Kinematics is the study of relative motion and geometric relationship of machine parts without considering forces.
Kinematics is the study of relative motion and geometric relationship of machine parts without considering forces.
Introduction
Machine is a device designed and used to transmit power or force and transform from a source (input) to a useful application (output).Kinematics of Machine Elements
Kinematic Diagrams
Kinematic diagram is a simplified scaled drawing of machine parts wherein only the dimensions that affects the relative motion is considered.Kinematic Diagram
Degree of Mobility
The Degree of Freedom (DOF) or also known as degree of mobility is used to define the number of parameters or variables to describe the overall movement of all the links in a mechanism.Degree of Mobility
Four Bar Mechanism
Mechanism are assembly of linkages that are designed to produce constrained motion. In a mechanism, one link is fixed. The fixed link is also known as the frame. Grashof's Criterion is useful in determining if one link in a four bar mechanism can complete one revolution. Kinematic Inversion is the process of fixing one link in a kinematic chain and allowing other links to move relative about the fixed link. A slider and crank mechanism is a revolute pair with axis at infinity perpendicular to the relative sliding movement.Four Bar Mechanisms
Crank and Rocker
Slider and Crank
Planar Mechanisms
Straight line mechanism are planar mechanisms consists only of revolute pairs wherein one point on the floating link generates a straight or approximately straight line.
Steering mechanism are usually found in front wheels of automobiles and is used to change the direction of wheel axles with respect to automobile body or chassis.Chebyshev Mechanism
Steering Mechanism
Velocity Analysis
Velocity is defined as the rate of change of displacement of a body with respect to time. Since, displacement is a vector quantity it is represented with magnitude and direction.
Relative Velocity Method is useful in determining the instantaneous linear and angular velocities of any point in the mechanism. One advantage of this method is its simplicity and good level of accuracy if proper care is taken in constructing the velocity polygon.
Acceleration Analysis
Acceleration plays an important role of mechanisms because of its effect on forces. If we know the value of acceleration, force can easily be determined by the product of mass and acceleration. These parameters in turn influence the stresses in different parts of the machine.
When a point on a link slides along a rotating link, such as in Crank and Slotted Lever Mechanism and Whithworth Quick Return Mechanism, then the Coriolis component of acceleration must be considered. The Coriolis Effect is the deflection of moving objects when viewed from a rotating reference point.Coriolis Acceleration
Velocity and Acceleration Image
Velocity and Acceleration Image are very useful concepts in the analysis of higher order links.
Cycle Analysis
When the crank rotates in uniform angular velocity, then, we can present the displacement of one point in the mechanism by means of a cycle diagram.
First we will construct the cycle displacement diagram that will show the displacement of the output link as a function of the location of the crank rotating in uniform angular speed.
Kinematic Synthesis
Kinematic of machine elements is divided into two different types of problems, generally defined as kinematic analysis and kinematic synthesis.
The first one is the study of motion existing in given mechanism. In kinematic analysis, displacement, velocity and acceleration for the given configuration of the mechanism are studied.
In Kinematic Synthesis, the mechanism is designed to produced to meet the required motion. Kinematic synthesis is the fundamental of engineering design process and presents creation of new machines to answer specific needs. Kinematic Synthesis
Cam and Follower
Cams are machine element having irregularly shaped profile used to transmit motion to a driven link known as follower to generate a predetermined and specified motion.