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True. I misread the part about the varying pressure distribution.

Thanks, Karachun, this was helpful.

Guys, i want to experiment a little with guyan reduction in a dynamic calculation. So far, I never found the need for it but as models are getting bigger and bigger I want to see if it is advantageous to use without losing accuracy or results. I have a model of a ship, and i want to do both a...

if the model is a single surface, and assuming the pressure is uniform, isn't the center of the pressure at the center point of the surface? which can be found using the section properties of the surface?

Thanks, I'll give it a try.

Hi guys, I need some help (yet again). i have an output set which contains the results of a forced frequency response calculation, spanning from 5 to 60 Hz, in 0,5 Hz steps. The calculation is performed in SI units, which results in vibration velocities in m/s. As the calculated values are low...

Hello Justine, Thanks for the link. I tried this, but i think the different frequency ranges cause problems.

Hello Justine, no, the other way around. I have 5 sets of results for individual sources (blade pressure excitation, unbalance, engine foundation forces etc). The are calculated for different frequency ranges, and i want to sum all those sets into a single output set. The easiest way is to...

Hi all, I need some help. I have a ship's model and performed some calculation with known excitation sources. For each source, I used a different load case. the aim is to calculate responses at several locations as velocity. I want to combine all loads to a single output files. Can someone...

Hello all, i have question regarding a calculation i performed. I did a calculation on the bolted flange connection, using 1/16th of the complete geometry (the flange has 16 bolt holes). I used symmetry and so far, so good, but i want to present the results for a full flange. I can easily copy...

The calculation is lineair. But i wanted it done in the right order. Preload first, with related lengthening of the bolt and compression of the structure, then pressure load. Apparantely NAstran does that automatically.

I thought i needed a restart, because i wanted to add pressure AFTER applying preload. I now understand that, in a combined load case using bolt preload, The effect of preloading is calculated first, after which any other load is applied. So, i can simply use a single loadcase. Happy days.

Bolt preload is a simple command in Femap, and the pressure load is a given design pressure. Working in the time domain isn't possible, because the combination non-linear and contact surfaces is not supported. I'm trying to figure out how the restart function might help me, but I can't get...

Hi there, I'm stuck in a Femap model. I modelled a section of a connection of two flanges, connected to each other by a pre-loaded bolt. Symmetry is applied to simulate a full model. In the pre-loaded model, i want to apply an internal pressure load. I tried to do this with a restart command...

Hello All, i'm examining a failed gear (pinion-wheel, straight teeth) in which the pinion lost a few tooth due to fatigue, starting from one side of the teeth. There is also a pattern screaming misalignment, but this pattern is present on both flanks, and in both cases on the side of the...

a four stroke diesel engine generates frequencies at 0.5x operating speed and multiples (1, 1½, 2, etc)

If i understand well, when they are moulded together, it is one stiffness, and one mass, it won't behave as two different systems.

The very few times such a failure occurs doesn't weigh up to the costs of a welded crankcase compared to a cast-iron one. Yes, from a perspective of having to replace a complete engine, for which often a hole has to be cut in the hull and much more, a repairable engine makes more sense. But...

Slipping caused by an UNLOADED bearing can be an issue to. Make sure the bearing carries sufficient load.

Ben you are right of course. my mistake.