QUESTION $2$A randomly oriented, shorter$-$fibre$-$reinforced composite plate having a central through$-$thickness crack of length $2$a is subjected to a uniaxial stress $,$ as shown in figure $1.$ Thecomposite has a fracture toughness KIc $=45$ MPa$-$m$1/2$ and a critical crack sizeac $=15$mm$\mathrm{.}2\mathrm{.}1$ Determine the critical stress that will cause crack growth. $(5)2\mathrm{.}2$ Determine the strain energy released by the crack, if the composite plate materialhas an elastic modulus of $30$ GPa and a plate thickness t $=2$ cm$.(5)$Fig