- •14 4.5 Reliability test requirements
- •2 Reliability engineering for complex systems requires a different, more elaborated systems approach than reliability for non-complex systems
- •9 4 Reliability program plan
- •11 4.2 Reliability prediction
- •9 4 Reliability program plan
- •52 Main articles: reliability theory, failure rate.
- •106 The parts stress modelling approach is an empirical method for prediction based on counting the number and type of components of the system, and the stress they undergo during operation.
- •18 7 Accelerated testing
- •39 The probability that a functional unit will perform its required function for a specified interval under stated conditions.
- •12 4.3 System reliability parameters
- •2 Reliability engineering for complex systems requires a different, more elaborated systems approach than reliability for non-complex systems
- •82 Reliability predictions:
- •20 9 Reliability operational assessment
- •21 10 Reliability organizations
- •7 2 Reliability theory
- •36 The capacity of a device or system to perform as designed;
- •20 9 Reliability operational assessment
- •34 Reliability may be defined in several ways:
- •57 Where is the failure probability density function and t is the length of the period of time (which is assumed to start from time zero).
- •58 Reliability engineering is concerned with four key elements of this definition:
- •2 Reliability engineering for complex systems requires a different, more elaborated systems approach than reliability for non-complex systems
- •48 Automotive engineers have reliability requirements for the automobiles (and components) which they design
- •49 Electronics engineers must design and test their products for reliability requirements.
- •127 Failures from occurring. Rcm (Reliability Centered Maintenance) programs can be used for this.
- •96 Serial System: Any assembly of units for which the failure of any single unit will cause a failure of the system or overall mission.
- •45 Many types of engineering employ reliability engineers and use the tools and methodology of reliability engineering. For example:
- •33 A reliability block diagram
- •58 Reliability engineering is concerned with four key elements of this definition:
- •40 The ability of something to "fail well" (fail without catastrophic consequences)
- •23 12 Reliability engineering education
- •148 Human error analysis
- •39 The probability that a functional unit will perform its required function for a specified interval under stated conditions.
58 Reliability engineering is concerned with four key elements of this definition:
59 First, reliability is a probability. This means that failure is regarded as a random phenomenon: it is a recurring event, and we do not express any information on individual failures, the causes of failures, or relationships between failures, except that the likelihood for failures to occur varies over time according to the given probability function. Reliability engineering is concerned with meeting the specified probability of success, at a specified statistical confidence level.
64 Reliability engineering differs from safety engineering with respect to the kind of hazards that are considered. Reliability engineering is in the end only concerned with cost. It relates to hazards that could transform into a particular level of loss of revenue for the company or the customer. These can be cost due to loss of production due to system unavailability, unexpected high or low demands for spares, repair costs, man hours, (multiple) re-designs, interruptions on normal production (e.g. due to high repair times or due to unexpected demands for non-stocked spares) and many other indirect costs. Safety engineering, on the other hand, is more specific and regulated. The related reliability Requirements are sometimes extremely high. It deals with unwanted dangerous events (for life and environment) in the same sense as reliability engineering, but does normally not directly look at cost and is not concerned with repair actions after failure. Another difference is the level of impact of failures on society and the control of governments. Safety engineering is often strictly controlled by governments (e.g. Nuclear, Aerospace, Defense, Rail and Oil industries). Furthermore, safety engineering and reliability engineering often have contradicting requirements.For example, in train control systems it is common practice to use many fail-safe devices and to lower trip settings as needed. This will unfortunately lower the reliability. Reliability can be increased here by using redundant systems, this does however lower the safety levels. The only way to increase both reliability and safety on a systems level is by using fault tolerant systems. In this case the "operational"
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160 A key aspect of reliability testing is to define "failure". Although this may seem obvious, there are many situations where it is not clear whether a failure is really the fault of the system. Variations in test conditions, operator differences, weather, and unexpected situations create differences between the customer and the system developer. One strategy to address this issue is to use a scoring conference process. A scoring conference includes representatives from the customer, the developer, the test organization, the reliability organization, and sometimes independent observers. The scoring conference process is defined in the statement of work. Each test case is considered by the group and "scored" as a success or failure. This scoring is the official result used by the reliability engineer.
204 Another highly respected certification program is the CRP (Certified Reliability Professional). To achieve certification, candidates must complete a series of courses focused on important Reliability Engineering topics, successfully apply the learned body of knowledge in the workplace and publicly present this expertise in an industry conference or journal.
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