Stress in beam
Stress in beam
(OP)
Hi Everybody,
I'm working on a beam diagrams and stress in beam.
First question, having a constant bending moment, such as 4 point flexural model, what does it mean on the shape? There is still bending, but does that mean that the area is not changing?
Also if the load is distributed, the curvature of the beam would be different from a point load I assume?
It might be obvious for most of you but just want to clarify some doubts I am having now!
Cheers
I'm working on a beam diagrams and stress in beam.
First question, having a constant bending moment, such as 4 point flexural model, what does it mean on the shape? There is still bending, but does that mean that the area is not changing?
Also if the load is distributed, the curvature of the beam would be different from a point load I assume?
It might be obvious for most of you but just want to clarify some doubts I am having now!
Cheers






RE: Stress in beam
If the load was applied as two distributed loads, rather than 4 point loads, the shear and moment over the loaded region would be different (because the shear would be changing rather than constant), but if the constant moment over the central unloaded zone was the same then the curvature would be the same.
Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/
RE: Stress in beam
SO what does it mean to have a constant curvature? There is still bending, the beam will not go flat?
RE: Stress in beam
no curvature ==> no bending
no bending ==> no curvature
best regards
Klaus
RE: Stress in beam
Apply a four point load to a ruler or some other flexible strip and see for yourself what it does.
Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/
RE: Stress in beam
the bending moment is constant between the 2 load point
but constant does not mean Zero !!
best regards
Klaus
RE: Stress in beam
Or a linear deflexion?
RE: Stress in beam
EIw''=-M,
where: E the elasticity modulus
I: inertia moment
w: elastic line (deflection)
M: moment diagram
So constant moment means constant curvature and a quadratic elastic line.
Jason McKee
proud R&D Manager of
Cross Section Analysis & Design
Software for the structural design of cross sections
Moment Curvature Analysis
Interaction Diagrams
Reinforcement Design etc.
RE: Stress in beam
RE: Stress in beam
Where did you get U shaped deflections from?
Over the region where the moment is constant the deformed shape is a circular arc, that is, it has a constant curvature.
I strongly recommend you have a look at:
https://youtu.be/khuPy_apnsE
Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/