KINEMATICS OF MECHANISMS KINEMATICS OF MECHANISMS (BDC 4043) Lecture Module 1: Introduction to Mechanisms and Kinematics Waluyo Adi Siswanto Universiti Tun Hussein Onn Malaysia This module is licensed under a Creative Commons Attribution 3.0 License.
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KINEMATICS OF MECHANISMSKINEMATICS OF MECHANISMS(BDC 4043)
Lecture Module 1: Introduction to Mechanisms and Kinematics
Waluyo Adi SiswantoUniversiti Tun Hussein Onn Malaysia
This module is licensed under a Creative Commons Attribution 3.0 License.
MachinesMachines are devices used to alter, transmit and direct forces to accomplisha specific objective.
A mechanismmechanism is the mechanical portion of a machine that has the function Of transferring motion and forces from a power source to an output. So, the mechanism is the hearth of a machine.
KinematicsKinematics deals with the way thins move.It is the study of the geometry of motion. Kinematic analysis involves determinationof position, displacement, rotation, speed, velocity and acceleration.
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Mechanism terminology
MechanismsMechanisms consist of connecting parts with the objective of producing desired motion.
A linkagelinkage is a mechanism where all parts are connected together to form a closed chain.LinksLinks are individual parts of mechanism. They are considered as rigid bodies. A rigidBody, hypothetically, does not change shape during motion.
One part is designated as the frameframe because it served as the frame or reference for themotion of all other parts.
A jointjoint is a movable connection between links and allows relative motion between links.There are two types of joints: primary jointsprimary joints (full joints) and higher-order jointshigher-order joints (half joints).
There are two primary joints. The revolute jointrevolute joint (pin or hinge joint). It allows pure rotationbetween the two links that it connects. The sliding joint sliding joint (piston or prism joint). It allows linearsliding between the links that it connects.
There are two higher-order joints: CamCam and GearGear. A cam joint allows both rotational and sliding between the two links that it connects. A gear connection allows rotation and sliding between two gears as their teeth mesh.
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Simple linkSimple link is a rigid body that contains only two joints, which connect it to other links.A crankcrank is a simple link that is able to complete a full rotation about a fixed center.A rockerrocker is a simple link that oscillates through an angle, reversing its direction atcertain intervals.
A complex linkcomplex link is a rigid body that contains more than two joints
A point of interest point of interest is a point on a link where the motion is of special interest. Once thekinematic analysis is performed, the displacement, velocity and acceleration of that pointare determined.
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Kinematics DiagramComponent Typical form Representation
Simple link
Simple link(with point of interest)
Complex link
Pin joint
Scanned pictures taken from “Machines and Mechanisms Applied Kinematic Analysis (3ed) by David H. Myszka
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Kinematics DiagramComponent Typical form Representation
Slider joint
Cam joint
Gear joint
Scanned pictures taken from “Machines and Mechanisms Applied Kinematic Analysis (3ed) by David H. Myszka
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Kinematics DiagramComponent Typical form Representation
Eccentric crank
Pin in a slot joint
Scanned pictures taken from “Machines and Mechanisms Applied Kinematic Analysis (3ed) by David H. Myszka
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Kinematic InversionEvery mechanismmechanism has a fixed link called a frame. Until the frame link has been chosen, a connected set of links is called a kinematic chainkinematic chain.
When different links are chosen as the frame for a given kinematic chain, the relativemotions between the various links are not altered, but their absolute motion motionsmay be changed drastically. The process of choosing different links of a chain for the frame is known asKinematic inversionKinematic inversion.