Question $4(10$ marks$)$

A rectangular composite panel has dimensions: length $a=1\mathrm{.}6m$ in the $x-$direction, width

$b=0\mathrm{.}8m$ in the $y-$direction and thickness $t=16mm.$

The laminate is made of E$-$glass epoxy laminae with properties

$E_1=44\mathrm{.}7$GPa,$E_2=12\mathrm{.}7$GPa,$v_{12}=0\mathrm{.}297$GPa,$G_{12}=5\mathrm{.}8$GPa,$t_k=1mm$

It is manufactured as a quasi$-$isotropic laminate with stacking sequence

$[090+45-45{]}_{2s}$

The panel is simply supported along all edges and loaded with a distributed load

$q=0\mathrm{.}02$MPa

If required in your calculations, note that the distributed load results in the following bending

moments per length acting on the panel

$M_x=577N,M_y=1,248N,M_{xy}=20N$

a$)$ Calculate the stress components in the principal material directions for each ply$.$

$(4$ marks$)$

b$)$ Calculate the maximum deflection $w_{\text{m}\text{a}\text{x}}$ of the panel using the equivalent elastic

properties

$E=\frac{12(1-v^2)}{t^3}(\frac{D_{11}+D_{22}}{2})$

$v=\frac{D_{12}}{D_{22}}$

and the deflection equation for a simply supported, isotropic rectangular plate with

$\frac{a}{b}=2,$ loaded with a distributed load

$w_{\text{m}\text{a}\text{x}}=\frac{aq{b}^4}{E{t}^3}$ with $=0\mathrm{.}111(4$ marks$)$

c$)$ Comment on the expected accuracy of the predicted maximum deflection based on the

laminate's level of anisotropy. $(2$ marks$)$