Bolted Connections in Cosmos Works
Bolted Connections in Cosmos Works
(OP)
Does anyone have any suggestions on how to deal with components that are bolted together in Cosmos Works? Assuming I want to analyze an assembly and included the fasteners, what sort of contact definitions are most appropriate? The problem I have is that one of the part in my assembly acts as a stiffener for another part, but I don't want to assume the two are bonded along the entire length of the stiffener. I am trying to represent the fastener connections as realistically as possible since it is far from a welded connection. Thanks.
-Joest
-Joest






RE: Bolted Connections in Cosmos Works
With the split curve feature, create surfaces representing the contact area that results from bolted connection.
For these surfaces choose the bonded contact/gap option.
For the other surfaces choose node to node.
Regards
RE: Bolted Connections in Cosmos Works
John Richards Sr. Mech. Engr.
Rockwell Collins Flight Dynamics
A hobbit's lifestyle sounds rather pleasant...... it's the hairy feet that turn me off.
RE: Bolted Connections in Cosmos Works
Its been a while now, but this could be useful for the case were the two parts are loaded so bolts are in axial tension only.
Make concentric circles around the bolt holes where the washers would be like macPT suggested. Add a rigid link to these areas for each bolt - this models bolt as rigid. It will also model the 2nd part acting as a stiffener because load is transferred through rigidly connected surfaces.
As for a friction type joint and other cases, I look forward to what JNR comes back with.
Dave
PS - There is an FEA forum that might help too.
RE: Bolted Connections in Cosmos Works
RE: Bolted Connections in Cosmos Works
John Richards Sr. Mech. Engr.
Rockwell Collins Flight Dynamics
"Heck, there are so many rules around here, it's hard to accomplish anything!" - Me.
RE: Bolted Connections in Cosmos Works
This method showed the plate needed to be thicker by at least .150”.
An inaccuracy is created by not using gap or some other element type to simulate the friction between the plate and washer as well as the washer and bolt.
You could search this on the Finite Element Analysis engineering forum for more ideas.
RE: Bolted Connections in Cosmos Works
Our expert is back now so I will ask him on Monday as we have both been real busy today (we're off Friday).
John Richards Sr. Mech. Engr.
Rockwell Collins Flight Dynamics
Forget rich and famous - I want to be rich and unknown.
RE: Bolted Connections in Cosmos Works
John Richards Sr. Mech. Engr.
Rockwell Collins Flight Dynamics
Forget rich and famous - I want to be rich and unknown.
RE: Bolted Connections in Cosmos Works
Can you explain with more detail your procedure? You simulate the preload using a temperature variation?
Regards
RE: Bolted Connections in Cosmos Works
Joset, do you have the thermal module in CW?
RE: Bolted Connections in Cosmos Works
RE: Bolted Connections in Cosmos Works
John Richards Sr. Mech. Engr.
Rockwell Collins Flight Dynamics
There are only 10 types of people in the world - those who understand binary and those who don't.
RE: Bolted Connections in Cosmos Works
It seems to be very useful for certain load simulations.
Regards
RE: Bolted Connections in Cosmos Works
"This is an unstable mechanism where you have rigid body displacements for the applied loads. This free rigid body rotations and displacements are not allowed if FE because of unique solution. You need to restrain the model somehow, so it doesn't exhibit mechanism."
I'm not too proud to admit that I don't follow everything in their reply.
In the past when I fastened parts together with more than one fastener and used a coefficient of friction, I assumed that some of the load was being resisted by the clamping force. Now I am not sure.
Any help is greatly appreciated,
Thank you
Tom Draxler
RE: Bolted Connections in Cosmos Works
John Richards Sr. Mech. Engr.
Rockwell Collins Flight Dynamics
There are only 10 types of people in the world - those who understand binary and those who don't.
RE: Bolted Connections in Cosmos Works
It is true that eventually a 'good' coefficient of friction will have to be determined. P166-167 in Vince Adams and Abraham Askenaze book provides a method. The above physical model is possibly another although without a spring the model will fail due to rigid body motion as an applied force overcomes friction and the two bars start to slide. And yes these values should be adjusted (usually downwards) for surface conditions.