Hi all,
I want to model the following in Abaqus (just the reinforcement for the rubber hose) : (See figure 1)
I want to do this in order to identify the value of the force at the contact region of the thread knots. (See figure 2)
These are very thin, membrane like structures made of Aramid. They will expand with the rubber hose under internal pressure. I would want to identify the force at the contact under tension/ expansion of the hose.
I am confused as to what is the best way to model these thread reinforcement structures. I would think that Rhino3D is a good option since it uses NURBS. I have a fairly good knowledge of Rhino.
However, I do not know what properties (section/ contact interaction) to give these reinforcements in Abaqus.
Dear Jonah,
In abaqus, use 1D spring element with nonlinear force-deflection input. Characterize the reinforcement for tension and compression. Find force vs axial deflection from experiment for the thread. And feed that data in non-linear spring. Check if the thread has any bending and torsional stiffness. Accordingly, define the stiffness components.
Once modeling is done, define contact among 1D elements. To apply the expansion load, you need to model the rubber hose with atleast elastic properties. Apply internal pressure to hose. This will expand the hose which in turn causes loading of the reinforcement (or net).
If you model the internal hose, you also need to define contact between hose and the net. If there is another casing outside the net that restricts radial movement of net, you need to model that as well and define the contact of net with the outer casing.
What outcome are you expecting from the simulation? Be careful about boundary conditions as the hose should be free to expand and may have restraint only at the inlet and outlet depending upon case to case.
Regards,
Chandrashekhar
Dear Jonah
To give reinforcements in Abaqus. you have to define the contact, try to do Face to face contact by layers with nonlinear-elastic behavior
Hakim
Hello Chandrashekhar,
Thank you so much for taking time out and writing your suggestions! It is very valuable for me. I have a few responses:
1. The outcome I am expecting is the deformation of the entire hose under internal pressure, and the burst pressure of the hose.
2. You are right : I will be modeling the external hose too. (Basically, the threads are sandwiched between the internal and the external hose layers.
3. The reason I am modeling the thread pattern is so that I can measure the stresses at the contact between the threads when the hose is expanding, and also the force it can take in the axial and radial directions around the pipe. I will then modify the angle of the threads and repeat the analysis. Basically I want to arrive at an OPTIMUM thread design that will let the hose burst at a higher pressure than the existing thread design.
From the very valuable suggestions you have given, I would like to ask you the following:
I have developed the following IGES data and imported from Rhino (see fig 1). It is basically the thread pattern that will repeat over the internal hose. Is there a way I can use this in my analysis, or do you suggest I should just model these as 1D curves and then apply the 1D spring element?
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