| Abstract: | 近年來航空運輸發展快速，航空公司相繼採用運能更大、航程更遠，如B777、A380、 與B787 等特殊輪軸型式及特大荷重之新型客機，以因應大幅增加的航空需求。為分析 機場鋪面之各種力學行為，FAA 自2003 年開始發表即積極從事將三維有限元素程式併 入鋪面設計法的研究。並於今年9 月新頒佈的AC 150/5320-6E 機場鋪面設計與評估法 中，大膽採用三維有限元素法於剛性鋪面設計流程，並提供FAARFIELD 程式來協助鋪 面設計。為簡化三維有限元素分析的複雜度，FAA 乃在該程式中對忽略許多重要參數， 但其所須的運算時間仍然相當長，因此有必要深入瞭解此全新之設計理念對現有設計法 可能產生之衝擊與實際應用之問題與有效解決途徑。 因此，本計畫擬以三年三期的方式(第一年計畫已獲核定執行中)，深入探討新的 FAARFIELD 程式的基本原理、各種機型之三維有限元素程式應力分析、疲勞損壞公式 之修正與應用、與航機側向位移與累積疲勞損壞因子計算等內容。並根據計畫主持人過 去在TKUAPAV 機場鋪面厚度設計方法與三維有限元素分析之研究成果，透過對前述重 要因素的臨界邊緣應力分析與驗證，並與現有TKUAPAV 程式相整合，以建立一套更簡 易的機場剛性鋪面厚度設計程式。茲將本研究擬探討之主要研究課題簡列如下： 1. 相關文獻蒐集與回顧。 2. FAARFIELD 程式與LEDFAA 程式之比較。 3. FAARFIELD 程式與TKUAPAV 程式之比較。 4. 三維與二維有限元素分析結果之比較(單輪、無限版長)。 5. 各種機型輪軸型式之臨界邊緣應力分析(多輪、無限版長)。 6. 雙層版之效應。 7. 有限版尺寸與多版塊荷重傳遞之效應。 8. 載重單獨作用之應力資料庫。 9. 臨界邊緣應力預測模式之建立。 10. 航機側向位移與累積疲勞損壞因子之計算。 11. 載重加上溫差之效應。 12. 載重與溫差效應之應力資料庫與預測模式。 13. 機場剛性鋪面厚度設計流程之探討與修正。 14. TKUAPAV 程式功能之擴充與驗證。 15. 研究成果之彙整與應用。 此外，本研究並將所建立的系統化分析流程與FAA現有鋪面設計程式(包括LEDFAA 與FAARFIELD)之分析結果相比較，以驗證程式分析之可靠性與適用性，以期將此成果 應用在未來鋪面分析與設計之工作上，使我國有限經費做最有效之利用。
Due to the rapid growth of recent air transportation, many airline companies have utilized the new B777, A380, and B787 aircrafts with special gear configurations and super-heavy loads to accommodate the dramatically increasing traffic demands. To analyze various structural responses of airfield pavements, the FAA have continuously strived to implement 3-D finite element (FEM) program into the pavement thickness design methodologies since 2003. The FAA have officially adopted 3-D FEM together with the FAARFIELD (FAA Rigid and Flexible Iterative Elastic Layered Design) program for airfield pavement thickness design in the latest Advisory Circular 150/5320-6E on September, 2009. To reduce the complexity of the 3-D FEM, the FAA have neglected many important design parameters in the aforementioned program, nevertheless the required run time is still very demanding. Thus, it is very crucial to investigate the possible impacts of these new approaches on thickness design and practical application problems. Thus, the entire project consists of three Phases (I, II, and III) to be completed within three years (Phase I has been approved and is an on-going project) to reevaluate the fundamental principles of the FAARFIELD program, 3-D finite element (FEM) stress analysis, revision and application of fatigue damage relationship, effects of aircraft lateral wandering on cumulative damage factors. Together with past research findings on TKUAPAV rigid airfield pavement thickness program and 3-D FEM stress analysis, this research will conduct in-depth investigation on critical edge stress analysis and verification so as to expand TKUAPAV program features. The major tasks include: 1. Literature review of rigid airfield pavement design methodologies. 2. Comparison of FAARFIELD and LEDFAA programs. 3. Comparison of FAARFIELD and TKUAPAV programs. 4. Conducting 3-D and 2-D FEM analysis (single wheel load, infinite slab length). 5. Analyzing critical edge stress under various gear load configurations (multiple wheel loads, infinite slab length). 6. Investigation on the effects of second bonded or unbonded layer. 7. Analyzing the effects of finite slab size and load transfer efficiencies of adjacent slabs. 8. Creating a stress analysis database under various loading only conditions on multiple slabs. 9. Development of edge stress prediciton models using modern regression techniques. 10. Analyzing the effects of lateral wandering on cumulative fatigue damages. 11. Analyzing the effects of loading plus curing on multiple slabs. 12. Creating a stress analysis database and developing predcition models under various load plus curling conditions on multiple slabs. 13. Reexamination and revisions of rigid airfield pavement thickness design procedures. 14. Expansion of TKUAPAV program features and verifications. 15. Integration and applications of the research findings into existing thickness design methodologies. The completion of this study will, hopefully, provide a sound basis for future pavement analysis and design activities so as to assure the best use of our limited resources. |
