JNTU B.Tech IV Year RELIABILITY ENGINEERING Previous Question Paper (May - 2019 - R15)

Define quality of a system.

What do you understand by reliability of a device?

What is hazard function? How is it related to reliability function?

What is MTTF? How is it related to reliability function?

In a lead there are 16 glow bulbs connected in series and the average reliability of each bulb is 0.99. Compute the reliability of the lead.

An equipment consists of 3 components A, B and C in parallel and the respective reliabilities are R_A= 0.92, R_B = 0.95 and R_C = 0.96. Calculate the equipment reliability.

How are the maintainability and repair rate related?

What is the value of MTTF of a two component redundant system with constant failure rate λ and constant repair rate µ, when the system is (i) active redundant (ii) standby redundant?

How would you explain reliability achievement cost for economics of reliability?

How would you describe the reliability programming for reliability management?

Define Reliability and also explain what are the important aspects of the definition of reliability needs careful consideration?

The density function of the time to failure in years of the gizmos (for use on widgets) manufactured by a certain company is given by f (t)= 200/(t+10)³, for t≥0. i) Derive the reliability function and determine the reliability for the first year of operation. ii) What is the design life for a reliability of 0.95?

How would you explain failures and failure modes of system?

In a certain manufacturing process, one percent of the products are known to be defective. If 50 items are purchased by a customer, what is the probability of getting two or less number of defectives?

What is random experiment and discuss about the probability density function, Cumulative probability distribution function of a continuous random variables.

A manufacturer determines that, on an average, a television set is used 1.8 hours per day. A one-year warranty is offered on the picture tube having a MTTF of 2000 hours. If the distribution is exponential, what percentage of the tubes will fail during the warranty period?

Define probability and give an example for conditional probability.

Night watchmen carry an industrial flashlight 8 hours per night, 7 nights per week. It is estimated that on the average the flashlight is turned on about 20 minutes per 8-hour shift. The flashlight is assumed to have a constant failure rate of 0.08/hour while it is turned on and of 0.005/hour when it is turned off but being carried. i) Estimate the MTTF of the light in working hours. ii) What is the probability of the light’s failing during one 8-hour shift? iii) What is the probability of its failing during one month (30 days) of 8-hour shifts?

How would you determine the reliability of system with series components?

It is known that the reliability function for a critical solid state power unit for use in a communication satellite is R (t) = 10/(10+t), for t≥0 and t measured in years. i) How many units must be placed in parallel in order to achieve a reliability of 0.98 for 5 year operation? ii) If there is an additional common mode with constant failure rate of 0.06 as a result of environmental factors, how many units should be placed in parallel?

Thermocouples of a particular design have a failure rate of 0.008 per hour. How many thermocouples must be placed in parallel if the system is to run for 100 hours with a system failure probability of not more than 0.05? Assume that all failures are independent.

Illustrate fault tree technique.

How would you explain the unit redundancy for reliability improvement?

A flange bolt wears out because of fatigue in accordance with the lognormal distribution with MTTF = 10,000 hours and σ = 2. If preventive maintenance consists of periodically replacing the bolt, what is the reliability at 550 hours with and without preventive maintenance? Assume that the bolts are replaced every 100 operating hours.

Show that preventive maintenance does not improve the reliability of a system with constant failure rate.

Preventive maintenance is to be performed every 5 days on a system having a rectangular failure distribution in (0, 100) days. Derive the reliability function for the system under preventive maintenance. Compare the MTTF and the reliability at 17 days with and without preventive maintenance.

How would you describe the manufacture’s cost and customer’s cost for economics of reliability?

How would you explain the management policies and decisions for reliability management?

How would you describe the reliability of depreciation cost models?

How would you explain managing people for reliability?