Hello
I have two bolt connectors in one example with an imposed load. In the resistance conditions I chose without any increase coefficient i.e. 1 and for the other connector a coefficient of 2, the calculation gives me a coefficient with respect to the material of the bolts of 1.15 and ............ The interpretation of the bolt connector gives me the one with 1 valid and the one with 2 non-compliant. How should we interpret this answer? 2 must cover the coefficient of 1.15 .
Kind regards.
Spectrum
coeff_securite_ok_nok.jpg
Hello
I have the impression that the question is rather why would you want to have a different CS.
That said, if the first CS comes out at 1.16 (which is low for a CS) it's a safe bet that the second one is also in these values, but since you're asking for a CS of 2 it seems normal that it indicates a non-conformity.
To say more, you would have to have an idea of the different volumes and bodies that make up the ASM (in your image we can only see one bolt) and also all the constraints you have put on.
I don't know your level of expertise in SW simulation but from my experience you can quickly make mistakes especially with the "bolt connectors"
Can you post your ASM with a pack and go or at least post images of all the parameters of your simulation.
Kind regards
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Hello
Thank you, the goal is to look for the influence of a pre load on the elongation and to choose the right quality of screws.
By hand with a supplier abacus to know the maximum load. It's attached.
The goal is to compensate for the elongation of the screw during tightening and compare by simulation using Solidworks
Basically, a safety factor is a chosen limit. For example Re with Rpe= Re/ safety coeffcient ditto Rg with Rpg, but here I chose 1 no weighting it calculates 1.15 and the solver gives valid connector, there something I don't interpret....
For the two different values it is to determine the problem of interpretation, I agree with you, I will not do it on my model.
See my approach to validate the quality of the screw according to the maximum tightening force according to the materials used.
Kind regards.
Spectrum
validation_effort_serrage_maxi.jpg
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Hello
I would like to carry out this study in parallel by simulation to obtain the real load supported by my screwed assembly of a project in the process of validation, control phase.
I finished doing it by hand this morning and it's quite a long ........ To obtain the different cones according to the stiffness of the elements, the goal is achieved to have the ratio between the stiffness of the parts and the stiffness of the screw with its nut;
Going through finite elements, I would like to validate the empirical angle of 30° which remains invariant with respect to materials.
Solidworks has a material base, so it's tempting to experiment.
And furthermore, is it possible to have the actual load coefficient in a bolted connection processed by simulation using SOLIDWORKS?
Thank you for any assistance.
Kind regards.
Spectrum.
raideur_boulon_ok.xlsx
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Hello @spectrum ,
From my discovery of Simulation, I would say that there is an error of interpretation (you talk about weighting coef) on the CS value: I think that the value we enter is a threshold value that allows SW to indicate if the connector is valid or not.
We find this idea in the image you provided: you ask for a coef of 1, SW finds a coef of 1.16 so the connector is valid, for the second, you ask for 2 and if SW finds a lower value it declares the connector invalid.
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I would like to hear from @stefbeno
That said, I am trying to understand your objective. ""The goal is achieved: to have the ratio between the stiffness of the parts and the stiffness of the screw with its nut""""
I am not as learned as you probably are, but I do a different reasoning: let's say a pragmatics of experience.
My point of view (to be discussed of course)
- The screws and bolts meet precise standards so I don't recalculate them. I choose the class according to the supposed effort or the information from the simulation for complicated or borderline cases.
- There is no obvious correlation when you say "the different cones according to the stiffness of the elements", indeed it depends on the shape of the parts and the type of bolt (screw, nut or anchor bolt.
- In the standards there is already a CS but this says nothing about the CS of the assembly since the part can be undersized or oversized. I add that the number of screws and bolts also changes the game (e.g. going from two bolts to three or four or changing the position of the holes).
- It depends on the degree of sophistication of the assembly if I compare the stresses in an engine subjected to high vibration or if I compare an airframe to a mechanically welded frame.
- Doing a static or dynamic study with, for example, taking into account an analysis of frequencies and natural frequencies also changes the game.
From my point of view, wanting to make comparisons out of context and outside of the constraints specific to the sector does not seem relevant to me and leads to over-quality or to the wrong objective, or even to be wrong about the desired result.
Kind regards
PS: wouldn't you be a student or in a Sup school at any chance ;-)
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Hello ZOZO,
I share your point of view, bolted connections are very delicate to manage depending on many parameters.
The manufacturer, through his experience , gives use values to be respected.
My approach is motivated by the use of the simulation module to carry out a pre-sizing and have a heading and cancel tracks and reduce the study in time.
A simpler orientation of my study will be carried out, I thank you for your advice.
I learn a lot by following the forum.
Kind regards.
Spectrum.
1 Like
Hello
Personally, I don't use the CS on the bolts (or on the rest for that matter).
But the principle is that if the safety factor (maximum stress / real stress) is exceeded, it shows you the area in red.
So a material with a yield strength of 100Mpa appears in red with a CS of 2 where the stress is greater than 50Mpa (because the safety coefficient will be less than 2). If the CS is at 1 (and with the same calculation), we will be red if we exceed 100Mpa
A nice simulation tool is in: Simulation / Result/force tool in connectors: this gives the forces in each connector (axial / shear and bending).
This tool may answer the question "is it possible to have the real load coefficient in a screwed assembly processed by simulation using SOLIDWORKS" (a rather vague question for me).
The weird thing about your Excel calculation is that it focuses on what happens in the tight material but not at all in the screw (which is usually the first question about a bolted assembly: is the cross-section of my screw(s) enough to handle my load).
Nb: At the level of the bolts in cosmos we can either apply a torque (which SW will use to calculate its axial prestressing force) or directly an axial force.
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