Von Mises Stress Calculator
Enter Stress Components (Plane Stress):
Results
Von Mises Stress (σv): 0
Factor of Safety (FoS): 0
Understanding Von Mises Stress
The Von Mises stress, also known as equivalent tensile stress, is a value used by engineers to determine if a given material will yield or fail under complex loading conditions. It is based on the Distortion Energy Theory, which suggests that yielding occurs when the distortion energy in a material reaches a critical level.
The Von Mises Formula
For a 2D plane stress state (most common in engineering simulations), the Von Mises stress (σv) is calculated using the following equation:
Where:
- σx: Normal stress in the x-direction.
- σy: Normal stress in the y-direction.
- τxy: Shear stress in the xy-plane.
Why is it Important?
In real-world engineering, parts are rarely pulled in just one direction. They are twisted, bent, and compressed simultaneously. The Von Mises criterion allows engineers to combine all these different stresses into a single scalar value that can be directly compared to the material's yield strength (determined from a simple tensile test).
Practical Example
Imagine a structural steel plate with a yield strength of 250 MPa. If the analysis shows:
- Normal Stress X (σx) = 120 MPa
- Normal Stress Y (σy) = 50 MPa
- Shear Stress (τxy) = 40 MPa
Using the calculator, the resulting Von Mises stress would be approximately 126.9 MPa. Since 126.9 MPa is less than 250 MPa, the material is safe and will not yield. The Factor of Safety would be 250 / 126.9 = 1.97.
Factor of Safety (FoS)
The Factor of Safety is a crucial design metric. It is calculated as:
An FoS greater than 1.0 indicates that the part is within the elastic limit. Many engineering standards require an FoS of 1.5 to 3.0 depending on the criticality of the component.