u	shortening of specimen
Lo	initial height of a specimen
${\sigma }_d$	$dynamic yield stress$
${\sigma }_s$	$static yield stress$
$\dot{\epsilon }$	$strain rate$
$C,P$	$constant Cowper–Symonds relation$
H	the half distance between adjacent plastic hinges
t	sidewall thickness
c	two widths of the profile
${\delta }_c$	$crushing distance$
$b_f$	radius of toroidal plastic hinge
I1, I3	integrals in Equation (5)
$F_m^d$	$average crushing force for dynamic analysis$
$v_m$	$average velocity of tup$