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    Surface, interphase and tensile properties of unsized, sized and heat treated basalt fibres
    (London [u.a.] : Institute of Physics, 2016) Förster, T.; Sommer, G.S.; Mäder, E.; Scheffler, C.
    Recycling of fibre reinforced polymers is in the focus of several investigations. Chemical and thermal treatments of composites are the common ways to separate the reinforcing fibres from the polymer matrices. However, most sizings on glass and basalt fibre are not designed to resist high temperatures. Hence, a heat treatment might also lead to a sizing removal, a decrease of mechanical performance and deterioration in fibre-matrix adhesion. Different basalt fibres were investigated using surface analysis methods as well as single fibre tensile tests and single fibre pull-out tests in order to reveal the possible causes of these issues. Heat treatment in air reduced the fibre tensile strength in the same level like heat treatment in nitrogen atmosphere, but it influenced the wetting capability. Re-sizing by a coupling agent slightly increased the adhesion strength and reflected a decreased post-debonding friction.
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    On a thermomechanical model of phase transitions in steel
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2007) Chełminski, Krzysztof; Hömberg, Dietmar; Kern, Daniela
    We investigate a thermomechanical model of phase transitions in steel. The strain is assumed to be additively decomposed into an elastic and a thermal part as well as a contribution from transformation induced plasticity. The resulting model can be viewed as an extension of quasistatic linear thermoelasticity. We prove existence of a unique solution and conclude with some numerical simulations.
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    A mathematical model for case hardening of steel
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2007) Fasano, Antonio; Hömberg, Dietmar; Panizzi, Lucia
    A mathematical model for the gas carburizing of steel is presented. Carbon is dissolved in the surface layer of a low-carbon steel part at a temperature sufficient to render the steel austenitic, followed by quenching to form a martensitic microstructure. The model consists of a nonlinear evolution equation for the temperature, coupled with a nonlinear evolution equation for the carbon concentration, both coupled with two ordinary differential equations to describe the phase fractions. We prove existence and uniqueness of a solution and finally present some numerical simulations.