2. Methods

Methods

2.1 Equipment List

-       5kg of ice cream sticks
                   
  •  4 tubes of Elmer’s all purpose glue
  • 1 Advanced load machine
-       1 weighing scale
-      West Point Bridge Designer 2014 (2nd Edition) (Bridge designing software)
-   Gym loads (320kg) of different weights
-   1 Measuring tape
-       1 Vice
-       1 Mini hand saw


2.2 Diagrams of experimental setup  

Figure 1: Experimental setup used to detect the radioactive levels of the Americium-241
2.3 Experimental Design

We first use the West Point Bridge design programme to design 5 bridges, before we built the actual one. Next, we use the decision matrix to streamline which design is the best. Lastly we would further improve the design, before building the bridge. The following is our bridge designs.


Design 1
design1.png

Design 2
Design2.png

Design 3
design3.png
Design 4
design4.png





Design 5
Decision Matrix
Next, we would use the ranking matrix, to decide which factors would be in our decision matrix. We discuss the matrix together as a group, and rank each factors. 1 signify that each member agree with the factor on the left hand side of the matrix is more important than the factor on the top. We later consolidate the
number of votes, and see which factor is the most important


Colour
Weight
Size
Cost to produce
Elegance
Robustness
Aesthetic
resources
time
skills
Required
safety
Ease of use
Environmental impact
role total
normalised
value

Colour
X
0
0
0
0
0
0
0
0
0
0
0
0
0
0

Weight
3
X
3
0
3
0
3
0
0
3
0
0
3
18
0.0711

Size
3
0
X
3
3
0
3
3
0
0
0
3
3
21
0.083

Cost to produce
3
3
0
X
3
3
3
3
0
0
0
0
3
21
0.083

Elegance
3
0
0
0
X
0
0
0
0
0
0
0
0
13
0.0909

Robustness
3
3
3
0
3
X
3
0
0
0
0
0
3
18
0.0711

Aesthetics
3
0
0
0
0
0
X
0
0
0
0
0
0
3
0.012

Resources
3
3
3
3
3
3
3
X
0
3
0
0
3
27
0.107

Time
3
3
3
3
3
3
3
3
X
3
0
3
3
33
0.1304

Skills- required
3
0
3
3
3
3
3
0
0
X
0
3
0
21
0.083

Safety
3
3
3
3
3
3
3
3
3
3
X
3
0
36
0.1422

Ease Of use
3
3
3
3
3
3
3
0
0
0
3
X
3
27
0.1304

Environmental Impact
3
0
0
0
3
0
3
0
0
3
3
3
X
15
0.0592














Total:
253


Suggested factors for consideration

Factors
Critical Thinking Questions
Weight
Is the weight suitable?
Size
Is the size suitable?
Cost to produce
Do you have the financial support to produce it?
Elegance
Is the solution simple, clever, or ingenious?
Robustness
Is the solution sturdy, resilient, and unlikely to fail?
Aesthetics
Is the solution tasteful and pleasing to look at?
Resources
Do you have or can you get the materials you need?
Time
Do have time to make the solution and debug it?
Skill required
Is the solution safe to build, use, store, and dispose of?
Safety
Is the solution safe to build, use, store, and dispose of?
Ease of Use
Is the device easy to use?
Environmental impact
Does the device in anyway, have a negative impact on the environment?
Decision matrix

Requirements

Design 1
Design 2
Design 3
Design 4
Design 5
factors
Normalised values
votes
(0-5)
Normalised votes
votes
(0-5)
Normalised votes
votes
(0-5)
Normalised
votes
votes
(0-5)
Normalised votes
votes
(0-5)
Normalised votes
safety
0.1422
9
1.2798
9
1.2798
9
1.2798
9
1.2798
9
1.2798
time
0.1304
9
1.1736
12
1.5648
12
1.5648
9
1.1736
9
1.1736
ease of use
0.1304
6
0.7824
15
1.956
12
1.5648
6
0.7824
15
1.956
skills required
0.083
15
1.245
12
0.996
9
0.747
9
0.747
12
0.996
total
0.486
39
4.4808
48
5.7966
42
5.1564
33
3.9828
45
5.4054

2.4 Procedures


  1. We first use this programme called, West Point Bridge Designer 2014 (2nd edition) to design and test out which design is the most suitable one.

  1. We later on then use popsicle sticks and glue to build our bridge.

  1. After that we would measure the mass of the bridge.

  1. There would be three people during the experimental process. The Supervisor, the Test Engineer and the Loader.

  1. First, the Supervisor will give instructions on the carrying out of the testing.

  1. Next The Test Engineer will place the mounting device on the bridge while the loader will hold on to the test tray to prevent it from loading on the bridge. There are markings on the trolley to make sure that the loading is evenly distributed.

  1. The Supervisor will give the go ahead, when he is ready, the Loader will release the trolley to allow the weight of 80N (8 kg) to be imposed on the bridge.

  1. If the bridge is intact, the Supervisor will call for additional weights to be loaded. The loader will make sure that the weights are placed at the center or are evenly distributed. This will continue until there is a structural failure to the bridge.

  1. The supervisor will call for unloading and the Loader will remove all the weights.

  1. The Loader will lift the tray and the Test Engineer will remove the device and the broken bridge.

  1.      The process will repeat until all the testing is completed.

  1. All three of us would collect the maximum data the bridge could hold on to in 4 video , as shown in the data analysis.

  1. We would redesign the bridge model, to make it stronger than the previous model.

  1. Repeat step 1-13 for the next 5 designs.

  1. Plot the data into a table as shown below, to see whether the mass of the bridge affects the maximum amount of weight it could hold.

2.5 Risk Assessment and Management  


Risk
Assessment
Management
As the weights are heavy they may drop off the tray and hurt the user.
High
We will make the weights  load toward the center and therefore balance.
The wood that is broken will create sharp edges and splinters, so the sharp wood parts would fly and may hurt the user.
Low
We will have safety precautions like gloves and goggles and stand at least 1 meter away from the test bed.
The mounting rods might slip and not support the mounting device, in turn the device would tilt and the weights on it would drop and injure the user
Medium
The loading is vertical, so we can use the hold the other weights on the test rod as it can hold more than the weights loaded. We will also have a safety rope to stop them from slipping sideways.
The load may drop on us and bruise us as it is rather heavy
Medium
Ensure that there is supervision in the lab, and that we follow the safety precautions on the manual in the load machine
The bridge may be heavy and drop on us which could injure ourselves
Low
We must ensure the bridge is stable during the construction stage.
The glue is toxic, and if we forget to wash our hands before consumption, we could be contaminated by the glue
High
we must wash our hands thoroughly before consuming anything.
There may be broken sticks, and we could injure ourselves when the sharp ends puncture our skin.
Low
Throw the broken sticks away bag to prevent it from injuring us.
2.6 Data Analysis

1.    Tabulate results.
2.    Plot a table based on the results.
3.    From the graph we can find out which design is the most suitable design.
4.  The graph would also allow us to find out if the weight of the bridge do affect the amount of load the bridge could hold before it collapse




example:

Design
Weight of the bridge (x)
Amount of load it hold, before collapsing (y)
Efficiency rate
(y/x)





















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