MAE 342 – Kinematics and Dynamics of Machinery
Analysis of Mechanism Velocity
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Velocity – Important Equations
• For calculating velocities, there are four important equations:
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Velocity and Point Displacement
• Velocity is related to point displacement through:
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Moving Body (Velocity Difference)
• What if we have two points on a rigid body?
MAE 342 – Kinematics & Dynamics of Machinery
Moving Body (Apparent Velocity) • What if we have two bodies (looking at a point on a
third body)?
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MAE 342 – Kinematics & Dynamics of Machinery
Moving Body(Apparent Angular Velocity) • What if we have two bodies (looking at the rotation
of a third body)?
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What is an “Instant Center”
• The instantaneous center of velocity is:
the instantaneous location of a pair of coincident points of two different rigid bodies for which the absolute velocities of the two points are equal.
• What happens:
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Finding the instant center
• For body with respect to absolute coordinate system
� If velocity of point and angular velocity are known:
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Finding the instant center
� If the velocities of two points are known
Velocities not parallel Velocities are parallel
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Aronhold-Kennedy Theorem
• If there are three bodies, the instant centers between each pair of bodies will lie on the same line.
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Application to automobile design
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