The predictive engineering of materials is matured from predicting properties from known morphology or constituents to engineering novel morphology for superior properties. The focus of this paper is about implementation of computational material mechanics modeling method in COMSOL multiphysics software for engineering the constituents for superior properties. A brief review of property prediction methods, advantages and potential superior properties of composite materials are given. Numerical implementation of representative volume based computational micromechanics in COMSOL with periodic boundary condition is detailed. The prediction methodology and results of linear and nonlinear bulk material properties are provided. The effect of reinforcement shape, size, orientation and length is also investigated and reported with particular emphasis on superior properties. The advantages of windowing approach, COMSOL parametric models, and the ability to investigate materials at micro level for superior macroscopic performance is detailed.

1. Micro Mechanical Exploration of
Composites for Superior Properties
Raj C Thiagarajan and K V Chiranjeevi
ATOA Scientific Technologies Pvt Ltd
ATOA Scientific Technologies
Engineering Simulation For Innovation

2. ATOAST
• We Provide Multiphysics
Engineering Design Solutions
• Driven by Material Unity Vision
• We are the first COMSOL
Certified Consultant from India
• ATOAST JOTHI foundation
• www.atoastech.com
ATOA Scientific Technologies Pvt Ltd | www.atoastech.com | COMSOL Conference 2011 | SM Micromechanics 2

3. Micro Mechanical Exploration of
Composites for Superior Properties
• Composites
• Super properties
• Micromechanics
• Simulation and prediction
• Results and Discussion
ATOA Scientific Technologies Pvt Ltd | www.atoastech.com | COMSOL Conference 2011 | SM Micromechanics 3

4. Composites
• Combination of any two are
more materials to perform better
than individual constituents.
• Macroscopically homogeneous
and microscopically
heterogeneous.
• Recent growth in industrial
application of composites.
ATOA Scientific Technologies Pvt Ltd | www.atoastech.com | COMSOL Conference 2011 | SM Micromechanics 4

5. After US 7838108
Super Properties
Normalized Property
• Additive
• Product
• Super
Relative Density
– Stiff and tough
– Super elastic
– Ultra low weight
Stiffness
Nature
– Extremal
– Nano
– Meta
Toughness
ATOA Scientific Technologies Pvt Ltd | www.atoastech.com | COMSOL Conference 2011 | SM Micromechanics 5

6. Micromechanics
• Continuum Micromechanics Localization relationship
based on homogenization theory
Micro Macro
– Aims at finding a volume fields fields
elements (Representative Homogenization relationship
Volume Element – RVE,
periodic Micro field- PMA)
response to prescribed
mechanical loads.
Where,
W -volume, G-surface,
u(x)– deformation vector
– Prediction of macro properties t(x)– surface traction vector
nG – surface normal vector
from micro structure and
constituents.
ATOA Scientific Technologies Pvt Ltd | www.atoastech.com | COMSOL Conference 2011 | SM Micromechanics 6

7. Numerical Implementation
• Periodic boundary condition
• u xl= u x0 + ex
• v yl= u y0 + ey
• Load
– Body force
• Global (macro) vs local (micro)
stress and strain
– Integration of variables
• Parametric model to predict the
stress strain prediction
ATOA Scientific Technologies Pvt Ltd | www.atoastech.com | COMSOL Conference 2011 | SM Micromechanics 7

8. Results and discussion
• Isotropic property
prediction
• Polymer composite
property prediction
• Macro properties
• Micro mechanical
exploration
ATOA Scientific Technologies Pvt Ltd | www.atoastech.com | COMSOL Conference 2011 | SM Micromechanics 8

9. Results and discussion..
• Super property prediction
• NPR effects
• -1 to 0.5
• Load vs deflection
performance
Matrix Fibre Composite Elastic
Poisson Poisson's modulus Predicted % of increase in
• 3X improvement in
ratio Ratio (GPa) Modulus
0.3 0.2 2.536 0.0
0.3 -0.5 2.576 1.6
performance 0.3 -0.9 2.602 2.6
0.4 0.2 2.762 8.9
-0.4 0.2 2.879 13.5
-0.5 0.2 3.206 26.4
• Internal resistive -0.6
-0.7
0.2
0.2
3.701
4.496
45.9
77.3
-0.8 0.2 5.937 134.1
mechanism due to NPR. -0.9 0.2 9.352 268.7
ATOA Scientific Technologies Pvt Ltd | www.atoastech.com | COMSOL Conference 2011 | SM Micromechanics 9

10. Future work
• 2D to Parametric 3D
• DoE to predict anisotropic properties.
• Extension to Thermal, Acoustical, Electrical, Magnetic,
and Transport properties.
• Multiphysics Optimization for superior properties
ATOA Scientific Technologies Pvt Ltd | www.atoastech.com | COMSOL Conference 2011 | SM Micromechanics 10