Structural and System Reliability

Based on material taught at the University of California, Berkeley, this textbook offers a modern, rigorous and comprehensive treatment of the methods of structural and system reliability analysis. It covers the first- and second-order reliability methods for components and systems, simulation methods, time- and space-variant reliability, and Bayesian parameter estimation and reliability updating. It also presents more advanced, state-of-the-art topics such as finite-element reliability methods, stochastic structural dynamics, reliability-based optimal design, and Bayesian networks. A wealth of well-designed examples connect theory with practice, with simple examples demonstrating mathematical concepts and larger examples demonstrating their applications. End-of-chapter homework problems are included throughout. Including all necessary background material from probability theory, and accompanied online by a solutions manual and PowerPoint slides for instructors, this is the ideal text for senior undergraduate and graduate students taking courses on structural and system reliability in departments of civil, environmental and mechanical engineering.

Reliability Engineering Techniques Applied to the Human Failure Analysis Process

Human reliability and human error are factors that are present in all areas: industrial, economic, social, etc. All these areas require to a greater or lesser extent a physical and mental effort to satisfy their own needs, those of others, or established requirements that, depending on the circumstances and the nature of the person, can lead to errors. Certainly, it is not possible to find a single human reliability method that can meet all the expectations and technical demands related to the analysis of human errors. However, it is important to note that the orientation of all human reliability methods is focused on the study and analysis of the risk factor (frequency by consequences). In other words, as can be observed throughout this chapter, all human reliability methodologies seek to help us reduce the uncertainty in the process of evaluating the frequencies of unforeseen events (human errors) and the consequences that such human errors can bring to safety, the environment, and the operations within the framework of an industrial production process.

COMPARISON OF SCAPULAR MORPHOLOGY IN DEGENERATIVE AND TRAUMATIC ROTATOR CUFF TEARS

Background: Degenerative cuff tears have impingement pathophysiology due to altered scapular morphology as measured by increased critical shoulder angle (CSA), decreased lateral acromial angle (LAA) and increased acromion index (AI). But scapular morphology in traumatic tears has neither been studied nor compared with degenerative tears. Aim: To compare scapular morphology with CSA, LAA, AI between traumatic and degenerative tears and determine their reliability. Methods: This observational study includes 100 patients (50 with traumatic and degenerative tears). We analyzed MRI and standardized AP shoulder radiograph of these patients. Parameters, such as CSA, LAA, AI, were measured on AP radiographs by two separate observers in a blinded manner. The 1st observer repeated measurements after four weeks. We compared age, gender, degree of cuff tear, and CSA values, LAA, and AI between the two groups. Results: On comparison using chi-square test, degenerative group had significantly higher age, higher CSA (mean 37.55, SD 0.88 versus traumatic group mean 36.6, SD 0.95, [Formula: see text]-[Formula: see text], highly significant), higher AI (mean 0.73, SD 0.02 versus traumatic mean 0.69, SD 0.04 [Formula: see text]-[Formula: see text], highly significant), and lower LAA (77.14, SD 2.03 versus traumatic mean 78.36, SD 2.73, [Formula: see text]-value 0.013, significant). Interobserver and intraobserver reliability of parameters using the intraclass correlation coefficient (ICC) revealed excellent (CSA, LAA) and good (AI) agreement. ROC curve analysis calculated sensitivity (0.7) and specificity (0.66) to diagnose degenerative tear for CSA above 37.05[Formula: see text]. Conclusion: Scapular morphology in traumatic tears differs from degenerative. CSA, LAA, AI can be reliably measured on standardized shoulder AP radiographs.

A Comprehensive Approach to Account for Weather Uncertainties in Ship Route Optimization

This work aims at defining in a probabilistic manner objectives and constraints typically considered in route optimization systems. Information about weather-related uncertainties is introduced by adopting ensemble forecast results. Classical reliability methods commonly used in structural analysis are adopted, allowing to achieve a simple yet effective evaluation of the probability of failure and the variability associated with the predicted fuel consumption and time of arrival. A quantitative example of application is provided, taking into consideration one of the main North Atlantic routes.

Electrothermal Reliability of the High Electron Mobility Transistor (HEMT)

The main objective of our paper is to propose an approach to studying the mechatronic system’s reliability through the reliability of their high electron mobility transistors (HEMT). The operating temperature is one of the parameters that influences the characteristics of the transistor, especially the electron mobility that represents an advantage over other transistor’s families. Several factors can influence this temperature. Thanks to thermal modeling, it is possible to determine the factors representing a great impact on the operating temperature, such as the power dissipation at the active area of the transistor and the reference temperature above the substrate. In our reliability study, these analytical methods, such as First and Second Order Reliability Methods (FORM and SORM, respectively), were used to analyze the HEMT reliability. Thanks to the coupling between two models—the reliability model coded on Matlab and the thermal modeling with Comsol multiphysics software—the reliability index and the failure probability of the studied system were evaluated.

Second-order reliability methods: a review and comparative study

Second-order reliability methods are commonly used for the computation of reliability, defined as the probability of satisfying an intended function in the presence of uncertainties. These methods can achieve highly accurate reliability predictions owing to a second-order approximation of the limit-state function around the Most Probable Point of failure. Although numerous formulations have been developed, the lack of full-scale comparative studies has led to a dubiety regarding the selection of a suitable method for a specific reliability analysis problem. In this study, the performance of commonly used second-order reliability methods is assessed based on the problem scale, curvatures at the Most Probable Point of failure, first-order reliability index, and limit-state contour. The assessment is based on three performance metrics: capability, accuracy, and robustness. The capability is a measure of the ability of a method to compute feasible probabilities, i.e., probabilities between 0 and 1. The accuracy and robustness are quantified based on the mean and standard deviation of relative errors with respect to exact reliabilities, respectively. This study not only provides a review of classical and novel second-order reliability methods, but also gives an insight on the selection of an appropriate reliability method for a given engineering application.