scholarly journals Design and Performance Evaluation of Porous Titanium Alloy Structures for Bone Implantation

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Jianping Shi ◽  
Huixin Liang ◽  
Jie Jiang ◽  
Wenlai Tang ◽  
Jiquan Yang
Keyword(s):  
Elastic Modulus ◽  
Stress Shielding ◽  
Porous Titanium ◽  
Shielding Effect ◽  
Host Bone ◽  
Test Results ◽  
Porous Implant ◽  
Biomechanical Simulation ◽  
Design And Manufacturing ◽  
And Performance

Implant parts prepared by traditional design and manufacturing methods generally have problems of high stiffness and heavy self-weight, which may cause stress shielding effect between the implanted part and the host bone, and eventually cause loosening of the implanted part. Based on the implicit surface function equations, several porous implant models with controlled pore structure were designed. By adjusting the parameters, the apparent elastic modulus of the porous implant model can be regulated. The biomechanical simulation experiment was performed using CAE software to simulate the stress and elastic modulus of the designed models. The experimental results show that the apparent elastic modulus of the porous structure scaffold is close to that of the bone tissue, which can effectively reduce the stress shielding effect. In addition, the osseointegration status between the implant and the host bone was analyzed by implant experiment. The pushout test results show that the designed porous structures have a good osseointegration effect.

Microstructures and Elastic Moduli of Binary Titanium Alloys Containing Biocompatible Alloying Elements

2005 ◽  
Vol 475-479 ◽  
pp. 2291-2294 ◽  
Author(s):  
Hi Won Jeong ◽  
Seung Eon Kim ◽  
Yong Taek Hyun ◽  
Yont Tai Lee ◽  
Joong Kuen Park
Keyword(s):  
Elastic Modulus ◽  
Titanium Alloys ◽  
Elastic Moduli ◽  
Stress Shielding ◽  
Lattice Parameter ◽  
Alloying Elements ◽  
Shielding Effect ◽  
Dominant Factor ◽  
Transition Elements ◽  
Pulse Echo

New titanium alloys with a low elastic modulus have been developed for biomedical applications to avoid the stress shielding effect of an artificial prosthesis. The newly developed alloys contained the transition elements like Zr, Hf, Nb, Ta which were non-cytotoxicity elements and β stabilizers. In the present paper the elastic moduli of Ti-xM containing Zr, Hf, Nb, Ta were evaluated by measuring the velocity of supersonic wave (Pulse Echo Overlap). The effectiveness of the alloying elements for lowering the elastic modulus was investigated. In addition, the dominant factors for the low modulus were discussed. Ta was the most effective in lowering the elastic modulus of the alloys. The effectiveness of Hf was not acceptable for decreasing the elastic modulus. The dominant factor was the lattice parameter for Zr, and the poisson's ratio for Nb, Ta, respectively, in lowering the elastic modulus of Ti.

scholarly journals Finite Element Analysis of Porous Ti-6Al-4V Alloy Structures for Biomedical Applications

2021 ◽  
Vol 2070 (1) ◽  
pp. 012224
Author(s):  
N Ganesh ◽  
S Rambabu
Keyword(s):  
Finite Element ◽  
Elastic Modulus ◽  
Cortical Bone ◽  
Bone Ingrowth ◽  
Stress Shielding ◽  
Shielding Effect ◽  
Element Analysis ◽  
Human Cortical Bone ◽  
Porous Ti ◽  
Manufacturing Technologies

Abstract In this article, design and finite element simulation of porous Ti-6Al-4V alloy structures was presented. Typically, titanium and titanium alloy implants can be manufactured with required pore size and porosity volume by using powder bed fusion techniques due to advancement in additive manufacturing technologies. However, the mismatch of elastic modulus between human cortical bone and the dense Ti-6Al-4V alloy implant resulted in stress shielding which accelerate the implant failure. The porous implant structures help in reduce the mismatch of elastic modulus between the cortical bone and implant structure and also improve the bone ingrowth. Hence, the present work focuses on design of Ti-6Al-4V alloy porous structures with various porosities ranging from 10% to 70% and simulated to determine the elastic modulus suitable for human cortical bone. The sample with 45% porosity is found to be best suited for replacement of cortical bone with elastic modulus of 74Gpa, preventing stress shielding effect and enhanced chances of bone ingrowth.

scholarly journals Mechanical property of octahedron Ti6Al4V fabricated by selective laser melting

2021 ◽  
Vol 60 (1) ◽  
pp. 894-911
Author(s):  
Yun Zhai ◽  
Sibo He ◽  
Lei Lei ◽  
Tianmin Guan
Keyword(s):  
Mechanical Property ◽  
Elastic Modulus ◽  
Selective Laser Melting ◽  
Mechanical Performance ◽  
Lattice Structure ◽  
Stress Shielding ◽  
Human Bone ◽  
Shielding Effect ◽  
Basic Unit ◽  
Laser Melting

Abstract The stress shielding effect is a critical issue for implanted prosthesis due to the difference in elastic modulus between the implanted material and the human bone. The adjustment of the elastic modulus of implants by modification of the lattice structure is the key to the research in the field of implanted prosthesis. Our work focuses on the basic unit structure of octahedron Ti6Al4V. The equivalent elastic modulus and equivalent density of porous structure are optimized according to the mechanical properties of human bone tissue by adjusting the edge diameter and side length of octahedral lattice. Macroscopic long-range ordered arrangement of lattice structures is fabricated by selective laser melting (SLM) technology. Finite element simulation is performed to calculate the mechanical property of octahedron Ti6Al4V. Scanning electronic microscopy is applied to observe the microstructure of octahedron alloy and its cross section morphology of fracture. Standard compression test is performed for the stress–strain behavior of the specimen. Our results show that the octahedral lattice with the edge diameter of 0.4 mm and unit cell length of 1.5 mm has the best mechanical property which is close to the human bone. The value of equivalent elastic modulus increases with the increase in the edge diameter. The SLM technology proves to be an effective processing way for the fabrication of complex microstructures with porosity. In addition, the specimen exhibits isotropic mechanical performance and homogeneity which significantly meet the requirement of implanted prosthetic medical environment.

Effect of β-Stabilizing Transition Elements on Elastic Modulus of Ti-M Systems

2004 ◽  
Vol 449-452 ◽  
pp. 865-868 ◽  
Author(s):  
Hi Won Jeong ◽  
Y.S. Kim ◽  
Seung Eon Kim ◽  
Yong Taek Hyun ◽  
Yont Tai Lee ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Titanium Alloys ◽  
Stress Shielding ◽  
Shielding Effect ◽  
Transition Elements ◽  
Generalized Gradient ◽  
First Principle Calculation ◽  
Treatment Conditions ◽  
Low Elastic Modulus ◽  
Artificial Prosthesis

New titanium alloys with a low elastic modulus have been developed for biomedical applications to avoid the stress shielding effect of the artificial prosthesis. The newly developed alloys contained the transition elements like Nb, Ta, Zr which were non-cytotoxicity elements. These elements produced β, ω, and α'' phases with heat treatment conditions in titanium alloys and determined the elastic modulus of the alloys. However, the clear mechanism of the low elastic modulus alloys has not been known. In the present paper, the total energy and elastic modulus of β and α'' phases were calculated using a first principle calculation employing the generalized gradient approximation (GGA). The mechanism of the low elastic modulus was discussed with calculated values.

Optimization of custom cementless stem using finite element analysis and elastic modulus distribution for reducing stress-shielding effect

2017 ◽  
Vol 231 (2) ◽  
pp. 149-159 ◽  
Author(s):  
Gurunathan Saravana Kumar ◽  
Subin Philip George
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Elastic Modulus ◽  
Stress Shielding ◽  
Von Mises Stress ◽  
Shielding Effect ◽  
Implant Design ◽  
Element Analysis ◽  
Von Mises ◽  
Reducing Stress

This work proposes a methodology involving stiffness optimization for subject-specific cementless hip implant design based on finite element analysis for reducing stress-shielding effect. To assess the change in the stress–strain state of the femur and the resulting stress-shielding effect due to insertion of the implant, a finite element analysis of the resected femur with implant assembly is carried out for a clinically relevant loading condition. Selecting the von Mises stress as the criterion for discriminating regions for elastic modulus difference, a stiffness minimization method was employed by varying the elastic modulus distribution in custom implant stem. The stiffness minimization problem is formulated as material distribution problem without explicitly penalizing partial volume elements. This formulation enables designs that could be fabricated using additive manufacturing to make porous implant with varying levels of porosity. Stress-shielding effect, measured as difference between the von Mises stress in the intact and implanted femur, decreased as the elastic modulus distribution is optimized.

scholarly journals Titanium Scaffolds by Direct Ink Writing: Fabrication and Functionalization to Guide Osteoblast Behavior

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1156
Author(s):  
Elia Vidal ◽  
Diego Torres ◽  
Jordi Guillem-Marti ◽  
Giuseppe Scionti ◽  
José María Manero ◽  
...  
Keyword(s):  
Stress Shielding ◽  
Total Porosity ◽  
Porous Titanium ◽  
Shielding Effect ◽  
Sintering Process ◽  
Thermosensitive Hydrogel ◽  
Recombinant Fragment ◽  
Direct Ink Writing ◽  
A Cell ◽  
Good Biocompatibility

Titanium (Ti) and Ti alloys have been used for decades for bone prostheses due to its mechanical reliability and good biocompatibility. However, the high stiffness of Ti implants and the lack of bioactivity are pending issues that should be improved to minimize implant failure. The stress shielding effect, a result of the stiffness mismatch between titanium and bone, can be reduced by introducing a tailored structural porosity in the implant. In this work, porous titanium structures were produced by direct ink writing (DIW), using a new Ti ink formulation containing a thermosensitive hydrogel. A thermal treatment was optimized to ensure the complete elimination of the binder before the sintering process, in order to avoid contamination of the titanium structures. The samples were sintered in argon atmosphere at 1200 °C, 1300 °C or 1400 °C, resulting in total porosities ranging between 72.3% and 77.7%. A correlation was found between the total porosity and the elastic modulus of the scaffolds. The stiffness and yield strength were similar to those of cancellous bone. The functionalization of the scaffold surface with a cell adhesion fibronectin recombinant fragment resulted in enhanced adhesion and spreading of osteoblastic-like cells, together with increased alkaline phosphatase expression and mineralization.

scholarly journals The Effect of Graphene Nanofiller on the Surface Structure and Performance of Epoxy Resin–Polyhedral Oligomeric Silsesquioxane (EP-POSS)

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 841
Author(s):  
Yanhong Fang ◽  
Ping Wang ◽  
Lifang Sun ◽  
Linhong Wang
Keyword(s):  
Epoxy Resin ◽  
Surface Structure ◽  
Polyhedral Oligomeric Silsesquioxane ◽  
Shielding Effect ◽  
Coating Film ◽  
Test Results ◽  
Cage Structure ◽  
And Performance ◽  
Oligomeric Silsesquioxane ◽  
Epoxy Groups

Epoxy resin–polyhedral oligomeric silsesquioxane (EP-POSS) has excellent mechanical properties and hydrophobic properties. In order to adapt for application in sensor and photovoltaic fields, graphene, nano-SiO2 and nano-ZnO were used to modify EP-POSS. FTIR was used to characterize changes on the surface structure after introducing nanoparticles. The change of hydrophobicity was measured using a contact angle test. TEM test results showed that nanoparticles were successfully inserted between the graphene sheets. However, the content of Si on the surface was low, as the cage structure of POSS in the molecular chain was coated by epoxy groups. XRD tests indicated that nanoparticles facilitated the dispersion of graphene in EP-POSS. XPS characterized the chemical state and content of the elements, confirming that the addition of graphene can induce the enrichment of Si on the surface of EP-POSS, which had a shielding effect on the main chain and improved the hydrophobicity. Wear resistance and adhesion tests showed that, after the introduction of nanoparticles, the EP-POSS coating film met the requirements of graphene materials.

scholarly journals Biocompatibility and Biological Corrosion Resistance of Ti–39Nb–6Zr+0.45Al Implant Alloy

2020 ◽  
Vol 12 (1) ◽  
pp. 2
Author(s):  
Yu-Jin Hwang ◽  
Young-Sin Choi ◽  
Yun-Ho Hwang ◽  
Hyun-Wook Cho ◽  
Dong-Geun Lee
Keyword(s):  
Corrosion Resistance ◽  
Elastic Modulus ◽  
Stress Shielding ◽  
Physiological Saline ◽  
Shielding Effect ◽  
Biomedical Implant ◽  
Implant Material ◽  
Biological Corrosion

Titanium and titanium alloys are promising implant metallic materials because of their high strengths, low elastic moduli, high corrosion resistances, and excellent biocompatibilities. A large difference in elastic modulus between the implant material and bone leads to a stress shielding effect, which increases the probability of implant separation or decrease in the bone density around it. Thus, a lower elastic modulus is required for a better implant metallic material. β titanium has a lower elastic modulus and high strength and can reduce the probability of the stress shielding effect. In this study, the applicability of the Ti–39Nb–6Zr+0.45Al alloy, obtained by adding a small amount of aluminum to the Ti–39Nb–6Zr alloy, as a biomedical implant material was evaluated. The mechanical properties and biocompatibility of the alloy were evaluated. The biocompatibility of Ti–39Nb–6Zr+0.45Al was similar to that of Ti–39Nb–6Zr according to in vitro and in vivo experiments. In addition, the biological corrosion resistances were evaluated through a corrosion test using a 0.9% NaCl solution, which is equivalent to physiological saline. The corrosion resistance was improved by the addition of Al. The yield strength of the Ti–39Nb–6Zr+0.45Al alloy was improved by approximately 20%. The excellent biocompatibility confirmed its feasibility for use as a biomedical implant material.

scholarly journals Development of Zirconium-Based Alloys with Low Elastic Modulus for Dental Implant Materials

2019 ◽  
Vol 9 (24) ◽  
pp. 5281
Author(s):  
Minsuk Kim ◽  
Seongbin An ◽  
Chaeeul Huh ◽  
Chungseok Kim
Keyword(s):  
Elastic Modulus ◽  
Stress Shielding ◽  
Melting Process ◽  
Shielding Effect ◽  
X Ray Diffraction ◽  
Two Phase ◽  
Arc Melting ◽  
Pure Zirconium ◽  
Low Modulus ◽  
The Difference

The stress-shielding effect is a phenomenon in which the mutual coupling between bones and bio-materials of the human body is loosened due to the difference in elastic modulus, and bone absorption occurs due to the difference in density, which causes a shortening of the life of the material. The purpose of this study is to develop a zirconium-based alloy with low modulus and to prevent the stress-shielding effect. Zr–7Cu–xSn (x = 1, 5, 10, 15 mass%) alloys were prepared by an arc-melting process of pure zirconium, oxygen-free copper, and tin, respectively. The Zr–7Cu–xSn alloy has two phase α-Zr and Zr2Cu intermetallic compounds. Microstructure characterization was analyzed by microscopy and X-ray diffraction. Corrosion tests of zirconium-based alloys were conducted through polarization tests, and zirconium-based alloys had better corrosion characteristics than other metal bio-materials. In general, the elastic modulus value (14–25 GPa) of the zirconium-based alloy is very similar to the elastic modulus value (15–30 GPa) of the human bone. Consequently, the zirconium-based alloy is likely to be used as a bio-material that negates the effect of stress shielding on human bones.

scholarly journals Additive Manufacturing of Porous Ti6Al4V Alloy: Geometry Analysis and Mechanical Properties Testing

2021 ◽  
Vol 11 (6) ◽  
pp. 2611
Author(s):  
Radovan Hudák ◽  
Marek Schnitzer ◽  
Zuzana Orságová Králová ◽  
Radka Gorejová ◽  
Lukáš Mitrík ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloy ◽  
Additive Manufacturing ◽  
Pore Size ◽  
Maximum Stress ◽  
Stress Shielding ◽  
Porous Titanium ◽  
Shielding Effect ◽  
High Porosity ◽  
Actual Weight

This work is devoted to the research of porous titanium alloy structures suitable for use in biomedical applications. Mechanical properties were examined on six series of samples with different structures and porosity via static compressive test to identify the type of structure suitable for elimination of the “stress shielding” effect. In addition, high porosity is desirable due to the overgrowth of bone tissue into the internal structure of the implant. The samples were made of titanium alloy Ti6Al4V by using selective laser melting (SLM) additive manufacturing. The series of samples differ from each other in pore size (200, 400, and 600 µm) and porous structure topology (cubic or trabecular). The actual weight of all samples, which plays an important role in identifying other characteristics, was determined. Compressive tests were focused on the detection of maximum stress. The highest porosity and thus the lowest weight were achieved in the samples with a trabecular structure and 600 µm pore size. All tested samples reached optimal values of maximum stress and tensile strength. The most appropriate mechanical properties were observed for samples with a 200 µm pore diameter and cubic structure.

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