系統可靠度評估軟體之設計

Abstract

本文引用可靠度理論中的直接積分法、干涉理論、機械可靠度理論和失效率方法，來建立一可評估一般機電系統可靠度的軟體。 首先應用所建之軟體評估餐廚系統的可靠度，餐廚系統是由電力系統、供排水系統和環控系統等三個單元所組成，其中每個單元又是由不同組區組合而成。由於任一單元或組區的失效都會導致餐廚功能的喪失，因此餐廚系統可視為一串聯系統。由於組成各組區的元件適用於不同的可靠度計算方法，因此必須個別處理每個元件後予以整合，再設計編寫成Fortran程式語言。 其次應用所建之軟體評估汽車引擎受振動下之可靠度，模擬引擎系統振動的理論乃依據現有的平面雙自由度理論來推導立體六自由度的可能情形。解其運動方程式的特徵值問題，得其解為■，在振動系統中■之物理意義為系統之第r個自然頻率。本文又輔以有限單元分析軟體ANSYS來加以比對所推導的公式在自然頻率值部分的差異性。接著藉由運動方程式的運算得知系統所受的作用力，而後改變勁度矩陣值，以求出其相對應的加速度值與各支承點上的加速度值。再經轉換求出座標中心的位移，代入可靠度評估程式中，即可算出引擎系統的可靠度。

This thesis uses the methods such as direct numerical integration、interference theory、mechanical and failure rate methods to establish a computer program for reliability assessment of electro-mechanical systems. First apply the developed computer program to assess the reliability of a galley system. The galley system consists of three units, namely, electrical system、drainage system and ventilation system. Each unit consists of different sub-systems. The galley system is modeled as a mixed system in which the components are connected in both series and parallel. For a series system, if any one component fails, the whole system will fail. On the other hand for a parallel system, the system will fail if only all the components fails. The failure modes of the mechanical components are studied and appropriate methods for determining the failure probabilities of the components are adopted. An interactive computer program written in Fortran language is presented for assessing the reliability of the galley system. The developed reliability assessment software is also applied to the reliability evaluation of an engine system subjected to vibration. A procedure is presented to study the vibration response of the engine system. The accelerations of the engine system subjected to different excitions are determined using the proposed vibration analysis procedure. A limit state equation is established using the calculated accelerations in the reliability assessment of the engine. The limit state equation can then be used in the proposed software to evaluate the reliability of the engine system.