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______________________________________________ ME3901 Project-Design Realization_
Department of Mechanical engineering
ME3901 Project Design Realization
Design Improvement of Goods Trolley
Final Report
Group No. 5
Group Name KTB
Group Members
Student ID Name Project Role
10945826T Li Ka Kin Project Manager
10947936T Chow Chi Hin Design Manager
10951673T Yu Sin Him Design Manager
10953120T Wong Tsz Yu Marketing Manager
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Abstract
Our group found that when we were using trolley to deliver the goods,
the whole trolley was oscillated during move and it made the goods
move on the platform even dropping down. Thus, this report shows
how to build a product to minimizing the vibration problem of a goods
trolley in our project. In our consideration, vibration is also the
parameter of producing other badly mechanical issues such as
excessive wear, fatigue failure, damage to structure, etc. Therefore,
we design anti-vibrators not only reduce vibration level but slow the
mechanical issues occur. For supporting our design can improve the
vibration problem, two vibration tests are held, one is for prototype
and other one is for design product, and those are conducted under
the same conditions. After the comparisons of the data which collect
from the two tests, we find that the anti-vibrators have actually
absorbed the part of vibration force during the movement of the goods
trolley. Especially, it obviously has a better performance during
moving in on-load condition. In addition, the practical experiment tests
the durability of anti-vibrators which withstood the vibration force and
ensure no components loosening during move.
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Acknowledgement
Dr. Udaya Kahangamage (The Lecturer of Project -
Design Realization)
Chan Yu-Ming (TA)
Dr. X J Jing (The Lecturer of Dynamics and Vibration)
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Table of Content
Chapter 1 Introduction
Chapter 2 Methodology
Chapter 3 Initial product analysis
Chapter 4 Building & improvements theconceptual design
4.1 Components
4.2 Production Process4.3 Modifying the design product
Chapter 5 Detail description of the vibration test
5.1 Instruments5.2 Test5.3 Data
5.4 Factor affecting the result
Chapter 6 Data analysis & Findings
Chapter 7 Conclusion
Chapter 8 Reflection on the learning experience
Reference
Appendix:
(a) Project Management(b) Manpower Management(c) Financial Management
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Chapter 1 Introduction
The aim of this final report is to describe and illustrate in detail about
the design problems, the data analysis, test and improvement which
were the experiments in our project.
First, our Group KTB is to design the anti-vibrator for minimizing the
vibration level between the wheels and the rough road during the
movement of a goods trolley. Before we decided to use now design to
become true, we had to consider and analyze which designs were
satisfied with easy for assembly and disassembly four anti-vibrators,
material requirements, replaceable or easy maintenance and also did
not over the budget, etc.
Second, after carried out the material selection, we started to
purchase the required components and applicable tools for making the
anti-vibrators (IBI manufacture) and installation.
Third, we started to measure and mark out the location for the
installation of anti-vibrators. Because the anti- vibrators needed to
compress for vibration isolation, we must remove the bracket whichwas bonded with wheels axles and the platform for allow mounting
anti vibrators between them. Then, we drilled the holes on the
wheels axles and the platform and mounted thread bolts on the
platform which was used to increase the intervals for putting the anti
vibrators on it. Finally, we installed the wheels axles and wheels and
were locked by fasteners.
(The details of assembly are illustrated in Chapter 4)
Forth, we were conducting the second vibration tests as same as the
first test for prototype with on-load and no load separately. Next, we
compared the data between the design product and prototype and
checked whether it was better than before and also the magnitude of
the improvement (reduced vibration level).
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In addition, during the installation of anti-vibrators, we found that two
problems were existed in our design and listed below:
1) The friction blocked the movement between thread bolts and the
holes. It caused the anti vibrator could not move so lost its
function. So we had to enclose part of the threads which may be
contacting with the holes by plastic tube and enlarge the holes for
allowing the thread bolts to pass through smoothly.
2) The four wheels were swaying during move as the thread bolts
could not be locked securely. We had to lock the each thread bolts
in the platform by two nuts to prohibit from sway.
During the vibration test, two problems were occurred in our design
and listed below:
1)The bottom nut which was mounting the anti-vibrator and the
wheels axle loosed during move on the rough floor. For prevent the
whole assembly to loose, we had dropped some screw glue
between thread bolts and nuts.
2)The wheels level was not aligned that only three or two wheels
could touch the ground during move or rest. We had to readjust
the height (stiffness) of anti vibratorsto align the level.
Finally, we did a practical experiment about conveyance of goods on a
general pedestrian road. The purpose of the experiment was testing
its durability and ensuring no iteration or other problems would be
occurred for affecting the safety. The aspect of design product was
almost completed.
The detail of test results, finding and conclusion are showed on the
following chapter.
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Chapter 2: Methodology
Prototype finding (After the vibration test)
Excessive vibration during moving on the rough road
The level of trolley wheels are not align
Implementation:1. Research and design a product to improve the problems
2. Use software to simulate our design product in the visual situation
Analysis
Problem Identification
Vibration affect the stability of the trolley
Balance affect the controllabilit of the trolle
Conceptualization
Design Feasibility
Implementation:
3. Material selection
4. Follow the layout to build the product
5. Conduct a vibration test for the design product
6. Collect and compare the data
Modification
Problems & Solutions:
a) Problem: Stability of the trolleySolution: Adjust the same height (stiffness) of antivibrators
b) Problem: Friction between holes and thread boltSolution: Put the plastic tubes outside the thread bolts and file the burrs onthe holes.
b) Problem: Nuts loosen during operationSolution: Use the thread locker glue or thread adhesive tape
Finding
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Testing: Vibration test
1. First Vibration test for design product2. Take data of loading & unloading
3.Key issues & Problems
3.1 Nuts loosen during movement
3.2 4-wheels unbalance
3.3 Friction produced between holes and thread bolt
4. Second Vibration test for modified product5. Take data of loading & unloading6. Compare the vibration level with whether add loading or
not after modification
7. Compare the vibration level difference between originaland modifiable one
8. Practical experiment for modified product9. Comment by the customer10.Summary : comments, data and problems & solutions
Calculation:
1. Vibration level
2. Average vibration level
3. Accuracy
Documentation:
Prepare the final report for the design
product
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On load /unload
Chapter 3: Initial product analysis:
Problem Identification
Vibration level affect the stability of trolley The relationship between vibration and loading weight
The relationship between vibration and operation speed
Balance of trolley
The friction of between rotating and stationary machinecomponents (shaft and wheels)
Environmental condition
Vibration can be defined as the cyclic or oscillating motion of a
product or component from its position of rest. It can cause damage to
structures and machine assemblies, resulting in operation, excessive
wear, or even fatigue failure For initial trolley, we found that many
parameters (above table) affect the vibration level of it. In this project,
we concerned and identified four main parameters which affect the
vibration level obviously.
Balancing
Parameters Operation
speed
Environmental
condition
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Balancing:
Unbalance is defined as an exciting force. The exciting force is trying
to cause vibration. In this case, we found that the wheels level was not
aligned that only three or two wheels could touch the ground. We need
to minimize the vibration by readjusting the height after modification.
Mass of the vibrating system:
We knew that mass (loading) is trying to oppose the exciting force and
control or minimize the vibration. So, our prediction is that the
oscillation in on-load test must be lower than the unload one. After
the test, we want to compare the vibration different against the unload
one and prove our assumption right through the result.
Operation speed:
When the operation speed is high
than the critical speed, the
vibration level will be lower at the
same time (refer to F.g3.1 chart).
Obviously, operation speed is theimportant part in vibration. In
following part, we will process the
vibration test in several speeds
and analyze the data different.
(F.g3.1)
Environmental condition:
Ground situation is also a main environmental condition in this project.
We decided to test the trolley on different ground condition and
thereby proved that ground condition had a great effect of vibration.
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Chapter 4: Building & improvements the conceptual
design
In this chapter, we would like to illustrate how to develop our
conceptual design and how to solve the design problems which isfound in the vibration test.
Initially, we would like to introduce the components which we had
used.
4 Thread bolts
4 Springs
Fasteners
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Production Process:
Step 1: Dismantling the 4 wheels and 2 wheels axles
(a) Disassembling the wheels (b) The wheels axles with brackets
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(c) Using a hand bow saw to disassemble the wheels axles with brackets
Step 2: Drilling the holes on the wheels axles and platform. Thosediameters of holes are 10 mm bigger than the diameters of thread bolts.
Dismantled
Mark out the drilling
location
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(d) Drilling the holes on the wheels axles by the portable electric drill
(e) Drilling the holes on the platform
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Step 3: Assemble all the components on the trolley.
(f) Using the fasteners to lock the thread bolts on the platform
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Modifying the design product:
(a)Put the plastic tube outside the thread bolts to minimize the
friction produced between the holes of wheel axles, and alsoprevent the components for wearing.
(b)Using the fasteners to lock the assembly on the wheels axles
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After the vibration test, we found that the fasteners would be loosened
during moving on a rough road.
(c) P.T.F.E thread seal tape wrap was used to prohibit the fasteners
loosening.
(d) Readjusting the height of anti-vibrators to align the wheels level
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Chapter 5: Detail description of the vibration test
We decide an experiment to test the vibration level of the trolley. In
our experiment, we measure the damping ratio by the signal analyzer
to isolate a single mode from the frequency response function. We testthe trolley on the rough path (Fig.5.4) with different load add on it (Fig
5.5 & Fig 5.6).
(a)Instrument
The Dual-Channel Signal Analyzers type 2032(Fig.5.1) is the instrument
to determine the modal parameters of simple structures. The model
frequencies are determined from the frequency response function. The model
damping is found from the decay rate, measured from the magnitude of the
impulse response function, which is produced by isolating a single mode from
the frequency weighting function. The charge amplifier (Fig.5.2) use to
transfers the input charge to another reference capacitor and produces an
output voltage equal to the voltage across the reference capacitor. The
accelerometer (Fig.5.3) is a device that measures proper acceleration.
Dual channel signal analyzer type 2032
Fig.5.1
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Charge amplifier
Accelerometer
Fig.5.2
Fig.5.3
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(b)Testing
We divide the experiment into two parts, no-load test & on-loadtest. We use same instrument and load to test the trolley beforeand after modification.
1. First test (before modification)Put the trolley on the rough path and pull it in a constant acceleration
10 kg add on the trolley for the test
20 kg add on the trolley for the test
Fig.5.4
Fig.5.5
Fig.5.6
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The value of Y is more negative, the less oscillation of
the trolley is presented.
Record the Y (-19.5dB)with fixed frequency bandwidth X
in different test
Fig.5.7
Fig.5.8
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2. Second test (after modification)Trolley after modification
Test without loading
10kg load add on the trolley
20kg load add on the trolley
Fig.5.9
Fig.5.10
Fig.5.11
Fig.5.12
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Data
X is the frequency bandwidth = 117.0Hz
1. Before modification,
1
st
test
2
nd
test
3
rd
test
4
th
test
Loading(kg) Vibration level Y (db)
0 -19.5 -17.9 -19.3 -20.1
10 -22.5 -21.8 -22.1 -24.0
20 -30.9 -29.0 -32.2 -30.9
2.After modification,1st
test
2nd
test
3rd
test
4th
test
Loading(kg) Vibration level Y (db)
0 -27.6 -22.6 -24.3 -25.4
10 -33.2 -33.3 -31.8 -32.5
20 -41.3 -43.2 -39.7 -41.1
To calculation the mean value ]101
log[101
10
N
i
Li
pN
L where Li = average of the dB
Before After
Loading(kg) Mean (db)
0 -24.6
10 -32.7
20 -41.2
Loading(kg) Mean (db)
0 -19.1
10 -22.5
20 -30.6
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(d)Factors affecting the result
Factor:
1. Uneven velocity of the trolley during the test
2. level of 4-wheels unbalances
3. Friction produced between holes and thread bolt
Remedial actions taken:
1. To get the accuracy data, we try to pull the trolley with a
constant acceleration. We also do the test 4 times to reduce the
error.
2. To keep to the trolley in a balance level, we adjust the nut to
balancing the trolley. We use the level bar to balance the 4-
wheels.
The friction produce between the holes and the thread bolt will affectthe vibration level. To improve this, we try to use the plastic tube to
cover it, as the result to reduce the friction between them.
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Practical experiment:
The main objective of our project is decreasing the vibration and norisk for human use. So, we need to provide a final practical experimentto test the trolley is functional and safety.
In experiment process, we decided to test the structure of sub-assemblies whether firm or not first. Base on previous experience, thesub- assemblies will be possible to loosen during operation. Weexpected the sub- assemblies will not be loosen and raise the reliabilityof product.
During experiment process, we trial use to keep the trolley in motionin 30 minutes continuously. After 30 minutes movement, the trolleycan still function normally and all parts are firmly.
Rough condition Smooth condition
In second part of practical experiment, each group-mate will try to pull
the trolley individually on several ground condition and make a
comment.
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Chapter 6: Dataanalysis & findingsVibration may be characterized by:
(i) The frequency in Hz;
(ii) The amplitude of the measured parameter, which may be
displacement, velocity, or acceleration. This is normally referred to as
the vibration amplitude when expressed in units, but vibration level
when expressed in decibels.
Thus if the measured amplitude is A1 and the reference amplitude is A0,
the vibration level expressed in decibels is:
1. From the data of first test,
Before
modify
1st
test
2nd
test
3rd
test
4th
test
Loading(kg) Vibration level Y (db)
0 -19.5 -17.9 -19.3 -20.1
10 -22.5 -21.8 -22.1 -24.0
20 -30.9 -29.0 -32.2 -30.9
In the first experiment before modify, after 4 trials, we find that the
vibration level of the trolley will decrease when loading is add on it.
In this analysis, we prove that increasing themass, reduce frequency.
Table 6.1
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2. From the data in both test,
Before Modify
Loading
(kg)
(Mean
(db)0 -19.1
10 -22.5
20 -30.6
Compare the mean vibration level before and after modification, it
shows that our design can reduce the vibration level as below chart:
After Modify
Loading
(kg)
(Mean
(db)0 -24.6
10 -32.7
20 -41.2
Fig. 6.1
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Chapter 7: Conclusion
Since vibration is characterized by the frequency and the amplitude, as
has been shown in preceding chapter. We have to aim at the above
parameters to design a product to solving the vibration problem.
We arranged two vibration tests, one for the prototype and other for
the design product. We recorded the data from the above tests and
compared these data. We made a vibration chart to represent our
finding, and it showed that the product which installed the anti -
vibrators have lower decibel than not installed.
The reasons of phenomenon are the amplitude of oscillation is
minimized by damping effect and also the frequency is reduced by
increasing the weight of the mass on the trolley. It means two
parameters are changed to cause the decease of decibel.
This finding proves that our design product (anti vibrators) can
achieve our target that minimizing the vibration level of the goods
trolley during move on a rough road.
Although the design successfully reduces the vibration level, some
problems are existed in our design. Since we did not have the drilling
machine and the holes may not be drilled accurately on the marked
location by electric hand drill, we need to enlarge the holes for fitting
the anti vibrator installation. During the test, we just push the
trolley by hand and no equipment monitors the speed of trolley so this
is the main factor to affect the accurate of the testing result.
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Chapter 8 Reflection on the Learning Experience
Name: Li Ka Kin Student ID: 1094826t
This project is a great experience and opportunity for me to learn how
to build from zero to a whole product for solving the problem. I am so
enjoyed the development process and satisfied the finished product. I
really have learned so much in this project. While you are effort to find
the information and sample to design your product, you will study lot
of academic information and your knowledge also improve so much. It
is an effective method for learning. Finally, this project can be finished
smoothly, thanks my group mates for their good-cooperation and
effort. I am so pound of them. Thanks.
Name: Yu Sin Him Student ID: 10951673t
I got a valuable experience during this project. Initially, our group
decided to design an automatic braking system for the good trolley. At
the beginning of project, we had full of ideas about the automatic
braking system. We found that our ideas all are not function after we
communicated with ourselves and hear the recommendation of teacher.In above event, the experience enriched my learning and strengthened
my communication skills. It will be a positive impact on my study even
career path. After that, we changed the topic from braking system to
anti-vibrator. During process of project, we met many design problems
on the anti-vibrator such as friction blocked the movement, wheels
sway In design process, we also appeared disagreement of opinions
between group mates .At last, we also can choose the better method
to solve the problem via a proper communication. So, I think that a
proper communication was important to ensure smooth collaboration
with each other Apart from learning vibration knowledge; I also learnt
teamwork is an important parameter of a successful project.
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Name: Chow Chi Hin Student ID: 10947936t
In this project, I am the design manager in our group. In the meetings,
I try to bring out the ideas for the project. Through this process, I
must have a clear concept of the design and do the presentation to my
group mates. After the modification part, we face some problem which
affecting our testing result. To solve those problems, we try to collect
all suggested solution and find out the suitable one by using my
knowledge of vibration. Besides, I also get the firsthand experience in
doing a project from problem identification to idea implement. It can
help my future continuality studying.
Name: Wong Tsz Yu Student ID: 10953120t
First of all, I should thank all of my group mates. During the project,
we face some barrier. There are many steps to connect the spring with
the trolley. This is the most difficult part of the project, since the
spring should be installed between the wheels and the base of the
trolley.
Second, I have learnt some technical knowledge form this design
project. For the push trolley, a hard spring is more suitable for our
situation. Due to the heavy loading of the trolley in real life, the spring
system will be broken, if we use soft spring. Thats mean, we should
choose the spring with larger spring constant.
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Reference
Reference website:
Vibration parameter
www.mech.gla.ac.uk/~sharpj/vibration.pdf
Vibration theory
www.newagepublishers.com/samplechapter/001216.pdf
Logarithmic Frequency Scaling
http://www.maintenanceworld.com/Articles/DLIEngineering/Whatis3.htm
Reference book:
Theory& formula of vibration
Vector Mechanics for Engineers Dynamics
Author: FERDINAND P.BEER, E.RUSSELL JOHNSTON,JR. &PHILLIP J. CORNWELL
Process of vibration analysis
The Vibration Analysis Handbook
Author: JAMES I. TAYLOR
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Appendix(a)Project Management
ProjectWorkSchedu
le
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(b)Manpower Management
Group
member
Project Role Activities Carried out
Li Ka Kin Project Manager Design, Make the product,
Test, Work distribution,
Organize the activities,
Control the progress and
Quality of works
Chow Chi Hin Design Manager Identify the problem of
prototype, Design, Make the
product and Test
Yu Sin Him Design Manager Identify the problem of
prototype, Design, Make the
product and Test
Wong Tsz Yu Marketing Manager Purchase, Financial
management, Record the
activities and Draw the
design layout
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(c)Financial Management
No.1 Item Description Receipt/invoice No. Price (HKD)
1 Goods Trolley 1 no. Not provided $170
2 Round File 1 no. Not provided $52
3 Springs 4 nos. Not provided $200
Total: $422-