Contents
What is stress concentration and how is it measured?
A stress concentration factor (Kt) is a dimensionless factor that is used to quantify how concentrated the stress is in a mechanical part. A stress concentration, also known as a stress riser/raiser, is a point in a part where the stress is significantly greater than its surrounding area.
What is stress concentration FEA?
A stress concentration is a place of the mesh where the stress raises above the applied nominal stress. It behaves in a similar fashion than stress singularities, but the stress will converge towards a finite value, not infinite, given that the mesh is sufficiently refined.
What is stress concentration factor?
The stress concentration factor, , is the ratio of the highest stress to a nominal stress of the gross cross-section and defined as. Note that the dimensionless stress concentration factor is a function of the geometry shape and independent of its size.
Is stress concentration factor a factor of safety?
Stress concentration factor (Kt), is a dimensionless factor which is used to quantify how concentrated the stress is in a material. To analyze stress concentration, we need to calculate the stress concentration factor, which is a critical parameter for the safety of the component.
How are stress concentrations calculated with finite element analysis?
Traditionally, one would calculate stress concentration factors theoretically by using charts [1] and factoring that into the overall limit state design. With today’s technology, one can analyze structures with finite element analysis to help identify and locate such stress risers.
How are stress concentrations calculated in ANSYS model?
The nominal stress calculated in the ANSYS model was 34,500 psi. By dividing the maximum stress of 98,927 psi by the nominal, a stress concentration factor (K) of 2.85 was calculated. In the RISA-3D model, the capacity of the square tube is at 85% as shown in figure 3. Unity is a ratio of actual stress to allowable.
Where does the maximum equivalent stress occur in FEA?
The maximum equivalent stress occurs at the toe of the corner welds and between the plate and square tube as shown in figure 2b. In FEA, singularities [2] (infinite stress) can occur in areas that have high stress concentration. To check for singularities, a mesh independence study was accomplished.
How is the nominal stress concentration factor calculated?
Stress concentration factor: Kt = σ max / σ nom. The nominal stress is calculated using basic elasticity formulas based on the cross-section of the structure. Sometimes the net section (the section accounting the stress concentration feature) is used, otherwise the gross section is used.