碳纖維自行車曲柄之設計與模壓製作

本研究針對碳纖維複合材料自行車曲柄的設計與模壓製程，其中複合材料包括長纖及短纖材料，而短纖材料是塊狀糰料 (Bulk Molding Compound)，是由一英吋長碳纖維的短纖材料與聚酯樹脂攪拌混合而成。自行車曲柄本體以複合材料取代傳統金屬材料之大部分重量與強度，同時利用傳統金屬材料之特性，例如耐磨耗、衝擊等特點，有效結合同質或異質材料，達到最佳結合之設計目的。透過模壓成型法，將長、短纖三明治層複合材料與金屬材料組件，經熱壓成型製成該曲柄本體，進而減輕曲柄重量，同時利用內壁設有四方柱面形狀開口或螺紋之金屬介面環以便與軸或其它元件套接或螺接，外壁則設有與複合材料嵌合之高摩擦表面溝道結構，以達到與異質材料結合及減輕重量之目的。最後利用有限單元及最佳化設計原理模式尋求最佳化纖維排列角度，並比較補強前與補強後主體纖維層之實驗強度。研究結果顯示，未施行最佳化纖維排列角度與局部結構補強前的最大應力為5.1 GPa，而經過最佳化纖維排列角度與局部補強結構的最大應力降至1.09 GPa，應力調降幅度可達80%，由此可證明最佳化纖維排列角度與局部補強的運用確實可有效提升碳纖維自行車曲柄的結構強度。

關鍵字

複合材料碳纖維自行車曲柄；模壓製程；塊狀糰料；三明治層；最佳化設計

並列摘要

This paper presents the design and manufacturing process of a carbon fiber composite bicycle crank by using the compression molding (CM) technology. Bulk molding compound (B.M.C) was manufactured by mixing strands (>1”) of chopped glass fibers in a mixer with polyester resin. The crank body was designed as a cantilever sandwich composite structure made up of long and short fiber (B.M.C) layers. The composite material was hot pressed and manufactured into crank body to reduce most of its weight. In the manufacturing process, the long and short fiber layers were joined together by a metal interface ring. The body is a sandwich structure, where the interior is a short fiber sandwich layer while the exterior is coated with a long fiber layer. Its characteristics include base composite material, interface ring, internal wall of tooth surface and exterior projected rib. In this paper, the ANSYS finite element program is extended to the study of optimal angle-ply orientations of laminated composite bicycle cranks with maximum stiffness subjected to bending load (or torque). The FE model was then calibrated on the basis of the constituent material characterization and the definition of suitable boundary conditions in order to achieve a reliable simulation of the experimental tests. Several designs of composite bicycle cranks were given to demonstrate the feasibility and applications of the proposed method.

並列關鍵字

Composite bicycle crank ； Compression molding technology ； Bulk molding compound ； Sandwich ； Optimum design

參考文獻

[1] Chang R.R., Kam T.Y., “Design of laminated composite plates for maximum shear bucking load”, J Energy Resource Tech ASME 1993; 115: PP. 314-22.

[2] Tsai S.W., Hahn H.T., “Introduction to Composite Materials”, Technomic 1980.

[3] Kam T.Y., Lai M.D., “Multilevel optimal design of laminated composite plate structures”, J Comp. Struct. 1989; 31: PP. 197-202.

[4] Kam T.Y., Chang R.R., “Optimal design of laminated composite plates with dynamic and static considerations”, J Comp. Struct. 1989; 32(2): PP. 387-393.

[5] Kam T.Y., “Optimum design of laminates composite structure via a multilevel sub-structuring approach”, Int. J Engng. Optim. 1992.

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碳纖維自行車曲柄之設計與模壓製作

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