An elastic perfectly plastic solid with a

uniaxial yield stress of $300$ MPa is assumed

to obey Mises yield critemion. If the

plastic work per unit volume is

$1\mathrm{.}2M\frac{W}{m^3},$ find the proincipal plastic strain

components when,

$($a$){}_1=300$MPa,${}_2=100$MPa,${}_3=0.$

$($b$){}_1=200$MPa,${}_2=-100$MPa,${}_3=0.$