Understanding the deflection of a cable under tension with a force applied in the middle

Click For Summary

Discussion Overview

The discussion revolves around understanding the deflection of a cable under tension when a force is applied at its midpoint. Participants explore the relationship between the applied tension and the resulting deflection, considering parameters such as material properties, cable geometry, and the nature of the applied force.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant presents a specific scenario involving a cable with given material properties and dimensions, seeking to understand how to limit deflection to 0.7m under a 1000N force.
  • Another participant questions whether the force is applied normal to the cable and raises the issue of the cable's length affecting the deflection.
  • Some participants reference "Roark's Formulas for Stress and Strain" to discuss the applicability of beam bending formulas to cables, noting that while the formulas are for beams, the flexibility of cables allows for similar treatment.
  • There is a mention of the complexities introduced when the load is applied off-center, suggesting that this could lead to different deflection behaviors.
  • A participant introduces the concept of the triangle of forces and references Lami's theorem, indicating a potential method for analyzing the forces involved.
  • One participant acknowledges a misunderstanding regarding a notation in the formulas, clarifying their earlier statement.
  • Another participant reminds others to consider the mass of the cable in their calculations.

Areas of Agreement / Disagreement

Participants express differing views on the applicability of beam bending formulas to cable deflection, and there is no consensus on the implications of force application points or the significance of cable length. The discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Some assumptions about the nature of the applied force and the cable's properties may not be fully articulated. The discussion also highlights the need for clarity regarding the definitions and conditions under which the formulas are applied.

McLaren50
Messages
1
Reaction score
0
TL;DR
I have a cable under tension. In the middle of the cable a force is applied. I want to understand the relationship between the force applied, the tension of the cable and the resulting deflection of the cable at the location of the applied force.
With the above in mind, I have a cable of E=60GPa, cross sectional area 7e-4m^2. I want to understand the relationship between the tension applied resisting the deflection of the cable when a force is applied so that the cable will not deflect more than 0.7m in this case. Take the force as 1000N.
Thanks
 
Engineering news on Phys.org
Would it be correct to say that the force is applied normal to the cable? Would you say that the length of the cable matters?
 
Go to YouTube and search for 'cable deflection'.
 
From "Roark's Formulas for Stress and Strain":

cable Roarks.jpg
 
FEAnalyst said:
From "Roark's Formulas for Stress and Strain":

View attachment 259449
this applies to beam bending, not cable or wire stretching.
 
Chestermiller said:
this applies to beam bending, not cable or wire stretching.

It's in the table of beam bending cases (with restricted horizontal displacement) but, as they say in the description, due to perfect flexibility this can be treated as a cable.
 
FEAnalyst said:
It's in the table of beam bending cases (with restricted horizontal displacement) but, as they say in the description, due to perfect flexibility this can be treated as a cable.
Oops. Sorry. I mistook that A as an I.
 
The fun comes when the load is applied at a location other than the center.
 

Similar threads

  • · Replies 4 ·
Replies
4
Views
6K
  • · Replies 19 ·
Replies
19
Views
2K
  • · Replies 6 ·
Replies
6
Views
4K
Replies
1
Views
2K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 20 ·
Replies
20
Views
11K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 10 ·
Replies
10
Views
14K
Replies
3
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K