Further Development of MPM and its Applications in Modeling Wood-Adhesive Bonds

154 Pages·2017·10.31 MB·English

AN ABSTRACT OF THE DISSERTATION OF
Chad Hammerquist for the degree of Doctor of Philosophy in Wood Science and
Mechanical Engineering presented on September 22, 2017.
Title: Further Development of MPM and its Applications in Modeling
Wood-Adhesive Bonds
Abstract approved:
John A. Nairn
This work is a culmination of a series of published works related to the use of the
Material Point Method (MPM) in modeling wood adhesive bonds. The use of wood
as construction material has the potential to play a small role in the solution to
the current CO and climate change crisis. Therefore, wood as an engineering and
2
structural material appears to have increased popularity among green-minded archi-
tects and builders. Much of wood used as a structural or engineering material is in
the form of a wood composite, common examples include plywood, oriented strand
board (OSB), laminated veneer lumber (LVL), particle board, cross-laminated timber
(CLT), and others. Clearly, a vital component of all these products is the adhesive
bond between the pieces of wood. The motivation of this work is to thoroughly un-
derstand the mechanics and properties of a wood adhesive bond through the use of
computational numerical modeling.
A detailed and full-featured customized numerical modeling paradigm for wood
adhesive bonds using MPM is introduced. The effective goal is to start with a specific
wood structure and the liquid properties of an uncured adhesive, and to fully model
and verify every aspect of the wood adhesive bond with MPM. This is a complex en-
deavor and has several intermediate steps, including modeling how adhesive flows into
the wood structure and modeling the mechanical performance of the wood adhesive
bonds.
To improve the modeling of fluids and fluid-structure interaction in MPM, an
advancement called XPIC (eXtended Particle In Cell) was invented and introduced
to significantly reduce noise and high frequency oscillations in MPM simulations.
XPIC was used to improve MPM simulations in all the chapters of this dissertation.
MPMsimulationswereusedtomodelthepressure-drivenflowofuncuredadhesive
inawoodstructure, createdusingXCTscansofactualwoodadhesivebondsegments.
These simulations are verified against experimental x-ray data. To model the me-
chanical performance of a wood bond, mechanical properties are needed, ideally the
properties of the particular piece of wood. This is partially achievable with nanoin-
dentation. However, thestandardmethodsforanalyzingnanoindentationdon’tapply
to the anisotropic wood cell walls and further numerical modeling is needed. The use
of MPM for modeling nanoindentation is investigated and it is found that MPM is
well suited to handle this modeling and that numerical modeling is indeed important
for accurate and consistent material properties.
Finally, modeling the mechanical performance of a wood adhesive bond with the
geometry created from the adhesive squeezing simulations or from XCT data is inves-
tigated. MPM simulations investigating the mechanical behavior of wood-adhesive
bonds are compared with experimental data obtained from DVC analysis of XCT
scans of wood specimens under load.
Not every step in the proposed overarching modeling paradigm has been fully
completed but progress has been made toward each step. And the feasibility of
each step is demonstrated. Once the modeling paradigm has been fully implemented
with MPM and verified with experiments, the next phase is to use this modeling to
further the understanding of wood adhesive bonds, to suggest and inform additional
experiments, and to optimize adhesives and bonding procedures.
(cid:13)cCopyright by Chad Hammerquist
September 22, 2017
All Rights Reserved
Further Development of MPM and its Applications in Modeling
Wood-Adhesive Bonds
by
Chad Hammerquist
A DISSERTATION
submitted to
Oregon State University
in partial fulfillment of
the requirements for the
degree of
Doctor of Philosophy
Presented September 22, 2017
Commencement June 2018
Doctor of Philosophy dissertation of Chad Hammerquist presented on
September 22, 2017.
APPROVED:
Major Professor, representing Wood Science and Mechanical Engineering
Head of the Department of Wood Science and Engineering
Head of the School of Mechanical, Industrial and Manufacturing Engineering
Dean of the Graduate School
I understand that my dissertation will become part of the permanent collection of
Oregon State University libraries. My signature below authorizes release of my
dissertation to any reader upon request.
Chad Hammerquist, Author
ACKNOWLEDGEMENTS
This work was supported in part by the National Institute of Food and Agriculture
(NIFA) award #2013-34638-21483 of the United States Department of Agriculture
(USDA) and by the National Science Foundation Industry/University Cooperative
Research Center for Wood-Based Composites, Award No. IIP-1034975.
CONTRIBUTION OF AUTHORS
The following authors contributed to Chapter 2: John A. Nairn.
The following authors contributed to Chapter 3: John A. Nairn.
The following authors contributed to Chapter 4: John A. Nairn.
The following authors contributed data and analysis to Chapter 5: Daniel Ching
TABLE OF CONTENTS
Page
1 Introduction 1
1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Numerical modeling of wood-adhesive bonds . . . . . . . . . . . . . . . 2
1.3 Computational Mechanics and the Material Point Method (MPM) . . . 3
1.4 Grand Unifying Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 A New Method for Material Point Method Particle Updates that Reduces
Noise and Enhances Stability 13
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.2 Numerical Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.2.1 MPM Extrapolations . . . . . . . . . . . . . . . . . . . . . . . 15
2.2.2 FLIP and PIC Derivations by Inverse Methodology . . . . . . 18
2.2.3 XPIC(m) Derivation . . . . . . . . . . . . . . . . . . . . . . . 21
2.2.4 XPIC(m) Properties . . . . . . . . . . . . . . . . . . . . . . . 23
2.2.5 Implementation Details . . . . . . . . . . . . . . . . . . . . . . 27
2.3 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.3.1 Square velocity wave in an elastic bar . . . . . . . . . . . . . . 30
2.3.2 Velocity waves in an elastic square . . . . . . . . . . . . . . . . 31
2.3.3 Two Colliding Disks . . . . . . . . . . . . . . . . . . . . . . . 33
2.3.4 Performance considerations . . . . . . . . . . . . . . . . . . . . 35
2.3.5 Future research . . . . . . . . . . . . . . . . . . . . . . . . . . 38
2.4 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
3 Numerical Modeling of Nanoindentation with MPM. 48
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
3.2 Nanoindentation Simulations Methods . . . . . . . . . . . . . . . . . . 50
3.2.1 Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
3.2.2 Material Modeling . . . . . . . . . . . . . . . . . . . . . . . . . 53
3.2.3 MPM Grid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
3.3 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
3.3.1 Analysis of Load-Displacement Curves . . . . . . . . . . . . . 63
3.3.2 Hardening parameters . . . . . . . . . . . . . . . . . . . . . . 67
3.3.3 Strain-rate dependent materials . . . . . . . . . . . . . . . . . 70
3.3.4 Shape effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
3.3.5 Full 3D simulation and effective indenter shapes . . . . . . . . 75
3.4 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78