About Impulse Measures
An impulse measure returns the change in momentum due to a collision. This measure is a more quantitative way to track impact events. An object's momentum changes when a time-dependent force acts on it during a collision. The change in momentum is related to the force of collision by the following equation:
momentum =
F(t) dtYou can create impulse measures for the following types of connections:
• Motion Axis—Measure the momentum change after a motion axis contacts its limits. To measure impulse, you must specify motion axis limits and a coefficient of restitution for your connection. You can measure impulse in the direction of the joint's DOF for each type of connection.
• Cam-follower connections—Measure the momentum change after a cam-follower separates and reconnects. You must enable the liftoff option and specify a coefficient of restitution to measure impulse. You can measure the impulse for these components:
◦ Normal force—Measure the component of the impulse in the direction perpendicular to the cam curves at the point of contact between the two cams.
◦ Tangential force—Measure the component of the impulse that is tangential to the cam curves at the point of contact between the two cams.
• Slot-follower connections—Measure the momentum change after impact when a slot-follower contacts its endpoints. You must specify a coefficient of restitution to measure impulse. You can choose the starting or ending endpoints.
The coordinate system axes used in calculating impulse may or may not correspond to the WCS or any LCS in the mechanism. When you select a connection and a component to measure, a shaded, magenta arrow appears on the selected connection indicating the X or Y direction that is actually used in the calculation. Be sure to look at this direction carefully to decide whether it is actually the direction for which you want the impulse measurement.