Contribution of forces (3D beam case):
- Axial force (N) and bending forces (My, Mz) contribute to normal stress (σx) distribution in the section.
- Shear force components (Vy, Vz) and twisting (Mx) couple contribute to shearing stress (τy, τz) distribution in the section.
- Normal (σx) and shearing (τy, τz) stresses are used to determine principal stresses (σ1, σ2 ), maximum shearing stress (τmax) and operation (θ) of principal planes.
- Analysis is valid only to extent that conditions of applicability of superposition principle of Saint-Venant‘s principle are met.
Principal stresses for the beam cross section can be obtained like:
