Continued from the previous article (Redundancies in COSMOSMotion 2008 – Part I)
THE CURRENT SOLUTIONS
The user has two choices when it comes to addressing the above problem:
- Put some thought into creating mates. Address the five degrees of freedom by distributing them at the three hinge locations without repeating them. (As you can imagine, this can become a tedious procedure where you have to re-think the process of creating mates). However, this will ensure that the loading is distributed evenly to the three hinges.
- If redundancies are already present in a pre-existing model, then a workaround is to somehow make the joints have finite stiffness, instead of infinite stiffness. This will ensure that the extra weight of the door gets distributed to the other hinges. COSMOSMotion 2008 permits the user to specify finite stiffness to the joints by specifying the values when defining the mates (Create a mate > Go to the Analysis tab in the mate property manager). However, this presents two challenges by itself:
a) The user needs to account for a good approximation for the stiffness value and the damping effect so that the joint is neither over-stiff nor over-soft.
b) The user needs to figure out the right combination of stiffness values for the rotational and translational degrees of freedom for the mate.
The interface behind COSMOSMotion is now being rapidly revamped, and is guaranteed to grow by leaps and bounds in the years to come. If redundancies can be addressed during the mate-creation stage, rather than putting out fires later on, then running motion simulations would become a part and parcel of every design. One possible suggestion (if the developers are hearing) is to indicate graphically on the screen right during the mate creation stage that a particular part already carries constraints in specific directions, and has only so many degrees of freedom remaining. This would help the user make the best mate-choice while initially setting up the assembly in order to achieve solution 1 (from above) a modeling practice instead of a Simulation fix!!
The user has to spend a little time getting these issues addressed if there are redundancies in the model. Don’t get me wrong here – COSMOSMotion is a stellar product and does more than a great job in bringing virtual simulation to desktops!! I have seen a lot of success stories with it. One customer recently told me that using it in a project helped them finish a project on time (which was a company record!!). However, it seems to be one product that is facing an uphill battle in customers accepting the technology, learning it and using it in their day-to-day decisions.
The team that went back with the training from this week is now already on their first project in getting engineering data from using Motion. They used to generate prototypes that took forever to generate, test and gather valuable data, not to mention the resources, man-hours, time and money! COSMOSMotion 2008 has equipped them with the potential to revolutionize their product cycle and time to manufacturing!
Simulation Product Manager 3DVision Technologies