PSAM 16 - Paper Overview

PSAM 16 Conference Paper Overview

Welcome to the PSAM 16 Conference paper and speaker overview page.

Lead Author: Todd Paulos Co-author(s): Andrew Ho andrew.h.ho@gmail.com Curtis Smith curtis.smith@inl.gov

Reliability Modeling of Complex Components Using Simulation
This paper is a continuation of papers presented at the 15th and 16th Probabilistic Safety Assessment and Management Conference, in which discussions of modeling failure modes of complex components and the effects of censor bias were presented. The first paper demonstrated how the typical method of treating failure modes as being exponential in nature gives optimistic predictions when predicting how improvements to subcomponents will perform in the real world. Instead of relying on traditional analytical methods, it is a more accurate approach to model the failure modes as a race in time; unfortunately, this does not give a closed form solution. A simulation solution was presented that demonstrated the optimistic predictions of the classical techniques. The second paper demonstrated the effect of censor bias when dealing with large amounts of success only testing at the failure modes. Again, the censor bias also contributed to optimistic results. In our quest for closed-form solutions and simplicity, the world of reliability engineering relies on everything behaving like an exponential. It makes the solution closed-form in most cases, and easier to solve, but unfortunately, leads to incorrect results when making real-world decisions on improvements at the failure mode level. An excellent real-world example against using exponential distributions in this context is the common automobile. No one expects a new car to have the same failure intensity as an older car; this is one reason why people purchase a newer car—he or she wants a car with fewer problems. Conversely, there are many other examples that we see in every industry, but it is still common to use the simple method of treating failure modes as exponential variables for ease of finding a solution. In this paper, a simple system with complex components having different failure modes will be analyzed using a standard fault tree and data assessment approach and then compared to the simulation of complex assemblies discussed in the previous two papers. A discussion of the results will follow.

Reliability Modeling of Complex Components Using Simulation

This paper is a continuation of papers presented at the 15th and 16th Probabilistic Safety Assessment and Management Conference, in which discussions of modeling failure modes of complex components and the effects of censor bias were presented. The first paper demonstrated how the typical method of treating failure modes as being exponential in nature gives optimistic predictions when predicting how improvements to subcomponents will perform in the real world. Instead of relying on traditional analytical methods, it is a more accurate approach to model the failure modes as a race in time; unfortunately, this does not give a closed form solution. A simulation solution was presented that demonstrated the optimistic predictions of the classical techniques. The second paper demonstrated the effect of censor bias when dealing with large amounts of success only testing at the failure modes. Again, the censor bias also contributed to optimistic results. In our quest for closed-form solutions and simplicity, the world of reliability engineering relies on everything behaving like an exponential. It makes the solution closed-form in most cases, and easier to solve, but unfortunately, leads to incorrect results when making real-world decisions on improvements at the failure mode level. An excellent real-world example against using exponential distributions in this context is the common automobile. No one expects a new car to have the same failure intensity as an older car; this is one reason why people purchase a newer car—he or she wants a car with fewer problems. Conversely, there are many other examples that we see in every industry, but it is still common to use the simple method of treating failure modes as exponential variables for ease of finding a solution. In this paper, a simple system with complex components having different failure modes will be analyzed using a standard fault tree and data assessment approach and then compared to the simulation of complex assemblies discussed in the previous two papers. A discussion of the results will follow.

Paper TP76 Preview

Author and Presentation Info

Lead Author Name: Todd Paulos (todd.paulos@jpl.nasa.gov)

Bio: Dr. Todd Paulos has been involved with IAPSAM organization since its inception, and is a current Board Member and Treasurer for IAPSAM. He is the Technical Program Chair of this conference, was the General Chair of PSAM 12, and has served on many Technical Program Committees for PSAM conferences over the years. Dr. Paulos has almost 30 years working in aviation and space industries, and is currently the PRA Subject Matter Expert at NASA’s Jet Propulsion Laboratory overseeing the PRA efforts on all JPL programs. He is one of the prime authors for NASA’s PRA Procedures Guide and NASA’s soon to be released updated nuclear launch guidelines. Dr. Paulos has a degree in Engineering from Harvey Mudd College, and a Master’s and Doctorate in Mechanical Engineering from UCLA.

Country: United States of America
Company: NASA Jet Propulsion Laboratory
Job Title: System Reliability Engineer

PSAM 16 Conference Paper Overview

Welcome to the PSAM 16 Conference paper and speaker overview page.

Paper TP76 Preview

Author and Presentation Info

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