上海交通大学：《Systems Engineering 系统工程》课程教学资源（电子讲义）Lecture 11-2 Systems Reliability Basics

JIAOTONG UNIVERSIT AN 1096 Systems Engineering Lecture 11-2 Systems Reliability Basics Instructor(s) Prof.Jianjun Gao Department of Automation School of Electronic Information and Electrical Engineering 2014 Spring

Systems Engineering Instructor(s) + - 2014 Spring Systems Reliability Basics Prof. Jianjun Gao Department of Automation School of Electronic Information and Electrical Engineering Lecture 11-2

Gao's V-Model Stakeholder Systems Engineering Lifecycle Analysis Overview Managment Requirement Cost and Schedule Commissioning Analysis Management Operations System Verification and Architecture Validation Tradespace System Integration: Interface management Exploration Human System Factor Design Definition and Safety Optimization CLGO System Engineering by J.J.Gao 2

+ - System Engineering by J. J. Gao 2 Gao’s V-Model Stakeholder Analysis Requirement Analysis System Architecture Tradespace Exploration Design Definition and Optimization System Integration: Interface management Verification and Validation Commissioning Operations Lifecycle Managment Systems Engineering Overview Cost and Schedule Management Human Factor System Safety

Today's Agenda Reliability is important o Single component model Multiple components model CLGO System Engineering by J.J.Gao 3

+ - 3 Today’s Agenda  Reliability is important  Single component model  Multiple components model System Engineering by J. J. Gao

Reliability Importance One of the most important characteristics of a product it is a measure of its performance with time (Transatlantic and Transpacific cables) Products'recalls are common (only after time elapses). In October 2006,the Sony Corporation recalled up to 9.6 million of its personal computer batteries Products are discontinued because of fatal accidents (Pinto,Concord) Medical devices and organs(reliability of artificial organs) CLGO 4

+ - 4 Reliability Importance  One of the most important characteristics of a product, it is a measure of its performance with time (Transatlantic and Transpacific cables)  Products’ recalls are common (only after time elapses). In October 2006, the Sony Corporation recalled up to 9.6 million of its personal computer batteries  Products are discontinued because of fatal accidents (Pinto, Concord)  Medical devices and organs (reliability of artificial organs) 4

Reliability Importance Business data Table 1.Warranty Claims Paid by U.S.Manufacturers 2006 Claims 2005 Claims Company Million Million General Motors Corp. $4,463 $4,696 Ford Motor Co. $4,106 $3,986 Hewlett-Packard Co. $2,346 $2,353 Dell Inc. $1,775 $1,521 Motorola Inc. $891 $716 IBM Corp. $762 $831 Caterpillar Inc. $745 $712 General Electric Co. $665 $699 Deere Co. $509 $453 Whirlpool Corp. $459 $294 Boeing Co. $206 $146 Textron Inc. $167 $149 Warranty costs measured in million dollars for several large American manufacturers in 2006 and 2005. (www.warrantyweek.com) 5 CLGO

+ - 5 Reliability Importance  Business data Warranty costs measured in million dollars for several large American manufacturers in 2006 and 2005. (www.warrantyweek.com)

Repairable and Non-Repairable Another measure of reliability is availability (probability that the system provides its functions when needed). Maximum Reliability level With Repairs No Repairs Pp…PDi Time System Engineering by J.J. CLGO Gao 6

+ - System Engineering by J. J. Gao 6 Maximum Reliability level Reliability With Repairs Time No Repairs  Another measure of reliability is availability (probability that the system provides its functions when needed). Repairable and Non-Repairable

Some Initial Thoughts Warranty Will you buy additional warranty? Burn in and removal of early failures. (Lemon Law). Early Failures Increasing Constant Failure Failure Rate Rate Time CLGO 7

+ - Some Initial Thoughts Warranty  Will you buy additional warranty?  Burn in and removal of early failures. (Lemon Law). Time Failure Rate Early Failures Constant Failure Rate Increasing Failure Rate 7

Reliability Definitions Reliability is a time dependent characteristic. It can only be determined after an elapsed time but can be predicted at any time. It is the probability that a product or service will operate properly for a specified period of time (design life)under the design operating conditions without failure. CLGO 8

+ - 8 Reliability Definitions  Reliability is a time dependent characteristic.  It can only be determined after an elapsed time but can be predicted at any time.  It is the probability that a product or service will operate properly for a specified period of time (design life) under the design operating conditions without failure

Today's Agenda Reliability is important s Single component model Multiple components model CLGO System Engineering by J.J.Gao 9

+ - 9 Today’s Agenda  Reliability is important  Single component model  Multiple components model System Engineering by J. J. Gao

Basic Concepts We will introduce four important measures for the reliability of a nonrepairable item. The reliability(survivor)function R(t) The failure rate function z(t) The mean time to failure(MTTF) The mean residual life (MRL) We use variable X(t)to describe the state of an item X0= 1 if the item is functioning at time if the item is failed state at time The time to failure of item is denoted by T.Thus,T is a random variable. The time to failure T is not always the calender time.It may be other time concept:number of times a switch is operated,number of kilometers driven by a car,number of working cycles of a item.... CLGO System Engineering by J.J.Gao 10

+ - System Engineering by J. J. Gao 10 Basic Concepts