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Initial Work on Acoustic Simulation using Ansys APDL. Presented by Lee Chean Shen General Engineering Research Institute Electronic and Ultrasonic Engineering Group Supervisors Prof. Dave Harvey Dr. Guangming Zhang 22 January 2010. Introduction – Acoustic Microscopy. What is Acoustic?

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slide1

Initial Work on Acoustic Simulation using Ansys APDL

Presented by

Lee CheanShen

General Engineering Research Institute

Electronic and Ultrasonic Engineering Group

Supervisors

Prof. Dave Harvey

Dr. Guangming Zhang

22 January 2010

slide2

Introduction – Acoustic Microscopy

  • What is Acoustic?
  • Longitudinal wave which consists of compression and dilation

Infrasound

Audible

Ultrasound

20Hz

20kHz

100kHz

Seismology

Human Hearing

Animal

Navigation &

Communication

Medical Diagnostics.

  • Destructive Ultrasound
  • (>10 W/cm2)
  • Sonochemistry
  • Welding
  • Cleaning
  • Cell Disruption
  • Kidney Stone Removal
  • Non-Destructive Ultrasound
  • (0.1 – 0.5 W/cm2)
  • Flaw detection
  • Medical Diagnosis
  • Sonar
  • Chemical Analysis

Destructive & Non Destructive tools.

slide3

Introduction – Acoustic Microscopy

  • What is Acoustic Microscopy Imaging (AMI)?
  • Non-Destructive technique
  • Sensitive to voids, delaminations and cracks
  • Detects flaws down to sub-micron
  • Image nontransparent solids or biological materials
  • Study microstructures of specimen

X-Ray

AMI

Unreflowed Solder Bump, AMI presents better contrast of defect

slide4

Introduction – Acoustic Microscopy

  • Resolution characteristics of AMI technique.
  • Increasing frequency largely lowers depth penetration
    • Attenuation usually increase with frequency
  • Lower frequency reduces resolution

More information

captured

230MHz

50MHz

slide5

Introduction – Acoustic Microscopy

  • AMI Operational Characteristics - Transducer
  • Transducer is cut/tuned to specific frequency, typically three types;
    • Piezoelectric
      • High frequency, low power (MHz region)
      • Voltage applied to crystal, medium required
      • Transducer is cut to frequency
    • Magnetostriction (EMAT)
      • Metal core responds to magnetic field
      • Material dependant, no coupling required
        • Photoacoustic
          • Pulsed laser applied to specimen
          • Thermal wave phenomena
          • Very high frequency
          • Measures material properties
slide6

Introduction – Acoustic Microscopy

AMI Operational Characteristics - Medium

  • Tranducerlensed to modify beam focus

Ansys Model Construction

(results in Review section)

slide7

Introduction – Acoustic Microscopy

  • AMI Operational Characteristics - Medium
    • EMAT only applicable to specific materials
    • Photoacoustic may require protective layer
  • Piezoelectric - Couplant required
    • Usually deionized water
    • Reflection occurs at the interface between two mediums
    • Air has low acoustic Impedance (Z)
    • Z = ρV = density * sound velocity of medium
    • Water to Steel ratio ~ 20:1
    • Air to Steel ratio ~ 100,000:1 (near 100% energy reflected)

Pulse Echo

Change in

Impedance

(Interface)

slide8

Introduction – Acoustic Microscopy

  • AMI Operational Characteristics - Configuration
  • Two typical methods
    • Pulse Echo – Image derived from reflections (Popular)
    • Through Transmission – Image derived from received signal

Pulse Echo

Gate

Through Transmission

slide9

Issues

  • Current issues facing AMI
  • Electronic packages are shrinking and/or stacking
  • Technique is approaching resolution limits
  • Image processing techniques not broadly reliable
  • Transducers have relatively narrow operational frequencies
    • Optimal frequency difficult to determine
slide10

Objectives

  • Nonlinear acoustic Imaging
  • 2nd order harmonic provides higher resolution
  • Common in medical acoustics
  • Require single frequency transducer
  • Penetration depth proportional to fundamental wave
  • Not all material generate harmonic waves
  • Generated waves needs to reach receiver
  • Explore implementation
  • on stacked (3D) die
slide11

Objectives

  • Clarify defect detection mechanism
  • Limited published literature regarding subject
    • Primary focus on new generation 3D IC packages
    • Understand acoustic performance within 3D IC packages
  • Balance optimum resolution vs. penetration
  • Analyze defect detection mechanism of engineered faults
slide12

Methodology - Ansys

  • What is Ansys?
  • Finite Element Multiphysics Simulation Software
  • Accurate simulation of complex coupled-physics behaviour
  • Broadly defined into two interface
  • Structural Mechanics
  • Explicit Dynamics
  • Electromagnetics
  • Fluid Dynamics
  • Acoustics
  • ETC
  • Ansys Mechanical APDL
  • Ansys Workbench
slide13

Methodology - Ansys

  • What is Finite Element Method?
  • Complete system is distributed into a large number of discreet elements
  • Complex system of nodes which form mesh grids
  • Mesh grid contain material and structural properties
  • Area anticipating stress/load tend to have higher density of node
  • Mesh resolution increases computational time
slide14

Methodology - Ansys

  • Comparison of Mesh Resolution
  • Models usually tested with multiple mesh resolution/configuration
  • Ensure circular areas are adequately smooth/circular
  • Mesh resolution and type fits geometry size
  • Generally “look right”, results largely determined by mesh quality

Tetrahedral (triangular)

Hexahedral (square)

Coarse Mesh

Fine Mesh

Coarse Mesh

Fine Mesh

slide15

Methodology - Ansys

What is Ansys Mechanical APDL ?

  • Also known as;
    • Ansys Classic
    • “Old” Ansys
  • Reliant mostly on
  • command lines and scripts
  • Primitive GUI
slide16

Methodology - Ansys

What is Ansys Workbench?

  • Ansys with user friendly GUI
  • “Idiot-proof” Ansys
  • Powerful module based
  • project assembly/management
slide17

Review

Transducer Simulation – Pressure Magnitude

30,000Hz @ 1500m/s (water medium)

Ansys APDL

Mirror

Result

Mirror

Result

Main Lobes

Side Lobes

slide18

Review

Transducer Simulation – Acoustic Lens

30,000Hz @ 1500m/s (water medium)

Triangular mesh @ 15 elements per wave

Expected shift of focus point

Node reaction to applied load

PCIRC,0,1,0,90

RECTNG,0,0.025,0,0.1

CYL4,0,0.25,0.2

(double radius)

pcirc,0,1,0,90

RECTNG,0,0.025,0,0.1

CYL4,0,0.15,0.1

slide19

Further Work

  • Scale up transducer simulations to MHz region
  • Validate simulation with measured results
  • Implement Non-Linear simulation
  • General simulation cleanup
  • Introduce materials into focused region
    • Study acoustic defect detection mechanism
slide21

Source & Citations

Eindhoven University of Technology

http://w3.chem.tue.nl/en/the_department/research_groups/process_development/research/ultrasound/

The Principles of Medical Ultrasound

http://www.mrcophth.com/commonultrasoundcases/principlesofultrasound.html

HyperPhysics Utrasound Guide – Georgia State University

http://hyperphysics.phy-astr.gsu.edu/Hbase/sound/usound.html

CALCE – University of Maryland

http://www.calce.umd.edu/general/Facilities/sam.htm

Acoustic Microscopy Guide – University of Hawaii

http://www.soest.hawaii.edu/~zinin/Zi-SAM.html

Resolution improvement of acoustic microimaging by continuous wavelet transform for semiconductor inspection – LJMU GERI

Guang-Ming Zhang, David M. Harvey, Derek R. Braden.

The NDE Analysis of Tension Behaviour in Nicalon/SiC Ceramic Matrix Composites

Jeongguk Kim, Peter K. Liaw, Hsin Wang

http://www.tms.org/pubs/journals/JOM/0301/Kim/Kim-0301.html

Fundamentals of Ultrasonic Imaging and Flaw Detection – National Instruments

http://zone.ni.com/devzone/cda/tut/p/id/3368

Phased Array Tutorial - Olympus

http://www.olympus-ims.com/en/ndt-tutorials/transducers/construction/

About HIFU – Maple Leaf HIFU

http://www.hifu.ca/physician/about_hifu.php

Finite-element method – McGill University

http://audilab.bmed.mcgill.ca/AudiLab/teach/fem/fem.html

Introduction to Finite Element Analysis – Virginia Tech

http://www.sv.vt.edu/classes/MSE2094_NoteBook/97ClassProj/num/widas/history.html

Modeling and Meshing Guide, Chapter 7 – Ansys

http://www.kxcad.net/ansys/ANSYS/ansyshelp/Hlp_G_MOD7_3.html