Novel Reactive Flex Configuration in Kiwi Wing Foil Surfboard

Adrien M Fat Cheung,Klaudio Bari

doi:10.3390/jcs6010006

Abstract

The creation of an ideal surfboard is art. The design and construction depend on the individual surfer’s skill level and type of the required performance. In this research, four fuselage concepts were carefully explored to meet the following unique needs: lightweight, strong, and a fast-manufacturing process. The fuselages were manufactured by compression moulding using skin and core materials. The skin material was selected to be unidirectional (UD) carbon fibre, discontinuous carbon fibre (SMC) and Filava quadriaxial fibre impregnated with epoxy, while the core material was selected to be lightweight PVC foam. To assess the mechanical performance, three-point bending has been performed according to BS-ISO 14125 and validated using Finite Element Analysis (FEA) using Ansys software. As expected, the flexural test revealed that the UD carbon fibre fuselage was the strongest and SMC was the weakest, while large deflection was seen in Filava fibre fuselages before failure, showing great reactive flex that promotes projection during surfing. The experimental results show good agreement with FEA simulation, and the locations of the physical failure in the fuselage matches the location of maximum flexural stress obtained from FEA simulation. Although all fuselages were found to carry a surfer weight of 150 kg, including a factor of safety 3, except the SMC fuselage, due to shrinkage. The Filava fibre fuselages were seen to have a large deflection before failure, showing great flexibility to handle high ocean waves. This promotes the potential use of reactive flex in high performance sports equipment, such as surfing boards. A large shrinkage must be taken under consideration during compression moulding that depends on fibre orientation, resin nature, and part geometry.

Highlights

To validate the experimental results, Finite Element Analysis (FEA) simulations were performed on four fuselages using the experimental deflections listed in Table 7 as input parameters
The overall expectation from the results shows that all fuselages can carry 150 kg surfer weight and included a safety factor of shows that all fuselages can carry 150 kg surfer weight and included a safety factor of 3
All fuselages were able to carry a nominal surfer weight, but more important are the potential reactive flex seen in quadriaxial Filava fibre fuselage

Summary

Introduction

Bending in a surfboard plays a vital role in surfing performance; the principal comes from the board bending, or flexing, into the shape of the wave with the force put down on it, and how it bends back into original shape. It stores up all that energy and releases it, projecting the surfer forward. This causes build-up energy in the board as it is bending out of its natural shape. The fuselage is generally between 60 cm and 90 cm long—the shorter the fuselage the better the handle manoeuvring during surfing

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