複合材料羽球拍破壞分析及動態揮拍特性研究

Abstract

本研究共分為兩部分，第一部分為碳纖維羽球拍拍框結構破壞行為研究，第二部分則為碳纖維羽球拍動態揮拍特性研究。 在破壞行為研究中，目的係建立有限元素分析模型(Finite element model)，探討碳纖維複合材料羽球拍框之振動行為及壓縮破壞強度。首先藉由有限元素分析建立羽球拍框材料及幾何模型，並分析其自然頻率及振動模態，最後透過漸進破壞分析法則來預估拍框結構壓縮破壞強度，模擬分析並與實驗量測進行比較。羽球拍框結構之模態與自然頻率分析結果，均與實驗量測值相仿，最大的誤差約在9 %。在羽球拍框結構破壞研究方面，模擬分析與實驗結果約有4.8-14.1 %誤差，而分析破壞之位置則與實驗相當接近。經由模擬分析與實驗結果比較得知，本研究建立之有限元素分析方法，可以有效應用於碳纖維複材羽球拍框之自然頻率及振動模態分析；此外，經由漸進破壞法，即可預估羽球拍框之壓縮破壞強度。 在碳纖維羽球拍動態揮拍特性研究中，目的係建立一套研究方法，探討羽球運動員正手揮拍時，球拍受動態慣性力作用所產生之力學行為。首先透過3-D動作擷取系統(Motion capture)與應變規量測儀器組，擷取羽球選手揮拍時握把(Grip)動態軌跡及中桿(Shaft)應變歷程，並討論揮拍行為對於中桿應變所造成的影響。同時藉由有限元素法進行揮拍動態模擬分析，以樑元素建立具等效材料性質的球拍模型，並依據實驗球拍運動軌跡，作為分析邊界條件來模擬揮拍行為。結果顯示，分析與實驗之揮拍軌跡結果接近，並可藉由此分析軌跡探討中桿應變歷程。在中桿應變歷程討論中，分析之應變變化趨勢與實驗結果相符，故本研究所建立之揮拍數值分析將可針對揮拍時中桿動態行為進行預估。

This research is divided into two parts. The first part aims to establish a finite element (FEM) model characterizing the natural frequency and mode shape as well as the compressive failure of badminton racket frame made of carbon/epoxy composites. The second part aims to investigate the dynamic racket behavior in badminton swing. In the first part, The FEM model was generated initially based on the geometric configuration and the associated material properties of badminton racket frame. The natural frequency and model was analyzed and then the compressive failure of the frame was described using the progressive failure approach. Both simulation and experimental results were compared and discussed. The natural frequency obtained from simulation corresponded well to the experimental data, and the maximum deviation is around 9 %. In addition, the discrepancy in terms of the compressive strength of the frame structure between the model prediction and experiments is about 4.8-14.1 %, nevertheless, failure locations obtained from the model prediction and experimental observation are quite close. Based on the comparison of model analysis and experimental results, the FEM model proposed in this study is capable of characterizing the natural frequency and model shape of the badminton racket frame as well as the compressive failure behaviors with accuracy. In the second part, motion capture and strain gauge experiments are performed to clarify the movement and strain course of the badminton swing. Also, establishing an analytical method to characterize the badminton swing behavior, which is based on experimental racket-grip trajectory be seen as boundary conditions. The results revealed that the swing trajectory existing slight differences between the analytical and experimental results. Furthermore, under discussion about the shaft strain course, the trend of analytical strain course was close to the experimental data.