CGE676 - Reliability Analysis Quiz
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Questions and Answers

What is a key characteristic of a system with series components?

  • All units must operate successfully for system success. (correct)
  • Systems can be repaired without affecting reliability.
  • At least one unit must fail for system success.
  • The system can tolerate any failure without impact.

    • When calculating system reliability in a series configuration, which factor is crucial?

  • The mean time to failure of the individual units. (correct)
  • The design life of the system.
  • The number of sections in the network.
  • The capacity of each subsystem.

    • Which statement accurately describes a parallel configuration?

  • All subsystems must function for the system to operate successfully.
  • Failure rates of subsystems are irrelevant to system reliability.
  • If one subsystem fails, the system remains operable. (correct)
  • The reliability decreases with additional subsystems.

    • In a system composed of three independent and identical subsystems, with a failure probability of 0.1 for each, what factor determines the overall reliability?

    <p>The individual probabilities of success of each subsystem. (A)</p> Signup and view all the answers

    What defines the mean time to failure (MTTF) for a series configuration?

    <p>The average operational time before failure of the entire system. (A)</p> Signup and view all the answers

    What is the reliability allocation process primarily concerned with?

    <p>Assigning reliability requirements to individual components (A)</p> Signup and view all the answers

    In a series-parallel configuration, which components contribute to the overall system reliability?

    <p>Both series and parallel connected components (D)</p> Signup and view all the answers

    If a system has a reliability objective of 90% for five components, what reliability must each component have if allocated uniformly?

    <p>98% (B)</p> Signup and view all the answers

    What is a key challenge engineers face during reliability allocation?

    <p>Balancing reliability with other design constraints (A)</p> Signup and view all the answers

    What is the disadvantage of a uniform allocation of reliability to all components?

    <p>It often does not consider cost-effectiveness (B)</p> Signup and view all the answers

    Which of the following best describes the ideal approach to reliability allocation?

    <p>Optimizing reliability based on cost and difficulty of improvements (B)</p> Signup and view all the answers

    What is a benefit of understanding the relationships between the reliabilities of components?

    <p>To equally consider reliability with other design parameters (D)</p> Signup and view all the answers

    What is the reliability goal for a system designed with three components where two are in series and one in parallel?

    <p>Depends on the specific reliabilities of each component (B)</p> Signup and view all the answers

    In a bridge configuration consisting of five independent units with a failure rate of 0.0075 failures per hour, what is the system reliability after 100 hours?

    <p>0.589 (C)</p> Signup and view all the answers

    For an M-out-of-N configuration with four independent and identical units, if at least three units must operate normally and the unit failure rate is 0.0035 failures per hour, what represents the mean time to failure (MTTF)?

    <p>357.14 hours (C)</p> Signup and view all the answers

    How does the reliability of a combined configuration that includes both series and parallel sections differ from that of simple configurations?

    <p>It considers both individual section reliabilities and their interactions. (B)</p> Signup and view all the answers

    In a parallel configuration, if one unit fails, what is the immediate impact on system reliability assuming other units remain functional?

    <p>System reliability is unaffected. (D)</p> Signup and view all the answers

    What is the primary condition needed for a bridge configuration to be the most effective in terms of reliability?

    <p>Units must operate independently of one another. (B)</p> Signup and view all the answers

    What determines the success of an M-out-of-N configuration?

    <p>A specific minimum number of units must remain functional. (A)</p> Signup and view all the answers

    Which configuration is likely to yield higher overall system reliability for a unit containing identical components?

    <p>Parallel configuration (D)</p> Signup and view all the answers

    In terms of Mean Time to Failure (MTTF), which of the following conditions applies in a bridge configuration with identical units?

    <p>MTTF increases linearly with an increasing number of units. (B)</p> Signup and view all the answers

    Flashcards

    Series System Reliability

    Reliability of a system where all components must function for the system to function. System failure occurs if any component fails.

    Parallel System Reliability

    Reliability of a system where at least one component must function for the system to function. System failure occurs only if all components fail.

    System MTTF

    Mean Time To Failure of a system. The average time a system will operate before it fails.

    Series Configuration MTTFs

    Calculating the system's MTTF (Mean Time To Failure) in a series configuration depends on the individual MTTF of each component.

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    Parallel Configuration Reliability

    Calculating reliability of a system with multiple components working at the same time, where if one component fails, another operates successfully.

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    Bridge Configuration

    A system where units are connected in a way that allows for redundancy. If one unit fails, others can take over its function, ensuring continued operation.

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    Bridge Configuration Reliability

    The probability that a bridge configuration system will function successfully for a given time period. This depends on the reliability of individual units and their arrangement.

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    Bridge Configuration Calculation

    Involves calculating the reliability of each unit and combining them based on the bridge configuration. This accounts for parallel and series arrangements.

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    M-out-of-N Configuration

    A system where a certain minimum number (m) of units out of a total (n) must be operational for the system to work.

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    M-out-of-N Reliability

    The chance that the M-out-of-N system will function correctly for a specific time. It considers the number of units, their reliability, and the required minimum.

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    M-out-of-N MTTF

    The average time an M-out-of-N system will operate before failing. This depends on the failure rate of the units and the 'm' and 'n' values.

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    Combined Configuration

    A complex system that combines series and parallel configurations, creating a network of interconnected units. Analysis requires calculating individual reliabilities and combining them accordingly.

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    Combined Configuration Reliability

    The overall reliability of the system, taking into account the reliabilities of each individual series and parallel section and combining them based on their arrangement.

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    Reliability Network

    A representation of how components are connected within a system, showing their interdependence and how their failures affect the overall system reliability.

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    Series-Parallel Configuration

    A system where components are arranged in both series and parallel connections. Components in series must all function for the system to work, while components in parallel provide redundancy.

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    Reliability Allocation

    The process of distributing reliability requirements to individual components within a system to achieve the desired overall system reliability.

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    Reliability Allocation Benefits

    It helps engineers understand the relationships between component reliabilities and the overall system reliability. It also forces them to consider reliability as equally important as other design factors like cost and performance.

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    Uniform Reliability Allocation

    Distributing the reliability requirements equally among all components. This is a simple approach but often not the best way to optimize system reliability.

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    Optimum Reliability Allocation

    Distributing reliability requirements based on the cost or difficulty of improving the reliability of different components. It aims to achieve the desired system reliability while minimizing costs or effort.

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    Cost-Effective Reliability

    Balancing the goal of achieving high system reliability with the cost of improving the reliability of individual components.

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    Study Notes

    Maintenance & Reliability Engineering CGE676 - Reliability Analysis

    • The course covers reliability analysis, focusing on different system configurations (series, parallel, complex modular, bridge)
    • The analysis explores how components within a system relate to each other and their impact on overall system reliability.

    System Configurations

    • Series Configuration: All components must function for the system to function. System reliability decreases with the addition of more components in series.
    • Parallel Configuration: At least one component must function for the system to function. Increasing the number of components in parallel increases system reliability.
    • Complex Modular Systems: These can involve combined or M-oo-N (multiple-out-of-N) or bridge configurations.
    • Bridge Configurations: System reliability calculation involves complex formulas, considering multiple paths that can lead to success.

    Reliability of Systems

    • Components within a system can be related in series or parallel configurations.
    • For series, all components must function; for parallel, at least one must function.
    • A single point of failure in a series system can bring the entire system down.
    • Reliability networks can be complex, involving multiple series and parallel connections.

    Reliability Network

    • Systems may involve simple series arrangements without redundancy.
    • System reliability decreases as the number of components in series increases.
    • Examples in safety devices show financial consequences of failure.
    • Redundancy is key to mitigating risks.

    Formulas & Calculations

    • Series Systems' Reliability: The reliability of a system in series is calculated by multiplying the reliabilities of individual components. (Rsystem = R1 * R2 * ... * Rn)
    • Parallel Systems' Reliability: The reliability of a parallel system is 1 minus the product of the probabilities that each component fails. (Rsystem = 1 – [(1-R1) * (1-R2) * ... * (1-Rn)])
    • System Mean Time To Failure (MTTF): Calculated using specific integration formulas for different cases, which vary by configuration.

    Reliability Allocation

    • Reliability allocation assigns reliability requirements to individual components to ensure overall system reliability.
    • This balances achieving the required reliability with minimal cost and other factors (performance, weight).
    • Uniform allocation (distributing reliability equally) isn't always optimal
    • A given system configuration (series, parallel, combined) dictates how reliabilities are combined.

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    Related Documents

    CGE676 Chapter 3 PDF

    Description

    This quiz covers reliability analysis in maintenance and reliability engineering, focusing on various system configurations such as series, parallel, and complex modular systems. Test your understanding of how component interactions influence overall system reliability.

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