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