David Weed
Ansys Employee

Hello,

You need to insert a Fracture object so that the solver will recognize the highlighted vertex as a crack tip. To do this, right-click on Model and insert a Fracture object:

 

Then right-click on fracture and choose Pre-meshed Crack:

For the crack tip node, you'll have to convert the geometric Named Selection into a Nodal Named selection (by right clicking on it and choosing Create a Nodal Named Selection). Set the Crack Tip field to this Named Selection and also be sure to set up a local crack coordinate system (it should be placed on the open side of the crack with the x-axis in the direction of crack growth and y-axis normal to the crack plane):

To ensure accuracy, test different levels of mesh refinement around the crack tip. You also want to achieve convergence among contours 3-6. Please see the Mechanical documentation here for additional details: Defining a Pre-Meshed Crack