At several industry trade shows and professional conferences, members of the Relex Software Team are available to address your questions and comments in person. Our Application Engineers are always ready to listen to your concerns, hear your challenges, and provide the reliability answers you need. We often provide enhanced training sessions on the latest version of Relex software, and host receptions and seminars to highlight new software features and capabilities.

2009 Reliability and Maintainability Symposium

The theme for the 55^th Annual Reliability and Maintainability Symposium (RAMS) held in Fort Worth, Texas, on January 26-29, 2009 is "Reliability as a Competitive Advantage: From Theory to Practice.” You can find more information at the RAMS Web site.

The Relex Software Team meets with customers in Booths 9 and 10. The following five presentations given by Relex engineers highlight their ongoing work to expand and enhance reliability engineering knowledge and to solve real-world problems.

Reliability Analysis of Dynamic Fiber Bundle Models
by Suprasad V. Amari, PhD, CRE

Fiber bundle models are useful tools for explaining dynamic failure behavior in heterogeneous materials. Such models shed light on diverse phenomena such as fatigue in structural materials and earthquakes in geophysical settings. Building good theoretical models has proven straightforward, but analyzing them has required delving into statistical details of the interaction of various flaw features and failure configurations, which has proven to be unexpectedly difficult. This paper presents a new method for reliability analysis of dynamic fiber bundle models. As in previous works, the assumption is made that a fiber has a failure rate following a power law in its load level. However, unlike the exponential distribution used in the previous works, this work considers that the remaining lifetimes of the surviving fibers follow Weibull distributions according to either the cumulative exposure model or tampered failure rate model. Both exact asymptotic reliability formulas and easy-to-compute bounds are developed. Further, the paper describes a fast simulation algorithm that greatly increases the bundle sizes that can be analyzed.

A New Method for Reliability Analysis of Standby Systems
by Suprasad V. Amari, PhD, CRE, and Glenn Dill

When working with standby systems, a simple, accurate, and computationally-efficient method to find their reliability is needed. The proposed method efficiently analyzes systems with non-identical components, mixed cold-hot-warm standby components, and shared standby components. The analysis considers standby components for different subsystems, switching failures, and general failure time distributions. Redundancy is a basic and fundamental concept used in reliability engineering. However, the methods for analyzing the reliability of redundant systems, particularly for systems with standby redundancy, are limited. Using the concepts of counting processes, this paper proposes a method to find the reliability of standby systems. Several examples are used to demonstrate the proposed method. Also provided are the CPU times and a complete listing of the MATLAB code used. The examples demonstrate that the proposed method provides a practical and accurate way of evaluating the reliability of complex standby configurations that arise in a wide range of applications.

Optimization of Warranty Period, Price, and Allocated Reliability
by Karen Mohan, Duane Huffman, and Jennifer Akers, CREs

A manufacturer can set three parameters prior to production: reliability in the design, warranty period, and price. These parameters are interrelated so they should be set simultaneously during the design phase of a product. If the product is complex, it may be made of distinct subsystems with drastically different manufacturing and warranty costs. Therefore, the reliability of each subsystem should be allocated to maximize profit. This paper shows the method to choose the allocated reliability of each subsystem, the warranty period of the product, and the sales price of the product in order to maximize the profit. Multiple examples are shown for a product that has three distinct subsystems with various production and warranty costs.

Availability Analysis of a Solar Power System with Graceful Degradation
by Duane Huffman, CRE

An availability analysis of a gracefully degradable complex solar power distribution system, where the reduction in the output capacity of the system depends on the type and location of the failed components, is discussed. This system is modeled using standard reliability block diagrams (RBDs) that support capacity.

Tutorial: FRACAS Corrective Action Fundamentals, Best Practices, and Practical Application
by Dan Jacob and Jennifer Akers, CREs

Closed loop corrective action processes include FRACAS (Failure Reporting, Analysis, and Corrective Action System), CAPA (Corrective and Preventive Action), PRACA (Problem Reporting, Analysis, and Corrective Action), and others. Closed loop corrective action processes bring together a wide range of data, from test data to field data to repair data. Outputs can include both qualitative and quantitative results, customizable to the specific needs of the organization. Several of the key obstacles to deriving a successful closed loop corrective action process are addressed. The tutorial includes best practice suggestions and a proven methodology to fully realize the benefits of a closed loop corrective action process, which can lead to improvements in quality, reliability, and productivity with reduced costs. Several case studies are presented to highlight success stories from various groups that have implemented effective closed loop corrective action processes.