Mecway 10 . Pad Eye Shackle Bolted Cover Stud Bolts.

disla

Pad Eye Shackle Bolted Cover Stud Bolts.
Fully meshed, solved and postprocessed inside Mecway 10.
Dimensions of contact area between PadEye and Shackles calculated using Hertz's Theory
58 Contact BC's
nodes: 386.498
elements: 219.521 TET10

Time to solve 11min 35sec Intel I7 quad core 8Gb

Sergio

Nice model Disla! Have you applied bolt preloading? You can do by means of CalculiX *PRELOAD card or using thermal contraction. Honestly I had best and quick results using old thermal method.

disla

Thanks Sergio.

Actually not. Most of the models I’m working in are kind of “second opinion”. At this moment I feel much more confident with hand calculations.
My main concern here was to check my skills with contact and validate maximum stress/strain at the blind flange center.
My idea is to increase model complexity step by step to gain confidence.

-Reduce the model to ¼ and apply symmetry (maybe test cyclic).
-Bolt preload (Thanks for the hint. )
-Gasket interaction.
-Plasticity.
-Refine critical areas and find my hardware limitations.

Sergio

You are in the right track, from simple to complex things. Is a common mistake try to start with all the complexities to end leaving the project unfinished due to poor understanding or limitations on soft/hardware.

About symmetry, probably is easier just to model a quarter and apply the displacement restrictions normal to the simetry planes, than using the cyclic simmetry card. The only advantage of simmetry is that you can specify to write the results for the whole model (usefull to show to customers reluctant to understand the simmetry).

In the case of bolt preloading, was usefull to me to understand and see that in some cases the most stresses are caused not by the actual loading but for the bolt preloading, also if you want to check the bolted union will show you when the union really start to gap for axial loads or slide for lateral ones.

About gasket... never work with that parts, I always remove from the model. Have seen that in some solvers there are specifics element to represent gasket, don't remeber well if is also available in CCX.

disla

Nonlinear material and Quasi Static in tree steps.

Bolt Preload .
Internal Pressure.
Internal Pressure release.

-Reduce the model to 1/28 and apply symmetry: OK. I found slave nodes needs to be removed from symmetry plane in order to work. No need with frictionless support.

-Test cyclic. Ok. I found a trick to assure conformal mesh on both extremes. Apply a symmetry operation to the arbitrary mesh and then merge the middle nodes.

-Bolt preload . Thanks for the hint again Sergio. It worked straightforward.

-Gasket interaction. Tricky and not reproducing hand calculation gasket pressure yet for some reason. Maybe insufficient refinement.

-Plasticity. Easier than expected. Bilinear Isotropic.

-Refine critical areas and find my hardware limitations. I will test on a future winter cold night, just in case.

By the way, what are the compatible video formats in the forum?

Sergio

Awesome work! What material has used for the gasket? Probably you'll need more element in thikness to capture the compression effect.

About video formats, I have uploaded some video capture to youtube and then just add the link here. Another way is create an animated gif for quick visualization (I´m using Greenshot to capture several images that I combine in a single gif with the Convert utility included in bConverged CCX). The gif to me is usefull as it can be sended and readed in a mail without going to Youtube that in some offices can be blocked.

disla

KLINGERSIL C-4400
I used a constant value of 3 GPa.
¿Which constitutive model would you suggest?.

Sergio

About material properties of the gasket... well I have to investigate, there are a lot of types and materials for gaskets, and they perform different at every temperature. I don't understand your material curve, is E vs Stress? You must find a way to convert to strain/stress data.

I will investigate this issue in the future as I work with lot of gasket and flanges in my dairy work.


From this catalogue (page 23 for KLINGERSIL C-4400), there is a test "Klinger Hot and Cold Compression Test Method", and in the table they say that at 50 MPa the thikness decrease at 20ºC is 10% and 20% at 300º. Probably with this values you can compute the E value (or well, do two or three iterations changing the E value until you get that thikness decrease), and for Poisson I would use a low value as this is a mix of fibers, rubber and other materials, that probably will decrease the volume during compression (acting more like a compresible foam than a uncompresible rubber).

http://www.segamuhendislik.com.tr/assets/download/klinger-genel-urun-katalogu.pdf