1. CASE STUDY – Combined Loading Drill bit isolators for underground mining – all metal components and elastomer must be safe! Design requirement: 8,000 lb thrust load and 300 lb-ft (3,600 lb-in) torque – these are basically the cutting forces. Detailed FE analysis but ALWAYS verify with hand calculations!!

2. Drill Depth up to 48” Bit Isolator Chuck Isolator 2010 SME Annual Meeting & Exhibit Phoenix, Arizona

3. 35 mm (1 3/8 in) Isolator Load Requirements: Drill Bit Isolator ( Thrust Load = 8,000 to 10,000 lb Bending Load= 125 lbs)= K*  Torsion Load= 300 lb-ft Drill Rod Chuck Isolator Drill Bit HOT SPOT! 2010 SME Annual Meeting & Exhibit Phoenix, Arizona

4. Results showed that in combination, the bit isolator and the drill chuck isolator provided a 7 dB(A) reduction in sound pressure level at the operator position. 2010 SME Annual Meeting & Exhibit Phoenix, Arizona

5. 60 65 70 75 80 85 90 95 100 105 110 250315400500630800 1000125016002000250031504000500063008000 10000 Overall 1/3-Octave-Band Center Frequency (Hz) A-weighted Sound Level (dB) 108.9 dB(A) Baseline: 104.4 dB(A)T2 - 45 NR BISO, 45 NR CISO: 102.7 dB(A)T5 - 55 NR BISO, 55 NR CISO: 104.4 dB(A) T7 - 70 NR BISO, 70 NR CISO: A-weighted Sound Level Spectrum 2010 SME Annual Meeting & Exhibit Phoenix, Arizona

6. 6 1 3/8" DBI, R. Michael, PE 1 3/8” Drill Bit Isolator – Design Review: Chuck isolator: Drill Bit isolator: 2010 SME Annual Meeting & Exhibit Phoenix, Arizona

7. 78/9/2015 1 3/8" DBI, R. Michael, PE Look at metal components: Where would you expect max stress to occur? Critical Area!!

8. Critical component – inner member, thin wall, stress concentration!

9. Results: FE Analysis 1 3/8” DBI All cases, thurst load = 8,000 lb, torque = 300 lb-ft (3,600 lb-in) 98/9/2015 1 3/8" DBI, R. Michael, PE HOT SPOT!

10. Max Principal,  1 Min Principal,  1

11. Max shear stress,  max VERIFY FEA RESULTS WITH HAND CALCS!!!!

12. Verify Principal Stresses with Hand Calculations or Mohr’s Circle!! Thrust Load = 8,000 to 10,000 lb Torsion Load= 300 lb-ft HOT SPOT! y x

13. From Axial Load (Compression) From Torque HAND CALCS:

14. Principal Stresses: =-11.95 +/- 35.8 ksi HAND CALCS Cont’d: How do these values compare with FEA results? Next: use Mohr’s circle to resolve