Volume 3 nr 1 / 2011 - Academia Oamenilor de Stiinta din Romania

d/c 52 Mircea O. Popoviciu, Ilare Bordeasu, Liviu Marsavinaratio between the crack depth and length to have modifications from one zone toanother as result of composition and structure unevenness. A graphic representationof the disposable data is given in Figure 6 and is difficult to explain. In the future,the beneficiary must demand, in this direction, information that is more detailed.Table 7. Results of non-destructive controlHA1 HA2 HA6 HA9Running duration, N [hours] 167105 168626 148396 101199Crack depth, d [mm] 16.8 5 7 12Crack length, 2c [mm] 80 20 10 - 60 602c/d 4,76 4 1,43-8,57 5d/c 0.42 0.5 1.4-0.233 0.4HA - hydro aggregateIn the following computation we adopted an elliptical fissure having the semi axesratio of a/b= 0.5. The maximum possible depth of the fracture line is of maximum300 mm. Even if a crack attain this depth there will not exist dramatic damages (theshaft will not break apart), but the incident will lead to massive oil leakage (for theoil commanding the blade servomotor) and in this situation the turbine must bestopped and the shaft changed.0,90,80,70,60,50,40,3HA2HA6HA9HA12,5 5 7,5 10 12,5 15 17,5d Fig. 6. Dependence of measured d/c against d.2 22 2 2X yUsing the circle equations X Y R and the ellipse one 1, for2 2b aarbitrary chosen abscissa we obtain the ordinate values for the circles R and r:2 22 2Y R X , Y r X(1)as well as the ordinate for the ellipses:a 2 2y b X(2)bThe Y- ordinates of the ellipse which realize the crack „d” in relation to the originO(XY) are:Copyright © Editura Academiei Oamenilor de Știință din România, 2011Watermark Protected