Mq Whiteman Senior Design Poser I Mean Poster[1]

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VIBRATION REDUCTION DESIGN for WALK BEHIND TROWEL HANDLE DESIGN LOGIC: What we knew: •Forcing frequency (ω): The engine operates between 2,000 and 3,600 RPM (33 Hz to 60 Hz) •Handle weight and measurements What we needed to know: Natural frequency of handlebar system (ω n ) •This value extremely important to characterize vibration of the system. Frequency ratio (r) = ω/ ω n . System will experience maximum vibration when r = 1. Initial testing: Performed impact test to find ω n of handlebar system. •Handle struck with object; handle reaction to impact is captured via accelerometers and HP Infinium Oscilloscope. see chart 1 ω n determined from the period of steady state portion of impact time trace. ω n averaged from n = 30 test trials. Initial tests show ω n = 59 Hz. Operates in resonant range. Research and Development: Want to lower ω n so r is as far right on transmissibility curve as possible. •Governing equation for vibrating cantilevered beam: •Spread sheet designed to optimize parameters E,I, and L in order to predict prototype behavior. J. Chapple ● E. Ketelhut ● R. Garcilazo ● J. Bergh Mechanical Engineering Senior Design 2007 Boise State University Boise, Idaho, USA INTRODUCTION: MQ Whiteman is world renowned for being the industry leader in concrete finishing technology. Their flagship product is the walk behind trowel which they have been producing since the mid 1940’s. Walk behind trowels have seen a relatively small amount of evolution in the original design. PURPOSE: It is a top priority for MQ Whiteman to maintain a high level of safety with their products; our team was presented with the opportunity to find a solution for excessive handlebar vibration. Vibration exposure is known to cause White Knuckle Syndrome, which results in pain in the hands and arms, as well as a decrease in the range of motion, a significant decrease in feeling, and an overall whiteness of the knuckles and hands. The European Union has regulations currently in place (a.k.a CE compliance), with the U.S. soon to follow suit. The standard unit of measure in this industry is Hours of Run Time, which is based on a standard 8 hour workday. Our goal is to meet a rating of 4 Hours. The current handle is rated at 0.7 Hours. 3 3 mL EI n RESULTS: •Several design candidates considered consisting of shape and material alterations: •Material considerations: Steel, Aluminum, Magnesium, and Carbon Fiber •Shape considerations: Circular, Oval, Square, and I-Beam. •Engineering Team utilized decision matrix to decide on final candidate design. See following: •Final design followed engineering prediction. ω n actual = 26.9 Hz; ω n predicted = 26.6 Hz •Transmissibility vs. frequency ratio shows a desirable shift to the right of resonance peak. (The region between the green is the operating range of the new design, red is the original handle.) 0.1 1 10 100 0 0.5 1 1.5 2 2.5 3 Frequency R atio ( w / w n ) Transm issibility R atio Xk/F o Zeta = 0.01 Zeta = 0.02 Zeta = 0.1 Zeta = 0.2 Zeta = .75 Zeta = 1.0 U pperO perating R ange P rototype O perating R ange Decision Matrix Summary Steel, 3.9 Aluminum, 4.1 Magnesium, 3.2 Carbon Fiber, 2.7 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Material Weighted Rating Result Circle Importance Rating Wt. Rating Wt. Rating Wt. Rating Wt. MaterialAvailability 0.25 5 1.25 5 1.25 2 0.5 3 0.75 Manufacturability 0.20 5 1 4 0.8 2 0.4 1 0.2 Transmissibility 1 0.25 3 0.75 4 1 5 1.25 1 0.25 M ass 0.15 2 0.3 4 0.6 5 0.75 5 0.75 Strength 0.15 4 0.6 3 0.45 2 0.3 5 0.75 Total 1.00 3.9 4.1 3.2 2.7 S hape W inner 4.1 Steel Aluminum Magnesium C arbon Fiber DISCUSSION: The prototype design proved to be successful. This design would be compliant with CE regulations and significantly better than reported values from other manufacturers. Hours of Run Time was increased from 0.9 on the original handle, to 6 hours (average). This handle is not, however, recommended for production at this time. The handle meets vibration requirements but may not meet the robustness requirement of the construction industry. Secondly, MQ Whiteman is set up primarily as a steel fabrication shop. Aluminum is not used except where absolutely needed. The cost associated with producing this handle at the MQ Whiteman plant prohibits this design. RECOMMENDATION: It is the recommendation of this engineering team that several prototypes (approximately 10) of this design be produced and sent into the field for testing. Customer opinions should gathered and taken into consideration. We have proved that a solution exists, this being the first of many refined versions. Simultaneous research should be done to find a company more equipped to deal with the aluminum fabrication needs. AKNOWLEDGEMENTS & REFERENCES: Bateman, Cody- Design Engineer, MQ Whiteman Cunningham, Gary- R & D Technician, MQ Whiteman Eggert, Rudy- P.E., BSU Faculty; Design Engineering, Prentice Hall 2005 Guarino, Joe- P.E., BSU Faculty, Vibrations Expert Inman, Daniel- Engineering Vibration, 2 nd ed. Prentice Hall 2001 Prairie, Douglas- Engineering Manager, MQ Whiteman

Transcript of Mq Whiteman Senior Design Poser I Mean Poster[1]

Page 1: Mq Whiteman Senior Design Poser I Mean Poster[1]

VIBRATION REDUCTION DESIGN for WALK BEHIND TROWEL HANDLE

DESIGN LOGIC:•What we knew:

•Forcing frequency (ω): The engine operates between 2,000 and 3,600 RPM (33 Hz to 60 Hz)•Handle weight and measurements

•What we needed to know:•Natural frequency of handlebar system (ωn)

•This value extremely important to characterize vibration of the system. Frequency ratio (r) = ω/ ωn. System will experience maximum vibration when r = 1.

•Initial testing:•Performed impact test to find ωn of handlebar system.

•Handle struck with object; handle reaction to impact is captured via accelerometers and HP Infinium Oscilloscope. see chart 1•ωn determined from the period of steady state portion of impact time trace. ωn averaged from n = 30 test trials.•Initial tests show ωn = 59 Hz. Operates in resonant range.

•Research and Development:•Want to lower ωn so r is as far right on transmissibility curve as possible.•Governing equation for vibrating cantilevered beam:

•Spread sheet designed to optimize parameters E,I, and L in order to predict prototype behavior.

J. Chapple ● E. Ketelhut ● R. Garcilazo ● J. BerghMechanical Engineering Senior Design 2007

Boise State University Boise, Idaho, USA

INTRODUCTION:MQ Whiteman is world renowned for being the industry leader in concrete finishing technology. Their flagship product is the walk behind trowel which they have been producing since the mid 1940’s. Walk behind trowels have seen a relatively small amount of evolution in the original design.

PURPOSE:It is a top priority for MQ Whiteman to maintain a high level of safety with their products; our team was presented with the opportunity to find a solution for excessive handlebar vibration. Vibration exposure is known to cause White Knuckle Syndrome, which results in pain in the hands and arms, as well as a decrease in the range of motion, a significant decrease in feeling, and an overall whiteness of the knuckles and hands. The European Union has regulations currently in place (a.k.a CE compliance), with the U.S. soon to follow suit. The standard unit of measure in this industry is Hours of Run Time, which is based on a standard 8 hour workday. Our goal is to meet a rating of 4 Hours. The current handle is rated at 0.7 Hours.

                       

               

3

3mLEI

n

RESULTS:•Several design candidates considered consisting of shape and material alterations:

•Material considerations: Steel, Aluminum, Magnesium, and Carbon Fiber

•Shape considerations: Circular, Oval, Square, and I-Beam.

•Engineering Team utilized decision matrix to decide on final candidate design. See following:

•Final design followed engineering prediction.• ωn actual = 26.9 Hz; ωn predicted = 26.6 Hz• Transmissibility vs. frequency ratio shows a desirable shift to the right of resonance peak. (The region between the green is the operating range of the new design, red is the original handle.)

0.1

1

10

100

0 0.5 1 1.5 2 2.5 3Frequency Ratio (w/wn)

Tran

smis

sibi

lity

Rat

ioXk

/Fo

Zeta = 0.01

Zeta = 0.02

Zeta = 0.1

Zeta = 0.2

Zeta = .75

Zeta = 1.0

Upper Operating Range

Prototype Operating Range

Decision Matrix Summary

Ste

el, 3

.9

Alu

min

um, 4

.1

Mag

nesi

um, 3

.2

Car

bon

Fibe

r, 2.

7

00.5

11.5

22.5

33.5

44.5

MaterialW

eigh

ted

Rat

ing

Res

ult

Circle

Importance Rating Wt. Rating Wt. Rating Wt. Rating Wt.Material Availability 0.25 5 1.25 5 1.25 2 0.5 3 0.75Manufacturability 0.20 5 1 4 0.8 2 0.4 1 0.2Transmissibility 1 0.25 3 0.75 4 1 5 1.25 1 0.25Mass 0.15 2 0.3 4 0.6 5 0.75 5 0.75Strength 0.15 4 0.6 3 0.45 2 0.3 5 0.75

Total 1.00 3.9 4.1 3.2 2.7Shape Winner 4.1

Steel Aluminum Magnesium Carbon Fiber

DISCUSSION:The prototype design proved to be successful. This design would be compliant with CE regulations and significantly better than reported values from other manufacturers. Hours of Run Time was increased from 0.9 on the original handle, to 6 hours (average).

This handle is not, however, recommended for production at this time. The handle meets vibration requirements but may not meet the robustness requirement of the construction industry. Secondly, MQ Whiteman is set up primarily as a steel fabrication shop. Aluminum is not used except where absolutely needed. The cost associated with producing this handle at the MQ Whiteman plant prohibits this design.

RECOMMENDATION:It is the recommendation of this engineering team that several prototypes (approximately 10) of this design be produced and sent into the field for testing. Customer opinions should gathered and taken into consideration. We have proved that a solution exists, this being the first of many refined versions.

Simultaneous research should be done to find a company more equipped to deal with the aluminum fabrication needs.

AKNOWLEDGEMENTS & REFERENCES:

Bateman, Cody- Design Engineer, MQ WhitemanCunningham, Gary- R & D Technician, MQ WhitemanEggert, Rudy- P.E., BSU Faculty; Design Engineering, Prentice Hall 2005Guarino, Joe- P.E., BSU Faculty, Vibrations ExpertInman, Daniel- Engineering Vibration, 2nd ed. Prentice Hall 2001Prairie, Douglas- Engineering Manager, MQ Whiteman