大客車在承載人數上遠多於一般小客車，因此大客車的安全問題顯得格外重要。世界各國考慮大客車翻覆安全性之嚴重性，大多各自建立一套安全法規，其中最著名的就是歐規ECE R66 (Economic Commission for Europe, ECE)，此法規爲確保在翻覆意外發生時大客車可保有固定之乘客生存空間，整車翻覆試驗爲法規之基本認證方法，但試驗成本較爲高昂且試驗環境之準備較爲繁複，由於目前電腦科技的進步使用模擬計算較過去更爲精確與快速。在車輛設計方面，數值模擬與有限元素分析已成爲相當受歡迎的工具。本文以大客車翻覆強度作爲研究對象，根據歐規ECE R66新增之等效認證方法－零組件試驗之擬靜態計算法(Quasi-static calculation based on testing of components)以及整車翻覆試驗之數值模擬(Computer simulation of rollover test on complete vehicle)，首先應用有限元素分析軟體LS-DYNA建構大客車上層結構強度之數值研究環境，繼而探討法規中整車翻覆試驗之數值模擬與擬靜態計算法之差異性。研究結果發現兩認證法均能發現車身結構之弱點，但整車翻覆試驗之數值模擬具有較嚴苛之通過門檻；本文研究之結果應可提供大客車製造業者設計車身結構之參考依據。

Nowadays, buses are an integral part of the National Transportation System. A rollover is the most dangerous accident in the case of a bus. Rollover strength has become an important issue for bus manufacturers. Considering this, international organizations are developing an important task, in order to establish new safety measures. One of these safety measures is ECE-R66 (Economic Commission for Europe, ECE). The regulation ensures the stability of the coach structure during rollover accidents in order to maintain the residual space for a passenger .A Full-scale rollover test is the basic approval method of ECE R66, which is quite expensive and installing the vehicle correctly is not easy. Hence, numerical simulations are becoming more important and sophisticated in automotive industries to make the design process fast and affordable. Quasi-static Calculations based on testing of components is one of the equivalent approval methods of ECE R66, which is adopted and coupled with the nonlinear finite element code LS-DYNA to study the rollover strength of a bus in this paper. An extrusion simulation of a double deck bus is studied first by means of the developed calculation techniques and the implementation of adequate material models according to ECE R66, and then compared with the other equivalent approval method of the ECE R66-Computer simulation of rollover test on a complete vehicle, and discovered that the method of the rollover test on a complete vehicle is more accurate. The described work presents details of the bus model and discusses some important aspects of the vehicle modeling. Representative results and discussions are also provided.