Studies on Porous Titanium Alloy Implant Manufactured by Three Dimensional Solid Freeform Fabrication System

2007 ◽  
Vol 29-30 ◽  
pp. 107-110 ◽  
Author(s):  
K.K. Lim ◽  
P. Cheang ◽  
M. Chandrasekaran
Keyword(s):  
Solid Freeform Fabrication ◽  
Three Dimensional ◽  
Weight Ratio ◽  
High Strength ◽  
Porous Titanium ◽  
Water Soluble ◽  
Ti Alloy ◽  
Mechanically Alloyed ◽  
Freeform Fabrication ◽  
Ti Alloys

Titanium (Ti) alloys have emerged to become valuable biomaterials for biomedical and orthopedic applications due to their high strength to weight ratio, excellent biocompatibility and corrosion resistance. In this study, the authors utilized Solid Freeform Fabrication (SFF), also commonly known as a rapid prototyping technology to investigate a new porous three-dimensional (3D) Ti alloy implant. Elemental powders for producing a Ti-Al-Fe-Zr alloy were mechanically alloyed and blended with water soluble binder material. The blended powders were manufactured by Three Dimensional Printer (3DP), followed by debinding and sintering in an inert environment. The effects of process parameters on structural and geometrical requirements were assessed. Results from these investigations demonstrated that Ti alloys are promising biomaterials for near net shape fabrication of porous 3D implants, which retained their interconnected pore network. As an illustration, complex geometries of porous 3D Ti alloy specimens were manufactured as a demonstration of 3D SFF System.

Research on Titanium Alloys with High Toughness and High Damage Tolerance

2009 ◽  
Vol 618-619 ◽  
pp. 97-100
Author(s):  
Yong Qing Zhao ◽  
Heng Lei Qu ◽  
Jun Chen
Keyword(s):  
Damage Tolerance ◽  
Rapid Development ◽  
Crack Propagation Rate ◽  
High Strength ◽  
High Fracture Toughness ◽  
Ti Alloy ◽  
Chinese Market ◽  
High Fracture ◽  
High Toughness ◽  
Ti Alloys

The recent shift in the design focus for aeroplanes from strength to damage tolerance has led to a subsequent shift in the focus of Ti alloy research. China first started to research Ti alloys with damage tolerance from the year 2000. The first product stemming from this research is a Ti alloy with high strength, high toughness and damage tolerance (TC21). TC21 exhibits high strength (UTS  1100MPa), high fracture toughness (K1c  70MPa.m1/2) and a low crack propagation rate (da/dN being similar to Ti-6-4 with  annealing). Another Ti alloy, named TC4-DT, has also been produced. It has moderate strength, along with high toughness and damage tolerance (UTS  900MPa, K1c  70MPa.m1/2, da/dN being similar to Ti-6-4 with  annealing). Both TC21 and TC4-DT are now undergoing rapid development, with the former alloy also being applied to a full scale aeronautical application. Both TC21 and TC4-DT have promising futures in the industry. They will be the main Ti alloys with damage tolerance utilised in the Chinese market.

A Novel Packing Hollow Dodecahedron Model to Study the Mechanical and Thermal Properties of Stocastic Metallic Foams

2021 ◽  
Author(s):  
Rui Dai ◽  
Beomjin Kwon ◽  
Qiong Nian
Keyword(s):  
Thermal Properties ◽  
Physical Properties ◽  
Three Dimensional ◽  
Weight Ratio ◽  
High Strength ◽  
Specific Area ◽  
Deposition Process ◽  
Metallic Foam ◽  
Thermal Testing ◽  
Mechanical And Thermal Properties

Abstract Stochastic foam with hierarchy order pore structure possesses distinguished physical properties such as high strength to weight ratio, super lightweight, and extremely large specific area. These exceptional properties make stochastic foam as a competitive material for versatile applications e.g., heat exchangers, battery electrodes, automotive components, magnetic shielding, catalyst devices and etc. Recently, the more advanced hollow cellular (shellular) architectures with well-developed structure connections are studied and expected to surpass the solid micro/nanolattices. However, in terms of theoretical predicting and studying of the cellular foam architecture, currently no systematic model can be utilized to accurately capture both of its mechanical and thermal properties especially with hollow struts due to complexity induced by its stochastic and highly reticulate nature. Herein, for the first time, a novel packing three-dimensional (3D) hollow dodecahedron (HPD) model is proposed to simulate the cellular architecture. An electrochemical deposition process is utilized to manufacture the metallic foam with hollow struts. Mechanical and thermal testing of the as-manufactured foams are carried out to compare with the HPD model. HPD model is proved to accurately capture both the topology and the physical properties of stochastic foam at the similar relative density. Particularly, the proposed model makes it possible to readily access and track the physical behavior of stochastic foam architecture. Accordingly, this work will also offer inspiration for designing an efficient foam for specific applications.

An assessment into mechanical properties and microstructural behavior of TIG welded Ti-6Al-4V titanium alloy

2020 ◽  
Vol 10 (3) ◽  
pp. 281-292 ◽  
Author(s):  
Saurabh Dewangan ◽  
Suraj Kumar Mohapatra ◽  
Abhishek Sharma
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Weight Ratio ◽  
High Strength ◽  
Hardness Test ◽  
Content Type ◽  
Ti Alloys ◽  
Microstructure And Mechanical Properties ◽  
Grade 5 ◽  
Selection Of

PurposeTitanium (Ti) alloys are in high demand in manufacturing industries all over the world. The property like high strength to weight ratio makes Ti alloys highly recommended for aerospace industries. Ti alloys possess good weldability, and therefore, they were extensively investigated with regard to strength and metallurgical properties of welded joint. This study aims to deal with the analysis of strength and microstructural changes in Ti-6Al-4V (Grade 5) alloy after tungsten inert gas (TIG) welding.Design/methodology/approachTwo pair of Ti alloy plates were welded in two different voltages, i.e. 24 and 28 V, with keeping the current constant, i.e. 80 A It was a random selection of current and voltage values to check the performance of welded material. Both the welded plates were undergone through some mechanical property analysis like impact test, tensile test and hardness test. In addition, the microstructure of the welded joints was also analyzed.FindingsIt was found that hardness and tensile properties gets improved with an increment in voltage, but this effect was reverse for impact toughness. A good corroboration between microstructure and mechanical properties, such as tensile strength, hardness and toughness, was reported in this work. Heat distribution in both the welded plates was simulated through ANSYS software to check the temperature contour in the plates.Originality/valueA good corroboration between microstructure and mechanical properties, such as tensile strength, hardness and toughness, was reported in this study.

Modeling of Spatially Controlled Biomolecules in Three-Dimensional Porous Alginate Structures

2010 ◽  
Vol 4 (4) ◽  
Author(s):  
Ibrahim T. Ozbolat ◽  
Bahattin Koc
Keyword(s):  
Computer Aided Design ◽  
Solid Freeform Fabrication ◽  
Imaging Techniques ◽  
Release Kinetics ◽  
Three Dimensional ◽  
Control Release ◽  
Stochastic Approach ◽  
Distribution Characteristics ◽  
Porous Structures ◽  
Freeform Fabrication

This paper presents a computer-aided design (CAD) of 3D porous tissue scaffolds with spatial control of encapsulated biomolecule distributions. A localized control of encapsulated biomolecule distribution over 3D structures is proposed to control release kinetics spatially for tissue engineering and drug release. Imaging techniques are applied to explore distribution of microspheres over porous structures. Using microspheres in this study represents a framework for modeling the distribution characteristics of encapsulated proteins, growth factors, cells, and drugs. A quantification study is then performed to assure microsphere variation over various structures under imaging analysis. The obtained distribution characteristics are mimicked by the developed stochastic modeling study of microsphere distribution over 3D engineered freeform structures. Based on the stochastic approach, 3D porous structures are modeled and designed in CAD. Modeling of microsphere and encapsulating biomaterial distribution in this work helps develop comprehensive modeling of biomolecule release kinetics for further research. A novel multichamber single nozzle solid freeform fabrication technique is utilized to fabricate sample structures. The presented methods are implemented and illustrative examples are presented in this paper.

A Computational Design Framework for a Rapid Solid Freeform Fabrication Process

2000 ◽  
Author(s):  
Deepesh Khandelwal ◽  
T. Kesavadas
Keyword(s):  
Solid Freeform Fabrication ◽  
Optimization Technique ◽  
Three Dimensional ◽  
Computational Design ◽  
Freeform Fabrication ◽  
3D Cad ◽  
Build Time ◽  
Cad Models ◽  
Efficient Machine ◽  
Novel Concept

Abstract Solid Freeform Fabrication (SFF) techniques in recent years have shown tremendous promise in reducing the design time of products. This technique enables designers to get three-dimensional physical prototypes from 3D CAD models. Although SFF has gained popularity, the manufacturing time and cost have limited its use to small and medium sized parts. In this paper we have proposed a novel concept for rapidly building SFF parts by inserting prefabricated inserts into the fabricated part. A computational algorithm was developed for determining ideal placement of inserts/cores in the CAD model of the part being prototyped using a heuristic optimization technique called Simulated Annealing. This approach will also allow the designers to build multi-material prototypes using the Rapid Prototyping (RP) technique. By using cheaper pre-fabricates instead of costly photopolymers, the production cost of the SFFs can be reduced. Additionally it will also reduce build time, resulting in efficient machine utilization.

Fatigue in Ti-6Al-4V at Very High Cycles

2007 ◽  
Vol 561-565 ◽  
pp. 259-262 ◽  
Author(s):  
X.J. Cao ◽  
M.R. Sriraman ◽  
Qing Yuan Wang
Keyword(s):  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Weight Ratio ◽  
High Strength ◽  
Ambient Air ◽  
Ti Alloys ◽  
Structural Applications ◽  
Ultrasonic Fatigue ◽  
Reversed Loading ◽  
Very High

The importance of determining and understanding the very high cycle fatigue behaviors of materials has gained strength in recent years. Ti-alloys, in view of their high strength-to-weight ratio, have a range of structural applications. Of these, Ti-6Al-4V, belonging to the alpha-beta type is the most widely used. The present paper deals with investigations on the fatigue behavior of TC4, the Chinese equivalent to Ti-6Al-4V, up to very high cycles. Fatigue testing was carried out on a piezoelectric ultrasonic fatigue machine operating at 20 kHz frequency. Hourglass shaped resonant specimens were tested in ambient air at room temperature under completely reversed loading conditions (R = -1). Failure in the alloy was seen to occur right up to the gigacycle regime, with the fractures being found to initiate from the surface unlike in steels. The fracture surfaces exhibit brittle characteristics containing river patterns and cleavage facets, as well as striations.

Direct Freeform Fabrication Technique for Bio-Manufacturing of Pre-Seeded, Spatially Heterogeneous, Anatomically-Shaped Alginate Hydrogel Implants

2005 ◽  
Author(s):  
Daniel L. Cohen ◽  
Evan Malone ◽  
Hod Lipson ◽  
Lawrence J. Bonassar
Keyword(s):  
Tissue Engineering ◽  
Solid Freeform Fabrication ◽  
Crosslinking Agent ◽  
Three Dimensional ◽  
Patient Specific ◽  
Efficient Production ◽  
Alginate Hydrogel ◽  
Freeform Fabrication ◽  
Patient Specific Implants ◽  
Multiple Material

A major challenge in orthopaedic tissue engineering is the generation of cell-seeded implants with structures that mimic native tissue, both in terms of anatomic geometries and intratissue cell distributions. By combining the strengths of injection molding tissue engineering with those of Solid Freeform Fabrication (SFF), three-dimensional pre-seeded implants were fabricated without custom-tooling, enabling efficient production of patient-specific implants. The incorporation of SFF technology also enables the fabrication of geometrically complex, multiple-material implants with spatially heterogeneous cell distributions that could not otherwise be produced. Using a custom-built robotic SFF platform and gel deposition tools, alginate hydrogel was used with calcium sulfate as a crosslinking agent to produce pre-seeded living implants of arbitrary geometries. The process was determined to be sterile and viable at 94±5%. The GAG production was found to be about half that of a similarly molded samples. The compressive elastic modulus was determined to be 1.462±0.113 kPa.

Development of HA-PLGA Scaffold Encapsulating Intact BMP-2 Using Solid Freeform Fabrication Technology

2011 ◽  
Author(s):  
Jin-Hyung Shim ◽  
Jong Young Kim ◽  
Kyung Shin Kang ◽  
Jung Kyu Park ◽  
Sei Kwang Hahn ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Bone Regeneration ◽  
Porous Scaffold ◽  
Solid Freeform Fabrication ◽  
Three Dimensional ◽  
Porous Scaffolds ◽  
Prolonged Release ◽  
Cellular Activity ◽  
Freeform Fabrication

Tissue engineering is an interdisciplinary field that focuses on restoring and repairing tissues or organs. Cells, scaffolds, and biomolecules are recognized as three main components of tissue engineering. Solid freeform fabrication (SFF) technology is required to fabricate three-dimensional (3D) porous scaffolds to provide a 3D environment for cellular activity. SFF technology is especially advantageous for achieving a fully interconnected, porous scaffold. Bone morphogenic protein-2 (BMP-2), an important biomolecule, is widely used in bone tissue engineering to enhance bone regeneration activity. However, methods for the direct incorporation of intact BMP-2 within 3D scaffolds are rare. In this work, 3D porous scaffolds with poly(lactic-co-glycolic acid) chemically grafted hyaluronic acid (HA-PLGA), in which intact BMP-2 was directly encapsulated, were successfully fabricated using SFF technology. BMP-2 was previously protected by poly(ethylene glycol) (PEG), and the BMP-2/PEG complex was incorporated in HA-PLGA using an organic solvent. The HAPLGA/PEG/BMP-2 mixture was dissolved in chloroform and deposited via a multi-head deposition system (MHDS), one type of SFF technology, to fabricate a scaffold for tissue engineering. An additional air blower system and suction were installed in the MHDS for the solvent-based fabrication method. An in vitro evaluation of BMP-2 release was conducted, and prolonged release of intact BMP-2, for up to 28 days, was confirmed. After confirmation of advanced proliferation of pre osteoblasts, a superior differentiation effect of the HA-PLGA/PEG/BMP-2 scaffold was validated by measuring high expression levels of bone-specific markers, such as alkaline phosphatase (ALP) and osteocalcin (OC). We show that our solvent-based fabrication is a non-toxic method for restoring cellular activity. Moreover, the HAPLGA/PEG/BMP-2 scaffold was effective for bone regeneration.

Sign in / Sign up

Export Citation Format

Share Document