# Maximum Strain and Maximum Stress Criteria

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

- ${\sigma}_{1}\ge {X}_{T}$ or ${\sigma}_{1}\le -{X}_{C}$
- ${\text{\sigma}}_{2}\ge {Y}_{T}$ or ${\text{\sigma}}_{2}\le -{Y}_{C}$
- ${\text{\tau}}_{12}\ge S$

- $Xt,Xc$ 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:

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

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).