What is the impact of Youngs Modulus on copper cable torqueing?

In summary, the conversation discusses a situation in which a 16mm copper cable needs to be torqued to 4Nm in a box terminal to carry high electrical current. After about 5 hours, the terminal can be re-tightened to 4Nm. The issue is believed to be related to Young's Modulus and the characteristics of copper, but it is actually due to work hardening of the copper during torquing. Suggestions are made to potentially solve the issue, such as overtorquing the copper and then reapplying the load, or retorquing periodically until the copper stops yielding. The person is also open to other suggestions.
  • #1
MandyVol
2
0
I hope someone can help. I am an Production Engineer. We have a situation where we have to torque a 16mm copper cable in a box terminal by 4Nm. The cable will be used to carry a high electrical current.

We find that after torqueing (About 5 hours or so) the terminal can be re-tightened back to 4Nm.

I am told this is to do with Youngs Modulus and the characteristics of copper.
I have taken a look at Youngs Modulus but it all seems centred around the stretching of copper and not the compression / "squashing" of copper.

Would anyone know how to work out:
1. What interval we should wait before re-torque,
2. How many times you would need to re-torque,
3. Is re-torque the best option or is there an alternative.
4. Am I even on the right track with regards to Youngs Modulus or are there any other suggestions?

Any assitance would be greatly appreciated.
 
Engineering news on Phys.org
  • #2
Hi Mandy,
The modulus of elasticity (Young's modulus) is the same in both tension and compression, but the reason for the relaxing of the torque isn't due to the modulus. If the stress on the copper doesn't exceed yield during operation, it shouldn't require retorquing, but I suspect because the yield strength for copper is so low that it is being deformed when torquing and again to a small degree during operation.

As you crush (or stretch) a material like copper, it work hardens, so the yield strength increases. There's a risk of fatigue if there are alternating stresses in the material, but I suspect the alternating stresses are low and can be ignored. You'd need to look at that separately. The more important issue is getting the material to stop yielding during operation. Perhaps by overtorquing the copper to well above 4 Nm (if it can handle it) then removing the load and reapplying to 4 Nm, it might not need periodic retightening. Otherwise, I suspect you will need to retorque a number of times, each time you'll find it being a bit tighter than previously and eventually it won't need to be retightened at all. But I think it's getting loose over time because the copper is yielding.

If you try this, let me know as I'd be interested in your results. I have a similar issue using annealed copper.
 
  • #3
Thanks alot! I will try this and let you know if it works, any other suggestions will still be appreciated.
 

What is Young's Modulus of Copper?

The Young's Modulus of Copper is a measure of the stiffness or rigidity of the material. It is defined as the ratio of stress to strain in the elastic range of deformation.

What is the unit of measurement for Young's Modulus of Copper?

The unit of measurement for Young's Modulus of Copper is Pascals (Pa) or Newtons per square meter (N/m^2). It can also be expressed in other units such as Gigapascals (GPa) or Megapascals (MPa).

How is Young's Modulus of Copper determined?

You can determine Young's Modulus of Copper by subjecting a sample of the material to different levels of stress and measuring the corresponding strain. The slope of the stress-strain curve in the elastic region gives the value of Young's Modulus.

What factors can affect the value of Young's Modulus of Copper?

The value of Young's Modulus of Copper can be affected by factors such as temperature, impurities in the material, and the manufacturing process. The value may also vary depending on the orientation of the material and the direction of applied stress.

Why is Young's Modulus of Copper important in engineering and material science?

Young's Modulus of Copper is an important material property in engineering and material science because it helps in predicting the behavior of copper in different types of applications. It is used in designing and selecting materials for various structural and mechanical applications, such as in building construction and manufacturing of tools and equipment.

Similar threads

  • Materials and Chemical Engineering
Replies
2
Views
1K
  • Materials and Chemical Engineering
Replies
5
Views
4K
  • Materials and Chemical Engineering
Replies
7
Views
3K
  • Introductory Physics Homework Help
Replies
17
Views
1K
Replies
4
Views
1K
Replies
2
Views
4K
  • Materials and Chemical Engineering
Replies
1
Views
5K
  • Engineering and Comp Sci Homework Help
Replies
2
Views
2K
  • Materials and Chemical Engineering
Replies
4
Views
13K
  • Materials and Chemical Engineering
Replies
13
Views
54K
Back
Top