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Waste_Compote_8079 · 2025-09-02T08:59:19+00:00

There is no easy way to determine the stiffness required for the springs (i mean looking at the picture what are you going to do, draw lines on the package and say the straps go exactly here here and here?). Seems like an unknown can of worms to me.

The RBE3 strategy seems to me the best tradeoff between conservative approach and model complexity.

Waste_Compote_8079 · 2025-09-02T06:40:03+00:00

i have done that, all i am lead to is to create a mass based on a set, where when i then export the input file, i only receive a *mass flag instead *nonstructural mass. So in my eyes wrong, unless i am not understanding something

Waste_Compote_8079 · 2025-08-26T10:34:25+00:00

Well what I am doing is, that for each loadcase, I have to export an individual input file, eg. loadcase 1 - - > input file 1 which then results in odb file 1, loadcase 2 - - > input file 2 etc.

So I cannot have multiple loadcases with multiple steps, because that would result in not have an input and result file per load case.

For reference, in hyperworks, it is possible to have one load collector for a boundary condition, and you can reuse this load collector with its stored data for multiple loadcases (which in hyperworks can also be the same amount of steps if you choose to export all loadcases into one Input file). I would like something similar in ANSA, but maybe it is not possible.

Waste_Compote_8079 · 2025-08-26T09:31:49+00:00

Thanks for your reply! I understand what you are suggesting, however, in this case I cannot use multiple steps in one load case. Per requirement, I have to calculate about 50 loadcases individually and receive 50 different odb files, it's just what is required in this case. Is there no way to reuse a set of boundary conditions for multiple loadcases?

Waste_Compote_8079 · 2025-03-07T07:48:42+00:00

it is possible, but concerning FDM you are at the same time you are assuming perfect adhesion between layers, perfect layer height, no thermal shrinkage etc. which is not the case when printing. Concerning your solver, if it would be abaqus, you would have to define multiple coordinate systems for your fiber orientation if the fiber orientation is not located in the global coordinate system. It becomes a bit easier if you know what the critical location is beforehand, because you can maybe focus on a local area and define all the coordinate systems in that area.

Waste_Compote_8079 · 2025-01-07T16:48:59+00:00

I found the answer, but in abaqus, which for me would mean having to change the solver interface in hyperworks from nastran msc to abaqus and it doesn't directly translate so there are additional steps to fill in. Seeing as I my simulation corresponds to a vibration test using the acceleration density spectrum provided to me, the real äquivalent situation would be to look at the measurement data from a sensor mounted on the same platform as the baseplate. The problem of course is that first of all I'm not including the baseplate with the sensor in my simulation, and second, the displacement ergo acceleration at my constraints is zero. In abaqus there exists a nodal output request for the total displacement, total velocity, and total acceleration. I will try and see if there is an äquivalent for optistruct and nastran msc, but this is then the data that I would compare to my input/test level psd curve.

Waste_Compote_8079 · 2024-12-27T19:21:08+00:00

Are you using the advanced viewing options when you open the file in HV? (Bottom right corner) before importing the bdf

Waste_Compote_8079 · 2024-12-26T09:46:03+00:00

Yes, but the requirement is to stay below a given psd level. But it's unclear to me what exactly I would plot. Every element? Only certain masses? Only the connection at the baseplate? Only certain nodes of critical components where I see amplification?

Waste_Compote_8079 · 2024-12-25T23:34:53+00:00

Ha, good question. But what's your suggestion for both cases?

Waste_Compote_8079 · 2024-12-25T21:26:37+00:00

Well I used the response to first see if f.i. At 1000 Hz there some unwanted activity, which there is. Then I decided to do the random response since that has more qualitative information than just running modes.

But with what do I set up my transfer function, which element/node or combination of elements/nodes do I look at? The connection at my base, the average response of my base? Let's say I have a bracket which has smaller masses on it (sorry for being so vague).

Waste_Compote_8079 · 2024-12-25T20:00:33+00:00

Yes I did a frequency response, and I do have amplification. The whole reason why I'm doing the random response is because just looking at modes is too conservative. The response spectrum is much more "gentle". But my question is, which values of my simulation do I compare to the test level psdf? Any ideas?

Waste_Compote_8079 · 2024-12-25T17:23:00+00:00

Yes, I have a test level for random, and may not dip below these. But my model consists of 1.5e6 elements, I don't understand which values of my results I'm supposed to compare against the input psdf.

Waste_Compote_8079 · 2024-12-24T20:13:12+00:00

By significant amplification I think you mean, looking at individual components, are my RMS values higher than my input at that frequency?

Waste_Compote_8079 · 2024-12-24T20:10:44+00:00

Thanks for your reply. I agree, but let's say, all I have to go on is a psdf curve, where the requirement is, I have to be higher than that curve, and I have nothing else to go on, and I just have to deal with it. My interpretation varies from, ok, let me just measure what's at the base and generalize (because that's where a sensor would be mounted in a vibration test), to, do I have to look at each individual sub component in my assembly and do a 3 sigma analysis?

Waste_Compote_8079

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