The THELMA (Thermal-Hydraulic-ELectro-MAgnetic) code has been developed with the aim of simulating the main aspects of superconductors to be used in the coils of the International Thermonuclear Experimental Reactor (ITER). An application of the code is presented here, where THELMA is used to simulate a single strand by considering, as cable elements, groups of superconducting (SC) filaments and the corresponding portion of the resistive matrix. This approach is used to reproduce the voltage-current characteristic of a Nb 3 Sn bronze route strand when subject to a bending mechanical load. Attention is focused particularly on the effect of the applied mechanical load on the critical current, which is considered a relevant item in the explanation of the degradation of the coil performance observed in several ITER Model and Insert Coil experiments. The longitudinal strain of the SC filaments is calculated by means of a composite beam model of the strand, taking into account the nonlinear, temperature-dependent material characteristics of the components. The whole load history is simulated, computing first the thermal strain due to cool-down, and then the mechanical strain due to the bending at 4.2 K.

No abstract

No abstract

High spee[1 machining eonsists to use high spood fbod rates and high ttequencies of rotation in order to chtain a best finish surface integhty includmg geometric aecuracy, surfhce roughtiess but also lower residunl strcsses. We arc meanly interested by high spoed milling. This tec hnique is in constant development but the sttfety in the workng environment seams to be not realy stedied. For examp!e, if we assume a too1 breakage by using an electro-spindle with the foliowing characteristics:rnaxiinurn rotation speed of 45ooO rpm, maxirrium power of cut of 40 kW, and maximum too1 diameter of 50 um the prejectile is ejocted with a velocity of 235 m.s'i. Also it is necessary to detme thc good choice for gtazing in operator windcvws. An cxperimental investigation to assess the effbet of projeetile shape and velocity on the impact response ofthin polycarbonate target plates was performed. Deformation and failure phenomena were observed and discussed.Kay IYbtzls/ Qynamic.fi'acture. H}'gh speed machining, Polycarbonate

No abstract