賴柔均   Jou-Chun Lai

航太地面固定式組裝型架之受力變形預測與驗證

Finite Element Analysis of Aerospace Floor Assembly Jig Deflection and Verification

摘要

在航太產業中，未來20年亞洲區的經濟發展將會帶來遠高於其他地區的新機需求，並帶動當地的航空產業。而台灣的地理優勢與製造能力加上政府政策的鼓勵將帶給台灣航太業一個新的發展機會。然而航太製造業零件多、尺寸大、剛度小且緊公差的特性導致進入門檻高，型架設計的好壞是直接影響產品品質的重要因素 。

本研究之目的係針對組裝型架的結構做有限元素分析，確保此型架符合所需剛度與組裝精度要求，並結合縮小模型進行實驗，驗證其分析的可靠度。接著進一步提出結合簡化型架的預分析方法，能大幅減少因設計變更而需重新模擬的時間，最後再對於工件的組裝順序提出較佳的建議。

根據模擬結果顯示，原始型架在負載為最壞情況(Worst Case)的前提下，最大變形量皆在公差表分配的公差範圍內，說明此型架的設計能達到工件組裝的要求。而縮小模型的模擬結果與實驗比對，最大誤差為 -.0013”，誤差百分率為25.8%，雖已超過聯邦航空10%的標準，然而透過誤差分析可得到合理的解釋，也代表本研究的分析方式是合理且可靠的。在工件的組裝順序研究也發現，組裝過程中能夠越平均分配變形量的組裝順序將會達到越好的組裝品質，而組裝順序從中間到兩邊為最優化模式。

Abstract

    Over the next 20 years, the aerospace industry will bring many opportunities to the world’s economic development, particularly in Asia. Taiwan's geographical advantage, manufacturing capacity and special government policy will bring a new competitive edge to Taiwan's aerospace industry. However, aerospace manufacturing parts are large in size, with very tight production tolerances and low rigidity which will cause high barriers for local engineering firms to meet the challenge. An answer to this problem is found in the Assembly Jig design which has a direct impact on the production quality.

    The aim of this study is to perform Finite Element Analysis of the Assembly Jig to investigate the Jig stiffness requirement, and also build a scale model test to verify the relationship between analysis and real-world outcomes. This‘Pre-analysis Method with Simplified Model’ is seen to significantly reduce the time needed to resume analysis each time a design change occurs. Finally recommendations to the assembly sequence is proposed, which can provide for a better production quality control.

    From the simulation, the max displacement of Jig in the worst case is within the Tolerance Matrix requirement, which means the jig can meet the MDCD assembly requirement. The comparison between analysis and real-test based on scaled model gives -.0013” error, which is 25.8%. Although it’s over the 10% error standard from Federal Aviation Regulation, the overall results are found justifiable through the error analysis, which means the analysis method is considered reasonable and reliable. The assembly sequence which can uniformly distribute the deformation will achieve a better assembly quality. The assembly sequence from the middle to both end sides is found to be the optimized mode.