a) Plane P3 is free to move
b) Plane P3 is a symmetry plane
Figure 15 First Principal Stress in the Cathode Block at 25h, with Shunts.
These tensile stresses are not sufficient to create permanent tensile deformation in the cathode
block when plane P3 is free to move. However, when P3 is a symmetry plane, the fillet of the
slots undergoes a localised permanent tensile strain, as shown in Figure 16a). Note that the
block in the same orientation as in Figure 15 and that the grey zone is free of permanent strains.
This permanent tensile strain localisation is an indicator of potential cracking since the material
is now beyond its yield stress. For the case with shunts, it has not reached its peak stress after
48 hours of preheating, but in the full line load case, cracking has occurred, as seen from the
softening parameter shown in Figure 16b). This parameter represents the local equivalent
permanent tensile strain beyond the peak stress of the material.
a) First Principal Permanent Tensile Strain in the
Cathode Block Slot at 48h, with Shunts
b) Softening Parameter in the Cathode Block Slot
at 48 h, Full Line Load.
Figure 16 Cathode Block Cracking Indicators