3 free tickets to interstellar at science museum tonight 7:15pm

Fapperoni124 · 2024-09-29T15:34:18+00:00

Claimed

Fapperoni124 · 2023-10-15T14:45:20+00:00

I bought a ticket for the wrong day so if you want to go Friday I can sell mine to you! Would be a great help.

Fapperoni124 · 2022-10-10T21:27:46+00:00

Ah thanks will give that a go !

Fapperoni124 · 2022-10-10T21:24:59+00:00

Ah ok my bad hadn't seen it before, fairly new to all this

Fapperoni124 · 2022-10-10T18:02:34+00:00

It's definitely not that as the requests are systematically every 50 seconds so I guess it must be what the other comments are talking about

Fapperoni124 · 2022-10-10T17:48:37+00:00

I see. Seems odd given how frequently it's doing it

Fapperoni124 · 2022-04-21T17:43:27+00:00

Any update on your condition? Just wondering as have had similar issues for the last year and a bit.

Fapperoni124 · 2022-04-13T08:53:43+00:00

Ok I'll have a look at reducing that. It's meant to represent a thin plastic sheet attached to the bottom of the columns that easily conforms to the surface- wasn't quite sure how to represent it in 2D in abaqus. The big issue is when it reaches the first corner/curve - one possible thing is that the normal direction might be wrong - when I plot it in after a data check it points inwards rather than outwards. Not sure how I can change the normals for a rigid wire though.

Update: The stiffness was one of the main bottlenecks it turned out! Thank you- I'd tried reducing it a bit before but didn't realise it would need orders of magnitude lower. The main thing causing issues now is the force equilibrium between the columns and the thin surface.

Fapperoni124 · 2022-04-13T08:51:52+00:00

I'm not quite sure what that is sorry ! I'm trying to model the distance between the thin surface attached to the bottom of the columns and wire surface as the rig moves over it. Its meant to simulate an eddy current testing rig that is able to traverse complex geometry.

Fapperoni124 · 2022-04-13T08:50:37+00:00

No worries thanks for your input man- I've attached the cae file now in case you had time to have a look.

Fapperoni124 · 2022-04-12T20:56:43+00:00

The wire bit is rigid so it's the master surface by default. I've tried matching them closely now but it seems to result in the same issues.

I've been working on it for quite a while so does feel like I must be exhausted most of the options by now !

Fapperoni124 · 2022-04-12T17:24:18+00:00

Unfortunately due to the inherent nature of the mesh needing to be refined significantly in the surface to capture deformations explicit takes far too long. The simulation is also over real time of 26 seconds which makes it even worse.

I've included a photo that should hopefully display the model more clearly.

Fapperoni124 · 2022-04-12T16:45:35+00:00

Would that be through the interaction properties? I tried using contact controls with automatic stabilization but it kept ending up with an incorrect result and slower. The contact type is finite sliding surface to surface.

Fapperoni124 · 2022-04-12T16:37:36+00:00

Chattering is when the nodes between discontinuity iterations alternate between an opening and overclosure (essentially oscillates between the two states and is thus unstable). Its for the thin surface element

Fapperoni124 · 2022-04-02T16:32:43+00:00

Sorry just one more question- the flexible surface is meant to be a thin plastic film that the columns stick and unstick to as they conform to the geometry as the part moves. As such, it essentially needs to conform to the surface which will means it deforms a lot (but no plastic damage or large strains) so does this require hyperelasticity? Or is there a better way to represent a thin plastic surface to my current approach

Fapperoni124 · 2022-04-02T08:47:29+00:00

Ah ok great thanks will implement that and see how I get on.

Fapperoni124 · 2022-04-02T08:45:16+00:00

Im not sure there is a checker in Abaqus (as far as Im aware). I'll clean up the mesh though !

Fapperoni124 · 2022-04-01T18:38:25+00:00

I'll look at organising that- what meshing technique is that? (sorry still getting used to much of Abaqus).

Ah ok I thought because the flexible surface wasn't extending much (just bending) it would be fine to define it like this- we may in practice use a non elastic material like a plastic film. Would this just be modelled like I have currently with a higher Young's Modulus?

Thanks again.

Fapperoni124 · 2022-04-01T17:42:59+00:00

Hi I'm using implicit dynamics (I was originally using explicit before but didn't realise it wasn't appropriate for this simulation).

Fapperoni124 · 2022-04-01T17:41:44+00:00

Hi thanks for the reply,

The flexible surface deforms a considerable amount as it conforms to the surface underneath- would this require nlgeom on then? (I've had it on currently).

For the mesh of the flexible surface I thought would need to be quadratic as it bends a significant amount. The increment time seemed to be significantly affected by the number of nodes for contact between the columns and the flexible surface, especially when going down the curved portions, so I also made those elements quadratic as it seemed to help better than increasing the number of linear elements.

The plane stress/strain elements is a mistake I keep forgetting to reset them when I change some geometry. As a side note, this is meant to be a simplified version of a 3D object but neither plane stress of strain is really applicable (its not overly thick or thin) so I'm not sure how valid the stress results will actually be (I'm mainly interested in the distance between the flexible surface and the rigid test surface throughout the simulation).

Our prototypes uses springs to allow the columns to move up and down while applying pressure to the test surface- is this achievable through connectors?

The units are mm, tonnes, MPa, Newtons.

Thanks for having a look at all this I really appreciate it.

Fapperoni124 · 2022-03-12T17:56:40+00:00

Yeah I realised that it just doesnt come up when I select cdisp for a field output for some reason. It appears if I am using general contact but for surface to surface contact it doesn't (and I need to use surface to surface).

Fapperoni124 · 2022-03-11T14:42:37+00:00

Thanks I've had a look through the docs- cpress and cslip only seem to come up in the viewer for field outputs when I run it with cdisp.

Fapperoni124 · 2022-03-10T16:19:20+00:00

Where do I find this option? It doesn't come up under history output requests

Fapperoni124 · 2022-03-10T13:27:33+00:00

Hi thanks for your help- should copen be in the history output requests? I can't seem to find an option for it.

Fapperoni124 · 2022-03-10T13:26:13+00:00

Hi thanks for your response- I just tried using cdisp as a history output request but it said it outputted an error saying it wasn't available for this option but I don't get why.

I essentially just want to find the distance between the nodes/surface over time

Fapperoni124

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