2015 Summer Internship Final Presentation

Ash AbelClemson Mechanical Engineering

Exp. Graduation: May 2016CURI WTDTF

Introduction

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

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)

DEFINE THE PROBLEM

Problem Definition

• The 7.5MW test bench (specifically the HSS support structure) emits a 75dB sound during operationo The noise is uncomfortable to those working in the

control room and does not promote an efficient working environment for the test engineers

7.5MW Test Bench Layout

High Speed Shaft Cover Assembly

RESEARCH PHYSICS AND BACKGROUND INFORMATION

Legend

Variable Definition UnitsA constant -

Area (cross-sectional) m^2B constant -E Young's Modulus N/m^2f frequecy HzI Area Moment of Inertia m^4k Stiffness N/mL Length mM Mass kgρ Density kg/m^3ω natural frequency rad/s

ܣ

Stiffness

(𝑘𝑐𝑎𝑛𝑡 )𝑟𝑒𝑐𝑡=3𝐸𝐼𝐿3

(𝑘 𝑓𝑖𝑥𝑓𝑖𝑥 )𝑟𝑒𝑐𝑡=192𝐸𝐼𝐿3

(𝑘𝑎𝑥𝑖𝑎𝑙 )𝑟𝑒𝑐𝑡=𝐴𝐸𝐿

(𝑘𝑎𝑥𝑖𝑎𝑙 )𝑐𝑖𝑟𝑐=𝐺𝐽𝐿

Natural Frequency

𝑓 𝑛𝑓=12𝜋

𝛽𝑛2√ 𝐸𝐼𝜌 𝐴𝑐𝐿

4

𝑓 𝑛𝑓=𝐴2𝜋 √ 𝐸𝐼

𝑀 𝐿3

AMode 1 22.4Mode 2 61.7Mode 3 121.0

Mode 1 1.875Mode 2 4.694Mode 3 7.855

ߚ

Cantilever Beam

Fixed-Fixed Beam

Deflection

𝛿=𝐹𝐿𝐴𝐸

Deflection can be minimized by:

1. Increasing cross-sectional area2. Using a stiffer material with a higher Young’s Modulus value3. Decreasing the total length of the member4. Decreasing the loading on the member

Young’s Modulus of Various Steels:

1020 > 1040 > 4140 > 4340 >304SS > 316SS

Area Moment of Inertia

𝐼 𝑦𝑦=𝜋 𝑑4

64

𝐴=𝜋 𝑟2

𝐼 𝑦𝑦=¿¿¿

𝐼 𝑦𝑦=h𝑏3

12

𝐴=h𝑏

𝐼 𝑦𝑦=112

(𝐵𝐻3−2𝑏h3 )

𝐴=𝐻𝐵−h𝑏

𝐼 𝑦𝑦=112

(𝐵𝐻3−2𝑏h3 )

𝐴=𝐻𝐵−2h𝑏𝐼 𝑦𝑦=

13

(𝐵h13−𝑏h3+2 𝑡 h23 )

¿

h

b

b

B

H h

H

t

B

b

------------------h2h1h

r

𝑟0

𝑟 i

h H

b b

B

Relationships

Stiffness (k) increases as

L A E

Natural Frequency (ω) decreases as

L A E M k

HYPOTHESIZE POSSIBLE

SOURCES OF THE PROBLEM

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

DESIGN TEST(S) TO CONFIRM/DISMISS

HYPOTHESES

Accelerometer

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

DAS

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

𝑓 𝑛𝑎𝑡=𝐶 √ (𝑎𝑟𝑒𝑎𝑜𝑓 𝑤𝑎𝑥𝑢𝑛𝑑𝑒𝑟 𝑠𝑒𝑛𝑠𝑜𝑟 ) (𝑚𝑜𝑑 .𝑜𝑓 𝑒𝑙𝑎𝑠𝑡 .𝑜𝑓 𝑤𝑎𝑥 )( h𝑡 𝑖𝑐𝑘𝑛𝑒𝑠𝑠𝑜𝑓 𝑤𝑎𝑥 ) ( h𝑤𝑒𝑖𝑔 𝑡 𝑜𝑓 𝑠𝑒𝑛𝑠𝑜𝑟 )

𝑓 𝑛𝑎𝑡=3.13 √ (0.128356 𝑖𝑛2 ) (5656.472𝑝𝑠𝑖 )(0.0787 𝑖𝑛) (0.006614 𝑙𝑏 )

=3.70𝑘𝐻𝑧

𝑓 𝑛𝑎𝑡=3.13 √ (0.128356 𝑖𝑛2 ) (5656.472𝑝𝑠𝑖 )(0.0394 𝑖𝑛) (0.006614 𝑙𝑏 )

=5.23𝑘𝐻𝑧

2mm thickness

1mm thickness

Microphone & Acoustics

DAS DAS

610mm

60mm512mm

Acoustics

[Pa] (from microphone)

[dB] SPL (Sound Pressure Level)

[dB(A)]

1𝑃𝑎=94𝑑𝐵𝑆𝑃𝐿

Softwares and Apps

• DIAdem• Solidworks Simulation• FFT iPhone App• Tone Generator iPhone App

ANALYZE THE TEST DATA

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.

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.

DETERMINE HOW TO ELIMINATE THE PROBLEM

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

DESIGN AND TEST POSSIBLE SOLUTION(S)

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

--------

--------

-----

-----

Area Moment of Inertia ()

5.55

2800

110

70

110

97.3

30 50

6.35

11045

50

50

50

50

10

110110

20

90

20

x

y

9.43

5500

4800

1.13

2800

4.77

1

2.84

Area Moment of Inertia cont.

Rectangular beam

Hollow rect. beam

I-beam

H-beam

U-channel beam

0 10 20 30 40 50 60

Beam Cross-Section Comparison

Cross-Sectional Area ( ) Moment of Inertia ( )

Cros

s Se

ction

s

Cross Sections & Resulting Stresses (

*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

Boundary Conditions & Resulting Stresses ( *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

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

Solidworks Simulation: Frequency

Short support beam/no webbing/ high frequency test

No support beam/with webbing/ high frequency test

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.

𝑓 𝑛𝑓=𝐴2𝜋 √ 𝐸𝐼

𝑀 𝐿3(𝑘𝑎𝑥𝑖𝑎𝑙 )𝑟𝑒𝑐𝑡=𝐴𝐸𝐿

𝛿=𝐹𝐿𝐴𝐸

Redesigned Support Structure

ANALYZE DATA AND

IMPLEMENT EFFECTIVE

SOLUTION(S)

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

SIDE PROJECTS

A/C Unit Ordering & Installation

• Research tubing, fittings, pumps

• Prepare parts list to order

• Help set-up and assemble cooling system

• Troubleshoot condensation issues

Intern/Engineer Support Materials

ADC analog to digital converter PAU power amplification unitAI analog input KTD resistive temperature deviceASCII american standard code for information interchange (text file format) SCR silicon controlled rectifierBoolean true or false/on or off/ only two possible states SSR solid state relayCURI clemson university restoration institute IC integated circuitDAS data acquisition system DC direct currentDSA dynamic signal analyzer AC alternating currentEEPROM electronically erasable programmable read-only memory LED light emitting diodeGUI graphical user interface LCD liquid crystal displayIEPE integrated electronic piezoelectric (sensor) PCB printed circuit boardLAU load application unit NI National InstrumentsPCB printed circuit boards eGRID electric gris research innovation and developmentRC resistor capacitor (filter) POF plastic optic fiberRDDS Renk dynamic data system (test bench control) POE power over ethernetRENK AG (drivetrain and test bench supplier)RM reflective memorySEL 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

Thank you for your time, any questions?

End of Presentation