Plasma Facing Component Design Through Multiphysics Simulation

The safe fatigue design of metallic components fabricated by additive manufacturing (AM) is still a largely unsolved problem. This is primarily due to (a) a significant inhomogeneity of the material properties across the component; (b) defects such as porosity and lack of fusion as well as pronounced surface roughness of the as-built components; and (c) residual stresses, which are very often present in the as-built parts and need to be removed by post-fabrication treatments. Such morphological and microstructural features are very different than in conventionally manufactured parts and play a much bigger role in determining the fatigue life. The above problems require specific solutions with respect to the identification of the critical (failure) sites in AM fabricated components. Moreover, the generation of representative test specimens characterized by similar temperature cycles needs to be guaranteed if one wants to reproducibly identify the critical sites and establish fatigue assessment methods taking into account the effect of defects on crack initiation and early propagation. The latter requires fracture mechanics-based approaches which, unlike common methodologies, cover the specific characteristics of so-called short fatigue cracks. This paper provides a discussion of all these aspects with special focus on components manufactured by laser powder bed fusion (L-PBF). It shows how to adapt existing solutions, identifies fields where there are still gaps, and discusses proposals for potential improvement of the damage tolerance design of L-PBF components.

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Heat pipe technology based divertor plasma facing component concept for European DEMO

Fusion Engineering and Design ◽

10.1016/j.fusengdes.2020.112184 ◽

2021 ◽

Vol 164 ◽

pp. 112184

Author(s):

Wen Wen ◽

Bradut-Eugen Ghidersa ◽

Wolfgang Hering ◽

Jörg Starflinger ◽

Robert Stieglitz

Keyword(s):

Heat Pipe ◽

Plasma Facing Component

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Difference in patient-reported outcomes of various patellar component designs in total knee arthroplasty: A randomized clinical study

Journal of Orthopaedic Surgery ◽

10.1177/2309499021996068 ◽

2021 ◽

Vol 29 (1) ◽

pp. 230949902199606

Author(s):

Takeshi Mochizuki ◽

Koichiro Yano ◽

Katsunori Ikari ◽

Ken Okazaki

Keyword(s):

Knee Osteoarthritis ◽

Clinical Effects ◽

Patellar Component ◽

American College Of Rheumatology ◽

Randomized Clinical Study ◽

Component Design ◽

Patient Reported ◽

Total Knee ◽

The Difference ◽

And Function

Purpose: This study investigated the clinical effects of different patellar components without being affected by the femoral component design in total knee arthritis (TKA) for patients with knee osteoarthritis (OA). Methods: In total, 48 patients with OA who met the criteria of the American College of Rheumatology for OA were enrolled and randomly assigned in a 1:1 ratio to two groups according to the usage of patellar component design for TKA (medialized dome type [dome group] or medialized anatomic type [anatomic group]). To evaluate the clinical outcomes for TKA, knee range of motion (ROM), pain intensity of 0–100 mm visual analog scale (pain VAS), and the Japanese Knee Osteoarthritis Measure (JKOM) score were obtained at baseline and year 1. Results: The difference in knee ROM, pain VAS, or total JKOM score at year 1 was not significant between the dome and anatomic groups ( p = 0.398, 0.733 and 0.536, respectively). Moreover, similar results were obtained for changes in knee ROM, pain VAS, or total JKOM scores from baseline. In both groups, the pain VAS and total JKOM scores were significantly improved at year 1. Conclusion: Both dome and anatomic groups in TKA are significantly effective for pain and function using the JKOM score. However, their efficacy did not differ, according to the JKOM score. Results of this study are rare information focusing on the patellar component design and provide one of the insights into the TKA clinical management.

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Feasibility of a Helium Closed-Cycle Gas Turbine for UAV Propulsion

Applied Sciences ◽

10.3390/app11010028 ◽

2020 ◽

Vol 11 (1) ◽

pp. 28

Author(s):

Emmanuel O. Osigwe ◽

Arnold Gad-Briggs ◽

Theoklis Nikolaidis

Keyword(s):

Gas Turbine ◽

Gas Turbines ◽

Pressure Ratio ◽

Low Noise ◽

Closed Cycle ◽

Propulsion Systems ◽

Component Design ◽

Readiness Level ◽

Aerial Vehicle ◽

Turbine Design

When selecting a design for an unmanned aerial vehicle, the choice of the propulsion system is vital in terms of mission requirements, sustainability, usability, noise, controllability, reliability and technology readiness level (TRL). This study analyses the various propulsion systems used in unmanned aerial vehicles (UAVs), paying particular focus on the closed-cycle propulsion systems. The study also investigates the feasibility of using helium closed-cycle gas turbines for UAV propulsion, highlighting the merits and demerits of helium closed-cycle gas turbines. Some of the advantages mentioned include high payload, low noise and high altitude mission ability; while the major drawbacks include a heat sink, nuclear hazard radiation and the shield weight. A preliminary assessment of the cycle showed that a pressure ratio of 4, turbine entry temperature (TET) of 800 °C and mass flow of 50 kg/s could be used to achieve a lightweight helium closed-cycle gas turbine design for UAV mission considering component design constraints.

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