Today's manufacturers are under tremendous pressure to develop new technological and high reliability products in record time. This has motivated reliability engineers to evaluate the reliabilities of such products. Reliability testing under accelerated environment — accelerated life testing helps to meet this challenge.This comprehensive and must-have edition provides a broad coverage of the optimal design of Accelerated Life Test Plans under time-varying stress loadings. It also focuses on the formulation of Accelerated Life Test Sampling Plans (ALTSPs) which integrate accelerated life tests with quality control technique of acceptance sampling plans. These plans help to determine optimal experimental variables such as appropriate stress levels, optimal allocation at each stress levels, stress change points, etc, depending on the stress loading scheme. ALTSPs determine optimal plans such that the producers' and consumers' risks are safeguarded.
Provides authoritative guidance on statistical analysis techniques and inferential methods for one-shot device life-testing Estimating the reliability of one-shot devices—electro-expolsive devices, fire extinguishers, automobile airbags, and other units that perform their function only once—poses unique analytical challenges to conventional approaches. Due to how one-shot devices are censored, their precise failure times cannot be obtained from testing. The condition of a one-shot device can only be recorded at a specific inspection time, resulting in a lack of lifetime data collected in life-tests. Accelerated Life Testing of One-shot Devices: Data Collection and Analysis addresses the fundamental issues of statistical modeling based on data collected from accelerated life-tests of one-shot devices. The authors provide inferential methods and procedures for planning accelerated life-tests, and describe advanced statistical techniques to help reliability practitioners overcome estimation problems in the real world. Topics covered include likelihood inference, competing-risks models, one-shot devices with dependent components, model selection, and more. Enabling readers to apply the techniques to their own lifetime data and arrive at the most accurate inference possible, this practical resource: Provides expert guidance on comprehensive data analysis of one-shot devices under accelerated life-tests Discusses how to design experiments for data collection from efficient accelerated life-tests while conforming to budget constraints Helps readers develops optimal designs for constant-stress and step-stress accelerated life-tests, mainstream life-tests commonly used in reliability practice Includes R code in each chapter for readers to use in their own analyses of one-shot device testing data Features numerous case studies and practical examples throughout Highlights important issues, problems, and future research directions in reliability theory and practice Accelerated Life Testing of One-shot Devices: Data Collection and Analysis is essential reading for graduate students, researchers, and engineers working on accelerated life testing data analysis.
The accelerated life testing is used to quickly demonstrate the ability of a product to perform its role, by increasing the stress conditions compared to those of its operational life. This educational book on the implementation of accelerated life testing therefore explains its theoretical foundations and offers a practical application guide which covers state-of-the-art thinking on design techniques and optimal planning of tests.
With today's high technology and highly reliable products, the traditional life tests result in none or very few failures by the end of the test. The life test is, therefore, fully or partially accelerated to induce early failures and obtain quickly information about the life distribution of the product. The test data obtained at accelerated conditions are extrapolated by means of an appropriate model to the use conditions to quantify the life characteristics of the product under normal use conditions. In fully accelerated life testing all the test units are run at accelerated condition, while in partially accelerated life testing they are run at both normal and accelerated conditions. Stress under accelerated condition can be applied using constant-stress, step-stress, progressive-stress, cyclic-stress, random-stress, or combinations of such loadings. The choice of a stress loading depends on how the product or unit is used in service and other practical and theoretical limitations.
Over the last 50 years, the theory and the methods of reliability analysis have developed significantly. Therefore, it is very important to the reliability specialist to be informed of each reliability measure. This book will provide historical developments, current advancements, applications, numerous examples, and many case studies to bring the reader up-to-date with the advancements in this area. It covers reliability engineering in different branches, includes applications to reliability engineering practice, provides numerous examples to illustrate the theoretical results, and offers case studies along with real-world examples. This book is useful to engineering students, research scientist, and practitioners working in the field of reliability.
The book presents highly technical approaches to the probabilistic physics of failure analysis and applications to accelerated life and degradation testing to reliability prediction and assessment. Beside reviewing a select set of important failure mechanisms, the book covers basic and advanced methods of performing accelerated life test and accelerated degradation tests and analyzing the test data. The book includes a large number of very useful examples to help readers understand complicated methods described. Finally, MATLAB, R and OpenBUGS computer scripts are provided and discussed to support complex computational probabilistic analyses introduced.
Accelerated Life Testing (ALT) is an efficient approach to obtain failure observations by subjecting the test units to stresses severer than design stresses and utilize the test data to predict reliability at normal operating conditions. ALT plans under multiple stresses needs to be designed to resemble the normal operating conditions and obtain useful failure observations for accurate reliability prediction. However, to date there is little research into the theory of planning ALT for reliability prediction with multiple stresses. Multiple stresses can result in a large number of stress-level combinations which presents a challenge for implementation. We propose an approach for the design of ALT plans with multiple stresses using Latin hypercube design (LHD) and demonstrate the proposed method with examples based on actual tests. The obtained optimal test plans are compared with those based on full factorial design. The comparison shows that ALT based on LHD not only increases the accuracy of reliability prediction significantly but also reduces the test duration dramatically. ALT under Type-I and Type-II censoring has been extensively investigated. We generalize the one stage censoring to multi-stage progressive censoring, where the surviving test units are removed at intermediate stages other than the final termination of the test. This procedure further minimizes the test time and cost. We also combine the progressive censoring scheme with competing risk when test units experience different failure modes to investigate general, practical and optimal ALT plans. ALT is usually conducted under constant-stresses which need a long time at low stress levels to yield sufficient failure data. Many stress loadings, such as step-stresses obtain failure times faster than constant-stresses but the accuracy of reliability predictions based on such loadings has not yet been investigated. We develop test plans under different stress applications such that the reliability prediction achieves equivalent statistical precision to that of the constant-stress. The research shows indeed there are such equivalent plans that reduce the test time, minimize the cost and result in the same accuracy of reliability predictions.
Analysis of Step-Stress Models: Existing Results and Some Recent Developments describes, in detail, the step-stress models and related topics that have received significant attention in the last few years. Although two books, Bagdonavicius and Nikulin (2001) and Nelson (1990), on general accelerated life testing models are available, no specific book is available on step-stress models. Due to the importance of this particular topic, Balakrishnan (2009) provided an excellent review for exponential step-stress models. The scope of this book is much more, providing the inferential issues for different probability models, both from the frequentist and Bayesian points-of-view. Explains the different distributions of the Cumulative Exposure Mode Covers many different models used for step-stress analysis Discusses Step-stress life testing under the competing or complementary risk model
