You don't need "the feel"´when doing the computer model. You chose appropriate material (or define your own) and let the computer do the crunching. CosmosWorks will not only do the FEM for you, it will even calculate approximate deformation of material. It's just a matter of picking the right colour (red?) for loads which exceed elastic area of chosen material. Then look for the red areas on FEM model. If you find that stresses are too high (and it's actually prudent to have substantial margin on this), re-model the part until stresses are evenly distributed.
Bending of the rod-bolt? No problem, model the bolt and let FEM do the rest...it will calculate bending and loads on the rod-bolt >in the piston< as well.
Want to take this one step further? No problem, calculate piston accelleration at highest revs you might expirience. Knowing piston accelleration and mass will give you approximate forces applied to rod. Most of aftermarked rod manufacturers have CAD-drawings of rod readily available at their home-pages. Having rod drawings will allow you to easily model the rods in software and apply approximate loads that you expect in your application.
That being said, rod manufacturers usually did this number-crunching already and can give you good recomendation from the scratch.
Cheap FEM software is a gift from heaven. This sort of calculations were impossible to do for a layman just ten years ago. It was only aerospace industry with high powered mainframes that could afford the tools. It's now being possible thanx to influx of hi-powered PC's ... indirectly, we have Doom, Quake and Windows bloatware to thank to, which pushed hardware vendors to produce ever faster home computers.
I modelled a solid valve tappet that we planned to use in our project. Reddish hue was used to indicate stress limit which I found appropriate. The small rectangular part is approximate calculated footprint of camshaft (it's actually riding on oil-film so it's not 100% accurate).
Unfortunately, manufacturing the part prooved to be more complicated/expensive than actually modelling it
