Static analysis of bicycle frame - Need some clarification

Click For Summary

Discussion Overview

The discussion centers around the static analysis of a bicycle frame in the context of a vertical fall, exploring the forces involved and the effects of suspension. Participants engage with concepts related to energy principles, force calculations, and the impact of damping in suspension systems.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Daniel proposes using the energy principle to analyze the forces acting on a bicycle frame during a vertical fall, specifically using the formula F = mv²/r, where v is derived from gravitational potential energy.
  • He identifies the deformation at the contact point (r) as a critical unknown, which he assumes to be related to the suspension travel of the bicycle.
  • Daniel expresses concern about not accounting for the damping effect of the suspension during the fall and considers using the spring constant to estimate suspension behavior.
  • He contemplates subtracting forces to incorporate the effects of suspension but acknowledges confusion between forces and energy in this approach.
  • Andrew critiques the clarity of Daniel's question, suggesting that it lacks comprehensibility and completeness.
  • Daniel acknowledges the feedback and considers rephrasing his question in a new thread to clarify his thoughts.
  • Another participant encourages Daniel to seek help without hesitation, emphasizing the supportive nature of the community.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the clarity of the problem presented. There is disagreement regarding the comprehensibility of the initial question, with some participants suggesting it needs to be articulated more clearly.

Contextual Notes

Daniel's analysis depends on assumptions about the suspension system and the relationship between forces and energy, which remain unresolved in the discussion.

DanielSu
Messages
5
Reaction score
1
Hey,
I am interesting in analyzing a bicycle's frame statically from a vertical fall of x metres, this after using the energy principle i get that the force F = mv^2/r, where v = sqrt(2*g*h), r is the deformation of the bicycle at its contact point and m is total mass from the cycle and cyclist. The only unknown i have is r, which i assume to be the suspension travel (there is one at the front and one in the rear) and i use the linkage to get the correct travel at the contact point.

The issue i find is that when i use this formula i do not consider the "damping" effect that the suspension has during its travel, i can of course do some backwards-engineering and use the knowledge of my spring constant and calculate at what height will the suspension reach the bottom but even then will i not take in consideration at how the suspension has dampened the fall.

My first idea was to simply subtract forces and use the abundant force from maxing out the suspension and use this in my static analysis, however it seems like i confuse forces with energy by doing this.

For my analysis i use Ansys btw.

Kind regards,
Daniel
 
Physics news on Phys.org
Hi DanielSu. Welcome to PF!

Your question, I am afraid, is incomprehensible. If you wish others to help you with a problem you have to state the problem clearly. You also have to actually show us what you have done to solve the problem.

AM
 
You're right Andrew, i will delete this thread and repost a new (better) one If i find the time, i think by just writing this thread i made stuff clear in my own head (and things unclear in yours).
 
There is no shame in asking for help! If writing this the way you have makes you think you have made it clear in your mind, that should be a bit of a red flag. Feel free to ask for help - you would be surprised how kind and helpful PF can be!
AM
 
  • Like
Likes   Reactions: berkeman

Similar threads

  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 4 ·
Replies
4
Views
4K
  • · Replies 11 ·
Replies
11
Views
4K
  • · Replies 10 ·
Replies
10
Views
4K
  • · Replies 22 ·
Replies
22
Views
5K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 20 ·
Replies
20
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K