Strain Rate Calculator
Calculate the rate of material deformation over time
Calculation Results:
Total Strain (ε): 0
Strain Rate (ε̇): 0 s⁻¹
Percentage Increase: 0%
Understanding Strain Rate in Material Science
Strain rate is a critical parameter in physics and engineering that measures how fast a material deforms under stress. Unlike simple strain, which only looks at the total change in shape, strain rate accounts for the speed of that change, which significantly impacts how materials like polymers, metals, and biological tissues behave.
The Strain Rate Formula
The calculation involves two primary steps. First, we determine the engineering strain (ε), then we divide it by the time elapsed (t).
Strain Rate (ε̇) = ε / Δt
Where:
- L₀: The original length of the object before force is applied.
- L: The final length of the object after deformation.
- Δt: The time interval over which the deformation occurred.
- ε̇: The strain rate, typically expressed in reciprocal seconds (s⁻¹).
Real-World Examples
Example 1: Slow Creep in Construction
If a steel beam measuring 10,000 mm stretches to 10,001 mm over the course of 1,000,000 seconds (about 11.5 days), the strain is 0.0001. The strain rate would be 0.0000000001 s⁻¹. This is a very low strain rate typical of creep deformation.
Example 2: High-Speed Tensile Test
A 50 mm plastic specimen is pulled to 60 mm in exactly 2 seconds.
1. Change in length = 10 mm
2. Strain = 10 / 50 = 0.2
3. Strain Rate = 0.2 / 2 = 0.1 s⁻¹.
Why Does Strain Rate Matter?
Many materials are "strain-rate sensitive." For instance, Silly Putty acts like a liquid at low strain rates (it flows when pulled slowly) but acts like a brittle solid at high strain rates (it snaps when pulled quickly). Engineers must calculate strain rate to ensure safety in automotive crashes, aerospace structural integrity, and manufacturing processes like metal forging.