# Pure bending lab report

The deflection equations for two common cases are listed below in equations 1 and 2. Load Experimental The scope and applicability of the bending tests are defined as: 1 Used as a direct means of evaluation behavior under bending loads, particularly for determining limits of structural stability of beams of various shapes and sizes.

### Deflection of beam lab manual

Handgrip force measurements are not exactly accurate. Therefore, slight curvature was present initially resulting in less stress required to perform the same strain. The deflection equations for two common cases are listed below in equations 1 and 2. From these charts it is clear to see that as the modulus of elasticity decreased from material to material, the deflection increased for the same applied load. Also, the way one grips the gripper also affects the actual strength exerted by one on the beam. It is important to note that in a symmetrical 2-point loading scenario, the center portion of the beam will be in a condition of pure bending as such the bending stresses may be considered separately. Looking at the tables it is clear that the material with the smallest cross section, 3mm Steel, experienced the largest deflection which was expected because that specimen has the smallest moment of inertia. The second part of the lab will focus on using the SM Beam Apparatus to determine the deflection of point-loaded simply-supported beams made of steel, brass or aluminum. The term flexure is used to refer to bending tests of beams subjected to transverse loading Ref.

Load Experimental. Load Theory The table contains the applied load, the distances to the load, a and b, the dial gauge readings and the modulus of elasticity based on the data. Other than that, the gradient of the theoretical lines are also observed to be consistently higher than the experimental lines.

I have also managed to obtain Youngs Modulus and Poissons ratio of a beam material through experimental values and graphs. Figure 2 - Bending Action caused by Transverse Loads Figure 2, shown above, is an illustration of bending action in a beam acted upon by transverse loads.

### Sources of error in beam deflection experiment

This is an acceptable error for this kind of test and we accounted for this error when we found the average E value in Test 3. The basic principle of this strain-stress electrical measurement method: measuring a specimen's surface strain with strain gage, then the specimen's surface stress state is determined according to the strain-stress relationship. Figure 1 - Bending on a Cross Section It can be seen from Figure 1 that the compressive force, C, and the tensile force, T, acting on the member are equal in magnitude because of equilibrium. Bending may be accompanied by direct stress, transverse shear or torsional shear, however for convenience; bending stresses may be considered separately Ref. Figure 5 - Loading Arrangement for Test 3 13 Summary of Data The results from Test 1, the verification of the sensitivity and accuracy of the apparatus, are shown below in Table 1. The average error for Test 1 is also shown in Table 1 and it was determined that the average error for this Test is 2. From these charts it is clear to see that as the modulus of elasticity decreased from material to material, the deflection increased for the same applied load. The term flexure is used to refer to bending tests of beams subjected to transverse loading Ref. Hence, experiment will only give rough estimate of the strength exerted. Deflection of a beam is the displacement of a point on the neutral surface of a beam from its original position under the action of applied loads Ref. Handgrip force measurements are not exactly accurate.

Linearity of the normal stresses against distance from the built-in-end can also be concluded from the 12 straight lines shown in the graph which is consistent to the fact that the material is a homogeneous linear-elastic material.

The basic principle of this strain-stress electrical measurement method: measuring a specimen's surface strain with strain gage, then the specimen's surface stress state is determined according to the strain-stress relationship.

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