Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech IV MAINTENANCE AND SAFETY ENGINEERING Previous Question Paper (September - 2020 - R16)
Answer any Five Questions. All Questions Carry Equal Marks.
Main
Write notes on the engineering maintenance strategies for the 21st century.
Answer
In the 21st century, maintenance has evolved from a reactive necessity to a proactive strategic function focused on reliability and asset lifecycle management. Key strategies include:
- Reliability Centered Maintenance (RCM): A systematic approach to determine the maintenance requirements of physical assets based on their functional importance and failure modes.
- Predictive Maintenance (PdM): Utilizing IoT sensors, big data analytics, and machine learning to monitor equipment condition in real-time, predicting failures before they occur to minimize downtime.
- Total Productive Maintenance (TPM): A holistic approach involving all employees, from operators to management, to maximize equipment effectiveness through autonomous maintenance and continuous improvement.
- Condition-Based Maintenance (CBM): Scheduling maintenance tasks only when specific indicators show decreasing performance or impending failure, optimizing resource allocation.
- Digital Twin Technology: Creating virtual replicas of physical systems to simulate maintenance scenarios, test interventions, and optimize performance without risking actual operations.
You are given the following information about a project consisting of six activities. Construct the network diagram for this project and find the critical path.
| Activity | Immediate Predecessors | Estimated Duration |
|---|---|---|
| A | - | 5 months |
| B | - | 1 month |
| C | B | 2 months |
| D | A, C | 4 months |
| E | A | 6 months |
| F | D, E | 3 months |
Answer
To construct the network diagram, we identify the sequence of activities:
- Start node connects to A and B.
- A leads to D and E.
- B leads to C.
- C leads to D.
- D and E converge at F.
The paths and their durations are:
The critical path is the path with the longest duration, which is A → E → F, with a total duration of 14 months.
Discuss the important elements of Effective Maintenance Management.
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Distinguish between the PERT and CPM techniques.
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Derive the formulae for the E.O.Q., Optimal time between two consecutive production runs (or) two consecutive purchase orders, and the minimum total cost for the following Deterministic model: Economic Lot Size Model with Uniform Rate of Demand, Finite Rate of Replenishment, and having no Shortages.
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Discuss the important elements of Preventive maintenance.
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Define Preventive maintenance. What is its primary goal?
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Distinguish between Mean Preventive maintenance time, Maximum Preventive maintenance time, and Median Preventive maintenance time.
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Distinguish between the two types of maintenance budgeting approaches: Historical approach, Zero-based approach.
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List at least ten maintenance safety-related questions for equipment manufacturers that can improve maintenance safety of their products.
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Give two examples of engineering system catastrophe due to poor-quality maintenance.
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List the important reasons for the safety problems in maintenance.
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Define the following indices associated with RCM:
- Emergency percentage index
- Maintenance overtime percentage index
- Equipment availability
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What is the difference between hazard rate and failure rate? Explain with examples.
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Explain the following Maintainability Measures and Functions: Mean preventive maintenance time, Mean maintenance downtime.
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Obtain maintainability functions for the following times to repair probability density functions:
- Exponential
- Lognormal
- Gamma
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