Fully Plastic Action of A36 Steel

Testing Parameters

IDE 120 Flexure Test for Fully Plastic Action File name: fully plastic action.is_flex.doc
Temperature		75.0 F		Crosshead speed		2.000 in/min
Humidity		29.0%		Diameter		0.623 in
Fixture type		3-point		Support span		5.000 in
Source for flexure strain		Extension

Results

Provided by Instron's "Bluehill Materials Testing Software."

 

	Fully-Plastic Point	Max. Load
Load (lbf)	1673	2352
Extension (in)	0.087	0.533

Provided by Instron's "Bluehill Materials Testing Software."

		Experimental Value
Tensile Yield Point	σyp	49.0 ksi 3
Torsion Yield Point	τyp	24.3 ksi 4
Direct Shear Yield Point	τavg, yp	36.5 ksi 5
Bending Yield Point	σyp	51.9 ksi

³ From "Tension Test on Carbon Steel" experiment performed by Jeff Thomas several semesters ago.  These results are no longer used in the tension lesson.
⁴ From "Elastic and Inelastic Torsion" experiment performed by Jeff Thomas several semesters ago.  These results are still used in the torsion lesson.
⁵ From "Direct Shear" results in the torsion-direct shear lesson.

Summary of Results

Direct Shear Yield Point	τavg,yp	36.5 ksi
Average of Tensile and Torsion Yield Points	(σyp + τyp) / 2	36.7 ksi
Average of Bending and Torsion Yield Points	(σyp + τyp) / 2	38.1 ksi

Interesting!  τ_avg isn't defined as an average of σ and τ, but this is definitely an interesting coincidence.  I wonder if it holds true for other materials?

 

	Experimental Ratio	Maximum Shear Stress Theory		Maximum Octahedral Shear Stress Theory		Maximum Principal Strain Theory		Maximum Principal Stress Theory
		Theoretical Ratio	Percent Difference	Theoretical Ratio	Percent Difference	Theoretical Ratio	Percent Difference	Theoretical Ratio	Percent Difference
	0.496	0.500	0.8%	0.577	15.1%	0.800	46.9%	1.000	67.4%
	0.468	0.500	6.6%	0.577	20.9%	0.800	52.4%	1.000	72.5%