Handbook of reliability prediction procedures for mechanical equipment
->>>> Click Here to Download <<<<<<<-
A reliability prediction is performed in the early stages of a development program to support the design process. Performing a reliability prediction provides for visibility of equipment reliability requirements in the early development phase. A well done prediction also provides an awareness of potential equipment degradation during theequipment life cycle. As a result of performing a reliability prediction, equipment designs can be improved, costly over-designs prevented and development testing time optimized.
Performance of a reliability prediction for electronic equipment is well established by research and development. Development of this document was made possible because the standardization and mass production of electronic parts has permitted the creation of valid failure rate data banks for high population electronic devices. Such extensive sources of quality and reliability information can be used directly to predict operational reliability while the electronic design is still on the drawing board.
A commonly accepted method for predicting the reliability of mechanical equipment based on a data bank has not been possible because of the wide dispersion of failure rates which occur for apparently similar components. This tool can be used to make average failure rate estimates for items that do not exhibit a constant failure rate, such as for mechanical components. The average failure rate is calculated using the following equation Ref. Example: A ball bearing has a Weibull shape parameter of 1.
What is the average failure rate for the bearing? If the bearing is scheduled for preventive maintenance replacement every 10 years, the hazard rate varies from a lower value of zero at "time zero" to an upper bound of 31 failures per million hours FPMH for bearings that survive to the 10 year point. The average failure rate for a population of these bearings is estimated to be approximately 20 FPMH, as depicted by the green line shown in the left-hand figure below.
Conversely, if the bearing is replaced every 2 years, the failure rate will vary between 0 at "time zero" to 19 FPMH at the two year point, with the average failure rate estimated to be 14 FPMH, as represented by the green line in the right-hand figure.
Because average component failure rate is constant for a given maintenance renewal concept, an overall system failure rate can be estimated by summing the average failure rates of the components that make up a system.
Decimal places: 2 0 1 2 3 4 5 6 7 8 9 10 15 20 Plot x-axis end: 20 years 1 year 3 years 5 years 10 years 15 years 20 years 25 years 30 years Plots: R t F t f t h t Table Equations. Bazovsky, Igor, Reliability Theory and Practice. Bloch, Heinz P. Selected articles from www. Typical Failure Rates for Sensing Elements 1 thermistor, thermocouple, infrared sensor, thermostat, force transducer, strain gauge, fluid pressure sensor, fluid flow sensor, fluid level sensor, air flow sensor, photodiode, phototransistor, photodetector, solar cell, potentiometer, optical rotary encoder, magnetic rotary encoder, displacement sensor, velocity sensor, proximity sensor, infrared sensor, altitude, humidity, accelerometer, strain gauge, smoke detection.
Typical Failure Rates for Sensing Elements 2 accelerometer, hall effect switch, pneumatic switch, solid state device, thermocouple, torque sensing device, fluid flow sensor, air flow sensor, pressure sensor, fluid level sensor, humidity sensor. Chandler, Gregory; Denson, William K. Introduction to Machinery Reliability Assessment. Renewal interval T : years hours.
Seal, static, gasket N. Seal, static, o-ring N. Seal, dynamic, shaft N. Spring, compression N. Spring, extension N. Spring, torsional N. Solenoid N. Contactor N. Gear, bevel N. Gear, planetary N. Gear, spline N. Actuator, linear N. Actuator, rotary N. Pump, centrifugal, axial flow N. Pump, centrifugal N. Pump, displacement, reciprocating N. Pump, displacement, rotary N. Filter, fluid, oil N. Brake, band N. Brake, drum N. Brake, disk N.
Brake, magnetic N. Clutch, friction N. Clutch, plate N. Clutch, cone N. Clutch, rim N. Clutch, block N. Clutch, centrifugal N. Clutch, coil N. Clutch, magnetic N. Compressor, centrifugal N. Compressor, reciprocating N.
Compressor, rotary N.