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This dataset contains the images of 24 selected thin sections examined with polarized light microscopy. The thin sections were examined with a Leica DMRB polarizing microscope (Leica Microsystems GmbH, Wetzlar, Germany) using a magnification of 2.5 times. The photographs during examination were acquired with a digital camera (sony α7, Sony, Tokyo, Japan) using the following settings: exposure time of 1/160 s, ISO sensitivity of 125. Three photographs are available for each thin section. The first photograph shows the examination using conventional polarized light microscopy with the polarizer and analyzer rotated at 90° to each other (cross-polarized PLM, or PLMc). The second photograph displays the thin section using polarized light microscopy as in PLMc with an additional λ-plate prior to the analyzer (red-plate PLM, or PLMr). The third photograph shows the examination with transmission light microscopy without the analyzer being used (bright-field microscopy, or PLMb). The order of the images in the folders is always the same: PLMc, PLMr, PLMb, where for each photo always a processed .JPG file and the raw data as acquired .ARW file is available. The pixel size in each image is 2.28 µm x 2.28 µm.
High-speed processes can lead to significant technological advantages like an increased formability, reduced springback or an improved quality of cutting edges. For conventional forming processes, quasi-static conditions are a good approximation and numerical process optimisation is state of the art. However, there is still a need for research in the field of material characterisation for high speed forming and cutting processes. Production technologies with high velocities leads to high strain rates and the dependency of strain hardening and failure behaviour on the forming velocity cannot be neglected. Therefore, the data of the material behaviour at high strain rates is required for modelling high velocity processes. The challenge here is the measurement of relevant process quantities due to short process time that requires a very high sampling rate and the limited size and accessibility of the specimen. In this context, an inverse method for determining material characteristics at high strain rates was developed. The approach here is the measurement of auxiliary test parameters, which are easier to measure and then used as input data for an inverse numerical simulation. Two devices were implemented for different ranges of strain rates: a pneumatically driven device for strain rates up to 1.000 1/s and an electromagnetically driven accelerator for strain rates up to 100.000 1/s. The method developed by Psyk et al. is presented in detail in the contribution "Determination of Material and Failure Characteristics for High-Speed Forming via High-Speed Testing and Inverse Numerical Simulation". https://doi.org/10.3390/jmmp4020031. In order to test and comprehend the inverse method for material characterisation the experimental data and the FE-model (LS-Dyna) are presented in case of the electromagnetically accelerated unit. The experimental data are the displacement curve of the flyer and the recorded elastic strain curve of the solid rod for determining the force. The FE-model contains the whole test setup (flyer, specimen, measurement rod) and the determined flow curves as well as the data for the damage behaviour.
High-speed processes can lead to significant technological advantages like an increased formability, reduced springback or an improved quality of cutting edges. For conventional forming processes, quasi-static conditions are a good approximation and numerical process optimisation is state of the art. However, there is still a need for research in the field of material characterisation for high speed forming and cutting processes. Production technologies with high velocities leads to high strain rates and the dependency of strain hardening and failure behaviour on the forming velocity cannot be neglected. Therefore, the data of the material behaviour at high strain rates is required for modelling high velocity processes. The challenge here is the measurement of relevant process quantities due to short process time that requires a very high sampling rate and the limited size and accessibility of the specimen. In this context, an inverse method for determining material characteristics at high strain rates was developed. The approach here is the measurement of auxiliary test parameters, which are easier to measure and then used as input data for an inverse numerical simulation. Two devices were implemented for different ranges of strain rates: a pneumatically driven device for strain rates up to 1.000 1/s and an electromagnetically driven accelerator for strain rates up to 100.000 1/s. The method developed by Psyk et al. is presented in detail in "Determination of Material and Failure Characteristics for High-Speed Forming via High-Speed Testing and Inverse Numerical Simulation". https://doi.org/10.3390/jmmp4020031
This dataset contains the raw sequences and images of 24 selected thin sections cut from 17 tooth samples, which were examined with advanced polarized light microscopy. Using a polarization camera with a 2x2 pattern of polarizers on the sensor and varying linearly polarized illumination states, depolarized light microscopy images were created by evaluating the degree of polarization (DOP) within thin sections. To generate the data, the thin sections were examined using a modified Leica DMRB microscope (Leica Microsystems GmbH, Wetzlar, Germany) with the complementary implementation of a FLIR polarization camera (FLIR Integrated Imaging Solutions Inc., Ludwigsburg, Germany). The pixel size of the processed images is 3.93 µm x 3.93 µm. Since multiple areas of interests were examined for several thin sections, 29 data sets are available. For each data set, the sequence of raw images of the polarization camera as well as processed DLM images including representations of the DOP and of the intensity are available. Note, that the DLM images must be flipped horizontally compared to the conventional polarized light microscopy images acquired with the same microscope.