The guidance for contact target selection is based on the guidelines provided in this link

Also refer this link for bolt thread simulation.

Thank you very much, Sir
Very useful information.

Dears,

I need some clarifications regarding the ANSYS Bolted Joint analysis methodology, when the Bolt thread behavior is approximated by creating the Bolt Sections and assigning these to contact elements which is defined between Bolt threaded portion and the hole.

- When the Bolt threads are modelled by the Bolt Section simulation method by assigning the bolt section to contact elements, what diameter of the Bolt cylinder of treaded section is used upon which the contact elements with Bolt section assignment are laid.
The parameters to define the Bolt Section are given below,

Dm = Mean pitch diameter, dm
P = Pitch distance, p
ALPHA = Half-thread angle, α
N = Number of starts (defaults to 1)
X1, Y1, Z1, X2, Y2, Z2 = Two end points of the bolt axis in global Cartesian coordinates

Is the diameter of the cylindrical surface representing the threaded portion of the Bolt will be Minor Diameter of the threads or the major diameter of the bolt?
- The FEA stresses with elastic material model at the first threads engagement are very high, much higher than the yield strength of the material, does the elastic plastic material model will give the more realistic results at the first few threads engagement.

Thanks for our help and valuable input.