The “displacement extraction method” was proposed to calculate the contact stress of the zig-zag shroud contact surface according to the convergent displacement of contact surface. The contact stress can be obtained accurately with the surface mesh size of 0.202 mm

and the maximum value was 453.48 MPa. The stress level and torsion degree of the shrouded blade under different conditions were analyzed. The stress level increased with the increase of initial installation tightness

and the blade torsion angle increased with the increase of centrifugal load. According to the relationship between the load on the contact surface and the torsion angle

the compressional rigidity and torsional rigidity of blade were obtained. The compressional rigidity was much higher than torsional rigidity

so the stress of blade body restricted the stress of contact surface. It was proposed that the average contact stress of shroud should not be greater than 40% nominal yield limit and the equivalent stress of blade body should not be greater than 75% nominal yield limit as a criterion for the static load strength analysis

and the shrouded blade model of 0.127 mm initial installation tightness can meet this strength requirement.