanced due to these stresses. In addition at higher strain rate, the mobile dislocation velocity increases to accommodate the required plasticity per Equation 3.

What is effect of strain hardening?

With the increase in strain hardening, the resistance to deformation of a material increases and the material becomes capable of carrying a higher amount of load in a smaller contact area.

What is strain formula?

Strain occurs when force is applied to an object. Strain deals mostly with the change in length of the object. If the original length of the body L 0 L_0 L0​ changes by Δ L \Delta L ΔL , then stress can be expressed as. Strain = Δ L L = Change in Length Original Length .

What is stress vs strain?

Stress is a measure of the force put on the object over the area. Strain is the change in length divided by the original length of the object.

What is plastic strain rate?

The plastic strain rate plays a central role in macroscopic models on elasto-viscoplasticity. The dynamic variable is given by the distribution function of relative strains between adjacent layers, and the plastic strain rate emerges as the average hopping rate between energy wells.

What is a high strain rate?

High-strain-rate superplasticity describes the ability of a material to sustain large plastic deformation in tension at high strain rates of the order of 10-2 to 10-1 s-1 and is of great technological interest for the shape-forming of engineering materials.

What is effective strain?

Effective plastic strain is a monotonically increasing scalar value which is calculated incrementally as a function of (Dp)ij, the plastic component of the rate of deformation tensor. Effective plastic strain grows whenever the material is actively yielding, i.e., whenever the state of stress is on the yield surface.

What is high strain rate loading?

High strain-rate loading processes. Material responses to loading at high strain-rates can be experimentally investigated and analyzed. One of the widely used techniques is the split Hopkinson pressure bar (SHPB) that consists of a striker and the incident and transmission bars between which a specimen is placed in.

What are the effects of high strain rates?

High strain rates—events that occur over a short period of time—tend to favor the elastic properties of materials. Elasticity is associated with load-bearing performance as embodied in properties such as strength and stiffness.

How does strain rate affect the performance of plastic?

The rate of loading for a plastic material is a key component of how we perceive its performance. High strain rates—events that occur over a short period of time—tend to favor the elastic properties of materials. Elasticity is associated with load-bearing performance as embodied in properties such as strength and stiffness.

What happens to a material during strain hardening?

Figure 1 shows what theoretically happens during strain hardening. A certain amount of strain (deformation) is put into the material (gray line). When the load is removed, the material returns to a state of zero stress along a path perpendicular to the elastic loading line (purple squares).

When does the ratio of stress to strain increase?

The point up to which this proportional behaviour is observed is known as the proportional limit. With increasing stress, strain increases linearly. In the diagram above, this rule applies up until the yields strength indicator. It is defined as the ratio of longitudinal stress to strain within the proportional limit of a material.