Development of a Finite Element Model of an Ant Neck Joint for Simulation of Tensile Loading ...

101 Pages·2012·4.44 MB·English

Development of a Finite Element Model of an Ant Neck Joint for
Simulation of Tensile Loading

THESIS

Presented in Partial Fulfillment of the Requirements for the Degree of Master of Science
in the Graduate School of The Ohio State University
by
Vienny N. Nguyen
Mechanical Engineering Graduate Program

The Ohio State University
2012

Thesis Committee:
Dr. Blaine Lilly, Advisor
Dr. Carlos Castro
Dr. Joseph Raczkowski
Copyright by
Vienny N. Nguyen
2012
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ABSTRACT
Insects have been optimized for form and function over millions of years. Ants in
particular can lift and carry extraordinarily heavy loads in relation to their own body
weight (up to 1000X their own weight). We hypothesize that the ant’s ability to carry
extremely large loads relative to its body mass is the result of a highly integrated system
comprised of composite materials, internal muscle mechanisms, and material
microstructure. The work completed for this thesis focuses on studying the neck joint,
which bears the full mechanical load, of Formica exsectoides. Through mechanical
testing, the load-displacement behavior was recorded and used as a reference for a
computational model of the neck joint. SEM and microCT imaging was used to
supplement and create a 3-dimensional finite element model. The results from the
mechanical tests and finite element model reveal that the load-displacement behavior is
dependent on the direction of the applied load, and that the typical rupture location occurs
at the material transition between the neck membrane and stiffer exoskeleton on the head.
This project serves as a gateway to better understanding the design of the neck joint;
future work may include the characterization of the neck membrane material, a kinematic
analysis of the joint including muscle and ligament contributions, and a comparison of
the functional morphology between multiple species.

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This work is dedicated to my family and friends.

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ACKNOWLEDGEMENTS
I thank the National Science Foundation’s Graduate Research Fellowship
Program for their support and investment in not only my research, but also the research of
my peers that will contribute to our future. This work was also supported in part by The
Ohio State University Institute of Materials Research and an allocation of computing time
from the Ohio Supercomputer Center. I thank Dr. Richard Hart for use of the MicroCT
Laboratory in the Department of Biomedical Engineering at The Ohio State University;
SimpleWare for providing the necessary software for 3-D modeling; and Dr. Joe
Raczkowski and Dr. John Wenzel for sharing their myrmecological expertise with the
project.
I owe a great deal to Dr. Blaine Lilly for his patience and willingness to support
projects that are outside of the box, and to Dr. Carlos Castro for adopting me into the
Nanoengineering and Biodesign Lab.
For those who have helped me get to where I am today, there is not enough I can
do or say to thank you for your support: Dr. Kinzel, Dr. Staab, Dr. Harper, Joe West and
the rest of the mechanical engineering faculty and staff for giving me a hard time; the
Robonaut Team at JSC for the privilege of learning how to apply my lessons from an
amazing group of engineers; Dr. Freuler and the FEH family for setting the bar high; the
Office of Minority of Affairs for making Ohio State possible; Dan McCarthy, Neil
Gardner, and Dave Torick for introducing me to engineering just in time; all of my
teachers in primary and secondary school for their dedication in dealing with students
like me; my friends who supported me through the years and were there to remind me to
have fun; my mom for being a constant worry wart; and my dad for letting me climb to
the top of the jungle gym and for (usually) trusting that I would always get the job done.
I also thank my husband, my partner in crime, and my rock. Thank you for loving,
challenging, and believing in me.
I finally thank God for all that He has given me.

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VITA
December 26, 1986………………………………………...Born – Columbus, Ohio, USA
2010……………………………B.S. Mechanical Engineering, The Ohio State University
2010-2011………………………………….University Fellow, The Ohio State University
2011-2012………………………………………..NSF Fellow, The Ohio State University

PUBLICATIONS
V.N. Nguyen, B.W. Lilly, and C.E. Castro, “Reverse Engineering the Structure and
Function of the Allegheny Mound Ant Neck (Insecta, Hymenoptera, Formica
exsectoides),” in ASME International Mechanical Engineering Congress and
Exposition, Houston, TX, 2012.
FIELDS OF STUDY
Major Field: Mechanical Engineering
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TABLE OF CONTENTS
ABSTRACT ....................................................................................................................... iii
ACKNOWLEDGEMENTS ................................................................................................ v
VITA ................................................................................................................................ vi
TABLE OF CONTENTS .................................................................................................. vii
LIST OF FIGURES ............................................................................................................ x
LIST OF TABLES ........................................................................................................... xiv
Chapter 1. Introduction ..................................................................................... 1
Chapter 2. Background ..................................................................................... 4
2.1 Taxonomy .............................................................................................. 4
2.2 Anatomy ................................................................................................ 6
2.2.1 External Anatomy ........................................................................... 7
2.2.2 Internal Anatomy............................................................................. 7
2.3 Terminology .......................................................................................... 8
Chapter 3. Literature Review ............................................................................ 9
3.1 Introduction ........................................................................................... 9
3.2 Exoskeleton Material Properties ............................................................ 9
3.3 Additional Functions of Insect Exoskeleton ........................................ 14
3.3.1 The Folded Cuticle of a Dragonfly Neck ...................................... 14
3.3.2 The Microsculpture of Fly Cuticle Armor .................................... 16
3.4 Summary of Literature Review ........................................................... 22
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Chapter 4. Experimentation ............................................................................ 23
4.1 Introduction ......................................................................................... 23
4.2 Instrument Design................................................................................ 24
4.3 Methods ............................................................................................... 26
4.3.1 Specimen Collection and Maintenance ......................................... 26
4.3.2 Experimental Protocol ................................................................... 27
4.4 Experimental Results ........................................................................... 31
4.5 Summary of Experimentation .............................................................. 34
Chapter 5. Imaging and Modeling .................................................................. 36
5.1 Introduction ......................................................................................... 36
5.2 MicroCT Methods ............................................................................... 36
5.3 SEM Methods and Images ................................................................... 40
5.4 Conversion of MicroCT Data to a 3-Dimensional Mesh .................... 43
5.5 Finite Element Model .......................................................................... 50
5.5.1 Model Data, Boundary Conditions, Loading, and Parameters ...... 50
5.5.2 Material Verification ..................................................................... 51
5.5.3 Model Results ................................................................................ 53
5.6 Summary of Imaging and Modeling .................................................... 56
Chapter 6. Discussion and Conclusion ........................................................... 58
6.1 Introduction ......................................................................................... 58
6.2 MicroCT and SEM imaging ................................................................ 58
6.3 Experimental and Finite Element Results Comparison ....................... 59
6.4 Summary and Conclusions .................................................................. 63
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Bibliography ..................................................................................................................... 66
Appendix A: Glossary....................................................................................................... 71
Appendix B: Circuit Diagrams ......................................................................................... 73
Appendix C: Arduino Source Code .................................................................................. 74
Appendix D: Mechanical Testing Protocol....................................................................... 77
Appendix E: MATLAB Image Processing m-file ............................................................ 80
Appendix F: CT Specimen Staining and Preparation Protocol ........................................ 86

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LIST OF FIGURES
Figure 1: Examples of load carrying Oecophylla ants. A) O. smaragdina workers
contructing a nest [2]; B) O. Longinoda worker holding a dead baby bird [1]; and
C) O. smaragdina worker holding a weight from a glassy surface [3]. .................. 2
Figure 2: Arthopod Classification ....................................................................................... 5
Figure 3: Ant Classification ................................................................................................ 6
Figure 4: External and Internal Anatomy of the Ant [6] .................................................... 6
Figure 5: Anatomical Terms of Location. Photograph by Alexander Wild. ...................... 8
Figure 6: A material property chart for natural materials, plotting Young's Modulus
against density. Guide lines identify structurally efficient materials which are
light and stiff [10]. ................................................................................................ 10
Figure 7: Locust in the Oviposition [13]........................................................................... 11
Figure 8: SEM of neck area in damselflies. (A) Dorsal aspect with head removed of
Ischnura elegans; (B) Semi-thin cross section of the neck region of I. elegans; (C)
Dorsal aspect with head removed of Coenagrion puella; (D) Semi-thin cross
section of the neck region of C. puella. a, anterior direction; d, dorsal direction;
m, medial direction; EC, epidermal cells; ML, midline; NM, neck membrane; PN,
pronotum; SP, postcervical sclerite; TRD, dorsal trachea; TRV, ventral trachea;
TS, trichoid sensilla. Scale bars: 380 nm (A & B); 75 µm (C); 86µ (D) [11]. ..... 15
Figure 9: Three orders of the neck membrane profile in adult Odonata [11]. .................. 16
x