A review on the performance characteristics, applications, challenges and possible solutions in electron beam melted Ti-based orthopaedic and orthodontic implants

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Kashif Ishfaq ◽  
Mudassar Rehman ◽  
Ahmed Raza Khan ◽  
Yanen Wang
Keyword(s):  
Electron Beam ◽  
Elastic Modulus ◽  
Mechanical Performance ◽  
Performance Characteristics ◽  
Medical Implants ◽  
Orthopaedic Implants ◽  
Content Type ◽  
Ti Alloys ◽  
Orthodontic Implants ◽  
Recent Trends

Purpose Human aging is becoming a common issue these days as it results in orthopaedic-related issues such as joints disorderness, bone-fracture. People with age = 60 years suffer more from these aforesaid issues. It is expected that these issues in human beings will ultimately reach 2.1 billion by 2050 worldwide. Furthermore, the increase in traffic accidents in young people throughout the world has significantly emerged the need for artificial implants. Their implantation can act as a substitute for fractured bones or disordered joints. Therefore, this study aims to focus on electron beam melted titanium (Ti)-based orthopaedic implants along with their recent trends in the field. Design/methodology/approach The main contents of this work include the basic theme and background of the metal-based additive manufacturing, different implant materials specifically Ti alloys and their classification based on crystallographic transus temperature (including α, metastable β, β and α + β phases), details of electron beam melting (EBM) concerning its process physics, various control variables and performance characteristics of EBMed Ti alloys in orthopaedic and orthodontic implants, applications of EBMed Ti alloys in various load-bearing implants, different challenges associated with the EBMed Ti-based implants along with their possible solutions. Recent trends and shortfalls have also been described at the end. Findings EBM is getting significant attention in medical implants because of its minor issues as compared to conventional fabrication practices such as Ti casting and possesses a significant research potential to fabricate various medical implants. The elastic modulus and strength of EBMed ß Ti-alloys such as 24Nb-4Zr-8Sn and Ti-33Nb-4Sn are superior compared to conventional Ti for orthopaedic implants. Beta Ti alloys processed by EBM have near bone elastic modulus (approximately 35–50 GPa) along with improved tribo-mechanical performance involving mechanical strength, wear and corrosion resistance, along with biocompatibility for implants. Originality/value Advances in EBM have opened the gateway Ti alloys in the biomedical field explicitly ß-alloys because of their unique biocompatibility, bioactivity along with improved tribo-mechanical performance. Less significant work is available on the EBM of Ti alloys in orthopaedic and orthodontic implants. This study is directed solely on the EBM of medical Ti alloys in medical sectors to explore their different aspects for future research opportunities.

scholarly journals Tensile and Creep Properties Improvement of Ti-6Al-4V Alloy Specimens Produced by Electron Beam Powder Bed Fusion Additive Manufacturing

Metals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1207 ◽  
Author(s):  
Placido Aliprandi ◽  
Fabio Giudice ◽  
Eugenio Guglielmino ◽  
Andrea Sili
Keyword(s):  
Electron Beam ◽  
Additive Manufacturing ◽  
Mechanical Performance ◽  
Hot Isostatic Pressing ◽  
Processing Route ◽  
Powder Bed Fusion ◽  
Metal Powders ◽  
Surface Smoothing ◽  
Powder Bed ◽  
Ti Alloys

Thanks to their excellent mechanical strength in combination with low density, high melting point, and good resistance to corrosion, titanium alloys are very useful in many industrial and biomedical fields. The new additive manufacturing methods, such as Electron Beam Powder Bed Fusion based on the deposition of metal powders layers progressively molten by electron beam scanning, can overcome many of the machining problems concerning the production of peculiar shapes made of Ti alloys. However, the processing route is strictly determinant for mechanical performance of products, especially in the case of Ti alloys. In the present work flat specimens made of Ti-6Al-4V alloy produced by Electron Beam Powder Bed Fusion (or Electron Beam Melting) have been built and post-processed with the purpose of obtaining good tensile and creep performance. Preliminarily, the process parameters were set according to literature evidence and machine producer recommendations, validated by the results of a thermal analysis, aimed at satisfying the best processing conditions to reduce defects, as unmelted regions, microstructure coarsening or porosity, that are detrimental to mechanical behavior. Subsequently, Hot Isostatic Pressing and surface smoothing were considered, respectively, in order to reduce any internal porosity and lower roughness. Microstructure of the investigated specimens was characterized by optical and scanning electron microscopy observations and by X-ray diffraction measurements. Results show enhanced tensile behavior after the hot pressing treatment that allows to relieve stresses and reduce defects detrimental to mechanical properties. The best ductility was obtained by the combined effects of machining and densification. Creep test results verify the beneficial effects of surface smoothing.

Portrayals of autism and social awareness: a scoping review

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Rosa Fontes ◽  
Margarita Pino-Juste
Keyword(s):  
Social Awareness ◽  
Social Categories ◽  
Content Type ◽  
Media Portrayals ◽  
Broadcast Media ◽  
News Broadcasts ◽  
The Social ◽  
Recent Trends ◽  
The Subject

Purpose The purpose of this paper is to look at recent trends in scientific literature on the portrayal of autism in published and broadcast media and social awareness of the subject. Design/methodology/approach A bibliometric analysis of content of such publications was performed. Findings Results show that portrayals of autism from books, newspapers, news broadcasts, films and TV series are being scrutinized. Research focuses on the social categories of resulting stereotypes, the quality of such depictions, the benefits and downsides, stigmatization of individuals (with autism) and how society responds to these portrayals. Originality/value It is important to understand if media portrayals of autism are creating a realistic and constructive awareness of autism in society.

scholarly journals Evaluation of vehicle lightweighting to reduce greenhouse gas emissions with focus on magnesium substitution

2018 ◽  
Vol 16 (6) ◽  
pp. 869-888 ◽  
Author(s):  
Siddharth Kulkarni ◽  
David John Edwards ◽  
Erika Anneli Parn ◽  
Craig Chapman ◽  
Clinton Ohis Aigbavboa ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Fuel Economy ◽  
Internal Combustion Engines ◽  
Mechanical Performance ◽  
Material Design ◽  
Torsional Stiffness ◽  
Gas Emissions ◽  
Content Type

Purpose Vehicle weight reduction represents a viable means of meeting tougher regulatory requirements designed to reduce fuel consumption and control greenhouse gas emissions. This paper aims to present an empirical and comparative analysis of lightweight magnesium materials used to replace conventional steel in passenger vehicles with internal combustion engines. The very low density of magnesium makes it a viable material for lightweighting given that it is lighter than aluminium by one-third and steel by three-fourth. Design/methodology/approach A structural evaluation case study of the “open access” Wikispeed car was undertaken. This included an assessment of material design characteristics such as bending stiffness, torsional stiffness and crashworthiness to evaluate whether magnesium provides a better alternative to the current usage of aluminium in the automotive industry. Findings The Wikispeed car had an issue with the rocker beam width/thickness (b/t) ratio, indicating failure in yield instead of buckling. By changing the specified material, Aluminium Alloy 6061-T651 to Magnesium EN-MB10020, it was revealed that vehicle mass could be reduced by an estimated 110 kg, in turn improving the fuel economy by 10 per cent. This, however, would require mechanical performance compromise unless the current design is modified. Originality/value This is the first time that a comparative analysis of material substitution has been made on the Wikispeed car. The results of such work will assist in the lowering of harmful greenhouse gas emissions and simultaneously augment fuel economy.

Influence of different flow regimes on the performance characteristics of a four-pad hydrostatic squeeze film damper loaded between pads

2019 ◽  
Vol 71 (3) ◽  
pp. 440-446
Author(s):  
Amina Nemchi ◽  
Ahmed Bouzidane ◽  
Aboubakeur Benariba ◽  
Hicham Aboshighiba
Keyword(s):  
Turbulent Flow ◽  
Load Capacity ◽  
Flow Regimes ◽  
Performance Characteristics ◽  
Squeeze Film ◽  
Eccentricity Ratio ◽  
Flow Conditions ◽  
Content Type ◽  
Turbulent Flow Regime ◽  
Squeeze Film Dampers

Purpose The purpose of this paper is to study the influence of different flow regimes on the dynamic characteristics of four-pad hydrostatic squeeze film dampers (SFDs) loaded between pads. Design/methodology/approach A numerical model based on Constantinescu’s turbulent lubrication theory using the finite difference method has been developed and presented to study the effect of eccentricity ratio on the performance characteristics of four-pad hydrostatic SFDs under different flow regimes. Findings It was found that the influence of turbulent flow on the dimensionless damping of four-pad hydrostatic SFDs appears to be essentially controlled by the eccentricity ratio. It was also found that the laminar flow presents higher values of load capacity compared to bearings operating under turbulent flow conditions. Originality/value In fact, the results obtained show that the journal bearing performances are significantly influenced by the turbulent flow regime. The study is expected to be useful to bearing designers.

Structure Optimization on FEM Biomechanical Model of Bioabsorable Pure Magnesium Skin Staple

2014 ◽  
Vol 1049-1050 ◽  
pp. 511-514
Author(s):  
Yong Hua Lao ◽  
Yue Shan Huang ◽  
Wei Rong Li ◽  
Ying Jun Wang
Keyword(s):  
Stainless Steel ◽  
Mechanical Strength ◽  
316L Stainless Steel ◽  
Mechanical Performance ◽  
Structure Optimization ◽  
Biomechanical Model ◽  
Pure Magnesium ◽  
Structural Deformation ◽  
Medical Implants ◽  
Surgical Suture

Skin Stapler is an alternative instrument, which makes surgy easily and quickly and owns fine-looking effect without scars after the wound healed, to traditional surgical suture for the wound skin sewing. Magnesium recently is considered to develop medical implants because of its beneficial biocompatibility and bioabsorability. Due its less mechanical strength than traditional 316L stainless steel used in common staple, this paper try to optimize the structure of pure magnesium skin staple by FEM models and simulation as so to assure its biomechanical safty. Using ADINA software, two staples with different pre-bended shoulders and the traditional staple without shoulder are modeling to analyze its stress and plastical strain during structural deformation under load. The results, not only of pure magnesium models but also of 316L stainless steel models, showed that the shoulders optimization on staple structure has important role in its mechanical performance. The research increases the possibility of bioabsorable magnesium material application on medical skin staple.

scholarly journals Multiscale, thermomechanical topology optimization of self-supporting cellular structures for porous injection molds

2019 ◽  
Vol 25 (9) ◽  
pp. 1482-1492
Author(s):  
Tong Wu ◽  
Andres Tovar
Keyword(s):  
Topology Optimization ◽  
Mechanical Performance ◽  
Mechanical Load ◽  
Design Method ◽  
Three Dimensional ◽  
Optimization Method ◽  
Cellular Structures ◽  
Injection Mold ◽  
Computationally Efficient ◽  
Content Type

Purpose This paper aims to establish a multiscale topology optimization method for the optimal design of non-periodic, self-supporting cellular structures subjected to thermo-mechanical loads. The result is a hierarchically complex design that is thermally efficient, mechanically stable and suitable for additive manufacturing (AM). Design/methodology/approach The proposed method seeks to maximize thermo-mechanical performance at the macroscale in a conceptual design while obtaining maximum shear modulus for each unit cell at the mesoscale. Then, the macroscale performance is re-estimated, and the mesoscale design is updated until the macroscale performance is satisfied. Findings A two-dimensional Messerschmitt Bolkow Bolhm (MBB) beam withstanding thermo-mechanical load is presented to illustrate the proposed design method. Furthermore, the method is implemented to optimize a three-dimensional injection mold, which is successfully prototyped using 420 stainless steel infiltrated with bronze. Originality/value By developing a computationally efficient and manufacturing friendly inverse homogenization approach, the novel multiscale design could generate porous molds which can save up to 30 per cent material compared to their solid counterpart without decreasing thermo-mechanical performance. Practical implications This study is a useful tool for the designer in molding industries to reduce the cost of the injection mold and take full advantage of AM.

First-principles calculations for development of low elastic modulus Ti alloys

2004 ◽  
Vol 70 (17) ◽  
Author(s):  
Hideaki Ikehata ◽  
Naoyuki Nagasako ◽  
Tadahiko Furuta ◽  
Atsuo Fukumoto ◽  
Kazutoshi Miwa ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
First Principles ◽  
First Principles Calculations ◽  
Ti Alloys ◽  
Low Elastic Modulus

The influence of load direction, microstructure, raster orientation on the quasi-static response of fused deposition modeling ABS

2019 ◽  
Vol 25 (3) ◽  
pp. 462-472 ◽  
Author(s):  
Oluwakayode Bamiduro ◽  
Gbadebo Owolabi ◽  
Mulugeta A. Haile ◽  
Jaret C. Riddick
Keyword(s):  
Additive Manufacturing ◽  
Fused Deposition Modeling ◽  
Mechanical Response ◽  
Mechanical Performance ◽  
Bead Geometry ◽  
Static Response ◽  
Load Direction ◽  
Content Type ◽  
Fused Deposition ◽  
Deposition Modeling

Purpose The continual growth of additive manufacturing has increased tremendously because of its versatility, flexibility and high customization of geometric structures. However, design hurdles are presented in understanding the relationship between the fabrication process and materials microstructure as it relates to the mechanical performance. The purpose of this paper is to investigate the role of build architecture and microstructure and the effects of load direction on the static response and mechanical properties of acrylonitrile butadiene styrene (ABS) specimens obtained via the fused deposition modeling (FDM) processing technique. Design/methodology/approach Among additive manufacturing processes, FDM is a prolific technology for manufacturing ABS. The blend of ABS combines strength, rigidity and toughness, all of which are desirable for the production of structural materials in rapid manufacturing applications. However, reported literature has varied widely on the mechanical performance due to the proprietary nature of the ABS material ratio, ultimately creating a design hurdle. While prior experimental studies have studied the mechanical response via uniaxial tension testing, this study has aimed to understand the mechanical response of ABS from the materials’ microstructural point of view. First, ABS specimen was fabricated via FDM using a defined build architecture. Next, the specimens were mechanically tested until failure. Then finally, the failure structures were microstructurally investigated. In this paper, the effects of microstructural evolution on the static mechanical response of various build architecture of ABS aimed at FDM manufacturing technique was analyzed. Findings The results show that the rastering orientation of 0/90 exhibited the highest tensile strength followed by fracture at its maximum load. However, the “45” bead direction of the ABS fibers displayed a cold-drawing behavior before rupture. The morphology analyses before and after tensile failure were characterized by a scanning electron microscopy (SEM) which highlighted the effects of bead geometry (layers) and areas of stress concentration such as interstitial voids in the material during build, ultimately compromising the structural integrity of the specimens. Research limitations/implications The ability to control the constituents and microstructure of a material during fabrication is significant to improving and predicting the mechanical performance of structural additive manufacturing components. In this report, the effects of microstructure on the mechanical performance of FDM-fabricated ABS materials was discussed. Further investigations are planned in understanding the effects of ambient environmental conditions (such as moisture) on the ABS material pre- and post-fabrication. Originality/value The study provides valuable experimental data for the purpose of understanding the inter-dependency between build parameters and microstructure as it relates to the specimens exemplified strength. The results highlighted in this study are fundamental to the development of optimal design of strength and complex ultra-lightweight structure efficiency.

Mechanical Performance of a Non-weldable Ni-Base Superalloy: Inconel 738 Fabricated by Electron Beam Melting

2020 ◽  
pp. 1075-1084
Author(s):  
Michael M. Kirka ◽  
Patxi Fernandez-Zelaia ◽  
Yousub Lee ◽  
Peeyush Nandwana ◽  
Sean Yoder ◽  
...  
Keyword(s):  
Electron Beam ◽  
Electron Beam Melting ◽  
Mechanical Performance ◽  
Base Superalloy

scholarly journals β-type Ti Alloys for Biomedical Applications

2020 ◽  
Vol 3 (2) ◽  
Author(s):  
Ridvan Yamanoglu
Keyword(s):  
Elastic Modulus ◽  
Life Quality ◽  
Developed Countries ◽  
Medical Product ◽  
The Body ◽  
Shielding Effect ◽  
Metallic Biomaterials ◽  
Ti Alloys ◽  
The World ◽  
Product Industry

In the world market, medical products emerge as a sector that directly concerns people’s life quality and related activities. The medical product industry continues to grow rapidly in the world, especially in developed countries in line with the advances in technology, along with the elderly population and welfare level. In this context, biomedical implants constitute an important branch of the medical product industry. Among the materials preferred for implant production, the metallic biomaterials are very popular due to their superior mechanical properties. Ti and Ti alloys, among the metallic biomaterials, draw more attention considerably compared to stainless steel and Co-Cr alloys due to their characteristic features such as high specific strength and superior corrosion resistance, low density and low modulus of elasticity. Although the elastic modulus of titanium and its alloys is low compared to the other metallic biomaterials, it remains higher than bone. β-type Ti alloys have been developed to prevent the stress shielding effect caused by the elastic modulus mismatch and sterilization of the biomaterials used in the body from toxic alloy elements. In this article, the effect of the use of β-type Ti alloys, which are extremely prospective materials and open to development, in the body on host organisms, and the efficiency of the developed alloys have been investigated.

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