The discussion centers on the concept of pure bending in beams, specifically addressing the absence of shear force and its implications on stress concentration. Participants clarify that in the context of pure bending, as illustrated in Figure 3.11, the bending moment remains constant while stress concentration occurs at any changes in cross-sectional area. The confusion arises from the interpretation of figures 3.10 and 3.11, where it is established that both figures depict scenarios without shear force, yet only figure 3.11 shows a change in cross-section that leads to stress concentration.
PREREQUISITESEngineering students, structural engineers, and professionals involved in mechanical design and analysis of beam structures.
why there's a cross sectional area change in the middle ? i didnt see it . I just noticed that the cross sectional area is constant throughout the beam ...Chestermiller said:
You're saying you didn't notice a cross sectional area change in Fig. 3.11?chetzread said:
It has nothing to do with no shear force acting there. I has to do with the stress concentration at the change in cross sectional area.
yes , is there any cross sectional area change ? it's a straight beam , am i right ?Chestermiller said:
Are we looking at the same figure? I'm looking at Fig. 3.11. Do you not see a cross section change in the figure?chetzread said:
which is pure bending??.3.11 or 3.10 ?Chestermiller said:
Both.chetzread said:
Yes. So??
so , in 3.10,Chestermiller said:
Why do you persist in saying that a shear force is the cause of the stress concentration? It is not. In the center of the beam in both Fig. 3.10 and 3.11, there is no shearing force. In Fig. 3.11, there is no shearing force throughout the entire length of the beam. In Fig. 3.10, the shearing force is zero throughout the section that is inboard of the two loads P.chetzread said: