Your Reliability Engineering Professional Development Site
A listing in reverse chronological order of articles by:
If I must date myself, I cut my teeth as a product development engineer in the automotive industry in the bad old days when warranty terms were shockingly poor. Let’s examine this through the lens of my first new car which I purchased in 1984. Why was my warranty coverage so bad, what drove the significant improvements seen in the industry since that time, and how do we now validate our products to keep it that way?
We like to think we make decisions based on information. We don’t. We make decisions based on emotions. And the most important emotion we rely upon for decision-making is confidence. We can be provided all the information in the world, but if we can’t understand it, trust it or believe it, we look for confidence in other ways. Often to disastrous outcomes.
The number of ‘well-funded’ production efforts full of ‘very smart people’ that routinely generate expensive but unreliable products is sadly, very high. And it all comes down to the wrong types of confidence that well-paid decision-makers chase.
In the current century, data is ubiquitous but how to make use of it to drive product decisions can take time and effort. Data visualization is a useful technique to identify patterns in a dataset and derive exploratory statistics to analyze trends.
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Let’s say that you and your team have done well. Your products or systems are reliable. They work, customers are happy, and the cost of unreliability is low. That’s the goal, right? Congratulations are in order.
However, enjoying great reliability performance was the goal. It is what we expected. It’s what we worked to achieve. Now what?
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Since I published my first contribution about reliability, I’ve received a number of emails asking where the stress and strength distributions come from (Figure 1).
[Read more…]What does it mean to be a ‘visionary leader’? It starts with being different to most people. You can’t just become a visionary leader by completing a leadership course, being mentored by someone awesome, or by compiling an impressive curriculum vitae (although these can help people with the potential to become visionary leaders get there).
One of the first things that the then United States Army Chief of Staff (General George C. Marshall) did at the outbreak of World War II was to fire the majority of his officers who had climbed the ladder of military ranks throughout the previous 20 years of relative peace.
Boeing is really having a bad stretch. Or more specifically, the passengers flying in its 737 MAX aircraft are.
Most recently a ‘plug’ flew off the side of Boeing 737 MAX 9 plane in flight, leaving a refrigerator sized hole next to startled (but mercifully still living) passengers. A ‘plug’ is a panel that seals up a hole in the fuselage that is included during manufacture to allow an optional emergency exit to be installed.
This failure is not a good look … especially for a three-month-old plane. Lots of manufacturers of different machines throughout history have been able to successfully bolt panels to cover holes of a similar size to that of an aircraft emergency exit. It is not hard to do. Nor is it hard to have systems in place to make sure it is done right.
A month ago, I received a question, “Why the castles for the artwork?” It was not the first time someone wondered why we use line drawings of old stone building features or sketches of castle layouts. It is safe to say it was and remains a purposeful artwork selection to promote community around Accendo Reliability.
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The bathtub curve is one of the most famous graphical representations in reliability. It shows the typical trend of failure rate over time (Figure 1). This curve can be divided into three parts corresponding to decreasing, constant and increasing failure rate.
High but decreasing failure rate in the first part of the curve (1) indicates products defective or prone to fail due to manufacturing or design issues. The middle section (2) is characterized by low and constant failure rate. Failures in this phase are caused by unpredictable external events like flatting tire or power surge causing electronic failures. The right-hand side of the bathtub curve (3) shows increasing failure rate. In this stage, failures occur due to wear-out damage mechanisms such as fatigue, creep, ageing, wear and corrosion.
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The calculation of reliability consists of the comparison between stress and strength. If we consider stress and strength as deterministic quantities, failure occurs when the stress exceeds strength. In reality, stress and strength are stochastic variables (Figure 1a). If the two curves overlap (Figure 1b), failure may occur. Let us suppose that s and S are continuous random variables with probability density functions f(s) and f(S), respectively.
[Read more…]Apple new iPhones will be somewhat different to those of the past. They will now have a USB-C charging and data port, and not Apple’s lightning cables. Why? Because the European Union said so. And they said so because they are not happy with the number of different charging cables we all now need for our various devices. Having a single cable that can charge an iPhone, Samsung smartphone, and virtually every other small electronic consumer product makes sense. It means fewer cables, smaller carbon footprints, less electronic waste, and prices will come down as less and less products assume that they need to provide a charging cable in their packaging. I have at least 20 power cables in my office that have been provided with various electronic gadgetry over the years.
It looks like 2023 will be the hottest year on record. Along with all the cyclones, hurricanes, floods and bushfires we have already had. Those who study and take climate change seriously unanimously agree that man-made changes to the environment are causing the climate to change so fast that mother nature will struggle to keep up.
And for the minority (yes, it is a minority as has been confirmed by many surveys and studies across the world), their arguments against climate change go something like this …
It might not be because of us …
… so it’s definitely not because of us.
Climate change is universally accepted. And when I say ‘universally,’ I mean that the only people who think it is not a thing are fringe elements of society who are predisposed to specific interpretations of religion or commercial greed that would be harmed by any attack on fossil fuels and the energy we derive from them.
The good thing about this is that organizations who are serious about being successful and profitable can’t do so by sharing the ideology of a small minority. More and more people (including younger humans who will be the decision makers of tomorrow) are demanding more and more from the organizations they buy services and products from – especially when it comes to environmental concerns.
So to be successful, you need to take this stuff seriously.
Fatigue involves localized, permanent damage to metals exposed to cyclic stress. In a previous article I discussed the fatigue mechanism. This article covers factors that can be addressed to improve high-cycle fatigue life
Factors that influence fatigue life
Several design, material, and fabrication factors influence component and joint fatigue life, including the following: [Read more…]
Once word got out that I was taking graduate-level courses in statistics, I dreaded the knock on the door. Colleagues, some of which I knew and others from some far reach of the company, would ask if I could take a look at their data. I didn’t learn the necessary first steps with a stack of data in class.
I’ve lost count of the number of data sets I’ve reviewed and analyzed. I know there are important considerations and questions before creating the first plot. Let’s review the essential first steps you should take when presented with data.
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