IV$\_(2.)$PROBLEMS$*$ON$*$STRESS$-$STRAIN$*$CURVES$$

I

$1.-$ A $*$ cylindrical $*$ aluminum $*$ sample $*$ has $*$a$*$diameter$*$of$*12\mathrm{.}8*$mm$*$ and $*$ an $*$ initial $*$ base $*$ length $*$of$*12\mathrm{.}5*$mm$*$ and $*$ it $*$

is $*$ subjected to $*$ uniaxial $*$ tension. $*$ Use $*$ the $*$ data $*$ from $*$ the $*$ loa$($d$)/($e$)$longation $*$ table $*$ to $*$ answer $*$ the $*$ following $*$

questions:$-$

a$.$ Represent $*$ the engineering $*$ stress $*$ data $*$ versus $*$ the $*$ engineering $*$ strain. $||$

c$.$ Calculate the $*$ yield $*$ strength, assuming $*$ that $*$ the residual $*$ strain $*$ at $*$ the $*$ yield $*$ point $*$ is $*0\mathrm{.}002.||\backslash$sigma $\_($y$)=740*$MPa $11\%*$ load $*($N$)*$ and $*$ the $*$ elongation $*($mm$)*$of$*$ the sample $*$ at $*$ the $*$ yield $*$ point. $*$F$=*9\mathrm{.}5\backslash$times $104$N$,*\backslash$Delta l$=0\mathrm{.}075$mm $^(-)$

h$.$ Calculate $*$an approximate $*$ working $*$ stress $*$ for $*$ this $*$ material. Solution: $\{$:$\backslash$sigma $\_($w$)=365*$MPa$)$q

i$.$ With $*$ the $*$ values $-$ obtained, is $*$it possible to $*$ calculate $*$ the $*$ load $*$ applied $*$ to $*$ the $*$ sample $*$ if $*$ the $*$ elongation $*$

an $-$alternative $-$method. cdotscdotsF$=10\mathrm{.}3$x$10^(4)*$N f