title: Failure mechanisms of additively manufactured porous biomaterials: Effects of porosity and type of unit cell.
abstract: Since the advent of additive manufacturing techniques, regular porous biomaterials have emerged as promising candidates for tissue engineering scaffolds owing to their controllable pore architecture and feasibility in producing scaffolds from a variety of biomaterials. The architecture of scaffolds could be designed to achieve similar mechanical properties as in the host bone tissue, thereby avoiding issues such as stress shielding in bone replacement procedure. In this paper, the deformation and failure mechanisms of porous titanium (Ti6Al4V) biomaterials manufactured by selective laser melting from two different types of repeating unit cells, namely cubic and diamond lattice structures, with four different porosities are studied. The mechanical behavior of the above-mentioned porous biomaterials was studied using finite element models. The computational results were compared with the experimental findings from a previous study of ours. The Johnson-Cook plasticity and damage model was implemented in the finite element models to simulate the failure of the additively manufactured scaffolds under compression. The computationally predicted stress-strain curves were compared with the experimental ones. The computational models incorporating the Johnson-Cook damage model could predict the plateau stress and maximum stress at the first peak with less than 18% error. Moreover, the computationally predicted deformation modes were in good agreement with the results of scaling law analysis. A layer-by-layer failure mechanism was found for the stretch-dominated structures, i.e. structures made from the cubic unit cell, while the failure of the bending-dominated structures, i.e. structures made from the diamond unit cells, was accompanied by the shearing bands of 45°.
authors.affiliation: Department of Mechanical Engineering, Shahid Rajaee Teacher Training University, Tehran, Iran; Institute for Materials Testing, Materials Science and Strength of Materials (IMWF), University of Stuttgart, Stuttgart, Germany. Electronic address: j.kad@srttu.edu.
authors.forename: J
authors.initials: J
authors.lastname: Kadkhodapour
authors.affiliation: Department of Mechanical Engineering, Shahid Rajaee Teacher Training University, Tehran, Iran.
authors.forename: H
authors.initials: H
authors.lastname: Montazerian
authors.affiliation: Department of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran.
authors.forename: A Ch
authors.initials: ACh
authors.lastname: Darabi
authors.affiliation: Department of Mechanical Engineering, Shahid Rajaee Teacher Training University, Tehran, Iran.
authors.forename: A P
authors.initials: AP
authors.lastname: Anaraki
authors.affiliation: Department of Biomechanical Engineering, Delft University of Technology, Mekelweg 2, Delft 2628CD, The Netherlands.
authors.forename: S M
authors.initials: SM
authors.lastname: Ahmadi
authors.affiliation: Department of Biomechanical Engineering, Delft University of Technology, Mekelweg 2, Delft 2628CD, The Netherlands.
authors.forename: A A
authors.initials: AA
authors.lastname: Zadpoor
authors.affiliation: Institute for Materials Testing, Materials Science and Strength of Materials (IMWF), University of Stuttgart, Stuttgart, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Schmauder
mesh_terms: D000497:Alloys; D001672:Biocompatible Materials / Q000737:chemistry*; D019245:Compressive Strength; D007834:Lasers; D055595:Mechanical Phenomena; D008958:Models, Molecular; D008968:Molecular Conformation; D016062:Porosity; D013314:Stress, Mechanical; D014025:Titanium / Q000737:chemistry
chemical_list: D000497:Alloys; D001672:Biocompatible Materials; C031462:titanium alloy (TiAl6V4); D014025:Titanium
keywords: Bone substitutes; Cellular biomaterials; Lattice structures; Selective laser melting; The Johnson–Cook damage model; Ti6Al4V