Matrix not factorable: Too constrained or not enough?


#1

The project is here https://www.simscale.com/projects/mhere/ta3-1-layer-axle-/

Is there any advise on how to eliminate some of the 9 possible causes for this error?

I’ve simplified and simplified to the point that removing anything else would render the model useless.

I’ve tried adding extra constraints; removing constraints; increasing and decreasing the tolerance; upping the number of iterations; I don’t believe there are any shared faces/nodes.

The one possibility that stands out is: “3: One of the structure is hold only by the contact.”;

I don’t know if this is true or not, but think it might be a possibility that the axle on my 2 volume sim is not constrained enough but the single (Z)axis rotating motion constraint, but I do not know what to do about it if not?

Help?


#2

Hi @mhere, your angle of rotation is very high, 2*pi radians is one complete turn of the body. Is this your intention?

Why are you using a dynamic analysis? To you need to see the transient response of the system or just the final loaded state?

If you explain a little more about what you want to achieve with this simulation I may be able to help you out.


#3

Thanks for the prompt reply. (Warning: some of the settings and constraints have been added (almost at random) in order to try to make something/anything change!)

The grey bit (round with flats) is an electric motor axle.
The blue bit (spanner shaped; hereafter ‘TA’) is a torque control arm. (1x 0.5mm layer of 12; the others removed to simplify in the hopes of getting a run to complete.)

The TA is made from spring steel. As the axle attempts to rotate (either direction, drive or regen), the jaws of the TA (which are annealed set curved forward out of the screen; and pressed flat by the axle nut) are designed to close around the axle flats precluding the freedom for the axle to accelerate before contact and generating impact stresses.

The TA is an Add-on to the standard bicycle dropout plates.

the intention of the sim is to determine what level of torque the TA can contain before it deforms sufficiently for the (edges of) the axle flats contact the standard dropout faces and start imposing shear forces on them.

I’m using dynamic, because (I think) as the axle motion can and does reverse rapidly, and in use oscillates between drive and regen, I think I need to see what happens over time./


#4

BTW: The 2pit was stolen from another project that worked.

I intend to modify it once I have something that completes.

(I hate this forum software, it keeps loging me out!)