模流分析應用於大型曲面模具灌注之驗證

VALIDATION OF MOLDFLOW ANALYSIS APPLIED TO LARGE CURVED MOLD INFUSION

Moldex3D是國內自主開發的模流分析軟體，目前已廣泛地應用於塑膠射出成型產業。近年來，隨著FRP產品的大型化與製程的選用，導入模流分析可以協助我們進行製程規畫並減少試誤次數。因此本研究使用Moldex3D軟體預估水上摩托車甲板在真空輔助樹脂轉注成型（vacuum-assisted resin transfer molding, VARTM）製程下之灌注行為，並與實際灌注結果比對，驗證模流分析的可行性。Moldex3D主要使用達西定律來預估樹脂在纖維孔隙中的流動速率，模擬所需的滲透率與孔隙率等流動參數均由本研究團隊以一維流動試驗獲得。最終我們證實模流分析結果與實際灌注結果相符，Moldex3D可正確預估樹脂在複雜模具內的流動波前；在灌注時間的模擬上，模流分析預測樹脂灌注完成的時間比實際灌注完成時間提早15分鐘，誤差14.14%，考量實際纖維布在生產時至少具有5～10%的孔隙誤差，且玻璃纖維布鋪設在複雜曲面上難免會有壓實不確實的問題，因此該模流分析結果的誤差屬可接受範圍。

Moldex3D is a mold flow analysis software independently developed in Taiwan, which has been widely used in the plastic injection molding. In recent years, FRP products have become increasingly large-scale, and the introduction of mold flow analysis can assist us to reduce the number of trials and errors. Therefore, this study uses Mold-ex3D to predict the infusion behavior of the personal water craft (PWC) deck using vacuum-assisted resin transfer molding (VARTM) process and compares simulation results with the actual infusion results to verify the feasibility of mold flow analysis. Moldex3D mainly uses Darcy's law to predict the flow rate of resin in fiber pores. The flow parameters such as permeability and porosity required for simulation are obtained by one-dimension flow test. Finally, we confirmed that mold flow analysis results are consistent with the actual infusion results, and Moldex3D can correctly predict the flow front of resin in complex mold. However, in the simulation of infusion time, the mold flow analysis predicts that the time to complete the resin infusion is 15 minutes earlier than the actual infusion, and the error is 14.14%. The reason is that the fiber cloth has at least 5~10% pore error during production, and the stacking of glass fiber cloth on complex curved mold will inevitably cause inaccurate compaction. Therefore, the error of mold flow analysis is within an acceptable range.