How to improve fatigue resistance?

This property is especially crucial when it comes to plastics subjected to fluctuating loads over time, such as in automotive, aerospace, and industrial machinery components. 

• Longevity & reliability: For parts in automotive, appliances, or industrial machinery, maintenance intervals and failure rates are dominated by fatigue life
• Moving parts & cyclic stress: Components like hinges, seals, connectors, or vibration-exposed structural parts must endure repetitive motion without fatigue failure
• Weight reduction & multifunction design: Using lightweight plastics or composites often increases stress per cycle; good fatigue resistance lets designers push weight lower without compromising durability

What factors influence fatigue resistance?

• Polymer structure: Polymers with flexible molecular backbones or lower crosslink density tend to fare better under cyclic loading
• Crystallinity & morphology: Semi-crystalline plastics can offer higher stiffness but may have weak interfaces or crystalline boundaries that are crack initiation sites under fatigue
• Reinforcements: Fiber reinforcements, nano-fillers, or hybrid fillers can help share load and slow fatigue crack growth
• Thermal & environmental stress: Exposure to elevated temperatures, moisture, UV, chemicals can accelerate fatigue damage
• Design & geometry: Sharp corners, stress concentrators, surface defects drastically reduce fatigue life; proper design avoids these