Special Services for Design Engineers
Some people want a failure analysis or material characterization to put in their files. This is fine. It might come in useful some day. If that is all you want, many laboratory services can provide it.
If, on the other hand, you want to know why something worked well or why it did not work so well, there are not so many laboratory services that can provide that information. That is because what you need is not just information, but information based on knowledge of a lot of things. For example, steel has a fatigue endurance limit. That means that if there is no corrosion or other damage to a steel component, if it is properly designed to have operating stresses below the endurance limit, it could last forever! This phenomenon is thought to be related to the way the deformation process in steel happens. In SOME cases, the material can actually get stronger in the presence of a small repeated stress. So, you may think you have a great design, but really, you have just been lucky! If you change to a different material, such as aluminum, or even a different type of steel, or EVEN the "same" steel processed differently, these life enhancing atomic interaction characteristics will or may also change.
Even if you are a little more savvy, and decide to check out the characteristics of the material "that worked," are you sure that you are checking all the characteristics of importance to the application? Maybe you send it to a commercial lab, and ask for the hardness. Most labs will check the hardness and send you a bill and a report. But what about the yield strength? In many structural applications, that is more important, and is often difficult to determine in even an approximate method without doing a tensile test. What about the crack resistance? Should you use a Charpy test? V- Notch or un-notched? At what temperature? What about a fracture toughness test? What size?
In many cases it is difficult for a design engineer to select a characterization method, because the stresses and environmental conditions in which the component must operate have never been determined in a detailed way. If you don't have any idea what the stresses are in your component, why bother to determine the strength? You just guess at a design, build it, try it and if it works, sell it. If it doesn't work, you beef it up and retest, and if it works, sell it.
This method is time consuming and dangerous. There are many situations where using a higher strength or thicker component can actually make it WEAKER! Engineering theory is pretty well developed, but people still are not using it. Even companies well known for the durability of their products are starting to take risks with their product design, promoting the use of virtually no actual component or assembly testing. Product testing is all done in cyberspace. The models use material properties that are typical, or maybe at the "low" end of the specified range. (What is the "low" end if higher strength makes some materials more prone to unexpected cracking?) These companies then specify the characteristics of their components, many of which are made on the outside, and NEVER check the components themselves. They leave it to the supplier to ship only "in- spec" product. They do not think it is important to know where in that range they are. This whole concept of product design leaves a lot to be desired in many of the industries that are using it.
The people who have the most reason to use it are perhaps the aerospace industry. But they actually have proven their models again and again, using actual testing of real components to back up their cyber models.
However, there are many other industries that are starting to use these advanced design technologies, but WITHOUT the experience of matching actual components to modeled characteristics.
However, even the aerospace engineers need to acknowledge today's business climate. Companies go in and out of business very fast these days. It is quite unrealistic to assume that you will be getting "an equivalent" component from a different company. Anyone who has done failure analysis of structural components for a while has seen numerous examples of parts that "met the spec" and still failed miserably. There are simply too many characteristics to specify them all. But you can still benefit from THINKING about how to characterize the most important properties to YOUR APPLICATION. This effort to decide what properties to characterize should be a team effort involving individuals with experience in design, manufacturing, materials, and product maintenance and service, at the very least.
Whether you are characterizing the properties of a new design, so that you know what you are putting out into the marketplace, or characterizing the properties of a field failure, in an effort to figure out what went wrong, it is not a simple task of checking the dimensions, composition and the hardness, as a lot of people think. The exact position of each test and proper selection of the test method are critical variables that need to be decided based on criteria which vary with the situation. There is currently no exact recipe which will ensure that you do it right. Materials characterization in the service of understanding the strengths and weaknesses of your product IS a complex task. Materials characterization in the service of understanding the strengths and weaknesses of your product IS A WORTHWHILE task! Call for information and assistance with your next design project!
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