Investigation on True Stress-Strain Curves of Flat and Corner Regions of Cold-Formed Section Using 3D Digital Image Correlation Method

Table 3

Mechanical parameters of engineering and true stress-strain curves of corner coupons.

Types of curves	Specimens	(MPa)		(MPa)		(MPa)
Engineering stress-strain curves	TB-1	410.62	0.002	437.99	0.013	357.15	0.109
	TB-2	383.75	0.002	441.94	0.018	338.52	0.136
	TB-3	370.78	0.002	441.35	0.02	343.64	0.125
	BB-1	380.78	0.002	440.13	0.023	366.35	0.109
	BB-2	380.78	0.002	443.23	0.024	377.68	0.109
	BB-3	395.22	0.002	443.44	0.013	373.94	0.107
True stress-strain curves	TB-1	411.55	0.002	441.59	0.028	396.57	0.105
	TB-2	384.96	0.002	458.03	0.039	384.67	0.128
	TB-3	392.64	0.002	450.32	0.021	386.67	0.128
	BB-1	404.35	0.002	451.08	0.029	406.28	0.103
	BB-2	382.45	0.002	460.51	0.034	419.02	0.104
	BB-3	414.21	0.002	451.09	0.029	414.09	0.102
Average values of engineering curves		386.99	0.002	441.35	0.0185	359.55	0.116
Average values of true curves		398.36	0.002	452.10	0.03	401.22	0.112
Improvements of average values		2.94%	0%	2.44%	62.16%	11.59%	−3.45%