Internal thread tensile strength

[rmf17]

calculation of internal thread tensile strength

Hi All!
I've got a coupling device that has two internal threads of different pitch, length, diameter. The smaller thread takes a lifting bolt, the larger attaches to a piece of machinery.
I've been asked to work out the safe working load (SWL) limit of the coupling. I have the lifting bolt and thankfully it is stamped by the manufacturer and so I've been able to easily calculate it's maximum lifting capacity.
What I need help with is working out the maximum load that can be applied on the internal threads of the coupling device in pure tension.
To make it harder I don't yet know the material of the device or the thread and pitch of the largest internal thread, but I'm working on it!
Can anyone suggest a good method for the calculation? It does not need to account for shear forces, pre-load or torque. The coupling is hand tightened and lifted purely along it's axial line.

 

[Achy47]

Hello there! I would suggest using the following method for calculating the internal thread tensile strength of your coupling device:

1. Determine the material of the device and the thread: The first step would be to identify the material of the coupling device and the thread. This information is crucial in determining the properties of the material, such as its yield strength and ultimate tensile strength.

2. Calculate the cross-sectional area of the internal thread: Using the diameter and pitch of the thread, you can calculate the cross-sectional area of the internal thread using the formula: A = (π/4) x d^2, where A is the cross-sectional area and d is the diameter of the thread.

3. Determine the yield strength of the material: The yield strength is the maximum stress that a material can withstand without permanent deformation. This information can be obtained from material data sheets or by conducting tests on the material.

4. Calculate the tensile strength of the material: The tensile strength is the maximum stress that a material can withstand before breaking. It is usually higher than the yield strength. This information can also be obtained from material data sheets or by conducting tests.

5. Use the appropriate safety factor: To ensure the safety of your coupling device, it is important to use a safety factor. This factor takes into account any unexpected loads or variations in the material properties. A safety factor of 2 or 3 is commonly used in engineering calculations.

6. Calculate the maximum load: Finally, you can calculate the maximum load that can be applied on the internal thread by multiplying the cross-sectional area with the tensile strength of the material and dividing it by the safety factor. This will give you the safe working load (SWL) limit of your coupling device.

I hope this method helps you in calculating the internal thread tensile strength of your coupling device. Please keep in mind that this is a general method and may need to be adjusted based on the specific details of your device. Good luck!