Boundary conditions in Ansys

[clab]

Hi, I have one question related to the boundary conditions I should apply in a Static Structural simulation for the following support.

The support is subjected to the following loading conditions shown below.

• Interface 1: 0.75 inch diameter pin. The pin is to be considered infinitely stiff.
• Interfaces 2 – 5: 0.375-24 AS3239-26 machine bolt. Nut face 0.405 in. max ID and 0.558 in. min OD. The bolts are to be considered infinitely stiff.
• Load Conditions:
• 1. Max static linear load of 8,000 lbs vertical up.
• 2. Max static linear load of 8,500 lbs horizontal out.
• 3. Max static linear load of 9,500 lbs 42 degrees from vertical.
• 4. Max static torsional load of 5,000 lb-in horizontal at intersection of centerline of pin and midpoint between clevis arms.

When performing the support edge condition by applying the remote displacement, I must consider the constraints generated by the bolts on both displacement and rotation. Which displacement and rotation components should be free or fixed? (as shown in the last screenshot).

I am considering that the screw only makes contact/pressure with the bracket on the face of the countersunk hole. as shown in the following image.

 

[FEAnalyst]

It would be best to add simplified models of the bolts for higher accuracy. You don’t even have to use solid representation, beam elements with rigid links may suffice. There is an interesting book published last year that discusses bolt modeling in detail, among other topics: "Practical Finite Element Analysis for Mechanical Engineers" by D. Madier.

 

[jrmichler]

I have modeled similar parts by specifying a force equal to bolt preload force on the area contacted by the bolt head, and a distributed spring under the base. The spring constant needs to be quite stiff, on the order of 1,000,000 to 10,000,000 lbs/inch/inch^2. The spring constant can be limited to a region around each bolt of about twice the bolt head diameter. That simulates the bolt preload force, while allowing the part to deform similar to the real part bolted to a solid surface, and avoiding modelling contact.

 

[clab]

Thanks for your answer, but for the simulation I am not considering the bolt, I am only considering the support in question, my question is which are the displacement and rotation components should be fixed or free to define the boundary conditions of the system.