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Failure and Design

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

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Failure and Design

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  1. Failure and Design Jaime Baber October 12, 2000 BME 272: Dr. Paul H. King

  2. 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

  3. 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

  4. Failure is a fact of life...

  5. Failure is a fact of life... • Define operational issues/normal operation • Failure rate • Anticipate the worst • Failure Mode Analysis • Design around it: FAIL SAFE

  6. Hardware Failure • Early: First 1,000 hours • Random: Mid-life • Wearout: Late • Artificial Hip

  7. Software Failure • Specification errors • Design Error • Typo • Ommission • Lack of Verification

  8. Human Error….

  9. Human Error • Most important • Documentation: Not up-to-date or missing • Engineers must review and test • Track Failures

  10. 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

  11. Mechanical Reliability • Due to deterioration of design strength or assembly

  12. Electronic Reliability • Three distinct time periods

  13. Software Reliability

  14. Overall Device Reliability

  15. Reliabilty Assurance • Design Fault Tolerance • Improve Manufacturing • Quality Assurance Teams/ Inspect • Service Manuals • Test • Monitor

  16. Design….

  17. designsafe... • Task Based Safety Analysis • Hazard Analysis • Users • Tasks • Risk Assessment • Four levels of severity

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