Ash Abel completed a summer internship with Clemson University's Mechanical Engineering department. Their main project involved vibration and acoustic testing of a 7.5MW test bench that emitted uncomfortable noise levels. Through research, testing, and analysis, Ash identified possible causes such as loose connections and resonance. They designed tests using accelerometers and microphones to analyze vibration and acoustic data. Potential solutions like shortening the support beam or changing its cross-section were modeled and tested. Analysis showed modifying connections and the beam's design could effectively reduce noise levels. Ash also assisted engineers and created support materials during their internship.

1. 2015 Summer Internship
Final Presentation
Ash Abel
Clemson Mechanical Engineering
Exp. Graduation: May 2016
CURI WTDTF

2. Introduction
• First UPIC Internship with Clemson University
• Engineering Mentor: Nicholas Matthias
• Main Project: Vibration and Acoustic Testing
• Secondary Projects: Assist Test Engineers

3. Methodology
1. Define the Problem
2. Research Physics and Background Information
3. Hypothesize Possible Sources of the Problem
4. Design Test(s) to Confirm/Dismiss Hypotheses
5. Analyze the Test Data
6. Determine How to Eliminate the Problem
7. Design and Test Possible Solutions
8. Analyze Data and Implement Effective Solution(s)

4. DEFINE THE PROBLEM

5. Problem Definition
• The 7.5MW test bench (specifically the HSS
support structure) emits a 75dB sound during
operation
o The noise is uncomfortable to those working in the
control room and does not promote an efficient working
environment for the test engineers

6. 7.5MW Test Bench Layout
High Speed Shaft
Cover Assembly

7. RESEARCH PHYSICS AND
BACKGROUND INFORMATION

8. Legend
Variable Definition Units
A constant -
Area (cross-sectional) m^2
B constant -
E Young's Modulus N/m^2
f frequecy Hz
I Area Moment of Inertia m^4
k Stiffness N/m
L Length m
M Mass kg
ρ Density kg/m^3
ω natural frequency rad/s

9. Stiffness
𝑘 𝑎𝑛𝑡 𝑟𝑒 𝑡 = 3
𝐸𝐼
𝐿3
𝑘 𝑓𝑖𝑥𝑓𝑖𝑥 𝑟𝑒 𝑡
= 192
𝐸𝐼
𝐿3
𝑘 𝑎𝑥𝑖𝑎𝑙 𝑟𝑒 𝑡 =
𝐸
𝐿
𝑘 𝑎𝑥𝑖𝑎𝑙 𝑖𝑟 =
𝐺𝐽
𝐿

10. Natural Frequency
𝑓𝑛𝑓 =
1
2𝜋
𝛽 𝑛
2 𝐸𝐼
𝜌 𝐿4
𝑓𝑛𝑓 =
2𝜋
𝐸𝐼
𝑀𝐿3
A
Mode 1 22.4
Mode 2 61.7
Mode 3 121.0
Mode 1 1.875
Mode 2 4.694
Mode 3 7.855
𝛽
Cantilever Beam
Fixed-Fixed Beam

11. Deflection
𝛿 =
𝐹𝐿
𝐸
Deflection can be minimized by:
1. Increasing cross-sectional area
2. Using a stiffer material with a higher Young’s Modulus value
3. Decreasing the total length of the member
4. Decreasing the loading on the member
Young’s Modulus of Various Steels:
1020 > 1040 > 4140 > 4340 >304SS > 316SS

12. Area Moment of Inertia
𝐼 𝑦𝑦 =
𝜋𝑑4
64
= 𝜋𝑟2
𝐼 𝑦𝑦 =
𝜋(𝑑0
4
− 𝑑𝑖
4
64
= 𝜋(𝑟0
2
− 𝑟𝑖
2
𝐼 𝑦𝑦 =
ℎ𝑏3
12
= ℎ𝑏
𝐼 𝑦𝑦 =
1
12
𝐵𝐻3 − 2𝑏ℎ3
= 𝐻𝐵 − ℎ𝑏
𝐼 𝑦𝑦 =
1
12
𝐵𝐻3
− 2𝑏ℎ3
= 𝐻𝐵 − 2ℎ𝑏
𝐼 𝑦𝑦 =
1
3
𝐵ℎ1
3
− 𝑏ℎ3
+ 2𝑡ℎ2
3
= 𝑡(2𝐻 + 𝑏
h
b
b
B
H h
H
t
B
b
------------------
ℎ2
ℎ1
h
r
𝑟0
𝑟i
h H
b b
B

13. Relationships
Stiffness (k) increases as
L A E
Natural Frequency (ω) decreases as
L A E M k

14. HYPOTHESIZE POSSIBLE
SOURCES OF THE PROBLEM

15. Possible Sources of Problem
1. Loose Connections at each end of the
support beam
2. Resonation of various parts of the
support assembly during operation
3. Large displacements of the assembly
during operation

16. DESIGN TEST(S) TO
CONFIRM/DISMISS HYPOTHESES

17. Accelerometer
• Accelerometer has a peak of 10kHz and therefore
acts as a low pass filter with a resonance peak
DAS

18. Accelerometer cont.
• Beeswax was used to connect the accelerometer to the
cantilever support assembly
• As shown below, the beeswax’s natural frequency exceeds
the test conditions and is therefore a viable “adhesive”
option for this test
𝑓𝑛𝑎𝑡 = 𝐶
𝑎𝑟𝑒𝑎 𝑜𝑓 𝑤𝑎𝑥 𝑢𝑛𝑑𝑒𝑟 𝑠𝑒𝑛𝑠𝑜𝑟 𝑚𝑜𝑑. 𝑜𝑓 𝑒𝑙𝑎𝑠𝑡. 𝑜𝑓 𝑤𝑎𝑥
𝑡ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠 𝑜𝑓 𝑤𝑎𝑥 𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑠𝑒𝑛𝑠𝑜𝑟
𝑓𝑛𝑎𝑡 = 3.13
0.128356𝑖𝑛2 5656.472𝑝𝑠𝑖
0.0787𝑖𝑛 0.006614𝑙𝑏
= 3.70𝑘𝐻𝑧
𝑓𝑛𝑎𝑡 = 3.13
0.128356𝑖𝑛2 5656.472𝑝𝑠𝑖
0.0394𝑖𝑛 0.006614𝑙𝑏
= 5.23𝑘𝐻𝑧
2mm thickness
1mm thickness

19. Microphone & Acoustics
DAS DAS
610mm
60mm
512mm

20. Acoustics
[Pa]
(from microphone)
[dB]
SPL (Sound Pressure Level)
[dB(A)]
1𝑃𝑎 = 94𝑑𝐵 𝑆𝑃𝐿
𝑊𝐴 = 10𝑙𝑜𝑔
1.562339𝑓4
𝑓2 + 107.652652 𝑓2 + 737.862232
+ 10log
2.242881 × 1016
𝑓4
𝑓2 + 20.5989972 2 𝑓2 + 12194.222 2
𝑃 𝑑𝐵 = 𝑊𝐴 × 𝑃 𝑑𝐵

21. Softwares and Apps
• DIAdem
• Solidworks Simulation
• FFT iPhone App
• Tone Generator iPhone App

22. ANALYZE THE TEST DATA

23. Vibration Data
I am currently post-processing test data to
determine which frequencies have the highest
loads and the amplitudes of those loads. The
results from this analysis will be used to
determine which solution to employ.

24. Acoustic Data
I am currently post-processing test data to
determine which frequencies produce the
loudest noises and the severity of those noises.
The results from this analysis will be used to
determine which solution to employ.

25. DETERMINE HOW TO
ELIMINATE THE PROBLEM

26. Solutions to the Problem Statement
1. Loose Connections
• Install more bolts or better positioned bolts in the assembly
• Loctite bolted connections
• Install a damping material between parts
2. Resonation
• Increase cross-sectional area
• Use a stiffer material
• Alter the natural frequency
3. High Displacement Values
• Increase cross-sectional area
• Shorten the support beam

27. DESIGN AND TEST
POSSIBLE SOLUTION(S)

28. Shorten the Length
• Shortening the
length of the
support beam by
29% results in an
increase in
stiffness of 279%
• Geometric ability
to produce vertical
lifting force is
increased by 41%
540
540
936
663
764
384 490
110
Cantilever Structure
Support Beam
326
326
--------
--------
-----
-----

29. Area Moment of Inertia (𝐼 𝑦𝑦)
𝐼 𝑦𝑦 = 5.55× 106
𝑚𝑚4
= 2800𝑚𝑚2
110
70
110
97.3
30 50
6.35
110
45
50
50
50
50
10
110110
20
90
20
x
y
𝐼 𝑦𝑦 = 9.43× 105
𝑚𝑚4
= 5500𝑚𝑚2
= 4800𝑚𝑚2
𝐼 𝑦𝑦 = 1.13× 106
𝑚𝑚4
= 2800𝑚𝑚2
𝐼 𝑦𝑦 = 4.77× 105
𝑚𝑚4
= 1253𝑚𝑚2
𝐼 𝑦𝑦 = 2.84× 105
𝑚𝑚4

30. Area Moment of Inertia cont.
0 10 20 30 40 50 60
Rectangular beam
Hollow rect. beam
I-beam
H-beam
U-channel beam
CrossSections
Beam Cross-Section Comparison
Cross-Sectional Area ( ) Moment of Inertia ( )

31. Cross Sections & Resulting Stresses ( 𝑁
𝑚2
*cantilever model
Original C-beam: 11.7kg, 4.49E8 Short C-beam: 10.0kg, 6.28E7
Short Rect. beam: 29.5kg, 5.41E7Short I-beam: 18.6kg, 5.76E7
Short W-beam: 18.9kg, 7.07E7
Short Hollow beam: 25.0kg, 5.45E7

32. Boundary Conditions & Resulting Stresses ( 𝑁
𝑚2
*cantilever model
Short C-beam, M12 x4: 6.273E7 Short C-beam, M14 x4: 6.202E7
Short C-beam, M12 x2: 1.86E8Original C-beam, M12 x2: 4.49E8

33. Solidworks Simulation: Static
Current Setup with Support Beam
Max Stress:2.73E7 [N/m^2]
FACTOR OF SAFETY: 13.39
New Setup with new End-piece and
without Support Beam
Max Stress:3.90E7 [N/m^2]
FACTOR OF SAFETY: 5.66
Current Setup without Support Beam
Max Stress: 2.036E7 [N/m^2]
FACTOR OF SAFETY: 10.83

34. Solidworks Simulation: Frequency
Short support beam/no webbing/
high frequency test
No support beam/with webbing/
high frequency test

35. Materials
• 304 Stainless Steel and 1080 Steel are the most
cost-effective options to stiffen the beam and
decrease deflection while maintaining a relatively
low natural frequency.
𝑓𝑛𝑓 =
2𝜋
𝐸𝐼
𝑀𝐿3𝑘 𝑎𝑥𝑖𝑎𝑙 𝑟𝑒 𝑡 =
𝐸
𝐿
𝛿 =
𝐹𝐿
𝐸

36. Redesigned Support Structure

37. ANALYZE DATA AND
IMPLEMENT EFFECTIVE
SOLUTION(S)

38. Solutions
1. Remove Support Beam
2. Modify Bolted Connections (add bolts, secure connections)
3. Modify Current Support Beam’s Cross-Section (stiffen)
4. Install New Support Beam (rectangular, shorter length)
5. Remove Current End Piece and Install New End Piece
6. Remove Current Support Beam and End Piece and Install
New End Piece with New Support Beam

39. SIDE PROJECTS

40. A/C Unit Ordering & Installation
• Research tubing,
fittings, pumps
• Prepare parts list
to order
• Help set-up and
assemble cooling
system
• Troubleshoot
condensation
issues

41. Intern/Engineer Support Materials
ADC analog to digital converter PAU power amplification unit
AI analog input KTD resistive temperature device
ASCII american standard code for information interchange (text file format) SCR silicon controlled rectifier
Boolean true or false/on or off/ only two possible states SSR solid state relay
CURI clemson university restoration institute IC integated circuit
DAS data acquisition system DC direct current
DSA dynamic signal analyzer AC alternating current
EEPROM electronically erasable programmable read-only memory LED light emitting diode
GUI graphical user interface LCD liquid crystal display
IEPE integrated electronic piezoelectric (sensor) PCB printed circuit board
LAU load application unit NI National Instruments
PCB printed circuit boards eGRID electric gris research innovation and development
RC resistor capacitor (filter) POF plastic optic fiber
RDDS Renk dynamic data system (test bench control) POE power over ethernet
RENK AG (drivetrain and test bench supplier)
RM reflective memory
SEL Schweitzer Engineering Laboratories (manufacturer of breakers)
TEDS transducer electronic data sheet (sensor)
UIC user identification code (within real-time operating system)
VI virtual interface (LabVIEW)
WTDTF wind turbine drivetrain testing facility
• Created a DIAdem software tutorial based on instructional
videos and personal experience
• Collaborated with Nick and Konstantin to revise a LabVIEW
tutorial for the control room
• Started a shared document that defines common acronyms
used at the Clemson WTDTF by engineering personnel

42. Thank you for your time,
any questions?
End of Presentation