The Nut Torque Problem: Analyzing Pressure Differences

In summary, the conversation discusses a problem involving the torque on a nut and bolt system with a square thread. The individual is not satisfied with proofs based on equilibrium and wants to calculate the forces on each leg of a chair to prove that the total x and y components are zero. They also mention that with a square thread, the torque increases with the radius and that the force is canceled by the reaction from the nut thread, making the net torque zero. The conversation ends with a discussion about the slope and pressure on the surfaces and how it affects the torque on the nut.
  • #1
Gh778
421
0
With a standard bolt and nut. Create 2 areas, red and green, red surface = green surface. Green surface is closer to the center than red surface. Red surface is between up surface of bolt and bot surface of nut. Green surface is between down surface of bolt and top surface of nut. We put the same pressure from fluid in green and red volumes. Like surfaces are equal the bolt can move up or down without need energy. The nut turn only and the bolt move up/down only. Like green surface is closer to the center, the torque on the nut is bigger with red surface. The outside pressure is lower than pressure in red/green volumes. Like this it seems the nut turn with a torque, where is the problem ?
 

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  • #2
Hi Gh778,

It seems your problem is not solved yet. I don't think its that complicated but you jump from one example to another one.
Another thing is that you are not satisfied with proofs based on equilibrium. For example if a chair is placed on a flat surface, and it is not moving, due to equilibrium, the total reaction forces from the surface on the chair has no x and y component , but you want to calculate the forces on each leg ( the legs have some angle rather than 90 degree with the surface) and prove that the total x and y components are zero.
 
  • #3
Yes, sorry I change and I don't explain all I think :( I thought with square thread, you're remind ? It's not like the drawing show; With square thread we have calculate the torque increase with the radius not like a circular thread where the torque is the same with different radius. Imagine the bolt move up/down, the up force can be equal to the down force. The nut has a torque due to the difference of radius and when it turn it give energy. Where is the problem in this case ?
 
  • #4
The force is canceled by the reaction from the nut thread because the bolt thread is not free to move alone the force direction. All the force due to pressure is normal to the surface and the the bolt thread can't move in that direction, means ALL the force is cancelled. Then what remains to cause a net torque?
 
  • #5
The slope is different that's why the nut don't turn with torque I think.
 
  • #6
Even with zero pressure on one of the surfaces, the net torque is zero.
 
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1. What is the nut torque problem?

The nut torque problem refers to the phenomenon of pressure differences that occur when a nut is tightened onto a bolt. This pressure difference can impact the stability and durability of the bolted joint, making it an important consideration in engineering and construction applications.

2. Why is it important to analyze pressure differences in the nut torque problem?

Analyzing pressure differences in the nut torque problem allows engineers and scientists to better understand the behavior and potential failure points of bolted joints. It can also help to determine the optimal torque value for a given application, ensuring the joint is secure and able to withstand external forces.

3. What factors can influence pressure differences in the nut torque problem?

There are several factors that can impact pressure differences in the nut torque problem, including the type of bolt and nut being used, the surface finish of the components, and the lubrication between them. Additionally, the material properties and dimensions of the joint can also play a role in the pressure differences observed.

4. How is pressure difference measured in the nut torque problem?

Pressure difference in the nut torque problem is typically measured using a strain gauge, which is a device that can detect changes in strain or deformation on the surface of a material. The strain gauge is attached to the bolt and nut, and as torque is applied, it can measure the changes in pressure and provide data for analysis.

5. What are some potential solutions for minimizing pressure differences in the nut torque problem?

One potential solution for minimizing pressure differences in the nut torque problem is to use a flanged joint, which can distribute the pressure more evenly and reduce the likelihood of failure. Additionally, lubricants can be used to reduce the friction between the bolt and nut, resulting in more consistent pressure distribution. Another solution is to use a torque wrench to ensure the proper torque value is applied to the joint, reducing the risk of over or under-tightening.

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