This work is a part of an industrial waste development program. It is devoted to the study of recyclability of chips resulting from the machining of steel parts as reinforcement for concrete. We are particularly interested in this study in the rheological behavior of chips reinforced fresh concrete and its mechanical behavior at young age. The evaluation of the workability indicates that the sand over gravel optimal ratios (S/G), corresponding to the composite minimum flow time, are S/G = 0.8 and S/G = 1. The study of the chips content (W) influence on the workability of the concrete shows that the flow time and the optimal ratio S/G increase with W. Mechanical characterization tests (direct tension, compression, bending and splitting) show that mechanical properties of chips reinforced concrete are comparable to those of the two selected reference concretes (concrete reinforced with conventional fibers: EUROSTEEL fibers corrugated and DRAMIX fibers). Chips provide to control concrete a significant increase in strength and some ductility in the post-failure behavior of the composite. Recycling chips as reinforcement for concrete could be thus favorably considered.
The paper proposes a novel approach to assess the integrity of Electrical Insulation Systems (EIS) by evaluating the response of the Transient Voltage Signature Analysis (VSA) to voltage source inverters correlated with changes in the Insulation Capacitance (IC). The involved model structures are derived from the in-situ estimation of high-frequency electromagnetic RLMC lumped network parameters. Different physical phenomena such as inductive and capacitive effects, as well as skin and proximity effects are combined. To account for these phenomena, we use an approach based on equivalent multi-transmission line electric circuits with distributed parameters (R: resistances, L, M: self and mutual inductances, and C: capacitances) which are frequency-dependent. Using the finite element method, firstly the turn-to-ground and turn-to-turn capacitance parameters are performed by solving an electrostatic model with a floating electric potential approach, and secondly, the resistance and self/mutual inductances are computed from the strongly coupled magneto-harmonic and total current density equations, including the conduction and displacement eddy current densities. The sensitivity of the capacitances is measured according to insulation thickness, and the dielectric properties are adopted to test the degradation order scenarios of the EIS and comparing their time and frequency domains of transient voltage waveform behavior with respect to healthy assessed insulation systems.
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