Designing a proper test for the life of an electromechanical compoent involves several steps and considerations. Here are six steps that provides an outline to create a meaningful component life test.
[Read more…]Test Design for Component Life
on Product Reliability
A listing in reverse chronological order of articles by:
- Kirk Grey — Accelerated Reliability series
- Les Warrington — Achieving the Benefits of Reliability series
- Adam Bahret — Apex Ridge series
- Michael Pfeifer — Metals Engineering and Product Reliability series
- Fred Schenkelberg — Musings on Reliability and Maintenance series
- Arthur Hart — Reliability Engineering Insights series
- Chris Jackson — Reliability in Emerging Technology series
Reliability Block Diagram Fundamentals
Basic Definitions
- Reliability: Ability to provide continuous and stable system/component function under defined operating conditions without failure(s).
- Mean Time Between Failures (MTBF): Average expected time interval between failures. Often a measure of reliability.
- Failure Rate is the expected no. of failures over a period of time. MTBF is the inverse of failure rate.
- Availability: Percentage of time a system or component can perform its intended function without failure.
- Key aspects involve individual component reliability, system architecture, redundancy, and implementation of control strategies to ensure uninterrupted service.
- Availability = Uptime/(Total Operation Time) = MTBF/(MTBF+MTTR), MTTR is a measure of time to repair the system/component
- For example, 99.999% (5-9’s of availability) -> 5 min downtime in one year
- Reliability Block Diagram: Reliability Block Diagram (RBD) is a graphical representation used to model reliability in complex systems. Illustrates interconnections between various components or subsystems within a system.
One-sample t-test
A one-sample t-test is a statistical test to determine if the sample mean differs significantly from a known or hypothesized population mean (expected value). It is commonly used when we have a single sample and want to compare its average to an expected value.
[Read more…]What is ALT? Models
Introduction in ALT:
Accelerated life testing (ALT) is a method used to enhance product reliability by subjecting prototypes to stress levels significantly higher than those encountered in actual use.
By increasing the stress on the component, failure is induced more rapidly, which is equivalent to speeding up the passage of time. This approach is particularly useful when waiting for failures to occur at their normal rate is not feasible, such as when a manufacturer needs to release a product to the market soon and cannot afford to spend several years performing a reliability test.
[Read more…]What is ALT? The Video Explainer
A short video defining accelerated life testing or ALT.
An introduction to ALT or accelerated life testing. ALT is a method used to enhance product reliability by subjecting prototypes to stress levels significantly higher than those encountered in actual use. In short, it’s a way to accelerate time.
[Read more…]Eight Disciplines (8D) in Root Cause Analysis (RCA)
Some history:
The executives of the Powertrain Organization (transmissions, chassis, engines) wanted a methodology where teams (design engineering, manufacturing engineering, and production) could work on recurring chronic problems. In 1986, the assignment was given to develop a manual and a subsequent course that would achieve a new approach to solving identified engineering design and manufacturing problems.
[Read more…]Why is Confidence Level so Important in Engineering Test Data Analysis
A short video discussing the importance to engineering test data analysis of confidence intervals.
[Read more…]FMEA or RCA?
Probably every engineer has heard once in his experience terms FMEA and RCA.
What is FMEA?
FMEA is a systematic method for identifying and preventing potential failure modes in a product or process. It helps in proactively addressing failure risks, improving reliability, and enhancing safety. FMEA is crucial in various industries, including automotive, aerospace, and manufacturing, to ensure product quality and customer satisfaction.
[Read more…]What is the job of a Validation Engineer?
Once upon a time in my former life, I served as the Quality Manager for a $300M tier-one automotive manufacturing plant that provided components and assemblies to OEM vehicle assembly plants. You would recognize our customers – most of the big names. This assignment was a departure from my previous roles in product development and testing. To say that the job was eye-opening is an understatement. Years later, I described this three-year experience to friends as my “tour of duty on the front lines.” Anyone who has spent any time in manufacturing can certainly relate!
Hypotheses Testing – What is That?
Well, this article will be a little bit challenging and full of statistical terms. I would categorize the “Hypothesis testing” as most of common use in statistical analysis.
First time of usage happened in 1700s, but actual popularisation at early 20th century:
[Read more…]Test Design for Component Life
Why make a Histogram graph?
Background:
A histogram – is an approximate representation of the distribution of numerical data. The term was first introduced by Karl Pearson:
[Read more…]Introduction to the t-test
A brief introduction to the statistical hypothesis test called the t-test. Useful when examining if there is a difference between the means of two groups.
[Read more…]Why is Confidence Level
Why is confidence level so important in engineering test data analysis?
From the name itself it gives us a very good hint; Confidence level is giving the confidence in data analysis. In the next graph, you can find 10 samples and fitted Weibull 2p distribution with 95% of Confidence level:
[Read more…]Boeing, Boeing, … Bugger. Now it’s the Starliner
There might not ever be a better demonstration of the saying that …
… a fish rots from it’s head.
Boeing is responsible for the half-baked Maneuvering Characteristics Augmentation System (MCAS) that was forced into its new 737 Max aircraft. This involved a decidedly awful attempt to convince the Federal Aviation Administration (FAA) that there was no need to subject said aircraft through all the checks and balances that you need to go through if it is in fact a brand-new and different type of plane. Which it was. This resulted in the deaths of 346 passengers and crew (along with plenty of claims that it was pilot error). And just to be clear, Boeing has since admitted that it’s employees defrauded the FAA during the original certification process – an admission it was not required to make if it was able to complete a three-year period of increased monitoring and reporting. Which it could not.
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