Prediction of the Flexural Modulus of Composite Materials for Sporting Equipment. P.D. EWART* AND CJR VERBEEK The Department of Materials and Process Engineering. The University of Waikato, Hamilton, New Zealand. E-mail: *p.ewart@waikato.ac.nz

Overview. Introduction Developing the model Experimental Results and discussion Conclusion

Introduction Composite materials enable production of lighter more ridged components Sporting equipment often subjected to flexural loading [1-4] Applied flexure in kayak paddling

Introduction (cont) Investigation of a model for predicting flexural modulus values of composite materials. The model is based on using simple beam theory to model a laminate beam section. Verified by three point bend tests comparing the measured modulus values to the predicted values.

Developing the model On a micro scale a reinforced composite can be considered laminate An infinite number of layers a homogeneous material Discreet layers represent a heterogeneous microstructure

Developing the model (cont) Simple beam theory If the bending moment of model element is the same as composite material After considering the matrix and the reinforcement component

Developing the model (cont) Where;

Experimental Test samples; Injection moulded wood fibre polyethylene Hand lay up glass fibre reinforced epoxy Vacuumed vinyl ester carbon fibre, hybrid carbon/aramid fibre kayak paddle blades ASTM D-790 flexural test procedure on Lloyd LR100 universal tester

Results and discussion

Results and discussion (cont)

Results and discussion (cont)

Results and discussion (cont) The five layer model gave the best results. A larger number of layers would represent the discreet layers found in a fibre composite. This could be due to limitations presented in the model. Ideal bonding between components Isotropic strength characteristics Homogeneous microstructure

Results and discussion (cont) With refinements to the model the number of layers in the model would increase for accuracy. Determination of reinforcement values to improve TGA, ASTM Positive results considering the basic nature of the model.

Conclusion Aim: Investigate a predictive model for flexural modulus of composites used in sports equipment. The model shows reasonable approximation for composites with Vf < 0.5 using the 5 layer curve. Further research is intended which will involve accounting for current limitations.

References Katsanis, D. and S.M. Grove. Design and prototype manufacture of a bicycle frame. in The 1st International Conference on the Engineering of Sport. 1996. Sheffield, united Kingdom. Hendry, M.A. and M. Hubbard. Effects of rod taper on fly casting performance. in The 4th International Conference on the Engineering of Sport. 2002: Blackwell Science. Carreira, R.P., Q.H. Ly, and G. Lagante. A bicycle frame Finite Element Analysis: standard tests and common cycling situations simulation. in The 4th International Conference on the Engineering of Sport. 2002: Blackwell Science. 4. Stanbridge, K., R. Jones, and S. Mitchell, The effect of shaft flexibility on junior golfers performance. 2003, Loughborough University. p18.

Acknowledgments The Department of Materials Engineering The University of Waikato, Hamilton, New Zealand. Nuplex Composites Auckland, New Zealand. Andrew Martin Kayaks Nelson, New Zealand.

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