In below present, which I have presented in biomaterials class, I focused on the hashtag#fatigue behavior of hashtag#porous_metallic biomaterials and described the important factors on this behavior.

1. Fatigue Behavior of Porous
Metallic Biomaterials
By Arvin Taghizadeh Tabrizi
Spring 2018

2. Bone

3. Ideal Implant Materials
• Chemically Inert
• Non-Toxic to the Body
• Great Strength
• High Fatigue Resistance
• Low Elastic Modulus
• Corrosion Proof
• Good Wear Resistance
• Inexpensive
• Porous material received
considerable attention due to
their properties such as
• Low density
• Unique Functional Properties

4. Porous Metal
Porous
Metals
Thermal
Insulation
Energy/So
und
Absorbing
Bio
Packagin
g
Bone Like Structure Stress Shielding

5. Porous Metal Fabrication
Fabrication
Methods
Liquid
Gas Injection
Blowing Agent
Solid
Diffusion
Bonding
Powder
Sintering
Space Holder
Additive
Manufacturing

6. Porous Metal Fabrication

7. Porous Metal Fabrication

8. Porous Biomaterials
Titanium and its Alloys
Biocompatiable Properties
Smaller Stiffness values as much as nature Bone
Easy Body Fluid Transport & Subsequent Bone
Growth inside Porous Structure
Precise Control over Unit Cell Size &
Shape

9. Importance of Fatigue
Implants are usually loaded several
times in daily activities
Understanding their Fatigue
properties is importance
Compression-Compression Loads
Compression-Tensile Loads
Under Cyclic Lading condition during
walking and running
1
2

10. Literature Review
Row Year Name Description
1 2011 Hrabe Compression fatigue behavior of Porous Ti64 fabricated by Selective
Electron Beam Melting (SEBM)2 2013 Yavari
3 2015 Asik Compression fatigue behavior of Porous Ti64 fabricated by Space
Holder method
4 2012 Li Fatigue Failure Mechanism of Porous Ti64 fabricated by SEBM
5 2015 Wauthle Compared the quasi-static compressive & Fatigue properties
between porous pure Ti & porous Ti64
6 2016 Ozbilen Influence of interstitials on the compressive fatigue properties of
pure Ti fabricated by Space holder
Fabrication Method2Surface Roughness1

11. Investigation on Fatigue
The Effect of Surface Roughness
Most cracks occur on the node of the porous structures

12. Investigation on Fatigue
The Effect of Relative Density
Van Hooreweder et al.
Compression-Compression Mood with different densities
Axial Compressive
Compression-Tensile Mood

13. Investigation on Fatigue
The Effect of Relative Density
Relative Density3
Microstructure3-1
Improved ductility
the fatigue life decreases with increasing porosity

14. Investigation on Fatigue
The Effect of Microstructure
• Constituent Phases
• Grain Size & Shape
• Grain Boundary
• Mis-orientation Angle
between Adjacent Grains
Schmid Factor
Plastic
Deformation
• A higher value of the Schmid factor indicates that the grain is more favorably
oriented for slip. Clearly, most β grains in the sample present a large Schmid
factor in the range of 0.37-0.5

15. Investigation on Fatigue
The Effect of Pore & Porosity Size
the porosity and pore size has minor effect on the normalized S-N curves.
The reason for this minor effect can be illustrated by the failure
mechanism of porous titanium during compression fatigue test

16. Fatigue Failure Mechanisms
Fatigue Crack
Growth
Cyclic
Ratcheting
Cyclic ratcheting is the gradual strain accumulation owing to the
plastic deformation of strut during compression fatigue test
which means strain accumulation rate
is unchanged for porous titanium
the ratcheting rate is the main factor determining the
fatigue life of porous titanium.
McCullough

17. Conclusion
The observed critical stress amplitudes of porous NiTi
alloy samples, with varying relative densities, corresponds
to 140% of respective 0.2% proof strength indicating that
these samples can sustain cyclic compression fatigue
stresses up to 1.4 times their yield strength without
failure.
• Surface Roughness
• Fabrication Method
• Relative Density
• Microstructure: Schmid Factor
• Fatigue Mechanisms

18. References
[1] R. Hedayati, H. Hosseini-Toudeshky, M. Sadighi, M. Mohammadi-Aghdam, and A. A. Zadpoor,
“Computational prediction of the fatigue behavior of additively manufactured porous metallic
biomaterials,” Int. J. Fatigue, vol. 84, pp. 67–79, 2016.
[2] R. Hedayati, S. Amin Yavari, and A. A. Zadpoor, “Fatigue crack propagation in additively
manufactured porous biomaterials,” Mater. Sci. Eng. C, vol. 76, pp. 457–463, 2017.
[3] B. Van Hooreweder, Y. Apers, K. Lietaert, and J. P. Kruth, “Improving the fatigue performance
of porous metallic biomaterials produced by Selective Laser Melting,” Acta Biomater., vol. 47, pp.
193–202, 2017.
[4] J. de Krijger, C. Rans, B. Van Hooreweder, K. Lietaert, B. Pouran, and A. A. Zadpoor, “Effects of
applied stress ratio on the fatigue behavior of additively manufactured porous biomaterials under
compressive loading,” J. Mech. Behav. Biomed. Mater., vol. 70, pp. 7–16, 2017.
[5] S. Amin Yavari et al., “Fatigue behavior of porous biomaterials manufactured using selective
laser melting,” Mater. Sci. Eng. C, vol. 33, no. 8, pp. 4849–4858, 2013.
[6] R. Hedayati, S. Janbaz, M. Sadighi, M. Mohammadi-Aghdam, and A. A. Zadpoor, “How does
tissue regeneration influence the mechanical behavior of additively manufactured porous
biomaterials?,” J. Mech. Behav. Biomed. Mater., vol. 65, pp. 831–841, 2017.

19. References
[7] F. Li, J. Li, T. Huang, H. Kou, and L. Zhou, “Compression fatigue behavior and failure mechanism
of porous titanium for biomedical applications,” J. Mech. Behav. Biomed. Mater., vol. 65, pp. 814–
823, 2017.
[8] Y. J. Liu et al., “Compressive and fatigue behavior of beta-type titanium porous structures
fabricated by electron beam melting,” Acta Mater., vol. 126, pp. 58–66, 2017.
[9] S. Bernard, V. Krishna Balla, S. Bose, and A. Bandyopadhyay, “Compression fatigue behavior of
laser processed porous NiTi alloy,” J. Mech. Behav. Biomed. Mater., vol. 13, pp. 62–68, 2012.
[10] L. Vikingsson, J. A. Gómez-Tejedor, G. Gallego Ferrer, and J. L. Gómez Ribelles, “An experimental
fatigue study of a porous scaffold for the regeneration of articular cartilage,” J. Biomech., vol. 48,
no. 7, pp. 1310–1317, 2015.
[11] S. Bernard, V. K. Balla, S. Bose, and A. Bandyopadhyay, “Rotating bending fatigue response of
laser processed porous NiTi alloy,” Mater. Sci. Eng. C, vol. 31, no. 4, pp. 815–820, 2011.
[12] I. Apachitei, A. Leoni, A. C. Riemslag, L. E. Fratila-Apachitei, and J. Duszczyk, “Enhanced fatigue
performance of porous coated Ti6Al4V biomedical alloy,” Appl. Surf. Sci., vol. 257, no. 15, pp. 6941–
6944, 2011.

20. Thank you for your
Attention