What is the required force to achieve constant radius beam bending?

AI Thread Summary
To achieve constant radius beam bending, a specific loading arrangement is necessary, as simply applying a point load will not suffice. The bending must follow the elastic bending curve, which requires a moment rather than a direct force. For a homogeneous beam with a constant cross-section, the moment must remain constant along the beam. This can be accomplished by applying a pure couple or a varying distributed load designed to counteract the elastic bending curve. Therefore, achieving constant radius bending involves careful consideration of the loading method.
DeereAdam
Messages
9
Reaction score
0
Hi All,
I need to calculate how much force is required to bend a beam to a constant radius. The beam will be simply supported on both ends and the force will be applied much like a 3 point bend but with a curved face instead of a single point. For most of my application, the beams are small enough and the radius is large enough to only experience elastic bending. Any help on this is appreciated
 
Engineering news on Phys.org
If you are bending beams elastically they will follow the elastic bending curve not one of constant radius.

So in order to force the beam to follow a constant radius curve you have to arrange a loading that is the inverse of this.

That is R = EI/M = a constant along the beam.

For a homogenous beam of constant cross section that means that M must be constant.

In other words you must load you beam with a pure couple only, not a force.
I will have a think to see if you can arrange a force loading to 'cancel out' the distance effect on the moment.
 
Last edited:
You definitely can't make a simply-supported homegenous beam of constant-cross section bend in a constant radius using a point load. You have to either do as Studiot said apply a moment at the end of the beam, or a varying distributed load which is shaped to counteract the elastic bending curve.
 
Posted June 2024 - 15 years after starting this class. I have learned a whole lot. To get to the short course on making your stock car, late model, hobby stock E-mod handle, look at the index below. Read all posts on Roll Center, Jacking effect and Why does car drive straight to the wall when I gas it? Also read You really have two race cars. This will cover 90% of problems you have. Simply put, the car pushes going in and is loose coming out. You do not have enuff downforce on the right...
I'm trying to decide what size and type of galvanized steel I need for 2 cantilever extensions. The cantilever is 5 ft. The space between the two cantilever arms is a 17 ft Gap the center 7 ft of the 17 ft Gap we'll need to Bear approximately 17,000 lb spread evenly from the front of the cantilever to the back of the cantilever over 5 ft. I will put support beams across these cantilever arms to support the load evenly
Thread 'Physics of Stretch: What pressure does a band apply on a cylinder?'
Scenario 1 (figure 1) A continuous loop of elastic material is stretched around two metal bars. The top bar is attached to a load cell that reads force. The lower bar can be moved downwards to stretch the elastic material. The lower bar is moved downwards until the two bars are 1190mm apart, stretching the elastic material. The bars are 5mm thick, so the total internal loop length is 1200mm (1190mm + 5mm + 5mm). At this level of stretch, the load cell reads 45N tensile force. Key numbers...
Back
Top