Inventor Dynamic Simulation

[Anonymous]

Back again with another question for the community!

I modeled a steam locomotive on inventor that I received help with in the past weeks, I was wondering if I could use the Dynamic Simulation feature to run a motion analysis and get graphs for velocity and acceleration based on the movement of the assembly? 

For some reason when I go to run a dynamic simulation the assembly gets pushed forward and all of my constraints break before I even get to select how I want the motion to engage.

[TheCADWhisperer]

No assembly Attached?

[Anonymous]

Sorry, here you go

[TheCADWhisperer]

I haven't had time to carefully go through all of the assembly constraints -

but first thing I notice is that you have a failed constraint.

The behavior will be unpredictable with failed constraints.

[Anonymous]

I deleted the relationship since it had no effect on the mating anyway. Thanks for pointing it out... but I am still getting that weird error when I try to do the simulation where all of my components are forced to one side... and then beyond that issue I am just generally unaware of how to do the motion analysis

[Anonymous]

Does anyone know what could be causing the assembly to become all jumbled when I try to start the dynamic modelling process? It is super frustrating

[Anonymous]

It seems like for whatever reason my middle wheel the center of its axel is being forced to align with the face of the chassis and I have no clue why

[TheCADWhisperer]

Chassis - two unconstrained sketches.

Large Wheel - Main multiple unconstrained sketches. Origin not in logical location.

Large Wheel - Front multiple unconstrained sketches. Origin not in logical location.

Coupling - multiple unconstrained sketches.

Large Wheel - Rear multiple unconstrained sketches. Origin not in logical location.

Connecting Rod - multiple unconstrained sketches.

Coupling Rod - multiple unconstrained sketches.

Crosshead - multiple unconstrained sketches.

Cylinder - multiple unconstrained sketches.

Piston - Sketch1 underconstrained.

Crosshead Arm - Sketch1 underconstrained.

Union Link - sketch5.

Combination Lever - Good.

Valve Stem Fork - wrong tap drill size - will not thread.  Bottom tap thread.

Piston Valve - Origin not in logical location. Missing dimensions.

Crank1 - Sketch1 not fully defined.

Driving Crank - Sketch2 underconstrained.

Parallel Crank - Sketch4 underconstrained.

Cylinder Head 2 - multiple unconstrained sketches.

Dynamic Simulation - 5 redundant joints.

Cylinder is not grounded

Cylinder Head 2 not grounded? (or otherwise logically positioned)

In Dynamic Simulation click on the Construction on Simulation Player.

Go back to Assembly Environment and drag one of the wheels (it pops back into position).

Go back to Dynamic Simulation Environment - what do you observe?

Turn on your sound.

I'm going to bed now - I will check back on your progress in the morning.

Screencast will be displayed here after you click Post.

f8aa91b0-4796-4708-93ae-b6b088a603b0

[TheCADWhisperer]

https://autode.sk/2QIQ2ly

[Anonymous]

Thanks for the help and the video.. It seems like my major issue is that the Piston Valve is not staying level to on its line of motion. I understand you were saying the cylinder head should be grounded but then there is an issue with my cranks that they are not able to get a full rotation of motion. It is something I will work on (along with your other corrections) until your next reply. 

[jan_priban]

hello,

basically Dynamic Simulation can be used for Kinematics - it can define actuator, get graph of position, velocity ...

Seeing how steam engine works, mostly used Egide Walschaerts I thing your model is missing part number 7. That' why your model has 2 degree of freedom (DOF)- not good for Dynamic Simulation - it needs DOF = 1 to define movement exactly (predictably). I just made a sketch simulating locomotive model (using schema Egide Walschaerts) . See all lines/linkages in sketch are blue, means all is constrained because I drive model by one parameter (angle of wheel) - without this parameter DOF = 1 which is what we need. So first make your model DOF = 1 and then we can move to Dynamic Simulation. Here I suggest remove one wheel (let just 2), crank on one side only .... because Dynamic Simulation is sensitive for constrains (Dynamic Simulation target is Number of redundancy = 0, DOF = 1). Less components = Less constrains = better/easier DS constrains definition

Regards

Jan Priban