PRELIM Flashcards

1
Q

What is DOF?

A

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.

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2
Q

Types of Motion and their definition.

A

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.

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3
Q

The body has a stationary center of rotation, and a reference line through it alters its angular orientation.

A

PURE ROTATION

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4
Q

the body changes its linear position but does not change its angular orientation.

A

PURE TRANSLATION

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5
Q

The body undergoes a simultaneous rotation and translation, with points traveling nonparallel paths and a rotating center constantly changing location.

A

COMPLEX MOTION

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6
Q

Define Linkage.

A

A basic building block of all mechanism. Linkage are made up of links and joints.

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7
Q

Define Link.

A

A link is an (assumed) rigid body which posses at least two nodes which are points for attachment to other links.

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8
Q

3 links with their definition

A

Binary link – one with two nodes
Ternary – one with three nodes
Quaternary – one with four nodes

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9
Q

Define Joints

A

A joint is a connection between two or more links (at their nodes), which allows some motion, or potential motion, between the connected links

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10
Q

Also called kinematic pairs

A

Joints

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11
Q

A kinetic chain is defined as:

A

An assemblage of links and joints, interconnected in a way to provide a controlled output motion in response to a supplied input motion.

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12
Q

A mechanism is defined as:

A

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).

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13
Q

A machine is defined as:

A

A combination of resistant bodies arranged to compel the mechanical forces of nature to do work accompanied by determinate motions

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14
Q

Joints can be classified in several ways:

A

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).

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15
Q

What is the RPHCSP joints

A

Rotation joints, Prismatic joints, Helical joints, Cylindric joints, Spherical joints and Planar joints.

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16
Q

How to determine overall DOF of any mechanism?

A

We must account for the number of links and joints, and for an interaction among them.

17
Q

Write the formula for Gruebler’s and Kutzbach’s equation.

A

M = 3(L-1)-2J
M = 3(L-1)-2J-J