Static and Cyclic Mechanical Behavior of 3D-Printed PEEK Under Tensile and Compressive Loads

Area of Science:

• Materials Science
• Biomedical Engineering
• Polymer Science

Background:

• Polyether ether ketone (PEEK) is a high-performance polymer valued for its mechanical properties.
• 3D printing enables patient-specific PEEK implants, but its fatigue behavior, especially under compression, is understudied.
• Understanding fatigue is crucial for PEEK's application in load-bearing biomedical devices.

Purpose of the Study:

• To investigate the static and dynamic mechanical performance of 3D-printed PEEK.
• To evaluate the effect of annealing on PEEK's mechanical properties and fatigue life.
• To establish the first S-N curve for 3D-printed PEEK under compressive loading.

Main Methods:

• Tensile and compression tests were performed on 3D-printed PEEK specimens with a ±45° raster orientation.
• Annealing treatment (270 °C for 5 h) was applied to assess its impact on material properties.
• Compression-compression fatigue tests (5 Hz and 2.5 Hz, R=0.1) and Micro-CT analysis were conducted.

Main Results:

• Annealing increased PEEK crystallinity but decreased tensile strength while increasing Young's modulus.
• Post-annealing, static compression strength improved significantly (80.1 MPa to 126.7 MPa), as did the modulus.
• Annealed specimens showed enhanced fatigue life, achieving infinite life at 83.3 MPa, and endured higher thermal loads during testing.

Conclusions:

• Annealing positively impacts the compressive mechanical performance and fatigue resistance of 3D-printed PEEK.
• The study provides the first compressive S-N curve for 3D-printed PEEK, crucial for design.
• 3D-printed PEEK, particularly after annealing, is a viable material for load-bearing biomedical applications subjected to cyclic compressive stress.