Three-dimensional boundary element analysis of cracks in vanes of Kaplan hydraulic turbine

There are a number of crack development and even fracture accidents in the vanes of Kaplan hydraulic turbines in the course of running, which severely threaten the safety of their operation. On the basis of linear elasticity fracture mechanics and by using the houndary element method, multi-domain boundary intergral equations are established to solve the crack problem. Singularity elements with r 1/2 displacement singularity and r” 1/2 traction singularity are introduced, so as to ensure the calculating accuracy of the displacement field and traction field near the crack fronts. Tn + he course of programming with FORTRAN-77, we have studied the intergral program of general element and singularity element, and have used the subregion technique and four-node changeable Gler l ITn + models so that the program can be used to handle crack problems of any shape conveniently. We also calculated several practical problems and obtained satisfactory results. In addition, we have programmed a mesh generator ‘he \ane of Kaplan turbines, and calculated the stress intensity factor in the cracked for discretization of vane for a Kaplan turbine runner with 6.00 m diameter.