Finite Element Analysis (FEA) is a powerful tool in mechanical engineering design. It breaks down complex structures into smaller, manageable pieces to analyze stress, deformation, and other critical factors. FEA helps engineers optimize designs and predict how they'll perform under real-world conditions.

In CAD and solid modeling, FEA takes digital designs to the next level. By simulating various loads and conditions, it allows engineers to test and refine their ideas virtually. This saves time and money by catching potential issues before physical prototypes are built.

FEA Model Setup

Mesh Generation and Element Types

• Mesh generation discretizes the CAD model into smaller elements (triangles, quadrilaterals, tetrahedra, hexahedra)
• Element types are selected based on the geometry and analysis requirements
  • 1D elements (beams, trusses) model slender structures
  • 2D elements (triangles, quadrilaterals) model thin structures (plates, shells)
  • 3D elements (tetrahedra, hexahedra) model solid structures
• Mesh density affects accuracy and computational cost
  • Finer mesh provides more accurate results but increases computation time
  • Coarser mesh reduces computation time but may compromise accuracy
• Adaptive meshing automatically refines the mesh in high-stress regions (stress concentrations)

Boundary Conditions and Load Application

• Boundary conditions define how the model interacts with its environment
  • Fixed supports prevent translation and rotation
  • Pinned supports allow rotation but prevent translation
  • Roller supports allow translation along one axis and rotation
• Loads are applied to simulate the forces acting on the model
  • Point loads are concentrated forces applied at specific nodes
  • Distributed loads are forces spread over a surface or edge (pressure, line load)
  • Thermal loads simulate temperature changes and resulting thermal stresses
• Constraints define how different parts of the model interact with each other (contact, tie)

Material Properties

• Material properties define the behavior of the model under load
  • Young's modulus (elastic modulus) describes the stiffness of the material
  • Poisson's ratio describes the lateral contraction of the material under axial load
  • Density is required for dynamic analyses and self-weight calculations
• Nonlinear material properties (plasticity, hyperelasticity) can be defined for advanced analyses
  • Plasticity models the permanent deformation of materials beyond their yield point
  • Hyperelasticity models the large deformations of rubber-like materials

FEA Analysis Types

Stress Analysis

• Stress analysis calculates the internal forces and stresses in the model under load
• Von Mises stress is a common failure criterion for ductile materials (steel, aluminum)
  • Compares the equivalent stress to the yield strength of the material
  • Regions exceeding the yield strength are likely to fail
• Principal stresses provide insight into the maximum tensile and compressive stresses
• Stress concentrations occur at geometric discontinuities (holes, fillets, sharp corners)

Deformation Analysis

• Deformation analysis calculates the displacements and strains in the model under load
• Displacement results show how much the model deforms in each direction (x, y, z)
• Strain results indicate the relative elongation or compression of the material
  • Tensile strain occurs when the material is stretched
  • Compressive strain occurs when the material is compressed
• Excessive deformation can lead to failure even if stresses are below the yield strength

FEA Results

Result Interpretation

• Post-processing tools visualize the results using color contours, animations, and graphs
• Stress and deformation results are compared to allowable limits (yield strength, maximum deflection)
• Factor of safety (FOS) indicates the margin between the actual and allowable stress
  • FOS > 1 means the design is safe under the given loads
  • FOS < 1 means the design is likely to fail and requires optimization
• Convergence studies verify that the mesh is sufficiently refined for accurate results
  • Mesh is refined until the results converge to a stable value
  • Helps balance accuracy and computational cost
• Sensitivity studies investigate the impact of design changes on the results
  • Identifies critical design parameters and optimizes the design
  • Helps engineers make informed design decisions based on FEA results