In this case, I would recommend that you create at least two simulations. I often do this is with large simulations that have many parts. By creating multiple simulations, you can devote your computational resources to the locations of interest and get much more accurate results in a shorter amount of time.
In one simulation switch over to solid elements and refine the mesh at the bolt holes. It's okay to leave the rest of the mesh relatively coarse. Then, in subsequent simulations, you can coarsen the mesh at the bolt holes and devote your computational resources elsewhere.
All the best,
Nick LuysterOnline SolidWorks Simulation Training
define a custom bolt material using a value of Enew=((old radius / new radius)^2)*Eold (this should make the strain of the bolt with reduced shank radius equal to the strain of the original bolt
Can you provide additional explanation for how you came up with this relation?
In theory, what you need to do for this to work is modify the material properties of the smaller shank bolt such that it has a stiffness matrix that matches the large shank bolt. This is where it gets tricky.
SW uses rigid links to connect the two ends of a beam element to the respective shell/solid elements. While I haven't found a specific reference to it, I'd be surprised if SW didn't use Timoshenko beam theory for their beam elements. A beam element has 6 DOF per node for a total of 12 DOF (although I think in the beam element for a bolt connection the on-axis rotational DOF is released, but we'll ignore that for the sake of this), so the stiffness matrix has 144 terms.
Some of the terms in the stiffness matrix are a function of the length of the beam (L), and some are a function of L, E (Young's Modulus), I (Second Monument of Inertia), G (Shear Modulus), A (cross-sectional area), and k_s (shear area factor). The coefficient for the entire stiffness matrix is a function of all of these variables. Now you see the problem.
This is an interesting work-around, but I think the more important question here is why the KB suggests to use solid elements when the ratio is a lot smaller than 5. Understanding this is required in determining whether your work-around (or any other for that matter) will in fact work, or whether it'll just lead to inaccurate results. If determining all of this isn't feasible, then I suggest going with previous methods that you know work for you.
I'd also like to point out that, at the end of the day, SW bolt connection tool is just an idealization; even under the best conditions theresults are not going to be highly accurate (at least the stresses around the bolted material...shear and tensile forces can be fairly reasonable).
what is the goal of the analysis? can you post a picture of what you're working with?
if you're just trying to hold things together and you don't care about the bolt forces, then there are better ways to do it
if you want the bolt forces, working around bolts isn't going to be a good idea. setup the analysis differently and extract the bolt forces a different way
if you want to go with your workaround, build a test case and test it. that is the only way to know if it works.