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Evaluation Of Flexure And Stress Distribution

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The objectives of this experiment were to evaluate flexure and stress distribution in a simple beam subject to varying loads in a four point bend test as well as to determine and compare the stresses present in a C-clamp subject to varying combined loads due to eccentric loading.

Background
In almost every structure, beams or flexural members are found. It is important then to understand how different beams will reach to different situations. To evaluate flexure and stress distribution in a simple beam, seen in Figure 1, a fundamental four point bending test can be conducted to induce pure bending on the center of a wide flange shape beam.

Figure 1: Schematic of simple I-beam

From a free-body diagram and statics, the general shear …show more content…

This is done via a free-body diagram and statics calculation, as seen in Appendix B. The known equation of axial stress and flexure formula can then be used to find the stress in the C-clamp under eccentric loading. Equation (3) finds axial stress, where P is the applied load and A is the cross sectional area of the section:

σ_axial=P/A (3)

The individual stresses on the C-clamp can be combined using the principle of superposition, which states that “the effect of several loads acting simultaneously is equal to the algebraic sum of the effects of each load acting individually.” By combining Equation (1) and Equation (3) we get an equation for stress under combined flexural and axial loading, seen in Equation (4).

σ_x=σ_axial+ σ_bending=P/A+((-My)/I) (4)

The initial axial and bending stress distributions as well their resultants stress distribution can be theoretically drawn across the width of the C-clamp to visualize a shift of the neutral axis, included in Appendix C.
Procedures
The experiment was conducted in accordance with the procedures detailed in the lab handout.

To begin the four point bending experiment, the T6 Aluminum 6061 beam was loaded on the Instron Universal testing machine. Eight strain gages were mounted to the center of the beam and vertically

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