Manikandakumar Shunmugavel, Ashwin Polishetty, Moshe Goldberg, Rajkumar Singh and Guy Littlefair
The purpose of this paper is to study and compare the mechanical properties and machinability characteristics of additive manufactured titanium alloy Ti-6Al-4V with conventionally…
Abstract
Purpose
The purpose of this paper is to study and compare the mechanical properties and machinability characteristics of additive manufactured titanium alloy Ti-6Al-4V with conventionally produced wrought titanium alloy,Ti-6Al-4V. The difference in mechanical properties such as yield strength, ultimate tensile strength, micro hardness, percentage of elongation and their effect on machinability characteristics like cutting forces and surface roughness are studied. It was found that higher strength and hardness of SLM Ti-6Al-4V compared to wrought Ti-6Al-4V owing to its peculiar acicular microstructure significantly affected the cutting forces and surface roughness. High cutting forces and low surface roughness were observed during machining of additive manufactured components compared to its wrought counterpart because of their difference in strength, hardness and ductility.
Design/methodology/approach
Mechanical properties like yield strength, ultimate tensile strength, hardness and percentage of elongation and machinability characteristics like cutting forces and surface roughness were studied for both wrought and additive manufactured Ti-6Al-4V.
Findings
Mechanical properties like yield strength, ultimate tensile strength and hardness were higher for additive manufactured components as compared to the wrought component. However additive manufactured components significantly lacked in ductility as compared to the wrought parts. Concerning machining, higher cutting forces and lower surface roughness were observed in additive manufactured Ti-6Al-4V compared to the wrought part as a result of differences in mechanical properties of these differently processed materials.
Originality/value
This paper, for the first time, discusses the machining capabilities of additive manufactured Ti-6Al-4V.
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AmirMahyar Khorasani, Ian Gibson, Moshe Goldberg and Guy Littlefair
The purpose of this paper is to improve the manufacturing of a prosthetic acetabular shell by analyzing the main factors leading to failure during the selective laser melting…
Abstract
Purpose
The purpose of this paper is to improve the manufacturing of a prosthetic acetabular shell by analyzing the main factors leading to failure during the selective laser melting (SLM) additive manufacturing (AM) process.
Design/methodology/approach
Different computer-aided design and computer-aided manufacturing processes have been applied to fabricate acetabular parts. Then, various investigations into surface quality, mechanical properties and microstructure have been carried out to scrutinize the possible limitations in fabrication.
Findings
Geometrical measurements showed 1.59 and 0.27 per cent differences between the designed and manufactured prototypes for inside and outside diameter, respectively. However, resulting studies showed that unstable surfaces, cracks, an interruption in powder delivery and low surface quality were the main problems that occurred during this process. These results indicate that SLM is an accurate and promising method for production of intricate shapes, provided that the appropriate settings of production conditions are considered to minimize possible limitations.
Originality/value
The contributions of this paper are discussions covering different issues in the AM fabrication of acetabular shells to improve the mechanical properties, quality and durability of the produced parts.
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AmirMahyar Khorasani, Ian Gibson, Moshe Goldberg and Guy Littlefair
The purpose of this study was to conduct various heat treatments (HT) such as stress relief annealing, mill annealing, recrystallization (α + β) annealing and β annealing followed…
Abstract
Purpose
The purpose of this study was to conduct various heat treatments (HT) such as stress relief annealing, mill annealing, recrystallization (α + β) annealing and β annealing followed by furnace cooling (FC) that were implemented to determine the effect of these on mechanical properties and the microstructure of selective laser melted and wrought samples. The mentioned annealings have been carried out to achieve the related standards in the fabrication of surgery implants.
Design/methodology/approach
In this paper, based on F2924-14 ASTM standard SLM and conventionally wrought parts were prepared. Then HT was performed and different characteristics such as microstructure, mechanical properties, macro-hardness and fracture surface for selective laser melted and wrought parts were analysed.
Findings
The results show that the high cooling rate in selective laser melting (SLM) generates finer grains. Therefore, tensile strength and hardness increase along with a reduction in ductility was noticed. Recrystallization annealing appears to give the best combination of ductility, strength and hardness for selective laser melted parts, whilst for equivalent wrought samples, increasing HT temperature results in reduction of mechanical properties.
Originality/value
The contributions of this paper are discussing the effect of different annealing on mechanical properties and microstructural evolution based on new ASTM standards for selective laser melted samples and comparing them with wrought parts.
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Michel Beuthe, Christophe Bouffioux, Cathérine Krier and Michel Mouchart
On 1 April 1978, the Israeli peace movement burst into world consciousness when an estimated 25,000 Israelis demonstrated in Tel Aviv to urge the administration of Prime Minister…
Abstract
On 1 April 1978, the Israeli peace movement burst into world consciousness when an estimated 25,000 Israelis demonstrated in Tel Aviv to urge the administration of Prime Minister Menachem Begin to continue peace negotiations with Egypt. A grassroots group called Peace Now is credited with organizing and leading that demonstration. Today, the “peace camp” refers to left‐wing political parties and organizations that hold dovish positions on the Arab‐Israeli conflict and the Palestinian issue. While some figures in the Labor Party view themselves as the peace movement's natural leader, political parties further to the left like the Citizens Rights Movement (CRM) and Mapam are more dovish. In the last 10 years, many grassroots peace organizations have, like Peace Now, formed outside the political party system, with the goal of influencing public opinion and eventually having an impact on policy makers. Peace Now is still the largest, most visible and influential of those organizations.
Religious minority groups often enjoy strong support systems and high levels of trust, providing for volunteering within the community, but under what conditions are members of…
Abstract
Purpose
Religious minority groups often enjoy strong support systems and high levels of trust, providing for volunteering within the community, but under what conditions are members of these groups likely to volunteer outside their community? Or, would they prefer the security, intimacy and commitment to their own communities. The paper aims to discuss these issues.
Design/methodology/approach
To answer this question, the authors examine the motivations of ultra-Orthodox young men who volunteered for National Civil Service in Israel, and compare the choices of volunteer frameworks: separatist-religious volunteering within the community compared to volunteering in secular institutions outside the community.
Findings
The authors associate the interest and motivations with different types of social capital, “bonding” and “bridging.”
Research limitations/implications
Research based on one case study.
Practical implications
Guidelines for encouraging volunteering among closed groups.
Social implications
Understanding of motivations and concerns among religious groups.
Originality/value
An original study of a relatively new phenomenon.
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This paper argues that the nation's immigration laws are being misused to craft a system of preventive administrative detention of immigrant men, predominantly of Middle Eastern…
Abstract
This paper argues that the nation's immigration laws are being misused to craft a system of preventive administrative detention of immigrant men, predominantly of Middle Eastern background. These detentions give rise to imprisonment without charge for weeks and months, denial of access to lawyers, physical and psychological abuse and ultimately deportations without a fair initial hearing or the exhaustion of available appellate recourse. I argue that this expanded use of civil immigration detention is designed to weaken constitutional due process protections, bringing into the U.S. detention tactics adopted abroad under the rubric of the war on terror. This paper also highlights similarities between the evolving administrative detention system in the United States and longer-standing practices in Israel.
The Technion is Israel's oldest institution of higher learning. Its origins date back to the years of pre‐World War I. To 1912 to be exact. But, due to the outbreak of hostilities…
Abstract
The Technion is Israel's oldest institution of higher learning. Its origins date back to the years of pre‐World War I. To 1912 to be exact. But, due to the outbreak of hostilities it begun to function only in 1924. Some years had to pass before it got over its birth pangs. Its infancy led to moderate accomplishments compared to the present fame. The Technion stands to‐day on 300 acres of wooded land. Its campus on Mount Carmel is one of the most beautiful in the world. A city within a city the Technion comprises some forty impressive, modern buildings that blend into their landscaped setting. It took the newly founded College for Higher Education, which is in the Negev, under its wings, and the young Haifa University is affiliated with the Technion. Academically, it is being compared to the Massachusetts Institute of Technology. Not only for being a Technical University but for the superior qualifications demanded from its teaching staff and the high standard expected from its students.
The paper examines two discourses of bereavement that crystallized simultaneously in Israel as the third millennium began. One is “the economic discourse of bereavement,” with…
Abstract
The paper examines two discourses of bereavement that crystallized simultaneously in Israel as the third millennium began. One is “the economic discourse of bereavement,” with which official organizations dealing with bereavement sought to “free themselves” from the state's directives on entitlement to compensation. Army widows argued that compensation should not depend on their refraining from remarriage, while bereaved parents demanded it would not be contingent on a means test. They urge for liberation from “role demands” and for presenting entitlement to compensation as entitlement to personal rehabilitation, without using it to support pro-establishment behavior or unending interactions with establishment supervision. Those claims express the linkage of bereavement to globalization and individuation, and the desire to rebel against the republican equation conditioning entitlement to welfare on “proper” establishment-compliant behavior. A second discourse is the “hierarchy of bereavement discourse” – which was placed on the agenda together with the first one, and by the same organizations. Unlike the economic discourse, this one acted to replicate the monopoly held by families of IDF dead in the Israeli pantheon, with attempts to bring into it a group of families of civilian bereavement (families of terror victims). The discourse relies on purely republican underpinnings, complying with the spirit of the local–national period. Exploring the two discourses, that were promoted simultaneously by the same agents, assists an analysis of the Israeli discourse of bereavement that results in its definition as “glocal.” This transpires from a review of the literature showing that – even in the face of globalization processes – national–local foundations remained stable. The paper first engages with the concept of glocalization, the ethos of republican citizenship, and, as a facet of it, the identification of social policy as an agent of the social hierarchy, as well as changes in citizenship during globalization. The second section reviews the status of bereaved families, and the central discourses they have promoted in Israeli society. The third and major part contains an analysis of both discourses – the economic discourse of bereavement, and the hierarchy of bereavement discourse. Finally, we attempt to analyze and explain how apparently antithetical discourses took shape in tandem, drawing on the term “glocalism” and the impact of citizenship models.