Failure and Design Jaime Baber October 12, 2000 BME 272: Dr. Paul H. King
Introduction Failure: Degradation of performance of a device outside of a specified value Non Performance or inability to perform for a certain time within space conditions Causes of Failure: Systemic and Random Diabetes Test Kit
Similar Terms Defect : An imperfection (which may/may not lead to failure) Deficiency: Lack of conformance to specifications Malfunction: Unsatisfactory performance Fault: Cause of failure Could be something in environment Something that happens to device: not internal
Failure is a fact of life...
Failure is a fact of life... Define operational issues/normal operation Failure rate Anticipate the worst Failure Mode Analysis Design around it: FAIL SAFE
Hardware Failure Early: First 1,000 hours Random: Mid-life Wearout: Late Artificial Hip
Software Failure Specification errors Design Error Typo Ommission Lack of Verification
Human Error….
Human Error Most important Documentation: Not up-to-date or missing Engineers must review and test Track Failures
Reliability Describes how dependable a device is over time Performs for a stated environment/time w/o failure Plan/Design/Manufacture reliability into product vs Quality
Mechanical Reliability Due to deterioration of design strength or assembly
Electronic Reliability Three distinct time periods
Software Reliability
Overall Device Reliability
Reliabilty Assurance Design Fault Tolerance Improve Manufacturing Quality Assurance Teams/ Inspect Service Manuals Test Monitor
Design….
designsafe... Task Based Safety Analysis Hazard Analysis Users Tasks Risk Assessment Four levels of severity