how to do with the deformed grid
 

I construct the model by 3d-max.and then i import yhe model into workbench in the docunment format of stl. I intend to conduct a 2d plane strain test .There is something wrong with my model.Some extral lines apper when the model generated in the designmodeler.,which cause the bad mesh with the sharp angels. I wonder there is some way to improve the bad mashes by use workbench

Usually its not recommended to use .stl as an import format, especially for 2D analysis. You should go for a cad format (parasolid, .step, .iges) instead of a faceted data as you need to convert it in DM.

If you can only export a .stl you have 2 options. When importing a .stl you often end up with those splits in your geometry so you should either merge the separated faces using > tools > merge faces. Or I would extrude the 2D geometry in 3d-max and then take a slice plane in DM.

Have fun ;)

Thank you!I have solved it by improving the mash quality