Modeling of interactions between formation and downhole drilling tool with wearflat

A computer-implemented method of designing a downhole drilling tool, the method comprising:

• generating a three dimensional (3D) downhole drilling tool model including a plurality of cutting elements on a plurality of blades;
• simulating engagement of the 3D downhole drilling tool model with a 3D model of a borehole bottom;
• calculating a cutting force of a cutting element of the plurality of cutting elements based on a comparison of a cutting energy associated with the cutting element and a failure energy of a volume of formation in the 3D model of the borehole bottom;
• calculating a wearflat frictional force of the cutting element;
• modeling a drilling efficiency of the 3D downhole drilling tool model based on the cutting force of the cutting element and the wearflat friction force of the cutting element;
• determining a design parameter of the 3D downhole drilling tool model based on the drilling efficiency of the 3D downhole drilling tool model;
• adjusting the 3D downhole drilling tool model based on the determined design parameter;
• and
• manufacturing a drill bit based on the 3D downhole drilling tool model.