Reliability of Maintained Systems Subjected to Wear Failure Mechanisms

Theory and Applications

Franck Bayle

• Publisher: Wiley-ISTE
• Year: 2019
• Print ISBN: 9781786303226
• eBook ISBN: 9781119610656
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Mechanical Engineering
• Index: Technology & Engineering

Today, the reliability of systems has become a major issue in most industrial applications. The theoretical approach to estimating reliability was largely developed in the 1960s for maintenance-free systems, and more recently, in the late 1990s, it was developed for maintenance-based systems. Customers' expectations concerning reliability (as well as maintenance, safety, etc.) are growing ever more demanding over the generations of systems. However, the theoretical methods used to handle the systems are not suitable when aging mechanisms are present. This book proposes a theoretical approach to estimate all of these quantities correctly. In addition to the theoretical aspect, it details a number of issues that any industrial system will meet sooner or later, whether due to design flaws, the batch of components, manufacturing problems or new technologies that result in the aging of mechanisms during their operational use.

1
Reliability of Systems Without Maintenance

I started my professional career as an electronics engineer. For more than 15 years, I covered many areas of electronics such as pressure sensor instrumentation, switching power supplies, high frequency electronics, etc. When I was asked to replace the reliability expert in place because of his imminent retirement, reliability did not mean much to me since it had not really been taught to me. After a few weeks working with the expert, I even found it rather easy because we talked about failure rate, MTBF, bathtub curve and so on.

Figure 1.1. The famous bathtub curve

It must be said that during my beginnings as a “reliability engineer”, I was mainly concerned with “forecast reliability”, where the exponential distribution is the “law” and where everything is “relatively” simple (constant failure rate, MTBF = 1/λ, etc.).

Then, just before the actual departure of the expert in place, it was necessary to demonstrate to a customer, following a failure due to a manufacturing problem, that the level of reliability of a DC/DC converter that we had previously designed was the one planned. There, it suddenly became much less simple.

I therefore “dived” into the theory of reliability more deeply and I must say that the following two books [GAU 07, RIG 00] were a great help to me. I realized that, in fact, we often did not fully understand these notions of failure rates and MTBF, which at first seem simple but are actually quite complex.

In this section, before going into these two concepts more deeply and realizing that they are part of two different fields of reliability (without and with maintenance), we will first of all deal with the basics of reliability without maintenance in section 1.2.

Reliability, in addition to the difficulties we cited in the introduction of this book, is a transverse activity because it is present throughout the life cycle of a product. This can be showed in a synthetic way in the following figure:

Figure 1.2. Product life cycle

Throughout this life cycle, we can enumerate three essential phases for estimating reliability:

• ‒ Predicted reliability of a product

Indeed, during the product design phase, the reliability engineer must make a prediction of reliability to verify compliance with the customer specification. This estimate of reliability is often ma...

Table of contents

• Cover
• Table of Contents
• Foreword by Christian Moreau
• Foreword by Claude Sarno
• Acknowledgments
• Introduction
• List of Acronyms
• List of Notations
• 1 Reliability of Systems Without Maintenance
• 2 Reliability of Systems with Maintenance
• 3 Application to Aging Mechanisms with Maintenance
• 4 Impact at the Reliability Level
• 5 Application to Maintenance
• 6 Application to Safety
• 7 Maintenance Strategy in Operational Safety
• Appendix
• References
• Index
• End User License Agreement