but at point B, the type of support reaction can only be in positive y direction as the support is a roller. If the reaction force is negative at B, it means some external force is acting at B which is not a support reaction.
3 years late but no it will NOT lift off, other wise this would be improperly constrained and not static. Rollers are often show to you in the 'positive centre convention', but if the force would lift the beam off the roller then the roller should be on redrawn the otherside. I think of it have two rollers on each side but we only show one. @emrage
Hello Professor, If I know the bending moment at a point on a cantilever beam, can I use that alone to find the bending moment at another point closer to the support? How? Thanks
Hmm, it would depend on knowing something about the loading. For example, it wouldn't be very hard to make up two very different loadings that generated the same moment at a single point, but were different everywhere else.
@@purdueMET Thank you for your reply. That does make sense now. I have a request. Can you do a video about beams that are not homogeneous for example, a sandwich structure with balsa in the core and carbon fibre on the faces? What would be the normal and shear stresses in each of the layers ? And the deflection? And how would they fail? Thanks
Haha that was fun explanation , thank you professor.
Thank you.👍🏼
but at point B, the type of support reaction can only be in positive y direction as the support is a roller. If the reaction force is negative at B, it means some external force is acting at B which is not a support reaction.
Yes technically it's a roller, which means the beam will lift off :)
3 years late but no it will NOT lift off, other wise this would be improperly constrained and not static. Rollers are often show to you in the 'positive centre convention', but if the force would lift the beam off the roller then the roller should be on redrawn the otherside. I think of it have two rollers on each side but we only show one. @emrage
Hello Professor,
If I know the bending moment at a point on a cantilever beam, can I use that alone to find the bending moment at another point closer to the support? How?
Thanks
Hmm, it would depend on knowing something about the loading. For example, it wouldn't be very hard to make up two very different loadings that generated the same moment at a single point, but were different everywhere else.
@@purdueMET Thank you for your reply. That does make sense now.
I have a request. Can you do a video about beams that are not homogeneous for example, a sandwich structure with balsa in the core and carbon fibre on the faces? What would be the normal and shear stresses in each of the layers ? And the deflection? And how would they fail?
Thanks
i love u