Bug 247426

Summary: Dashpot element
Product: [Applications] step Reporter: Todd <toddrme2178>
Component: generalAssignee: Vladimir Kuznetsov <ks.vladimir>
Status: REPORTED ---    
Severity: wishlist CC: aspotashev, sreejiththulaseedharan
Priority: NOR    
Version: 0.0.4   
Target Milestone: ---   
Platform: openSUSE   
OS: Linux   
Latest Commit: Version Fixed In:
Sentry Crash Report:

Description Todd 2010-08-11 21:49:22 UTC 
Version:           0.0.4 (using KDE 4.5.0) 
OS:                Linux

For the basic elements of machines for mechanical systems, there are four main basic components (besides massless rigid bodies).  These are the motor, the spring, the mass, and the dashpot.  These are the four basic elements of mechanical devices.  They are used in real mechanical systems as well as forming the basic building blocks that simulations of more complex systems are built out of.  As an example, a combination of a motor, spring, dashpot, and mass is a classic demonstration of a non-linear system.

Compared to electrical circuits, the motor is like a battery, the spring is like a capacitor, the mass is like an inductor, and the dashpot is like a resistor.  

Step has three of the four, the motor, the spring, and the mass, but it lacks a built-in dashpot.  A dashpot could probably be built using a combination of gasses and rigid bodies, but considering how critical dashpots are to mechanical systems I think having a built-in ideal dashpot like you do for the spring, motor, and mass is important for anyone wanting to do college-level and above demonstrations using step.

Reproducible: Didn't try
Comment 1 Vladimir Kuznetsov 2010-08-13 14:40:55 UTC 
Todd,

Currently you could set a "damping" parameter for a spring. This would have exactly the same effect as a dashpot (i.e., frictional force proportional to velocity and applied in the opposite direction). Is this what you are looking for ?
Comment 2 Todd 2010-09-07 21:59:01 UTC 
Although it does have the same effect, I think for the sake of being able to do physics demonstrations with the software there should probably be a separate dashpot element, or the ability to set a dashpot icon, even if its properties are exactly the same.  

Alternatively, the appearance could depend on the properties.  If it has a no stiffness but does has damping it could take on the appearance of a dashpot, if it has a stiffness but not damping it could take on the appearance of a spring, if it has both it could take on the appearance of a spring and dashpot in series.

Yet another possibility would be to just split up the spring and dashpot elements, if someone wants something with both stiffness and damping they can combine the two.