Tag Archives: Fred Schenkelberg

#122 – METHODS TO ESTIMATE ALT VALUE – FRED SCHENKELBERG

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ABC FredHere is an example of how to determine the future value of a specific reliability task. Many of us face the challenge of how to justify spending product development resources to provide insights and information to the rest of the team. Accelerated life testing (ALT) is particularly difficult: It is time consuming, expensive, and at times statistically complex. Having a clear method to estimate the value serves your career and the organization well, as both benefit from the right investments. Continue reading →

#121 – MECHANICAL RELIABILITY TESTING – FRED SCHENKELBERG

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ABC FredMechanical systems wear out and fail eventually. The ability of a structure to support a load, move though the specified range of motion, or spin degrades with use and time. Even our joints eventually wear out.

Accelerated life testing (ALT) has value as it provides information about a system’s reliability performance in the future. There is plenty of ALT literature concerning the failure mechanisms unique to electronic components and materials but less has been written about mechanical reliability testing. Continue reading →

#118 – HOW TO ESTIMATE RELIABILITY WITHOUT PROTOTYPES – FRED SCHENKELBERG

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ABC FredHOW TO ESTIMATE RELIABILTY EARLY IN A PROGRAM

In a few discussions about the perils of the mean time between failures (MTBF), individuals have asked about estimating MTBF (reliability) early in a program. They quickly referred to various parts count prediction methods as the only viable means to estimate MTBF. Continue reading →

#117 – FACING THE FEAR OF STATISTICS – FRED SCHENKELBERG

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ABC FredWhen reading a report and there is a large complex formula, maybe a derivation, do you just skip over it? Does a phrase such as 95% confidence of 98% reliability over 2 years not help your understanding of the result? When you read about hypothesis testing, confidence intervals, point estimates, parameters, independent identically distributed variables, random samples, orthogonal arrays, do you just shiver a bit? Do you know of folks around you who not only do not understand these terms but do not want to understand them? Continue reading →

#116 – THE CONSTANT FAILURE RATE MYTH – FRED SCHENKELBERG

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ABC FredHave you said yourself or have you heard someone say any of the following:

  • “Let’s assume it’s in the flat part of the curve”
  • “Assuming constant failure rate…”
  • “We can use the exponential distribution because we are in the useful life period.”

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