A Rectangular Beam in Bending

Vary the depth of the section h to meet the static strength requirement S . 

Compare any two materials, 1 and 2, on a strength basis with the same factor 

calculate the relative volume ratio. From Vi = bhiL and V2 = M2L, 

Finally, calculate the relative cost ratio. From Q = Wifi and Cj = W2P2, 

Equations 6.3 and 6.6 are used to prepare a material comparison table (Table 6.1) for rating three PF s. The first PF GP where GP refers to general purpose is used as the basis (material number 1 in the above equations) and the second and third PF s in the table are used alternatively as material number 2 for rating purposes. As evident the third material is better on a relative weight basis but the first is better on a relative cost basis. 

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As a first example of the design selection procedure, a rectangular beam in bending is considered as shown in Figure 6.1. Some assumptions need to be made to define the problem. Assume the following parameters to be held constant ... 

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