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:

$σ_{1} \geq X_{T}$ $σ_{1} \geq X_{T}$ or $σ_{1} \leq - X_{C}$ $σ_{1} \leq - X_{C}$
$σ_{2} \geq Y_{T}$ $σ_{2} \geq Y_{T}$ or $σ_{2} \leq - Y_{C}$ $σ_{2} \leq - Y_{C}$
$τ_{12} \geq S$ $τ_{12} \geq S$

Being

σ_{1} σ_{2}

$σ_{1} σ_{2}$ and

τ_{12}

$τ_{12}$ the in-plane normal stress components and the in-plane shear stress one respectively and where:

$X t, X c$ $X t, X c$ are the maximum allowable stresses in the 1-direction in tension and compression,
$Y t, Y c$ $Y t, Y c$ are the maximum allowable stresses in the 2-direction in tension and compression,
$S$ $S$ is the allowable in-plane shear stress

Relevant failure index is evaluated as per the following equation:

$F_{i n d e x} = max [\frac{σ_{1}}{X}, \frac{σ_{2}}{Y}, \frac{τ_{12}}{S}]$ $F_{i n d e x} = \max [\frac{σ_{1}}{X}, \frac{σ_{2}}{Y}, \frac{τ_{12}}{S}]$

being $X = X_{T}$ $X = X_{T}$ or $X = X_{C}$ $X = X_{C}$ if $σ_{1} \geq 0$ $σ_{1} \geq 0$ or $σ_{1} < 0$ $σ_{1} < 0$ and the same for $Y$ $Y$ .

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).