EGR100 Engineering Seminar

1
EGR100- Engineering Seminar

• Engineering Graphics I Basics of Display

2
EGR100- Engineering Seminar
Much Like Problem Solving there are Best
Practices in displaying graphical information.
Why draw graphs at all?
The graph will display a large quantity of data
in a compact form that suggests trends, scale,
and relationships that can not be seen easily
from a long column of data.
3
EGR100-Engineering Seminar
An engineering drawing has a title block to
inform you about the contents of the drawing
what it is about, the scale of the drawing, who
did it etc. A good graph must tell you the same
things. Unlike the Engineering drawing the graph
may have the title block in a variety of
locations on the page and there may be more than
one.
4
EGR100-Engineering Seminar
For example
Note Y axis is labels with unit name, letter and
unit
X axis has same designations
Graph has a title Speed of falling object
Info about graph analysis is in box out of the
way of main graph
5
EGR100-Engineering Seminar
Types of Graph Paper

• Coordinate grid Or X-Y paper
• Polar Paper
• Semi-Log Paper
• Log-Log Paper
• Tri-axis Paper

We will describe each type
6
EGR100-Engineering Seminar
Coordinate Grid or X-Y Paper
This is the most common type of paper used and
comes in a variety of shapes. Most common for
engineering has 10, 8 or 4 squares to the inch or
squares marked in millimeters. You will find a
file with this paper in your assignments section.
7
EGR100-Engineering Seminar
Polar paper is designed to graph equations that
have trig terms, such as sine or cosine, in them.
I personally have used these to identify the
reception pattern of radio antennas and
microphones.
8
EGR100-Engineering Seminar
Semi-log and Log-log Graphs These are common for
quantities that have a wide range of values. You
may have seen these used to present the frequency
response of stereo amplifiers. A Semi-log graph
is used in one experiment in the South Campus
course Intro to Electronics to demonstrate the
idea. Later, we shall show how to use these for
analysis.
9
EGR100-Engineering Seminar
Tri-axis Paper There are many specialized
papers and one is the Tri axis. This is used in
metals work to represent the phase change areas
in three part alloys. A smple is shown among the
Doc graph files.
10
EGR100-Engineering Seminar
An engineer needs to have a variety of these
papers on hand as you never know what analysis
may be necessary. This can be expensive and
inconvenient! Internet to the rescue! The site
listed below has an excellent FREE software
program to print any type paper you might need.
http//pharm.kuleuven.be/pharbio/gpaper.htm
11
EGR100-Engineering Seminar
Use the DOC file in your Course Documents to
print xy paper and plot the data shown below
It should yield a straight line. To check if it
is straight, fold a second piece of paper and use
the folded edge as a straight line. (You dont
always need a ruler to judge a straight edge!)
12
EGR100-Engineering Seminar
Put a title on your graph. Label the edges with
both x and y We have no units for this graph