# Beam Failures

The Beam config has 2 subtypes: Beam_member and Beam_shell. The first is made of 1D elements while the second points to freebody sections. Both configs come with their flavor of the same actual methods:
1. Stringer Axial Stress
2. Stringer compressive buckling

The Stinger Axial Stress is a simple method which calculates the Compressive/Tensile margin of safety as:

MS= [(Compressive Stress limit)*(section Area)/(Axial Force)] -1; (resp. Tensile Stress limit)

In the case of freebody sections, Axial Force is mapped to the freebody resultant Fx.

The compressive buckling method evaluates $MS={F}_{cc}/{\sigma }_{x}-1$ with:
• ${\sigma }_{x}$ : average axial stress as (Axial Force)/(Section’s area)
• ${F}_{cc}={F}_{cy}*\left(1-.272\left(L\text{'}/\rho \right)/\pi *\sqrt{E/{F}_{cy}}\right)$
• ${F}_{cy}$ : material compressive stress limit
• $L\text{'}=\left(\text{structural}\text{\hspace{0.17em}}\text{property}\text{​}\text{​}\text{\hspace{0.17em}}Length\right)/\sqrt{\text{K_constraint}}$
• K_constraint = “constraint coefficient” on structural property. Def=0.0699
• $\rho$ : beam section’s radius of gyration
• E: material young’s modulus