Evaluation and Repair of Wrought Iron and - Purdue e-Pubs ...

834.4.2 Overall Results from Tensile TestingA total of thirty-five tensile coupon tests were completed for this study. Of thethirty five tensile testing coupons, four had been heat straightened, five had been welded,and one had been mechanically straightened. Initially, all the specimens were comparedwithout differentiating between specimens that had been treated. In each tension coupontest the modulus of elasticity, yield strength, ultimate tensile strength, percent elongation,and strain hardening coefficient and exponent were determined. Tables 4.2 and 4.3 showthe results from the tensile coupon tests for the eyebar and round specimens.The first result determined from testing was the modulus of elasticity. Thismodulus is the slope of the elastic region of the stress strain curve for wrought iron. Theslope was found using linear regression methods, as performed with common spreadsheetsoftware, with the data found from the initial test of the tension coupons, as discussed inChapter 3.Figure 4.7 is a plot of the resulting modulus of elasticity from each tensile testingcoupon. In this plot, the results from the rectangular (eyebar) tensile coupons werecompared to the results from the round tensile coupons. The values for the modulus ofelasticity for all the tensile tests had very little variation between the square and roundtensile coupons. The average modulus of elasticity found from testing was 27,870,000psi with a standard deviation of 590,000 psi, which is only 2% of the average value.The second result determined from testing was the yield strength, which is thestress at which permanent deformations start to occur in the specimen. The yield strengthwas determined by offsetting a line, with the same slope as the Modulus of Elasticity, at astrain of 0.002 and determining where this line intersects the stress-strain curve. Figure4.8 is a plot showing the resulting yield strengths determined from testing for both therectangular and round tensile coupons. As seen in the plot, the yield strength values allfall between 25,000 psi and 35,000 psi, with little variation. The average of all the yield