P1246990956coKRG

1
Ultrasonic Sonic Crystal
Studying the Propagation of Ultrasound through
Sonic Crystals
2
Propagation of Ultrasound

• Ultrasound 20 kHz
• (20000 cycles per second)
• Operates at 40.28 kHz
• Distance between wave peaks wavelength? 8.5
  mm
• Propagates through a medium
• (air, water, etc.)

3
What is a sonic crystal?
A periodic arrangement of sound scattering
surfaces
4
My Sonic Crystal
Copper rods scattering surfaces
Arranged in a periodic pattern by aluminum casing
5
SC Theory
Reflection sound waves scatter, phase changes
occur

6
SC Theory
Reflection Most sound reflects off of the rod
and goes backwards
Not much sound
Sound!!
7
SC Theory
Diffraction overlapping waves cause
constructive and destructive interference
8
Inspirational article
Refractive Acoustic Devices for Airborne Sound F.
Cervera, L., et. al. PHYS ICAL REVIEW LETTERS 14
JANUARY 2002

• Audible sound 500 to 2000 Hz
• (Human range 20 to 20,000 Hz)
• (middle C 262 Hz)
• Rod diameter 4 cm

9
Inspirational article
Control
Lens
10
Ultrasonic Setup

• Ultrasound 20 kHz
• Operate at 40.28 kHz, ? 8.5 mm
• Rod diameter 3.43 mm
• Ultrasonic Transducer speaker/microphone

11
Ultrasonic Setup
Computer Interface
SC
Reflector
ADG (Automatic Detection Grid)
Frame
12
Ultrasonic Setup - ADG
Threaded Rod
Control Board
Stepper Motor
13
Ultrasonic Setup
Speaker
Microphone
14
Ultrasonic Setup
Parabolic reflector creates uniform sound field
15
Ultrasonic Setup
16
Ultrasonic Setup - Resolution
(2 mm)2 data collection grid chosen
12,300 data points
400 mm
12 hours per scan
130 mm
17
Ultrasonic Setup A top view
Scan Area
SC Case
Speaker
Parabolic Reflector
18
Results No SC Case
19
Results Empty SC Case
20
Results Focusing SC
21
Results Rectangular SC
22
(No Transcript)
23
(No Transcript)
24
To Do

• Sound Shields
• Sound wave guides
• Compare to computer models

25
Special Thanks
Prof. Rick Van Kooten STARS mentor and chief
project advisor
The IU STARS Program
Indiana University Graduate School Funding via
an Undergraduate Research and Creative Activity
Partnership
The IU Physics Professional Machine Shop
Eric Scott, Electronic Technician Master
Steve Hovious, Director of the Student Machine
Shop