Fiber-reinforced composites: reliable characteristic values at any temperature
Do you test fiber-reinforced composites to determine typical characteristic values, including the tensile modulus, shear modulus, Poisson's ratio and other values up to strain at break? Do you also determine these values under the influence of various temperatures? Then you are familiar with the challenges in terms of reproducibility of characteristic values and the discussions on whether deviations are due to the material or if they are caused by different measurement technologies.
The videoXtens biax 2-150 HP optical extensometer solves this problem: same attachment, same distance to the specimen, same technology and one-of-a-kind accuracy in the ZwickRoell temperature chamber: everything together ensures highly accurate, reproducible test results under temperature conditions (-55 to +250 °C). Up to the point of break.
Reproducible characteristic values for analysis of temperature influences are only achievable with the same measurement technology
Once the test results are available, the analysis or interpretation begins: are the differences in results and curves fully attributed to the material, or are influences caused by the test equipment?
Due to the requirements deviation for testing in temperature chambers, the extensometers used differ from those used at ambient temperature. Testers often turn to clip-on extensometers, which are highly accurate but are more complex to handle and cannot measure up to the point of break. However, sensor arm extensometers can, and they have special sensor arms for use in temperature chambers. Since these sensor arms are at a significantly greater distance to the specimen, measurement accuracy is limited. Strain gauges are highly accurate, but also time-consuming and cost-intensive.
The Gordian knot is solved with the videoXtens biax 2-150 HP:
- no converting, no shifting: no changes are made to the videoXtens for operation in the ZwickRoell temperature chamber
- The videoXtens measures contact-free and without influence on the measurement
- Measurement without gauge marks on opaque fiber-reinforced composites
- Every characteristic value is recorded with high accuracy up to break
High accuracy is a prerequisite for Poisson’s ratio & Co. – but what about under temperature conditions?
The videoXtens not only meets Class 0.5 (ISO 9513) for extension and change in width measurement, but easily fulfills the more stringent ISO 527-1 Annex C requirements for determination of the tensile modulus. The videoXtens biax 2-150 HP also meets these requirements for testing in a temperature chamber.
The high precision in testing under temperature is shown, for example, in the resolution: under temperature conditions, the videoXtens biax 2-150 HP provides a resolution of 0.15 µm. In the temperature chamber at a range of -20 to +250 °C, the resolution is max. 0.4 µm—one-of-a-kind in the world of materials testing.
Measurement up to break – because every bit of information counts
From the elastic range all the way to break, the videoXtens records the complete stress-strain behavior of the specimen with the highest level of accuracy. There is no risk of damage, since the strain measurement is contact-free. An important feature for testing fiber-reinforced composites with their sometimes high-energy specimen failure.
For opaque fiber-reinforced composites there is no need for manual specimen marking. The natural surface structure is sufficient to allow placement of virtual gauge marks via the software. This reduces the effort.
Another advantage of optical measurement: the extensometer has full view of the entire specimen, allowing it to provide even more information, such as digital image correlation in 2D.
The range of functions clearly shows: the videoXtens biax 2-150 HP is a specialist for fiber-reinforced composites, specifically designed for high-accuracy measurements and optimal handling.
