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Quality Control and Improvement, Reliability, Liability. P. King/Chapter 13 overview. Reliability is:. A characteristic that describes how good a device is. Must be planned for, designed in both in terms of the initial product and in maintenance of that product. Failure is:.
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Quality Control and Improvement, Reliability, Liability P. King/Chapter 13 overview
Reliability is: • A characteristic that describes how good a device is. • Must be planned for, designed in both in terms of the initial product and in maintenance of that product.
Failure is: • The degradation of the performance of a device (process) outside of a specified value AND non-performance or inability to perform its function for a given time period within specified conditions. • Defect: imperfection • Deficiency: lack of conformance to specs • Fault: Cause of failure • Malfunction: unsatisfactory performance
Failure Measures • Real life failure: fact of life, define normal operation, anticipate worst, try to design out. • Failure rate typically = #failures/unit time = failures/million hours for devices.
Unreliability is: • A measure of the potential for failure of a device (or process.) • Leads to high cost, wasted time, inconvenience, poor reputation, unsafe operation, … • - 9/9/99 more than 10,000 stepladders recalled by Home Depot – steps too short, improperly attached (RIDGID ladders, Louisville Ladder Co, Louisville KY)
Quality is: • The ability to provide stated needs NOW (and is implied during warranty period.) • Warranty period: that period of time that you guarantee to refund/replace/fix your product.
Safety & Quality in Health Care: • HHS Secretary Tommy G. Thompson today (10/11/2001) announced the release of $50 million to fund 94 new research grants, contracts and other projects to reduce medical errors and improve patient safety. • This research initiative is part of HHS' broader efforts to improve the quality of care in America and better assure safety across health care settings.
Reliability Implies: • MTBF of x years (for example, e-1 fail in 5 years), proportional to the probability of service over a period of time, T. • = performs stated function, without failure (even with misuse) in the stated environment, for a specified period of time.
Vanderbilt: Reliability & Risk Engineering & Management • NSF IGERT awarded 2001 • $2.7 M over 5 years • BME/ChE/CE/EECS/MT/Math/ME/Owen • 2 year support toward PhD • Sankaran Mahadevan, CE
Electronic Reliability Infant Mortality Wearout Corrosion, Cracking, Wear, Crazing, Shorts Failure Rate <-Useful Life -> Joints, Welds, Contamination, Misuse -- Design, Preventive Maintenance, Replacement, Repair Screening, Design, Burn-in Time ->
Mechanical Reliability Friction, Fatigue, Erosion, Corrosion, Cracking, Lack of PM Failure Rate Misassembly PM, Replacement <- Useful Life -> Time->
Software Reliability Debug errors, Spec. Errors, Special Cases Failure Rate Time ->
System Reliability: Bathtub Curve QI PM QI Lawsuit Failure Rate Lawsuit Time ->
Product Liability • Negligence - legal • Strict Liability - legal • Breach of warranty – legal • Defects • Failure to warn
Negligence • You owe a duty of care to another • The standards for that care have been breached • As a result a compensable injury results • There are damages or injury to the plaintiff
Strict Liability • The PRODUCT is defective or dangerous. • Risk is too high (risk/benefit higher than competition, etc.)
Breach of Warranty • Implied Merchantability (“King’s Pacemakers”) • Implied Warranty for particular purpose (pacemaker) • Breach of express warranty (written or oral contract: cures 100%)
Defect • Actual defect (sharp edges, …) • Consumer expectations • Risk/benefit • State of the art • Defective warnings • Inadequate guarding…
Failure to warn! • You have a duty to warn. If you do not warn that coffee is hot, you are likely to get in trouble…
Examples • Coffee burn • “found with head trapped in side rails…” • Stepladder recall • Fluidized air therapy bed • X-ray/Cobalt therapy accident • Morphine infusion 3 hours not 24 • LMA – cyanosis (see MAUDE)
Some final key phrases • Misuse • Negligent selection • Failure to inspect • Use with knowledge of defect • Alterations • Disclosure through MAUDE (FDA) • Disclosure through CPSC (non-FDA)