DMU Simulation doesn't "respect" Assembly constraints

[nana1218]

Hi,

I just have started to learn the DMU Kinematics Toolbar and I have some questions about it.

I have a simple Piston, crankshaft, rod assembly and when I create a revolution joint for the crankshaft, it rotates but the piston or the rod doesn't follow it. I have to update the assembly after I finished the simulation. If I move it in the Assembly environment it works great... but I would like a simulation.

I have switched on the automatic update in the options menu so something else should be the problem.

I have attached a picture showing it.

Thanks for any help!

 

[MrCATIA]

In the JOINTS branch, there is only one joint (Revolute.1 between the Crankshaft adn Blokk).

Add more Joints between the other parts to include them in the simulation.

 

[nana1218]

Thanks for the reply!

I have tried it but in this case I got an error message (it is in the attached picture).

If I switch on or of the Angle or Length driven options in the joints, I will get an error message that there are too many commands or there are not enough commands to simulate. I always left the same way the revolute joint because it was ok (it has set to angle driven). I have tried a lot of combinations (just to switch on the angle driven option or the legth driven option and I did it with all of the joints and with just some of them).

What joints would you apply in this case? In the assembly environment it works just fine so the constraints are ok so the problems can be with the commands....I guess.

Thanks!

 

[MrCATIA]

Too many commands! You only need one input command to run this simple mechanism. The input command is probably the first joint; the angle between the Crankshaft and the fixed Blokk, so switch off the drive option on all the other joints.

 

[nana1218]

I have tried it. If I switch of everything , except the revolute, I get a message that there is not enough commands. Although I see one command in the tree.
...??

 

[nana1218]

I have solved the problem. I made every constraints in the assembly and I have converted them. Now it works. The problem was that I had to change the coincidence joint to revolute between the crankshaft and the rod.
I am not sure why is that but it works now at least!