motor shaft acceleration

[Albertus]

greetings to all

I use mathworks simscape multibody software at amateur level.
I designed a simple hand crank mechanism
I applied a constant torque to the motor shaft
no other external load including friction
I asked the software to calculate the angular acceleration of the motor shaft
I suppose that the moment of inertia reduced to the motor shaft depends only on the distribution of the masses so it should be variable but periodic with the angle of crank
Of course the kinetic energy tends to the infinite but I would have expected the same periodic trend for the angular acceleration of the motor shaft
instead I get the attached chart
average acceleration is nothing while peaks continue to increase in absolute value
Is that correct?
thanks in advance

tree

 

[meccanicamg]

Perhaps a dissipative model is missing, that is, frictions.

 

[stevie]

exactly were not considered the desired friction that however small are not negligible and also the piston that flows is subject to friction

 

[cacciatorino]

greetings to all

I use mathworks simscape multibody software at amateur level.
I designed a simple hand crank mechanism
I applied a constant torque to the motor shaft
no other external load including friction
I asked the software to calculate the angular acceleration of the motor shaft
I suppose that the moment of inertia reduced to the motor shaft depends only on the distribution of the masses so it should be variable but periodic with the angle of crank
Of course the kinetic energy tends to the infinite but I would have expected the same periodic trend for the angular acceleration of the motor shaft
instead I get the attached chart
average acceleration is nothing while peaks continue to increase in absolute value
Is that correct?
thanks in advance

tree

constant torque, the angular acceleration should be constant, instead you see a mean null value, apart from the peaks due to the presence of the biella that disturbs the scheme. maybe the problem or the chart are not set well. If you do the same with a uniform cylinder (i.e. without the biella) what result do you get?
when you do not understand the source of a problem it is always advisable to start from the elementary case and then gradually to add a term to the problem and to understand which of these additional terms makes to pack everything.