Polymers three-point bending clamp

We perform flexural testing on polymer rods or beams in the same basic apparatus that we use for tensile or compressive testing. Figure 8.6 illustrates two of the most common flexural testing configurations. In two-point bending, shown in Fig. 8,6 a), we clamp the sample by one end and apply a flexural load to the other. In three-point bending, shown in Fig. 8.6 b), we place the sample across two parallel supports and apply a flexural load to its center. 

A small shear correction is normally apphed to clamped and three-point bending data by dividing fc by 1 +2.9 t/l) for clamped bending and l + 2.9 t/21) for three-point bending. This correction is based on an average Poisson ratio of 0.33 for glassy polymers and 0.5 for rubbers, namely 0.45. 

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