The advancement of medical 3D printing technology includes several enhancements, such as decreasing the length of surgical procedures and minimizing anesthesia exposure, improving preoperative planning, creating personalized replicas of tissues and bones specific to individual patients, bioprinting, and providing alternatives to human organ transplants. The range of materials accessible for 3D printing within the healthcare industry is significantly narrower when compared with conventional manufacturing techniques. Liquid silicone rubber (LSR) is characterized by its remarkable stability, outstanding biocompatibility, and significant flexibility, thus presenting substantial opportunities for manufacturers of medical devices who are engaged in 3D printing. The main objective of this study is to develop, refine, and assess a 3D printer that can employ UV-cured silicone for the fabrication of aortic heart valves. Additionally, the research aims to produce a 3D-printed silicone aortic heart valve and evaluate the feasibility of the final product. A two-level ANOVA experimental design was utilized to investigate the impacts of print speed, nozzle temperature, and layer height on the print quality of the aortic heart valve. The findings demonstrated that the 3D-printed heart valve’s UV-cured silicone functioned efficiently, achieving the target flow rates of 5 L/min and 7 L/min. Two distinct leaflet thicknesses (LT) of the heart valve, namely 0.8 mm and 1.6 mm, were also analyzed to simulate calcium deposition on the leaflets.

Taking advantage of the angular momentum of the rotating gyroscope, gyrostabilizer systems are expected to become more widely actualized as they provide an effective means of motion control with several significant advantages for various structures. In this paper, a symmetric gyro with coupling to the tip mass of a column mounted on a vibrating base is considered. The non- linear motions of the gyro-column system and the equations of motion for the system are derived following energy (Lagrange) based approaches and examples provided. On the other hand, the effect of the angular velocity of the gyroscope is studied, and it is shown that the angular velocity (spin velocity): of gyroscope has a significant effect on the behavior of the dynamic motion. It is also shown how the damper and spring due to the motion between the suporting gimbal and tip mass influence the dynamic behavior of the gyroscope. It was concluded that the numerical investigations of this combined system has not been investigated up to the present time

The present paper is based on experimental studies and numerical simulations on the surface fatigue failure of the PTFE-bronze layered journal bearings under real-time loading. 'Permaglide Plain Bearings P10' type journal bearings were experimentally tested under different real time dynamic loadings by using real time journal bearing test system in our laboratory. The journal bearing consists of a PTFE-bronze layer approximately 0.32 mm thick on the steel support layer with 2.18 mm thick. Two different approaches have been considered with in experiments: (i) under real- time constant loading with varying bearing widths, (ii) under different real-time loadings at constant bearing widths. Fatigue regions, micro-crack dispersion and stress distributions occurred at the journal bearing were experimentally and theoretically investigated. The relation between fatigue region and pressure distributions were investigated by determining the circumferential pressure distribution under real-time dynamic loadings for the position of every 10° crank angles. In the theoretical part; stress and deformation distributions at the surface of the journal bearing analysed by using finite element methods to determine the relationship between stress and fatigue behaviour. As a result of this study, the maximum oil pressure and fatigue cracks were observed in the most heavily loaded regions of the bearing surface. Experimental results show that PTFE-Bronze layered journal bearings fatigue behaviour is better than the bearings include white metal alloy.

In the healthcare industry, the selection of biocompatible materials suitable for 3D printing is markedly less extensive than what is typically available through conventional manufacturing processes. Liquid silicone rubber (LSR) is distinguished by its exceptional stability, excellent biocompatibility, and considerable flexibility, offering significant prospects for manufacturers of medical devices involved in 3D printing. The primary aim of this research is to examine the essential factors and their interconnections that affect the 3D printing process with a Direct Ink Writing (DIW) 3D printer, which is specifically tailored for the production of aortic heart valves made from UV-cured silicone. Additionally, this study aims to investigate how the size of the heart valve impacts cardiac performance. This study implements House of Quality (HOQ) and Interpretive Structural Modeling (ISM) techniques to evaluate the interrelations among the different factors identified in the 3D printing process. Liquid silicone is especially advantageous for Direct Ink Writing (DIW) due to its low-temperature curing properties and low viscosity, which enable precise printing for intricate designs. Two different sizes of aortic heart valves, namely 23 mm and 36 mm, will be manufactured using UV-cured silicone, with both sizes having the same leaflet thickness of 0.8 mm and 1.6 mm. An examination will be conducted to assess how the size of the valve influences its performance and functionality. A Mock Circulatory Loop experimental setup will be used to test the silicone-printed heart valves, focusing on their capacity to maintain unidirectional flow and inhibit backflow through the flexible leaflets that function in alignment with the cardiac cycle.

Many of today’s technologies and research techniques depend on process and methods in high and ultra-high vacuum chambers. High temperature vacuum chambers require innovative concept and use of unusual materials in design to achieve quality performance. In order to obtain quality performance, the temperature and gas delivery on the vacuum chamber surface must be uniformly distributed. In this work, a new funnel for high temperature vacuum chamber was successfully designed and tested using computer-based simulation techniques. The funnel was made of quartz crystal (Grade 2) due to ability to absorb temperature, properties of low gas permeability and low temperature coefficient. In order to mitigate O-rings from high temperature failure and to reduce non-uniformity effect during temperature delivery, a new quartz funnel was developed. The simulation and experimental results show that uniformity distributions in temperature of vacuum chamber surface were obtained with new funnel design. Özet: Günümüz teknolojilerinin ve araştırma tekniklerinin çoğu yüksek ve ultra yüksek vakum odalarındaki proses ve metotlara bağlıdır. Yüksek sıcaklık vakum odaları, yenilikçi kavram ve kaliteli performans elde edilen tasarımda alışılagelmedik malzemelerin kullanımını gerektirir. Kaliteli performans elde etmek için vakum odası yüzeyine sıcaklık ve gaz iletimi eşit dağılmalıdır. Bu çalışmada, bilgisayar bazlı simülasyon teknikleri kullanılarak yüksek sıcaklık vakum odası için yeni bir huni tasarımı başarılı bir şekilde tasarlanmış ve test edilmiştir. Huni, sıcaklık emme yeteneği, düşük gaz geçirgenliği ve düşük sıcaklık katsayısı özellikleri sebebi ile kuvars kristalinden yapılmıştır. Sıcaklık iletimi esnasında eşit olmayan dağılımın etkisini azaltmak ve yüksek sıcaklık düşüşlerini düşürmek için yeni bir kuvars huni geliştirilmiştir. Simülasyon ve deney sonuçları gösterdi ki, vakum odası yüzeyinin sıcaklığındaki eşit dağılımlar yeni huni tasarımı ile elde edilmiştir.