TWU String Testing Procedure

• 1. Tests: twelve dynamic impact tests are performed on each string:
  • 62 lbs reference tension slow speed impact
  • 62 lbs reference tension medium speed impact
  • 62 lbs reference tension fast speed impact
  • Prestretched 62 lbs reference tension slow speed impact
  • Prestretched 62 lbs reference tension medium speed impact
  • Prestretched 62 lbs reference tension fast speed impact
  • 51 lbs reference tension slow speed impact
  • 51 lbs reference tension medium speed impact
  • 51 lbs reference tension fast speed impact
  • 40 lbs reference tension slow speed impact
  • 40 lbs reference tension medium speed impact
  • 40 lbs reference tension fast speed impact
• 2. String length: Cut new test string of length = 330 mm.
• 3. Tension: string tensioned to reference tension.
• 4. Elongation: measure immediately after tensioning.
• 5. Static wait period: wait 60 seconds and record tension.
• 6. Stabilization impacts: 20 high speed (equal to force on a string during a 120 mph serve) impacts on string. Record tension after.
• 7. Test impacts: slow, medium, fast speed impacts in that order. Tensions, duration, forces, deflections, velocities all recorded.
• 8. Prestretch: After tests all performed on 62 lb string, raise tension back up to 62 and perform steps 5, 6, and 7 again.
• 9. Repeat: Repeat 2-7 for reference tensions of 51 and 40 pounds (prestretch not performed on these tensions).