Measuring force at a point

[fletchtim]

I am trying to determine the forces at the end of a backhoe boom using MDO. I have set up the model using both force motors to simulate the hydraulic cylinders, and by using external forces to act as the force that the hyraulic cylinders would provide. I have been able to get a "force balance" to give me a load at the end of the boom, but i'd like to be able to get the force at the tip of the boom as it travels through the range of motion. Any ideas on what type of measurement i need to put on a point at the end of the boom to get a loading as it travels through the range of motion.

 

[esundman]

If the tip of the boom is free, then the forces there are zero. I would lock the tip of the boom, and then you can get a meaningful number for what the force is there. Unfortunately, this means locking the tip in many positions to get a feel for at which geometry configuration the force is the minimum/maximum.

If anyone else knows a better way to do this, please chime in.

-Eric Sundman

 

[Schwick]

Instead of locking the tip of the boom completely, could you attatch springs to the tip of the boom.Adding springs with avery largeratewould allow the boom to still move, but also simulate a large reaction force?

 

[esundman]

Schwick,

Your method will definitely work, but the problem is still that once the boom moves away from a 'nominal' position the system-as-defined no longer gives meaningful results, so the system geometry must be redefined for a new set of angles and then either locked or 'springed' in place. This is still an iterative process.

But, I did think of something that could help FletchTim:

You could apply a force at the tip of the boom to simulate a loaded bucket, and then just keep increasing that force until the boom no longer moves as desired. This is a hack way to figure out how much force the boom can provide.

 

[gkbeer]

Isn't that what optimizations are all about?