PRELIM Flashcards
What is DOF?
The system of Degrees of freedom is equal to number of independent parameters (measurements) which defines its position in space at any instant of time.
Types of Motion and their definition.
PURE ROTATION - The body has a stationary center of rotation, and a reference line through it alters its angular orientation.
PURE TRANSLATION - the body changes its linear position but does not change its angular orientation.
COMPLEX MOTION - The body undergoes a simultaneous rotation and translation, with points traveling nonparallel paths and a rotating center constantly changing location.
The body has a stationary center of rotation, and a reference line through it alters its angular orientation.
PURE ROTATION
the body changes its linear position but does not change its angular orientation.
PURE TRANSLATION
The body undergoes a simultaneous rotation and translation, with points traveling nonparallel paths and a rotating center constantly changing location.
COMPLEX MOTION
Define Linkage.
A basic building block of all mechanism. Linkage are made up of links and joints.
Define Link.
A link is an (assumed) rigid body which posses at least two nodes which are points for attachment to other links.
3 links with their definition
Binary link – one with two nodes
Ternary – one with three nodes
Quaternary – one with four nodes
Define Joints
A joint is a connection between two or more links (at their nodes), which allows some motion, or potential motion, between the connected links
Also called kinematic pairs
Joints
A kinetic chain is defined as:
An assemblage of links and joints, interconnected in a way to provide a controlled output motion in response to a supplied input motion.
A mechanism is defined as:
A kinematic chain in which at least one link has been “grounded,” or attached, to the frame of reference (which itself may be in motion).
A machine is defined as:
A combination of resistant bodies arranged to compel the mechanical forces of nature to do work accompanied by determinate motions
Joints can be classified in several ways:
1 By the type of contact between the elements, line, point, or surface.
2 By the number of degrees of freedom allowed at the joint.
3 By the type of physical closure of the joint: either force or form closed.
4 By the number of links joined (order of the joint).
What is the RPHCSP joints
Rotation joints, Prismatic joints, Helical joints, Cylindric joints, Spherical joints and Planar joints.
