scholarly journals Microstructure and Defect-Based Fatigue Mechanism Evaluation of Brazed Coaxial Ti/Al2O3 Joints for Enhanced Endoprosthesis Design

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7895
Author(s):  
Johannes L. Otto ◽  
Ivan Fedotov ◽  
Milena Penyaz ◽  
Thorge Schaum ◽  
Anke Kalenborn ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Ceramic Surface ◽  
Structure Property ◽  
Hip Endoprosthesis ◽  
Wear Rates ◽  
Structure Property Relationships ◽  
Stem Taper ◽  
Probability Of Fracture ◽  
Process Structure ◽  
Viable Method

Alumina-based ceramic hip endoprosthesis heads have excellent tribological properties, such as low wear rates. However, stress peaks can occur at the point of contact with the prosthesis stem, increasing the probability of fracture. This risk should be minimized, especially for younger and active patients. Metal elevations at the stem taper after revision surgery without removal of a well-fixed stem are also known to increase the risk of fracture. A solution that also eliminates the need for an adapter sleeve could be a fixed titanium insert in the ceramic ball head, which would be suitable as a damping element to reduce the occurrence of stress peaks. A viable method for producing such a permanent titanium–ceramic joint is brazing. Therefore, a brazing method was developed for coaxial samples, and two modifications were made to the ceramic surface to braze a joint that could withstand high cyclic loading. This cyclic loading was applied in multiple amplitude tests in a self-developed test setup, followed by fractographic studies. Computed tomography and microstructural analyses—such as energy dispersive X-ray spectroscopy—were also used to characterize the process–structure–property relationships. It was found that the cyclic loading capacity can be significantly increased by modification of the surface structure of the ceramic.

scholarly journals Fused Filament Fabrication of PEEK: A Review of Process-Structure-Property Relationships

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1665 ◽  
Author(s):  
Ali Reza Zanjanijam ◽  
Ian Major ◽  
John G. Lyons ◽  
Ugo Lafont ◽  
Declan M. Devine
Keyword(s):  
High Performance ◽  
Space Station ◽  
Weight Ratio ◽  
High Strength ◽  
Structure Property ◽  
Fused Filament Fabrication ◽  
Space Applications ◽  
Structure Property Relationships ◽  
Complex Design ◽  
Process Structure

Poly (ether ether ketone) (PEEK) is a high-performance engineering thermoplastic polymer with potential for use in a variety of metal replacement applications due to its high strength to weight ratio. This combination of properties makes it an ideal material for use in the production of bespoke replacement parts for out-of-earth manufacturing purposes, in particular on the International Space Station (ISS). Additive manufacturing (AM) may be employed for the production of these parts, as it has enabled new fabrication pathways for articles with complex design considerations. However, AM of PEEK via fused filament fabrication (FFF) encounters significant challenges, mostly stemming from the semi crystalline nature of PEEK and its associated high melting temperature. This makes PEEK highly susceptible to changes in processing conditions which leads to a large reported variation in the literature on the final performance of PEEK. This has limited the adaption of FFF printing of PEEK in space applications where quality assurance and reproducibility are paramount. In recent years, several research studies have examined the effect of printing parameters on the performance of the 3D-printed PEEK parts. The aim of the current review is to provide comprehensive information in relation to the process-structure-property relationships in FFF 3D-printing of PEEK to provide a clear baseline to the research community and assesses its potential for space applications, including out-of-earth manufacturing.

Data-driven multi-scale multi-physics models to derive process–structure–property relationships for additive manufacturing

2018 ◽  
Vol 61 (5) ◽  
pp. 521-541 ◽  
Author(s):  
Wentao Yan ◽  
Stephen Lin ◽  
Orion L. Kafka ◽  
Yanping Lian ◽  
Cheng Yu ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Data Driven ◽  
Structure Property ◽  
Multi Scale ◽  
Structure Property Relationships ◽  
Process Structure

scholarly journals Study of process/structure/property relationships in probeless friction stir spot welded AA2198 Al-Li alloy

2017 ◽  
Vol 61 (2) ◽  
pp. 291-298 ◽  
Author(s):  
Q. Chu ◽  
W. Y. Li ◽  
X. W. Yang ◽  
J. J. Shen ◽  
Y. B. Li ◽  
...  
Keyword(s):  
Structure Property ◽  
Friction Stir ◽  
Structure Property Relationships ◽  
Process Structure ◽  
Spot Welded

Analysis of the Weld Seam Morphology of Polypropylene in Laser Transmission Welding

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Bastian Geißler ◽  
Tobias Laumer ◽  
Andrea Wübbeke ◽  
Thomas Frick ◽  
Volker Schöppner ◽  
...  
Keyword(s):  
Temperature Field ◽  
Weld Seam ◽  
Welding Process ◽  
Structure Property ◽  
Line Energy ◽  
Laser Transmission Welding ◽  
Β Phase ◽  
Structure Property Relationships ◽  
Maximum Temperatures ◽  
Process Structure

Laser transmission welding is a well-known joining technology for welding thermoplastics. Although the process is already used industrially, fundamental process-structure-property relationships are not fully understood and are therefore the subject of current research. One aspect of these mentioned process-structure-property relationships is the interaction between the temperature field during the welding process, the weld seam morphology of semi-crystalline thermoplastics, and the weld seam strength. In this study, the influence of the line energy on the weld seam morphology of polypropylenes is analyzed. For this purpose, the size of spherulites in the weld seam is investigated, as well as different occurring phases of polypropylene (α- and β-phase). It is shown that both the spherulite size of the α-phase and the amount of β-phase increase with increasing line energy. For the explanation and discussion of the results, a temperature-dependent thermal simulation model is used to derive characteristic attributes of the temperature field (maximum temperatures, cooling rates, temperature gradients).

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