Motion Analysis

SOLIDWORKS Motion Analysis is the easiest analytical tool to test for kinematics. Here are a few pointers to make sure you get the most out of your tests.

SOLIDWORKS Mates: while there are more than 100 ways to use different options in SOLIDWORKS environment, 3 mates should be enough to completely constrain a component. By defining mates user constrains a degree of freedom, so user should typically have a single mate controlling a degree of freedom. Having more mates makes the animation redundant leading to wrong results or analysis failure.

Mate location: Define mates at a point location central to reaction area. Meaning choose center of a circular area or midpoint of an edge as the mate location. SOLIDWORKS Motion makes calculations about a CG of an object and generates reactions at all mate locations. Well defined mates  help with result interpretation and improve accuracy.

Component Orientation: All part should be positioned before they undergo motion that is at zero position. Remember at time zero reaction forces are zero and hence where you start the simulation from matters.

Calculation: By taking small time steps, software predicts position of parts at next time step based on initial conditions or previous time step. The software solves for velocity of parts, Mates and then forces/accelerations.

Solvers : SOLIDWORKS Motion has three solvers

(a)    GSTIFF works very good for displacement based simulation

(b)    WSTIFF works great if step sizes suddenly change during a simulation. Compared to GSTIFF, WSTIFF is more accurate and smooth for discontinuous forces, or contact problems.

(c)    S12 : For velocity and acceleration problems S12 offers better control of accuracy.

      Hand Calculations: The only other option to using software is to come up with hand calculations. This is both confusing as well as time intensive. Take a simple four bar linkage. To start generating equations user needs to draw a free body diagram……

 I think I will stick to using SOLIDWORKS Motion. What about you???

Rajat Trehan

Product Manager – Design Validation

Computer Aided Technology Inc.