Beam Bending of a Non-Straight Beam

In summary, the speaker is designing a gear lever for a race car and is using FEA and hand calculations to validate it. They are struggling with understanding the theory for obtaining stress and bending moments for a non-straight beam and are asking for help. Another person suggests using the vertical and horizontal distances from the force to calculate the maximum bending moment and torque, potentially eliminating the need for curved beam theory.
  • #1
TowlieUK
2
0
Hi all,

I am designing a gear lever for a small race car, and am looking to validate my FEA of the lever through the use of hand calculations.

The beam is not straight, and i have never tackled a problem like this before. I am using Roarks Formulas for Stresses and Strains, however am struggling to grasp what it is trying to tell me what to do!

The beam bends in this manner:

Gear_Lever_Problem.jpg


The beam bends at 26 degrees and then back again 26 degrees to get it back to the vertical. The force, F, is applied in the Z direction (into the page) and the lever itself is pivotted about the green line (ie. it can 'rock' backwards and forwards). At the bottom the lever, in reality, is free to move a bit, but for this analysis i was thinking of just having it pinned to demonstrate the maximum loading condition.

Could anyone help me with the theory to obtain the Stress and bending moments of the beam. As I said i have been going through the Roarcks book but to no avail.

Many thanks!
 
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  • #2
TowlieUK: If the vertical distance of force F from the green line is y = h1, then the maximum bending moment occurs at the green line and is Mx = h1*F. If the horizontal distance of force F from the red dot is x = a1, then the beam is also subjected to torsion at the green line, and the torque is T = a1*F. Therefore, it currently appears you do not need to use curved beam theory to analyze the beam.
 

FAQ: Beam Bending of a Non-Straight Beam

1. What is beam bending?

Beam bending is the process of a structural element, such as a beam, experiencing external forces that cause it to deform or bend.

2. How does a non-straight beam differ from a straight beam in terms of bending?

A non-straight beam, also known as a curved beam, experiences bending in a different way compared to a straight beam. While a straight beam experiences bending in a single plane, a non-straight beam experiences bending in multiple planes due to its curved shape.

3. What factors affect the beam bending of a non-straight beam?

The factors that affect the beam bending of a non-straight beam include the shape and curvature of the beam, the material properties, the external forces applied, and the support conditions.

4. How is the bending stress calculated for a non-straight beam?

The bending stress of a non-straight beam can be calculated using the same formula as a straight beam, which is M*y/I, where M is the bending moment, y is the distance from the neutral axis, and I is the moment of inertia. However, for a non-straight beam, the bending moment and distance from the neutral axis may vary at different points along the curve, so the calculation must be done for each section of the beam.

5. What are some real-world applications of beam bending of a non-straight beam?

Some real-world applications of beam bending of a non-straight beam include curved bridges, arches in buildings, and curved beams in aircraft and ship structures. It is also commonly seen in natural structures such as tree branches and animal bones.

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