Maximum Normal Stress Theory

Maximum normal stress theory states that failure will occur if maximum main stress equal to or greater than maximum normal stress on failure in testing of uniaxial tension. The equation mathematically can be shown as follows:

σ₁ ≥ σ_f             σ₁ ≥ σ_c

σ₂ ≥ σ_f             σ₂ ≥ σ_c

σ₃ ≥ σ_f             σ₃ ≥ σ_c

Where:

σ₁, σ₂, σ₃          = main stresses

σ_f                     = uniaxial tensile strength

σ_c                     = uniaxial compressive strength

According to maximum normal stress equation above, failure will occur when uniaxial tensile or compressive strength is greater than main stress. Graphical representation of maximum normal stress theory is shown is Figure 1 below:

Figure 1: Graphic of Maximum Normal Stress