The intaglio mold was backed up by steel reinforced cements (see mark B in Fig.2). So, in order to maintain the structural stiffness and the sealing and tightening between the two molds, seventeen series of M30 binder bolts with high strength were arranged (see mark A in Fig.2). Therefore, if the RTM injection pressure was about 0.3 MPa, the vertical and horizontal press forces would be about 80 and 40 tons, respectively. The vertical and the horizontal projective areas of the yacht from BRP were about 2.7m 2 and 1.3 m 2, respectively. Both of the intaglio and relief molds are made of GFRP. The touching and jointing interface arrangement like this not onlyĮnefits drawing of patterns, but also can not be harmful to the yacht appearance. The touching and jointing interface between the intaglio and relief molds was located a position marked with A in Fig.4. Design of mold for RTM The RTM mold was designed into an intaglio mold (lower) and a relief mold (upper). As mentioned in Table 3, the back skin has to be slightly thickened because it has to be equipped with the motor. The normal direction (interlaminar direction) of the preforms was not reinforced by any method except the friction forces. The size difference of lamination into the space between the intaglio and relief GFRP yacht molds can be neglected. Outside the side skin, a ply of glass fiber cloth was laid in order to modify the lay-up processing of bamboo woven preform and to avoid forming a resin-rich area. However, the inside two preform plies could be discontinuous, and consisted from bamboo sheets with their green covering removed, which makes the yacht cost lower without influencing the properties. The outside two preform plies was continuous, and consisted from bamboo sheets with their green covering. These four preform plies, as reinforcements, were placed into the space between the intaglio and relief GFRP yacht molds. Modifying the calculated results by taking account into resin matrix thickness Lamination of the preforms Four preform plies can be woven along a same relief mold profile. Various part thickness of the GFRP reference yacht and the BRP yacht Location Front Side Back skin Bottom Various yachts skin skin (with motor) skin Gunwale GFRP yacht thickness (mm) 6.0 5.0 8.0 6.0 6.0S BRP yacht thickness 1 (mm) 8.5 7.0 11.5 8.5 8.5 BRP yacht thickness 2 (mm) 10 9 14 10 10 Surface density ratio (BRP/GFRP, %) 93 100 97 93 93 1. The weight of BRP yacht can be reduced by about 5% in comparison with the GFRP conference. The surface density ratio of yacht parts was also showed in Table 3. By taking account into the modulus of GFRP (see Table 1) and the various part thickness of the GFRP reference yacht (see Table 3), the various part thickness results of BRP yacht were calculated with equation (1), which were arranged in the third rank in Table 3. Taking the yacht stiffness as the objective function for designation, considering an equivalent stiffness in comparison with a conference yacht from GFRP, because stiffness of a plan is proportional to the square of its thickness, the following equation can be written: E B H B 2 = E GFRP H GFRP 2 (1) Where, E B and H B stand for Young’s modulus and thickness of the bamboo sheets, respectively, and E GFRP and H GFRP stand for Young’s modulus and thickness of the glass fiber reinforced polyester resins, respectively. Structural Design Yacht body The yacht’s overall length is 3 m, the width is 0.9 m, the depth is 0.45m, and the displacement is about 800 kg.
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