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PEEK Fatigue Resistance: Long-Term Performance in Dynamic Applications
PEEK Fatigue Properties
Grade | Fatigue Limit (MPa, 10⁷ cycles) | Ratio to Tensile Strength |
PEEK (unfilled) | 55-65 | 60-65% |
PEEK GF30 | 75-85 | ~50% |
PEEK CF30 | 90-100 | ~45% |
PEEK has the highest fatigue limit among common engineering plastics — approximately 2× higher than POM and 2.5× higher than PA66.
Factors Affecting Fatigue Performance
Temperature
At 150°C, fatigue strength drops ~30%. At 250°C, ~50% of room temperature values.
Stress Concentration
Sharp notches (Kt=3) reduce fatigue strength by 40-50%. Use generous fillet radii (≥0.5× wall thickness).
Surface Finish
Polished surfaces (Ra < 0.8 μm) improve fatigue life by 20-30%. See surface finish guide.
Frequency
High frequencies (>10 Hz) cause hysteresis heating, reducing fatigue life.
Design Guidelines
1. Design using S-N curves, not static strength
2. Apply safety factors: 2.0-3.0 for critical applications
3. Minimize stress concentrations — use generous fillets
4. Specify polished surfaces at critical areas
5. Consider filled grades for higher fatigue strength
6. Account for temperature derating
Applications
· Aerospace: Bearing cages, structural brackets (vibration)
· Automotive: Seal rings (pressure cycling), gears (meshing)
· Industrial: Pump impellers, valve seats, compressor components
· Oil & Gas: See PEEK in oil & gas
FAQ
Q1: Fatigue limit of PEEK?
Unfilled: 55-65 MPa at 10⁷ cycles. GF30: 75-85 MPa. CF30: 90-100 MPa — highest among engineering plastics.
Q2: Temperature effect?
At 150°C: -30%. At 250°C: ~50% of room temperature values.
Q3: PEEK vs other plastics?
~2× higher than POM, ~2.5× higher than PA66. Superior fatigue-to-tensile ratio.
Ready to source quality engineering plastics? Contact NAGOMER today for a free quote, or browse our PEEK sheets, POM rods, and ESD materials.
NAGOMER — Professional Engineering Plastics Solutions
www.nagomer.com | info@nagomer.com