Dynamic Left Atrioventricular Phantom Test Bed Emulating Mitral Valve Motion

2020 ◽  
Vol 14 (3) ◽  
Author(s):  
Toufic Azar ◽  
Stewart McLennan ◽  
Michael Walsh ◽  
Jorge Angeles ◽  
Jozsef Kövecses ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Blood Flow ◽  
Polyvinyl Alcohol ◽  
Computer Aided Design ◽  
Human Heart ◽  
Numerical Control ◽  
Test Bed ◽  
Numerical Control Machining ◽  
Valve Motion ◽  
Test Beds

Abstract Novel catheter-based medical procedures targeting heart valve structures are currently under development. These techniques entail installing a prosthetic implant on valves inside a beating heart. The development of these approaches requires a simple and effective validation test bed. Current early process testing methods rely on both static and dynamically pressurized excised porcine hearts. The variability between excised-tissue mechanical properties poses problems of reproducibility. In addition, these test beds do not emulate annulus motion, which affects the implant installation. A reproducible phantom of the left atrioventricular chambers was developed. The system consists of a hydraulic constant flow arrangement and a polyvinyl alcohol phantom heart with material properties that mimic passive myocardium mechanical properties and annulus motion. The system was then used to emulate blood flow through an actual heart. The building process starts by obtaining an accurate computer-aided design (CAD) model of a human heart, from which, a mold is produced using a novel rapid-freezing prototyping method and computer numerical control machining. The phantom is then cast-out of polyvinyl alcohol (PVA), a hydrogel, whose mechanical properties are set by subjecting the phantom to freeze and thaw cycles. Subsequently, blood flow is emulated at a constant volumetric rate at the atrial pressure observed in a healthy adult human heart at rest. The annulus motion is implemented by suturing the outside of the phantom to a one-degree-of-freedom cam-follower mechanism reproducing valve motion. Such test beds could play a significant role in future development of medical devices.

Computer Aided Design and Three-Dimensional Modeling of High-Order Deformed Elliptical Gear

2013 ◽  
Vol 391 ◽  
pp. 178-181
Author(s):  
Zhi Dong Huang ◽  
An Min Hui ◽  
Peng Chen ◽  
Yu Wang
Keyword(s):  
Computer Aided Design ◽  
Three Dimensional ◽  
High Order ◽  
Numerical Control ◽  
Element Analysis ◽  
Numerical Control Machining ◽  
Gear Teeth ◽  
Three Dimensional Modeling ◽  
Pitch Curve ◽  
Aided Design

The characteristics of high-order deformed elliptical gear is analyzed. The parameters of high-order deformed elliptical gear are chosen and calculated. The modeling method of high-order deformed elliptical gear is presented. The shape of pitch curve is determined. The position and orientation of gear teeth are clarified. The three-dimensional solid model of high-order deformed elliptical gear is achieved. The method and the result facilitate finite element analysis and numerical control machining simulation of high-order deformed elliptical gear.

Numerical Analysis of the VAD Outflow Cannula Positioning on the Blood Flow in the Patient–Specific Brain Supplying Arteries

2020 ◽  
Vol 22 (2) ◽  
pp. 619-636 ◽  
Author(s):  
Zbigniew Tyfa ◽  
Damian Obidowski ◽  
Krzysztof Jóźwik
Keyword(s):  
Blood Flow ◽  
Computer Aided Design ◽  
Volume Flow Rate ◽  
Flow Distribution ◽  
Primary Objective ◽  
Patient Specific ◽  
Blood Flow Distribution ◽  
Reconstruction Process ◽  
Outflow Cannula ◽  
The Brain

AbstractThe primary objective of this research can be divided into two separate aspects. The first one was to verify whether own software can be treated as a viable source of data for the Computer Aided Design (CAD) modelling and Computational Fluid Dynamics CFD analysis. The second aspect was to analyze the influence of the Ventricle Assist Device (VAD) outflow cannula positioning on the blood flow distribution in the brain-supplying arteries. Patient-specific model was reconstructed basing on the DICOM image sets obtained with the angiographic Computed Tomography. The reconstruction process was performed in the custom-created software, whereas the outflow cannulas were added in the SolidWorks software. Volumetric meshes were generated in the Ansys Mesher module. The transient boundary conditions enabled simulating several full cardiac cycles. Performed investigations focused mainly on volume flow rate, shear stress and velocity distribution. It was proven that custom-created software enhances the processes of the anatomical objects reconstruction. Developed geometrical files are compatible with CAD and CFD software – they can be easily manipulated and modified. Concerning the numerical simulations, several cases with varied positioning of the VAD outflow cannula were analyzed. Obtained results revealed that the location of the VAD outflow cannula has a slight impact on the blood flow distribution among the brain supplying arteries.

scholarly journals Evaluation of the Feasibility of NaCaPO4-Blended Zirconia as a New CAD/CAM Material for Dental Restoration

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3819
Author(s):  
Ting-Hsun Lan ◽  
Yu-Feng Chen ◽  
Yen-Yun Wang ◽  
Mitch M. C. Chou
Keyword(s):  
Computer Aided Design ◽  
Optical Microscope ◽  
Dental Restoration ◽  
Numerical Control ◽  
Test Results ◽  
Cnc Machine ◽  
Computer Aided ◽  
Cad Cam ◽  
Aided Design ◽  
Better Than

The computer-aided design/computer-aided manufacturing (CAD/CAM) fabrication technique has become one of the hottest topics in the dental field. This technology can be applied to fixed partial dentures, removable dentures, and implant prostheses. This study aimed to evaluate the feasibility of NaCaPO4-blended zirconia as a new CAD/CAM material. Eleven different proportional samples of zirconia and NaCaPO4 (xZyN) were prepared and characterized by X-ray diffractometry (XRD) and Vickers microhardness, and the milling property of these new samples was tested via a digital optical microscope. After calcination at 950 °C for 4 h, XRD results showed that the intensity of tetragonal ZrO2 gradually decreased with an increase in the content of NaCaPO4. Furthermore, with the increase in NaCaPO4 content, the sintering became more obvious, which improved the densification of the sintered body and reduced its porosity. Specimens went through milling by a computer numerical control (CNC) machine, and the marginal integrity revealed that being sintered at 1350 °C was better than being sintered at 950 °C. Moreover, 7Z3N showed better marginal fit than that of 6Z4N among thirty-six samples when sintered at 1350 °C (p < 0.05). The milling test results revealed that 7Z3N could be a new CAD/CAM material for dental restoration use in the future.

Adaptive spiral tool path generation for computer numerical control machining using point cloud

2021 ◽  
pp. 095440622199007
Author(s):  
Mandeep Dhanda ◽  
Aman Kukreja ◽  
SS Pande
Keyword(s):  
Tool Path ◽  
Cnc Machining ◽  
Numerical Control ◽  
Numerical Control Machining ◽  
Form Errors ◽  
Spiral Tool Path ◽  
Novel Method ◽  
Mesh Grid ◽  
Cloud Of Points ◽  
Cam Software

This paper reports a novel method to generate adaptive spiral tool path for the CNC machining of complex sculptured surface represented in the form of cloud of points without the need for surface fitting. The algorithm initially uses uniform 2 D circular mesh-grid to compute the cutter location (CL) points by applying the tool inverse offset method (IOM). These CL points are refined adaptively till the surface form errors converge below the prescribed tolerance limits in both circumferential and radial directions. They are further refined to eliminate the redundancy in machining and generate optimum region wise tool path to minimize the tool lifts. The NC part programs generated by our algorithm were widely tested for different case studies using the commercial CNC simulator as well as by the actual machining trial. Finally, a comparative study was done between our developed system and the commercial CAM software. The results showed that our system is more efficient and robust in terms of the obtained surface quality, productivity, and memory requirement.

scholarly journals Practical method for the fast generation of a CAM model for jet engine parts

2021 ◽  
Vol 13 (3) ◽  
pp. 168781402110027
Author(s):  
Byung Chul Kim ◽  
Ilhwan Song ◽  
Duhwan Mun
Keyword(s):  
Computer Aided Design ◽  
Feature Recognition ◽  
Practical Method ◽  
Numerical Control ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Jet Engine ◽  
Computer Aided ◽  
Cad Models ◽  
Cam Model

Manufacturers of machine parts operate computerized numerical control (CNC) machine tools to produce parts precisely and accurately. They build computer-aided manufacturing (CAM) models using CAM software to generate code to control these machines from computer-aided design (CAD) models. However, creating a CAM model from CAD models is time-consuming, and is prone to errors because machining operations and their sequences are defined manually. To generate CAM models automatically, feature recognition methods have been studied for a long time. However, since the recognition range is limited, it is challenging to apply the feature recognition methods to parts having a complicated shape such as jet engine parts. Alternatively, this study proposes a practical method for the fast generation of a CAM model from CAD models using shape search. In the proposed method, when an operator selects one machining operation as a source machining operation, shapes having the same machining features are searched in the part, and the source machining operation is copied to the locations of the searched shapes. This is a semi-automatic method, but it can generate CAM models quickly and accurately when there are many identical shapes to be machined. In this study, we demonstrate the usefulness of the proposed method through experiments on an engine block and a jet engine compressor case.

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