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Effect of Platelet Filler and Void Contents to the Mechanical Properties of Composites Timothy A. Fay ( Akkerman , Inc.) Tye B. Davis (Link Manufacturing, Inc.) Jin Y. Park (Minnesota State University) November 22, 2011. Presentation Outline. Objectives of the Research

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Presentation Outline

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  1. Effect of Platelet Filler and Void Contents to the Mechanical Properties of Composites Timothy A. Fay (Akkerman, Inc.)Tye B. Davis (Link Manufacturing, Inc.)Jin Y. Park (Minnesota State University)November 22, 2011

  2. Presentation Outline • Objectives of the Research • Problem Description • Conventional Approaches • Evaluation Procedure of the Proposed Method • Comparison and Discuss

  3. Objectives of the Research • Review conventional analytical approaches • Consider the filler and void contents as analytical/design parameters for polymer composites • Define the effects of platelet fillers and voids • Propose effective methods to evaluate mechanical properties

  4. Primitive Design Heterogeneous Materials Material Fabrication NO Properties by Testing Properties OK? YES Product Without an Analytical Model?

  5. Need a reliable analytical method to obtain the properties of composites containing fillers/voids prior to the fabrication!

  6. Analytical Modeling of Polymer Composite Materials • Matrix Models • Roving Layer Models • CSM Layer Models

  7. Micromechanical Structure of Pultruded FRP + E-glass Roving + Matrix Resin + Filler + Voids + E-glass CSM + Matrix

  8. Composite Properties Roving Layers CSM Layers Matrix Properties (or Particle composites) Roving fibers CSM fibers Resin Fillers Voids Conventional Approach Our Approach

  9. Clay Filler Particle

  10. Why Fillers? • More Stability (Reduce Void Content) • More Stiffness/Strength What kind of Fillers? Ceramic, Boron Nitride, Graphite, Alumina

  11. Analysis of Matrix(Mixture of Resin, Filler and Void) • Volume fractions of resin, fillers and voids in Matrix • Filler models (platelet and spherical models) • Void model (spherical model) • Properties of isotropic material containing inhomogeneities (micromechanical models) • This approach can be used for particle composites

  12. Matrix with Circular Platelet Filler Model Model #1 Unidirectional (theoretical) Model 3-D Random Model

  13. Unidirectional Fillers: Macroscopically Transversely Isotropic Material Evenly distributed Fillers

  14. Transversely Isotropic Materials [Cij]=Stiffness Matrix

  15. [C] [C’]=[Tx][C][Tx]T

  16. Transformed Stiffness about the x-axis Transformation Matrix about the x-axis by angle q Stiffness of Matrix having randomly (evenly) rotated platelet fillers about the x-axis

  17. Transformed Stiffness about the y-axis Transformation Matrix about the y-axis by angle f Stiffness of Matrix having randomly (Evenly) rotated platelet fillers about the y-axis

  18. Stiffness Matrix Having Random 3-D Platelet Fillers

  19. Extensional Modulus of the Matrix with 3-D Randomly Oriented Platelet Fillers Shear Modulus of the Matrix with 3-D Randomly Oriented Platelet Fillers where

  20. nxy(= nyx), nzx Obtain Ex(=Ey),Ez, Step 1 Gxy (=Gyx), Gzx of transversely isometric matrix using Chamis (1984) and Halpin-Tsai (1969) Step 3 Include voids in the matrix using analytical models Procedure to obtain Matrix Properties by Model #1

  21. Modified Mori-Tanaka Model - For spherical (or randomly oriented ellipsoidal) inclusions - For randomly oriented voids: Gi = Ki = 0

  22. Platelet Filler & Spherical Void Model • The matrix model is very close to the actual material structure • The obtained properties agree well with the experimental results • Randomly oriented ellipsoidal voids can be assumed as spherical inclusions [Que 1992]

  23. Spherical Filler and Void Model • Easy and Quick Method to Obtain Matrix properties • Randomly oriented ellipsoidal voids can be assumed as spherical inclusions • Is it really OK to assume the platelet shaped fillers as spherical inclusions?

  24. Matrix Properties Volume fractions of the constituents were provided by Composites Lab, Material Engineering, Georgia Institute of Technology

  25. STACKING SEQUENCE OF VP25 STACKING SEQUENCE OF VS25 STACKING SEQUENCE OF VS50 Provided by Strongwell, Inc.

  26. Composite Properties Roving Layers CSM Layers Matrix Properties Roving fibers CSM fibers Resin Fillers Voids

  27. Volume Fractions of Fibers and Matrix in the Roving Layer • Chamis (1984) and Halpin-Tsai (1969) Models Properties of Roving Layers • Volume Fractions of Fibers and Matrix in the CSM Layer • Tsai-Pagano (1968) Models Properties of CSM Layers

  28. Properties of Pultruded Composites where

  29. Properties of Pultruded Composites where

  30. ASTM D 5379 Shear Test Specimens (4” x .75” x .25”)

  31. G12exp/G12computed G12exp was determined by following ASTM D 5379

  32. 1.10 1.05 1.00 0.95 computed 12 0.90 /G exp 0.85 12 G 0.80 Group VP25 Group VS25 0.75 Group VS50 0.70 Pl-Es-Ch Pl-Es-HT Pl-MT-CH Pl-MT-HT Pl-SC-Ch Pl-SC-HT Micromechanical Models G12exp/G12computed

  33. Conclusions • Analytical models for polymer composite matrix having platelet fillers and voids were successfully established. • Conventional analytical equations can be modified for matrix models and particle composites. • The assumption of platelet fillers and spherical voids is valid for the composites under consideration. • All of the Analytically computed properties are higher than experimentally determined results.

  34. All of the analytically computed properties are higher than experimentally determined values. Why?/Future study Initial damage in resin-matrix Interfacial debonding Multi-stacks

  35. References Ma, H., Hu, G. and Huanr, Z., “A Micromechanical Method for Particulate Composites with Finite Particle Concentration, “ Mechanics of Materials, 36: 359–368, 2004 Geckeler, K. E. and Rosenberg, E., Functional Nanomaterials, American Scientific Publishers, Stevenson Ranch, CA, 2006 Mura, T. Micromechanics of Defects in Solids, MartiunsNijhoff, Boston, MA., 1987 Technical Report: Material Properties, Southern Kaolin Clay Inc., TX Park, J. Y., Fay, T. A. and Davis, T. B., " A Study on Clay Particle Effect to the Mechanical Properties of Pultruded Composites under Shear Loading," ASME International Congress and Exposition, Seattle, WA, 2007 Park, J. Y. and Fay, T. A., “Mathematical Modeling of Nanocomposite Properties Considering Nanoclay/Epoxy Debonding,” Journal of Reinforced Plastics and Composites, 29: 1230-1247, 2010 ASTM Standard D 5379 (2002). ASTM

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