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Material Testing in High and Low Temperatures

High or low temperature testing is made feasible by adding an environmental chamber to a universal testing machine (UTM). Environmental chambers come with their own temperature controller and, depending on the system’s compatibility, the temperature settings and recordings may be controlled with the UTM’s controller or software.

Universal Testing Machines can be ordered with environmental chambers, or, if testing requirements change afterwards, environmental chambers can later be added to a UTM. The 5 points below will discuss things to consider when selecting an Environmental Chamber. 

The full blog post can be found here.

1) Temperature Range

Your testing may require low-temperature testing only, high-temperature testing only, or both. It is important to specify the exact temperature range needed as this will play an important role in the cost of the chamber. ADMET offers standard and custom environmental chambers where customers may choose the appropriate temperature range for their testing.

2) Mounting Configuration

Universal testing machines may be ordered with an environmental chamber or, if the temperature testing becomes a requirement after a UTM is purchased, an environmental chamber can later be added to the testing system. If this is the case, in addition to the testing application, the specifications of the UTM to be used with the chamber need to be discussed in detail.

UTM makes and models have different specifications and the two classes of testing machines, electromechanical and servo hydraulic testing frames, come with different mechanical designs. When selecting an environmental chamber, the piston or the crosshead movement should be taken into account in order to properly mount the chamber on the system and allow sufficient space for sample testing. In addition, mounting an environmental chamber in a single column machine versus in a dual-column machine will have significant differences.

Furthermore, environmental chambers come with a slider rack that allows spacing when room temperature testing is performed and can be slid inside the machine space when high or low temperature testing is performed.

3) Space for Sample Testing

The external dimensions of the environmental chamber will depend on its mounting configuration discussed above. The wall thickness of the chamber will vary based on the temperature range chosen (if higher temperatures are required, wall thickness will be greater). The internal dimensions are crucial to the selection of a chamber as they will determine the testing space.

For configurations for tensile testing, the chamber will include the top and bottom grips and the sample. For compression testing configurations, the chamber will include the top and bottom compression platens and the sample. Extensometers, deflectometers, and other accessories can also be added and are discussed below. The heights of all the fixtures as well as their mounting adapters are important factors when determining the required internal chamber height.

Furthermore, in tension testing, the final length of the specimen will be greater than its original length. Thus, when specifying the internal height of the environmental chamber the final length should be taken into consideration instead of the original length. The final length can be calculated if the gauge length and % elongation values are known. See the article here for more information.

4) Grips and Fixtures

Grips and fixtures manufactured with special materials that can withstand custom temperatures should be selected for use within the environmental chamber. Most environmental chambers include a viewing door where the testing and the sample can be observed and grips may be oriented so that the specimen can be viewed in the proper manner. The window size may also be modified based on your needs but make sure to confirm the amount of radiative heat losses with the Sales Engineer if a large window size is requested.

5) Extensometers and Accessories

Various designs of extensometers exist for high or low temperature testing applications. Special extensometers measuring strain through the walls of the chamber can withstand temperatures up to 1200°C. Other types of extensometers can operate entirely inside the chamber and are designed to be used through specimen failure. Video extensometers capable of full-strain-field digital image correlation are also often preferred for use with testing applications requiring an environmental chamber.

ADMET environmental chambers are made to order. Below is a list of additional features that were not discussed above:

  • Internal Light
  • LN2 Cooling Module
  • Heated, anti-fog window
  • Air circulation blower
  • Humidity control

 

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