Methods for designing fixed cutter bits and bits made using such methods

1. A method for designing and manufacturing a fixed cutter drill bit, said method comprising:

(i) designing a fixed cutter drill bit, wherein designing includes analyzing the fixed cutter drill bit by at least:

(a) selecting at least one cutter;

(b) selecting an earth formation;

(c) simulating drilling performance of the fixed cutter drill bit having the at least one cutter thereon, wherein simulating drilling performance simulates the fixed cutter drill bit drilling the earth formation;

(d) performing finite element analysis using outputs from the simulated drilling performance;

(e) resolving the outputs into a component force normal to a cutter face of the at least one cutter and a component force tangent to the cutter face of the at least one cutter, wherein resolving the outputs further includes resolving the force tangent to the cutter face into a cutting frictional force on a diamond table of the at least one cutter and a tangent force applied to a bevel of the at least one cutter;

(f) determining a stress on the at least one cutter based on the finite element analysis; and

(g) outputting the stress on the at least one cutter; and

(ii) manufacturing the fixed cutter drill bit following designing the fixed cutter drill bit.

2. The method of claim 1 , wherein the resolved forces are modeled as linearly distributed pressure or traction along the depth of cut.

3. The method of claim 2 , wherein the resolved forces are modeled as linearly distributed pressure or traction along the depth of cut.

4. The method of claim 1 , wherein the resolved forces are applied to a formation/cutter interaction area resulting from the simulating.

5. The method of claim 1 , wherein analyzing the fixed cutter drill bit further includes determining a predicted, non-uniform depth of cut for a plurality of cutters and outputting the stress based on the predicted depths of cut.

6. The method of claim 5 , wherein analyzing the fixed cutter drill bit further includes comparing the stress resulting from non-uniform depths of cut to stress resulting from an average depth of cut.

7. The method of claim 1 , wherein analyzing the fixed cutter drill bit further includes analyzing the component force normal to the cutter face of the at least one cutter without the component force tangent to the cutter face of the at least one cutter.

8. The method of claim 1 , wherein the outputted stress is based on a second order distribution of forces on the at least one cutter.

9. The method of claim 1 , wherein analyzing the fixed cutter drill bit further includes graphically displaying at least one aspect of the simulating.

10. A method for designing a fixed cutter drill bit, said method comprising:

(a) selecting bit design parameters;

(b) selecting an earth formation;

(e) selecting drilling parameters;

(d) simulating drilling performance of the fixed cutter drill bit having a plurality of cutters thereon, wherein simulating drilling performance simulates the fixed cutter drill bit drilling the earth formation;

(e) performing finite element analysis using outputs from the simulated drilling performance, the finite element analysis using a non-uniform depth of cut for the plurality of cutters of the fixed cutter drill bit;

(f) determining a stress on the plurality of cutters based on the finite element analysis;

(g) comparing a stress of at least one cutter of the plurality of cutters based on the non-uniform depth of cut to a stress resulting from an average depth of cut;

(h) outputting the stress on the at least one cutter; and

(i) manufacturing the fixed cutter drill bit based on the selected bit design parameters and including the plurality of cutters.

11. The method of claim 10 , further comprising adjusting at least one of the bit design parameters or at least one of the drilling parameters and repeating at least one of the simulating drilling performance or performing finite element analysis.

12. The method of claim 11 , further comprising repeating the adjusting until the stress has been reduced below a selected amount.

13. The method of claim 11 , further comprising repeating the adjusting until the resulting lateral force is less than 1% of the weight on bit.

14. The method of claim 10 , further comprising predicting cutter failure mode based on the stress.