Executing Design for Reliability within the Product Life Cycle Executing Design for Reliability within the Product Life Cycle Ali Jamnia and Khaled Atua CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2020 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works International Standard Book Number-13: 978-0-8153-4897-9 (Hardback) This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The authors and publishers have attempted to trace the copy- right holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. 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Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com I would like to dedicate this book to Norah, my daughter and my best friend, and the memory of my late father, the teacher. Khaled Atua In turn, I too would like to dedicate this work to Naseem, my daughter, the apple of my eye, and to the memory of my late father. Ali Jamnia Contents List of Figures ................................................................................................................................xv Preface ...........................................................................................................................................xxi Authors .......................................................................................................................................xxiii 1. Reliability, Risk, and Their Significance ...........................................................................1 Introduction ..............................................................................................................................1 A History of Reliability and Background on Design for Reliability (DfR) .....................2 Reliability Metrics ....................................................................................................................4 Cost and Return of Reliability ...............................................................................................5 Quality, Reliability, and Robustness .....................................................................................7 Organizational DfR Maturity and Reliability Competency ..............................................8 A Cross-Functional Process ...............................................................................................9 Product Risk ...........................................................................................................................13 Notes ........................................................................................................................................14 2. Design for Reliability Process ...........................................................................................17 Introduction ............................................................................................................................17 Reliability Requirements, Planning, and Execution in the Design Process..................18 Elements of Design for Reliability .......................................................................................18 Product Use Profile ...........................................................................................................19 Life Expectancy, Design Life, and Failure Rate ............................................................20 Product Reliability Prediction and Modeling ...............................................................20 Reliability Modeling ....................................................................................................20 Reliability Testing ........................................................................................................21 Reliability Data Analysis .............................................................................................22 Reliability Allocation ...................................................................................................23 Other Aspects of Reliability .................................................................................................23 Reliability and Its Association with Product Risk .......................................................24 Note ..........................................................................................................................................25 3. The Design Process and the V-Model ..............................................................................27 Introduction ............................................................................................................................27 Product Development Models .............................................................................................27 The V-Model for Life Cycle Management......................................................................29 Engineering Activities ......................................................................................................31 Systems and Requirements ..................................................................................................32 Voice of the Customer and Voice of Stakeholders ........................................................34 Design Documents ............................................................................................................35 Subsystem Design Document.....................................................................................38 Subsystem Architecture Document ..........................................................................38 Assembly Design Document ......................................................................................38 Developing Product Requirements .....................................................................................39 Defining the Product to Be Developed ..........................................................................39 vii viii Contents Measuring What Customers Need .................................................................................40 Development of Product Requirements ........................................................................41 Translation from Needs to Requirements ................................................................42 Product Requirements Document .............................................................................42 Quality Function Deployment ........................................................................................43 Using QFD in Product Development ........................................................................44 Requirements Decomposition ....................................................................................45 The V-Model in a Nutshell ...................................................................................................47 Reliability Planning and Execution in the V-Model .........................................................47 Notes ........................................................................................................................................50 4. Reliability Requirements, Modeling, and Allocation ..................................................51 Introduction ............................................................................................................................51 Developing Reliability Requirements .................................................................................52 Reliability Metrics .............................................................................................................52 Mean Time between Failures .....................................................................................52 Mean Time to Failure (MTTF) ....................................................................................53 Failure Rate ...................................................................................................................53 Reliability and Life .......................................................................................................54 Availability ....................................................................................................................54 Mean Cumulative Function ........................................................................................54 Probability of Success Rate and Out-of-Box Failures ..............................................55 Required Inputs for Developing Requirements ................................................................55 Reliability Requirements Based on Voice of Business .................................................56 Reliability Requirements Based on Voice of Customer ...............................................57 Reliability Requirements Based on Use Profile ............................................................57 Product Mission ............................................................................................................57 Product Use Distribution ............................................................................................58 Use and Operating Conditions ..................................................................................58 Reliability Modeling and Allocation...................................................................................58 Reliability Modeling .........................................................................................................59 Example .........................................................................................................................61 Reliability Requirement Allocation ................................................................................63 Example .........................................................................................................................64 Developing the Apportionment Table .......................................................................65 Reliability Requirements Feasibility and Gap Analysis .........................................66 Case Study .....................................................................................................................66 Other Considerations in Reliability Requirements Development .............................71 A Summary of Criteria for Reliability Requirements ..................................................72 Notes ........................................................................................................................................72 5. Reliability Planning.............................................................................................................73 Introduction ............................................................................................................................73 Design for Reliability Plan Process .....................................................................................76 Business Plan .....................................................................................................................76 Design and Development Plan .......................................................................................76 Needed Inputs ...................................................................................................................78 Functional Requirements Document and System Architecture ...........................78 Use Profile Document ..................................................................................................80 Contents ix Detailed Design Documents .......................................................................................81 Failure Modes and Effects Analysis Documents .....................................................82 Test Articles ...................................................................................................................82 Design for Assembly (DfA) and Design for Serviceability (DfS) ..........................82 Design for Reliability Plan ...............................................................................................83 Baseline Reliability Model ..........................................................................................83 Design Documents .......................................................................................................83 Reliability Growth, Evaluation, and Demonstration Testing ................................83 Final Reliability Model ................................................................................................84 Highly Accelerated Stress Screening ........................................................................84 Design for Reliability Deliverables .................................................................................84 Notes ........................................................................................................................................85 6. Reliability Statistics .............................................................................................................87 Introduction ............................................................................................................................87 Basic Definitions ....................................................................................................................88 Continuous Distributions and Reliability Analysis .........................................................90 Normal Distribution Model.............................................................................................91 Example .........................................................................................................................92 Exponential Distribution Model .....................................................................................92 Example .........................................................................................................................93 Example .........................................................................................................................94 Gamma Distribution ........................................................................................................94 Application to Cumulative Damage ..........................................................................95 Case Study: Pressure Sensor First Failure after Partial Physical Damages .........95 Chi-Square Distribution ..............................................................................................97 Failure-Truncated Test .................................................................................................98 Time-Truncated Test.....................................................................................................98 Example .........................................................................................................................98 Lognormal Distribution ...................................................................................................99 Weibull Distribution .......................................................................................................100 A Modified Weibull Distribution .............................................................................101 Example .......................................................................................................................102 Selecting the Right Distribution for Continuous Variables ......................................102 The Exponential Distribution ...................................................................................103 The Lognormal Distribution ....................................................................................103 The Weibull Distribution ..........................................................................................104 Discrete Distributions and Their Applications to Reliability .......................................104 Binomial Distribution .....................................................................................................104 Example .......................................................................................................................105 Geometric Distribution ..................................................................................................106 Example .......................................................................................................................106 Hypergeometric Distribution ........................................................................................106 Example .......................................................................................................................107 Poisson Distribution .......................................................................................................108 Example .......................................................................................................................108 Case Study: New Product Launch ................................................................................109 Case Study: Expected Service Calls .............................................................................111 A Discussion on Reliability Metrics and the Bathtub Curve ........................................112 Notes ......................................................................................................................................114