Browsing by Author "Feuer, Anne"

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    Analytical model for the depth progress of percussion drilling with ultrashort laser pulses
    (2021) Holder, Daniel; Weber, Rudolf; Graf, Thomas; Onuseit, Volkher; Brinkmeier, David; Förster, Daniel J.; Feuer, Anne
    A simplified analytical model is presented that predicts the depth progress during and the final hole depth obtained by laser percussion drilling in metals with ultrashort laser pulses. The model is based on the assumption that drilled microholes exhibit a conical shape and that the absorbed fluence linearly increases with the depth of the hole. The depth progress is calculated recursively based on the depth changes induced by the successive pulses. The experimental validation confirms the model and its assumptions for percussion drilling in stainless steel with picosecond pulses and different pulse energies.
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    Heat accumulation during pulsed laser materials processing
    (2014) Weber, Rudolf; Graf, Thomas; Berger, Peter; Onuseit, Volkher; Wiedenmann, Margit; Freitag, Chistian; Feuer, Anne
    Laser materials processing with ultra-short pulses allows very precise and high quality results with a minimum extent of the thermally affected zone. However, with increasing average laser power and repetition rates the so-called heat accumulation effect becomes a considerable issue.
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    High-quality percussion drilling with ultrashort laser pulses
    (2021) Feuer, Anne; Weber, Rudolf; Feuer, R.; Brinkmeier, David; Graf, Thomas
    The influence of the laser fluence on the quality of percussion-drilled holes was investigated both experimentally and by an analytical model. The study reveals that the edge quality of the drilled microholes depends on the laser fluence reaching the rear exit of the hole and changes with the number of pulses applied after breakthrough. The minimum fluence that must reach the hole’s exit in order to obtain high-quality microholes in stainless steel was experimentally found to be 2.8 times the ablation threshold.