# Maximum Strain and Maximum Stress Criteria

These criteria do not consider any interaction between different stress (strain components).

The failure occurs if one of the following conditions are satisfied:
• ${\sigma }_{1}\ge {X}_{T}$ or ${\sigma }_{1}\le -{X}_{C}$
• ${\text{σ}}_{2}\ge {Y}_{T}$ or ${\text{σ}}_{2}\le -{Y}_{C}$
• ${\text{τ}}_{12}\ge S$
Being and ${\tau }_{12}$ the in-plane normal stress components and the in-plane shear stress one respectively and where:
• $Xt,Xc$ are the maximum allowable stresses in the 1-direction in tension and compression,
• $Yt,Yc$ are the maximum allowable stresses in the 2-direction in tension and compression,
• $S$ is the allowable in-plane shear stress

Relevant failure index is evaluated as per the following equation:

${F}_{index}=\mathrm{max}\left[\frac{{\text{σ}}_{1}}{X},\frac{{\text{σ}}_{2}}{Y},\frac{{\text{τ}}_{12}}{S}\right]$

being $X={X}_{T}$ or $X={X}_{C}$ if ${\sigma }_{1}\ge 0$  or ${\sigma }_{1}<0$ and the same for $Y$ .

The approach for maximum strain criterion is the same as per the maximum stress on, but with the corresponding strains in the condition for failure to be taken into account.

## Syntax

MaxStrainFT(tensor,xt,xc,yt,yc,s,sets,plies,elems,parts,props,pool_name,layer_index,opt_str)

## Arguments

tensor
Stress table
xt
Allowable tensile stress/strain in ply material direction 1
xc
Allowable compressive stress/strain in ply material direction 1
yt
Allowable tensile stress/strain in ply material direction 2
yc
Allowable compressive stress/strain in ply material direction 2
s
Allowable in-plane shear stress/strain
sets
Set table (D=NULL)
plies
Ply table (D=NULL)
elems
Element table (D)
parts
Part table (D)
props
Property table (D)
pool_name
Pool name (D=@current_pool)
layer_index
Layer index (D=@current_slice_index)
opt_str
This is an optional argument, which can passed if needed (D=option).