1 / 25

Chapter 8 – System Reliability

Chapter 8 – System Reliability. Motivation. How do you know how long your design is going to last? Is there any way we can predict how long it will work? Why do Reliability Engineers get paid so much?. Learning Objectives. By the end of this chapter, you should:

krios
Download Presentation

Chapter 8 – System Reliability

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 8 – System Reliability

  2. Motivation • How do you know how long your design is going to last? • Is there any way we can predict how long it will work? • Why do Reliability Engineers get paid so much?

  3. Learning Objectives By the end of this chapter, you should: • Have a familiarity with the basic principles of probability and understand how they apply to reliability theory. • Understand the mathematical definition and meaning of failure rate, reliability, and mean time to failure. • Understand how to determine the reliability of a component. • Understand how to derate the power of electronic components for use under different operating temperatures. • Understand how to determine the reliability of different system configurations.

  4. 8.1 Probability Review Definitions • Experiment • Event • Event Space

  5. Axioms of Probability • What is an axiom? • 2 of the 3 axioms

  6. Probability Density Functions • What is a random variable (RV)? • What is a PDF? • Math Definition

  7. Common PDFs Normal Density

  8. Common PDFs Uniform Density

  9. 8.2 Reliability Prediction • Reliability (defn) • Failure Rate

  10. The Bathtub Curve

  11. Derivations • See the book for derivation of R(t). • If the failure rate is constant, then R(t) = ?

  12. Failure Rate Estimates • What factors influence the failure rate?

  13. Failure rate estimates • Low Frequency FET, Appendix C. • How would you find each of these?

  14. Example 8.4

  15. Physical Model

  16. Resistive Model

  17. Physical Model with Heat Sink

  18. Resistive Model

  19. Power Derating Curve

  20. 8.3 System Reliability • So far, we have only looked at a single device. • We are interested in collection of devices into a system! • For example

  21. Series Systems • Def’n (Series System) = • We model this as

  22. Parallel Systems Definition: Redundancy Definition: Parallel System

  23. Parallel System Model

  24. Combination Systems

  25. 8.4 Summary • Probability Review • Random Variables • PDFs and CDFs • Mean and Variance • Reliability Estimation • Failure rate and the bathtub curve • Reliability & MTTF • Application to single components (MIL-SPEC) • System Reliability • Series systems • Parallel systems • Combination systems

More Related