If you were interested in the shear properties of a composite structure, you would measure them conventionally on a laminate scale. Applicable tests would be e.g., short beam shear, v-notch shear or ±45° tension shear tests. Each of these tests requires a unique sample and usually additional sensors e.g., strain gauges or digital image correlation systems. When the setup is complex, it increases the amount of time needed for testing, material usage grows, and there are added sources of errors. And when researching natural fibres, surface treatments, or experimental materials, this scale might not be possible when materials are scarce. Then it might be wise to change to microscale measurements.
Micromechanical testing has been around for decades, and there are multiple methods to measure the interfacial shear strength (IFSS) of a fibre matrix interface. The most well-known methods are microbond, pull-out, and single fibre fragmentation tests. These methods have had problems, either in sample manufacturing or getting consistent results from the measurements. There is a rising interest at the moment in multiscale modeling, where microscale properties of the material are the starting point for understanding the laminate behavior of composite materials. Industries are also interested in new materials, e.g., natural fibres, lignin and/or cellulose-based carbon fibres, vitrimers, and thermoplastic composites. These have increased the need for rapid testing equipment, which does not require pilot-scale production of materials. The aforementioned drivers have been one of the key factors in the development of FIBRODrop and FIBROBond devices. They can create a large set of samples from a small amount of material and measure them in a hasty schedule.
FIBRODrop and FIBROBond devices together are an excellent choice for developing sizings, characterization of new materials, comparison of batches of products, or determining the material properties for models. For testing, you would only need ~30 cm of rowing or tow and 100g of thermoset resin (or a few granulates of thermoplastic polymer) to perform the microbond measurements.
So, why would you waste your time measuring on macroscale and just save your energy and start measuring in microscale today? Hit us with a call, email, fill out the form or follow us @linkedin and we will guide you toward microscale measurements.
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Especially the applications of fibrous composites in miniature products, dental and other medical applications require accurate data of microscale mechanics. The characterization of adhesion between single filament and picoliter-scale polymer matrix usually relies on the experiments using so-called microbond (MB) testing. In this paper, a monolithic compliant based structure with an integrated Fiber Bragg Grating (FBG) sensor is developed and analysed. The developed strain-sensing CBPM-FBG holder shows excellent sensitivity during the MB tests for both synthetic and natural filaments, even at a low filament diameters as low as 7μm, making the monolithic compliant structure the first instrument capable of force-strain data output for bonded filament-droplet specimens.
"For the first time ever, force-filament strain data was systematically collected for droplet-filament specimens at a sampling rate of ≥50Hz when the integral FBG-CBPM specimen holder was operated in the Fibrobond MB tester; three different material systems were analyzed. FEA of the MB testing with glass filaments and epoxy droplets enabled fitting and exact interfacial CZM-based debond model and frictional sliding with a friction coefficient of 0.35." (Royson et al. 2021)
