Learning Forum

[lakshminarayana n]

I m modeling geometry of a steel plate containinga edge crack,when i am creating nodal named selections,getting cross mark(x) at selection, so ultimately i m unable to find SIF crack tip, pls some body help me in solving the problem.I m attaching screen shot of error also.

[David Weed]

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

[lakshminarayana n]

 Dear david Thnak you for your great reply...

But after choosing create nodal named selection only we can proceed for pre meshed crack..i m encountering problem at create nodal named selction stage itself..i m attaching scrren schot of the problem...pls help me out..

[David Weed]

Highlight the Mesh object in the Mechanical tree and go down to the Details window -> Sizing, and if Mesh Defeaturing is to 'Yes', please set it to 'No' and remesh: