Stress Results Calculation and Post-processing in ANSYS

In engineering structural analysis, ANSYS is commonly employed to compute stress distributions in complex structures. However, beyond obtaining the stress field, engineers often need to convert these results into sectional internal forces and subsequently calculate equivalent stresses using material mechanics formulas. For instance, in dam foundation analysis, equivalent stress evaluation is crucial for structural safety assessment.

First, ANSYS simulation results typically contain nodal stress or element stress distributions. To convert these into sectional internal forces (such as axial force, shear force, and bending moment), stress integration must be performed over specified cross-sections. The implementation involves the following key steps: Extracting Section Stresses: In ANSYS, select the dam foundation cross-section and retrieve normal stress components (σx, σy) and shear stress (τxy) across the section. Calculating Internal Forces: Through integration of stress components, obtain sectional internal forces. For example, axial force is derived by integrating normal stress over the sectional area, while shear force is obtained through shear stress integration. This process can be automated using ANSYS APDL scripting or Workbench Mechanical's solution combinations.

Next, apply material mechanics formulas to compute equivalent stress (such as Von Mises stress based on the fourth strength theory). For plane stress problems, the equivalent stress expression is typically: √(σx² + σy² - σxσy + 3τxy²) This calculation can be implemented through ANSYS's built-in stress tools or custom user-defined results using mathematical operations on stress components.

Finally, by comparing the equivalent stress with the material's allowable stress, engineers can evaluate the structural safety of the dam foundation. This methodology combines the precision of finite element computation with the simplicity of material mechanics, making it particularly suitable for critical component analysis in hydraulic engineering projects.