Your Reliability Engineering Professional Development Site
Find all articles across all article series listed in reverse chronological order.
The reliability engineer may have many roles within an organization.
You may be specialized and focused only on the analysis of field data. Or you may be a member of the organization’s strategic leadership team.
You might support one or more product development teams, or work with a team of reliability professionals supporting just one subsystem. [Read more…]
Monte Carlo relies on data that describes the variation of elements within the system. It also connects the elements such that they result is an estimate of performance.
For reliability modeling, this is easiest to imagine for a series system.
For a system with two elements in series, a very simple reliability block diagram multiples the expected reliability for each block to determine the system reliability value. Yet, it is possible to have both elements at the low end of the range of possible reliability values, or the high end or a mix.
That is the value of the Monte Carlo approach. [Read more…]
Most reliability engineers are familiar with the life cycle bathtub curve, the shape of the hazard rate or risks of failure of a electronic product over time. A typical electronic’s life cycle bathtub curve is shown in figure 1. [Read more…]
Ethics relate to the moral correctness of a person’s behavior given the groups moral principles.
Society, in general, has a set of standard expectations to guide our behavior. This includes fundamentals such as not harming others or behaving in a deceitful manner.
Religious, professional and informal ‘codes’ document the set or principles which guide our behavior in line with moral correctness. [Read more…]
Fault Tree Analysis (FTA) is a technique to explore the many potential or actual causes of product or system failure.
Best applied when there are many possible ways something may fail. For example, when my car doesn’t start, it could be a dead battery, faulty started, loose wire, no fuel, and on and on. [Read more…]
Each organization creates their own version of a product life cycle.
Often there are phase gate reviews that signal a transition from one phase to the next. In general, each set of phases follows a common progression from idea to retirement.
There are many references that include a description of the life cycle phases, so let’s explore two of them. [Read more…]
Customers experience product failures.
Understanding these failures that occur in the hands of customers is an essential undertaking. We need this information to identify increasing failure rates, component batch or assembly errors, or design mistakes. [Read more…]
Historically Reliability Engineering of Electronics has been dominated by the belief that 1) The life or percentage of complex hardware failures that occurs over time can be estimated, predicted, or modeled and 2) Reliability of electronic systems can be calculated or estimated through statistical and probabilistic methods to improve hardware reliability. The amazing thing about this is that during the many decades that reliabilityengineers have been taught this and believe that this is true, there is little if any empirical field data from the vast majority of verified failures that shows any correlation with calculated predictions of failure rates.
[Read more…]
The planning of environmental or reliability testing becomes a question of sample size at some point.
It’s probably the most common question I hear as a reliability engineer – how many samples do we need. [Read more…]
Estimating the set of stress and stress curves is an interesting exercise that may have a greater purpose: safety.
The connection is clear when considering the potential consequences of failure.
For example, the loss of braking power when landing an aircraft may result in the aircraft rolling off the end of the runway. This could be into a river or road and may have a rather poor outcome not only for the aircraft. [Read more…]
Becoming an ASQ CRE is one milestone in your career. It involved gathering experience and studying the broad reliability engineering body of knowledge.
It also involved an ongoing application of what you know and learn. I’ve found being a reliability engineer involves learning about materials, designs, systems, people, and tools & techniques. Mastery takes time and a good library. [Read more…]
Ideally, in every design of every component, the stress–strength relationship looks like this figure. The stress is well below the strength.
This implies there is very little chance of failure due to the element being overstressed.
Also, ideally, we fully characterize all stresses and all strengths for each element of a product. This is generally difficult to accomplish and it is rarely done to that extent.
Every once in a while I see a comment that by following the HALT methodology you will “over design” a product.
Many question at what point or operational limit do you quit increasing the stress-strength margins. Those who hold this view of HALT do not understand the essence of what was Gregg Hobbs’ principles and paradigm shift. [Read more…]
Embarking on a product development project contains many aspirations, including that the product should work as expected.
The device functions and does so over time. Enough time for the customer to deem the device reliable.
That is one way to approach setting a reliability goal for a project. Estimate what will delight the customer. Set a target for how long without failure your new design function.
The goal provides a focus for the team. [Read more…]
Reliability or life testing involves estimating the expected durability over time of an item.
This may be an entire system, a product, or an individual component. We may also focus on an element of a component, such has a material property.
At the end of the testing, we want to say something meaningful about the expected performance over time. [Read more…]