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?

The individual probabilities of success of each subsystem. Signup and view all the answers

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

The average operational time before failure of the entire system. Signup and view all the answers

What is the reliability allocation process primarily concerned with?

Assigning reliability requirements to individual components Signup and view all the answers

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

Both series and parallel connected components 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?

98% Signup and view all the answers

What is a key challenge engineers face during reliability allocation?

Balancing reliability with other design constraints Signup and view all the answers

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

It often does not consider cost-effectiveness Signup and view all the answers

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

Optimizing reliability based on cost and difficulty of improvements Signup and view all the answers

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

To equally consider reliability with other design parameters 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?

Depends on the specific reliabilities of each component 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?

0.589 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)?

357.14 hours 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?

It considers both individual section reliabilities and their interactions. 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?

System reliability is unaffected. 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?

Units must operate independently of one another. Signup and view all the answers

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

A specific minimum number of units must remain functional. Signup and view all the answers

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

Parallel configuration 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?

MTTF increases linearly with an increasing number of units. Signup and view all the answers

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. (R_system = R₁ * R₂ * ... * R_n)
Parallel Systems' Reliability: The reliability of a parallel system is 1 minus the product of the probabilities that each component fails. (R_system = 1 – [(1-R₁) * (1-R₂) * ... * (1-R_n)])
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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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.