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Friday 23 February 2018
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5 Common Problems with Tensile Testing and What Can Be Done

Measurement tools

If you are concerned about the your methods to determine the tension of a material or your load cell, you are not alone. For that reason, Quality Magazine put together some common problems that companies find and what can be done to correct them. Whether it is using the right measurement tool or taking a look at the system overall, there are ways to locate and fix these problems.

  1. Make sure you are using the correct load cell calibration. There are two ways your calibration may be off when it comes to load cells. The measurement tool may be registering the wrong percentage of the full amount or the reading percentage may be off. In either instance, if you have utilized a load cell that is not at a higher level of its capacity, you will get an error. One easy way to get the right reading from the calibration tools is to start with a good understanding of the specifications for that tolerance vs the forces you expect to be exerted on it.
  2. Make sure you have the correct grip. When people think of how to define or describe the importance of the grip, sports metaphors are often employes. Tennis coaches can make a large change in their students’ games by simply changing the way they hold a tennis racket. The same principle applies to tensile testing. The grip can be seen as where the measurement tool meets the sample. Getting this right can make all the difference in the world when it comes to the accuracy of tensile testing. The good news is it is not that hard to get the right grip. You will have a number of standard options for most measurement tools and if they are not working, you can get custom settings to bring the project home.
  3. Pay close attention to the weight of the grip. It is easy to spend so much time getting the right fit for the grip that you do not factor in its weight. In a number of cases, that is ok because the weight of the grip is so small that it has a negligible impact on the outcome of the testing but there are times when it will. To be on the safe side, you should just go ahead and factor the weight of the grip into your calculations. This will help you make sure you are getting the most accurate readings possible.
  4. Take care to get the axial aligned correctly. Typically, tensile testing in uniaxials uses a sample that will be moved on a straight axis. If everything is set correctly, the results will be accurate. However, if there is a problem with the way the axial is aligned, your results will be off. To prevent this from causing you problems, make sure the grip that is being used has as close a jaw width to the sample being tested. If you need it, you can add an adapter on a swivel to get the best reading.
  5. Do not forget to compensate for defection in the system. Most of the time when you are conducting tensile testing, you have to take into consideration defections in your system. There are a few causes of this problem on either the part of the load cells or on the frame for the test.You may find this problem is or is not linear. You can get measurement tools that can automatically compensate for this but if you think you are having an issue, you will have to make those adjustments manually. It is really impossible to correct for defections perfectly. Many people find that using measurement tool helpers such as extensometers can make a big difference in improving the accuracy of measurements.

Whenever you are looking at needing to do tensile testing, getting the most accurate readings is your end goal. It may be impossible to prevent all of these issues all of the time but it is always possible to work towards a better way to get the best readings from your measurement tools. This will greatly improve the quality of your work product.




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