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. 2023 Jun 16;15(12):2703.
doi: 10.3390/polym15122703.

An Experimental Investigation of the Mechanical Performance of EPS Foam Core Sandwich Composites Used in Surfboard Design

Sam Crameri  1 , Filip Stojcevski  1   2 , Clara Usma-Mansfield  1
Affiliations

An Experimental Investigation of the Mechanical Performance of EPS Foam Core Sandwich Composites Used in Surfboard Design

Sam Crameri et al. Polymers (Basel). .

Abstract

Surfboard manufacturing has begun to utilise Expanded Polystyrene as a core material; however, surf literature relatively ignores this material. This manuscript investigates the mechanical behaviour of Expanded Polystyrene (EPS) sandwich composites. An epoxy resin matrix was used to manufacture ten sandwich-structured composite panels with varying fabric reinforcements (carbon fibre, glass fibre, PET) and two foam densities. The flexural, shear, fracture, and tensile properties were subsequently compared. Under common flexural loading, all composites failed via compression of the core, which is known in surfing terms as creasing. However, crack propagation tests indicated a sudden brittle failure in the E-glass and carbon fibre facings and progressive plastic deformation for the recycled polyethylene terephthalate facings. Testing showed that higher foam density increased the flex and fracture mechanical properties of composites. Overall, the plain weave carbon fibre presented the highest strength composite facing, while the single layer of E-glass was the lowest strength composite. Interestingly, the double-bias weave carbon fibre with a lower-density foam core presented similar stiffness behaviour to standard E-glass surfboard materials. The double-biased carbon also improved the flexural strength (+17%), material toughness (+107%), and fracture toughness (+156%) of the composite compared to E-glass. These findings indicate surfboard manufacturers can utilise this carbon weave pattern to produce surfboards with equal flex behaviour, lower weight and improved resistance to damage in regular loading.

Keywords: E-glass; EPS; PET; carbon fibre; sandwich composites; surf engineering; surfboards; surfing; thin-walled structures.

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Conflict of interest statement

The authors declare that they have no known competing financial interest or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Figure 14
Figure 14
Typical acceptable and unacceptable fracture patterns of laminate and tow specimens in Iosipescu. Note: 0° is horizontal and 90° is vertical [35].
Figure 1
Figure 1
Typical surfboard sandwich composite.
Figure 2
Figure 2
Stages of foam core sandwich panel fabrication: (a) initial prepped mold plate with dry fibres, (b) composite laminates at cure stage under vacuum, (c) finished composite laminate with samples cut out.
Figure 3
Figure 3
Vacuum bagging schematic for sandwich panel production.
Figure 4
Figure 4
(a) Flexural sample cutting dimensions, (b) loaded schematic of flex sample. All dimensions are in mm.
Figure 5
Figure 5
(a) Fracture toughness sample cutting dimensions, (b) loaded schematic of fracture sample. All dimensions are in mm.
Figure 6
Figure 6
Determination of PQ from the force displacement graph.
Figure 7
Figure 7
Iosipescu sample cutting dimensions. All dimensions are in mm.
Figure 8
Figure 8
Tensile sample cutting dimensions. All dimensions are in mm.
Figure 9
Figure 9
(a) Flexure experiment results, (b) results filtered by H-density, (c) results filtered by M-density [28]. See the Supplementary Data for mean values and standard deviations (Tables S1 and S2).
Figure 10
Figure 10
(a) Shear and fracture experiment results, (b) results filtered by H-density, (c) results filtered by M-density. See the Supplementary Data for mean values and standard deviations (Tables S1 and S2).
Figure 11
Figure 11
Fracture experiment failure: (a,b) M-1EG, (c,d) H-1EG, (e) M-2EG, (f) H-2EG.
Figure 12
Figure 12
Fracture experiment failure: (a) M-90CF, (b) H-90CF, (c) M-45CF, (d) H-45CF.
Figure 13
Figure 13
Fracture experiment failure: (a,b) M-PET, (c,d) H-PET.
Figure 13
Figure 13
Fracture experiment failure: (a,b) M-PET, (c,d) H-PET.
Figure 15
Figure 15
Iosipescu experiment failure: (a) M-1EG, (b) M-2EG, (c) M-PET, (d) M-90CF, (e) M-45CF.
Figure 15
Figure 15
Iosipescu experiment failure: (a) M-1EG, (b) M-2EG, (c) M-PET, (d) M-90CF, (e) M-45CF.
Figure 16
Figure 16
Tensile experiment results. See the Supplementary Data for mean values and standard deviations (Tables S1 and S2).
Figure 17
Figure 17
Tensile experiment failure: (a) M-45CF, (b) M-90CF.
See this image and copyright information in PMC

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