Yavuz Goktas

Date of Graduation


Document Type



The level of production at a manufacturing system is limited by this system availability. Stage or component failures will decrease the available production time which in turn decrease the system throughput rate and increase the production cost. A problem that faces system designers is the need to adopt design and operating policies to enhance system availability economically to achieve their goals. This problem raises two major questions to study: (1) How to go about comparing different design and operating policy alternatives? (2) What kind of criteria should be used to pick a cost-efficient design and operating policy to satisfy the company's minimum Reliability, Availability, Maintainability (RAM) goals. This study integrates the modeling of design and operating parameters to obtain a cost-efficient system design to meet the company's minimum RAM requirements. As a result, an Integrated RAM (IRAM) modeling tool is developed for the use of system designers in studying the system design and operating problem. This modeling tool guides the designers step-by-step until they reach their RAM goals economically. The model integrates such major models and tools as A Stochastic Simulation Model, Fault Tree Analysis, An Availability (Throughput)-Based Life Cycle Cost Model, and Availability Enhancement Analysis. A stochastic simulation model called IRAMSIM, an acronym for IRAM SIMulator, is developed on VAX FORTRAN by the author to compare different design and operating alternatives. Fault tree analysis is incorporated into RAM modeling for selecting components for availability enhancement. An availability-based life cycle cost model is developed for studying the economics of design and operating alternatives prior to selection of a design. Availability enhancement analysis is developed to provide the logical system for employing the possible design and operating policy alternatives. The IRAM model is applied to a hypothetical series-parallel manufacturing system to show system designers how they can solve their design and operating problems economically. It is also intended to show the model's flexibility in trying different design and operating policies to pick the best policy for reaching the company's goals. Results show that the IRAM model is flexible and powerful enough to integrate system design and operating parameters to pick a cost-efficient system design that meets the company's RAM goals. Also provided is a recommended guideline for using availability enhancement analysis that considers possible design and operating policy alternatives for picking the system design.