The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform

Marc Gewillig - One of the best experts on this subject based on the ideXlab platform.

  • Stent expansion of stretch Gore‐Tex grafts in children with congenital heart lesions
    Catheterization and cardiovascular interventions : official journal of the Society for Cardiac Angiography & Interventions, 2010
    Co-Authors: Stephen C. Brown, Derize Boshoff, Ruth Heying, M Gorenflo, Filip Rega, Benedicte Eyskens, Bart Meyns, Marc Gewillig
    Abstract:

    To evaluate the efficacy and safety of expanding vascular shunt grafts beyond original Nominal Diameter using stents. Bench testing confirmed the expandability of 3.5 mm and 4.0 mm vascular Gore-Tex stretch grafts. A retrospective analysis included eleven systemic to pulmonary artery shunts with diminished flow which were stented with the aim of increasing the original Nominal Diameter of the shunts. During bench testing, the grafts could be expanded to 4.5 mm and 5.8 mm, respectively. Fourteen stents were implanted in 11 stretch grafts a median of 18.9 months (3.2; 21.6 months) after shunt surgery. There was a median increase in Diameter of 1.4 mm (0.9; 1.7 mm) [P = 0.001, 95% CI: 0.47; 1.7) from original Nominal to final stented Diameter of the shunts with a median gain of 28%. A simultaneous improvement in saturations from a median of 73% (66; 77%) to 87% (84; 89%) [P = 0.015; 95% CI: 3; 22] was observed. No complications were experienced during the procedures. In our limited experience, stretch Gore-Tex vascular grafts can be safely expanded beyond Nominal Diameters using high pressure vascular stents. This leads to improvement in saturation and pulmonary blood flow. It allows the clinician to tailor pulmonary flow in relation to pulmonary artery size and growth, ensuring best possible timing for the next surgical procedure. Copyright 2010 Wiley-Liss, Inc.

  • Stent expansion of stretch Gore-Tex grafts in children with congenital heart lesions
    Catheterization and Cardiovascular Interventions, 2010
    Co-Authors: Stephen C. Brown, Ruth Heying, M Gorenflo, Filip Rega, Benedicte Eyskens, Bart Meyns, Derize E. Boshoff, Marc Gewillig
    Abstract:

    Objective: To evaluate the efficacy and safety of expanding vascular shunt grafts beyond original Nominal Diameter using stents. Methods: Bench testing confirmed the expandability of 3.5 mm and 4.0 mm vascular Gore-Tex(R) stretch grafts. A retrospective analysis included eleven systemic to pulmonary artery shunts with diminished flow which were stented with the aim of increasing the original Nominal Diameter of the shunts. Results: During bench testing, the grafts could be expanded to 4.5 mm and 5.8 mm, respectively. Fourteen stents were implanted in 11 stretch grafts a median of 18.9 months (3.2; 21.6 months) after shunt surgery. There was a median increase in Diameter of 1.4 mm (0.9; 1.7 mm) [P = 0.001, 95% CI: 0.47; 1.7) from original Nominal to final stented Diameter of the shunts with a median gain of 28%. A simultaneous improvement in saturations from a median of 73% (66; 77%) to 87% (84; 89%) [P = 0.015; 95% CI: 3; 22] was observed. No complications were experienced during the procedures. Conclusion: In our limited experience, stretch Gore-Tex vascular grafts can be safely expanded beyond Nominal Diameters using high pressure vascular stents. This leads to improvement in saturation and pulmonary blood flow. It allows the clinician to tailor pulmonary flow in relation to pulmonary artery size and growth, ensuring best possible timing for the next surgical procedure. (c) 2009 Wiley-Liss, Inc.status: publishe

Stephen C. Brown - One of the best experts on this subject based on the ideXlab platform.

  • Stent expansion of stretch Gore‐Tex grafts in children with congenital heart lesions
    Catheterization and cardiovascular interventions : official journal of the Society for Cardiac Angiography & Interventions, 2010
    Co-Authors: Stephen C. Brown, Derize Boshoff, Ruth Heying, M Gorenflo, Filip Rega, Benedicte Eyskens, Bart Meyns, Marc Gewillig
    Abstract:

    To evaluate the efficacy and safety of expanding vascular shunt grafts beyond original Nominal Diameter using stents. Bench testing confirmed the expandability of 3.5 mm and 4.0 mm vascular Gore-Tex stretch grafts. A retrospective analysis included eleven systemic to pulmonary artery shunts with diminished flow which were stented with the aim of increasing the original Nominal Diameter of the shunts. During bench testing, the grafts could be expanded to 4.5 mm and 5.8 mm, respectively. Fourteen stents were implanted in 11 stretch grafts a median of 18.9 months (3.2; 21.6 months) after shunt surgery. There was a median increase in Diameter of 1.4 mm (0.9; 1.7 mm) [P = 0.001, 95% CI: 0.47; 1.7) from original Nominal to final stented Diameter of the shunts with a median gain of 28%. A simultaneous improvement in saturations from a median of 73% (66; 77%) to 87% (84; 89%) [P = 0.015; 95% CI: 3; 22] was observed. No complications were experienced during the procedures. In our limited experience, stretch Gore-Tex vascular grafts can be safely expanded beyond Nominal Diameters using high pressure vascular stents. This leads to improvement in saturation and pulmonary blood flow. It allows the clinician to tailor pulmonary flow in relation to pulmonary artery size and growth, ensuring best possible timing for the next surgical procedure. Copyright 2010 Wiley-Liss, Inc.

  • Stent expansion of stretch Gore-Tex grafts in children with congenital heart lesions
    Catheterization and Cardiovascular Interventions, 2010
    Co-Authors: Stephen C. Brown, Ruth Heying, M Gorenflo, Filip Rega, Benedicte Eyskens, Bart Meyns, Derize E. Boshoff, Marc Gewillig
    Abstract:

    Objective: To evaluate the efficacy and safety of expanding vascular shunt grafts beyond original Nominal Diameter using stents. Methods: Bench testing confirmed the expandability of 3.5 mm and 4.0 mm vascular Gore-Tex(R) stretch grafts. A retrospective analysis included eleven systemic to pulmonary artery shunts with diminished flow which were stented with the aim of increasing the original Nominal Diameter of the shunts. Results: During bench testing, the grafts could be expanded to 4.5 mm and 5.8 mm, respectively. Fourteen stents were implanted in 11 stretch grafts a median of 18.9 months (3.2; 21.6 months) after shunt surgery. There was a median increase in Diameter of 1.4 mm (0.9; 1.7 mm) [P = 0.001, 95% CI: 0.47; 1.7) from original Nominal to final stented Diameter of the shunts with a median gain of 28%. A simultaneous improvement in saturations from a median of 73% (66; 77%) to 87% (84; 89%) [P = 0.015; 95% CI: 3; 22] was observed. No complications were experienced during the procedures. Conclusion: In our limited experience, stretch Gore-Tex vascular grafts can be safely expanded beyond Nominal Diameters using high pressure vascular stents. This leads to improvement in saturation and pulmonary blood flow. It allows the clinician to tailor pulmonary flow in relation to pulmonary artery size and growth, ensuring best possible timing for the next surgical procedure. (c) 2009 Wiley-Liss, Inc.status: publishe

Toshiyuki Sawa - One of the best experts on this subject based on the ideXlab platform.

  • FEM Stress Analysis and Mechanical Characteristics of Bolted Pipe Connections With Larger Nominal Diameter Inserting PTFE Blended Gasket Under Internal Pressure
    Volume 2: Computer Technology and Bolted Joints, 2018
    Co-Authors: Koji Sato, Toshiyuki Sawa, Xing Zheng
    Abstract:

    The sealing performance prediction of bolted pipe flange connections with gaskets is important factor. However, it is known that the sealing performance of the larger Nominal Diameter connection is worse than that with smaller Nominal Diameter connection due to the flange rotation. Furthermore, recently PTFE blended gaskets were developed newly and the excellent sealing performance in the bolted pipe flange connection with smaller Nominal Diameter is found. So, it is necessary to examine the sealing performance and the mechanical characteristics of pipe flange connections with larger Nominal Diameter under internal pressure. The objectives of present study are to examine the mechanical characteristics of the pipe flange connection with PTFE blended gasket under internal pressure such as the load factor, the contact gasket stress distribution and the sealing performance using FEM and experiments. Using the obtained contact gasket stress distribution and the fundamental leak rate for smaller PTFE gasket, the leak rate of the connection is predicted under internal pressure. In the FEM calculation, the effects of the Nominal Diameter of pip flange connections on the mechanical characteristics are shown. In the experiments, ASME class 300 24” pipe flange connections is used and the gasket is chosen as No.GF300 in PTFE blended gaskets. The FEM results of the axial bolt forces are in a fairly good agreement with the experimental results. In addition, the leak rate obtained from the FEM calculations are fairly coincided with the measured results. The mechanical characteristics of pipe flange connection with PTFE blended gasket are compared with those with spiral wound gasket.

  • Mechanical Characteristics and Design Method for Bolted Circular Flange Joints Subjected to External Tensile Loads
    Volume 2: Advanced Manufacturing, 2016
    Co-Authors: Shunichiro Sawa, Mitsutoshi Ishimura, Yasuhisa Sekiguchi, Toshiyuki Sawa
    Abstract:

    The characteristics of bolted circular flange joints tightened with bolt number N are analyzed using FEM such as the interface stress distributions in initial clamping state, those in operation and the load factor under tensile loadings. Then the effects of the bolt pitch circle Diameter D and the bolt number N on the load factor and the interface stress distributions are examined. The FEM results of the load factor and a load when the interfaces starts to separate are fairly coincided with the experimental results. The value of the load factor is the smaller and it is less than 0.1. In addition, it decreases as the value of D increases. Another objective is to demonstrate a new design method and two typical cases are described. One is a problem how to determine the bolt Nominal Diameter when the bolt strength grade, bolt number N, the interface stress for keeping the joint function and external load are provided and the other is how to determine the bolt strength when the bolt Nominal Diameter, interface stress and external load are provided. The measured tightening coefficient Q is introduced in the design and the bolt strength is evaluated using the newly introduced equivalent stress taking account the shear stress due to torque in bolt initial tightening. Using the obtained Nominal Diameter, the bolt maximum stress, the bolt stress amplitude and the critical stress at the bearing surfaces are checked. The availability of the method is shown with the flowchart for design.

  • FEM Stress Analysis and the Sealing Performance Evaluation of Bolted Pipe Flange Connections With Large Nominal Diameter Subjected to Internal Pressure
    Volume 2: Computer Technology and Bolted Joints, 2016
    Co-Authors: Akira Muramatsu, Koji Sato, Maksud Uddin Khan, Toshiyuki Sawa
    Abstract:

    The gasket fundamental characteristics such as the stress-strain curves of compressed sheet gaskets (CSG) and the spiral wound gaskets (SWG) and the relationship between the average gasket stress and the leak rate using rigid platens were measured. Then, using the measured data of the gasket properties, the mechanical characteristics of bolted pipe flange connections under internal pressure are examined such as the contact gasket stress distribution, hub stress and changes in axial bolt forces (the load factor) using FEM. FEM code employed is ABAQUS. Using the obtained gasket stress distributions and the fundamental gasket relationship between the gasket stress and the leak rate, the leak rates of bolted pipe flange connections are predicted. In addition, the effect of Nominal Diameters (from 2” to 24”) on the mechanical characteristics is examined. For verification of the FEM calculations, experiments to measure the load factor, the hub stress and the leak rates were performed using 2” and 24” bolted pipe flange connections. The FEM results of the load factor, the hub stress and the leak rate are in a fairly good agreement with the measured results. The value of the load factor is found to be positive for 2” pipe flanged joints, while it is negative for 24” pipe flanged connection due to the flange rotation. It is noticed that the values of the load factor decreases with an increase of the Nominal Diameter of pipe flanges. The hub stress is kept constant when the gasket stress is held constant for each connection with each Nominal Diameter while it increases as the Nominal Diameter increases according to ASME codes. In addition, the leak rate increases as the Nominal Diameter increases.

  • 3-D FEM Stress Analysis and Mechanical Characteristics in Bolted Joints Under External Tensile Loadings
    Volume 2B: Advanced Manufacturing, 2015
    Co-Authors: Shunichiro Sawa, Mitsutoshi Ishimura, Yasuhisa Sekiguchi, Toshiyuki Sawa
    Abstract:

    In practical design for bolted joints, the stress concentration factor (SCF) of the first root in screw threads is important. In the present paper, the SCF in screw threads taking account of spiral in the screw threads is analyzed using three-dimensional Finite Element Method (FEM). In addition, the stress states of screw threads under repeated and static loadings are analyzed in elasto-plastic deformation range. The effect of bolt Nominal Diameter (M12, M24 and M33) on SCF is also examined. In addition, the experiment to measure the strains at the roots of screw threads was carried out newly. It is found that the FEM result is fairly coincided with the measured results. It is also found that the SCF increases as the bolt Nominal Diameter increases and the maximum stress is found to occur at the half pith from the engaged screw threads. The value of SCF is smaller in the coarse screw threads of M12 than that in the fine screw threads of M 12. Finally, the bolt ruptures for several Nominal Diameters are shown to occur from screw threads in the non-engagement in bolted joints under static loadings and under the repeated loadings the bolts are ruptured from the first root of screw threads due to fatigue even if the bolt preload is the higher.

  • Stress Analysis and Sealing Performance Evaluation of Bolted Pipe Flange Connections With Smaller and Larger Nominal Diameter Under Repeated Temperature Changes
    Volume 2: Computer Technology and Bolted Joints, 2014
    Co-Authors: Yuya Omiya, Toshiyuki Sawa
    Abstract:

    Pipe flange connections with gaskets in chemical plants, electric power plants and other industrial plants are usually exposed to elevated internal pressure with cyclic thermal condition. It is important to investigate the sealing performance of pipe connections under long term severe thermal exposure swings to ensure operational safety. In this study, the effects of cyclic thermal conditions on the sealing performance and mechanical characteristics in larger and smaller Nominal Diameter of pipe flange connection are examined using FEM calculations. Helium gas leakage is predicted using the contact gasket stress obtained from the FEM results. On other hand, the leakage tests using the smaller Nominal Diameter of pipe flange connection were conducted to measure the amount of helium gas leakage and to compare with the predicted amount of gas leakage. As the results, the contact gasket stress distributions were changed dramatically under cyclic thermal condition and elevated internal pressure. In the pipe flange connections with smaller Nominal Diameter, the contact gasket stress was the smallest in the restart condition. On other hand, the minimum contact gasket stress in the pipe flange connection with larger Nominal Diameter was depending on the materials of connection. In the pipe flange connection with larger Nominal Diameter, the contact gasket stress distributed and changed in the radial direction due to the flange rotation. A fairly good agreement was found between the experimental leakage result and predicted leakage results.

Ruth Heying - One of the best experts on this subject based on the ideXlab platform.

  • Stent expansion of stretch Gore‐Tex grafts in children with congenital heart lesions
    Catheterization and cardiovascular interventions : official journal of the Society for Cardiac Angiography & Interventions, 2010
    Co-Authors: Stephen C. Brown, Derize Boshoff, Ruth Heying, M Gorenflo, Filip Rega, Benedicte Eyskens, Bart Meyns, Marc Gewillig
    Abstract:

    To evaluate the efficacy and safety of expanding vascular shunt grafts beyond original Nominal Diameter using stents. Bench testing confirmed the expandability of 3.5 mm and 4.0 mm vascular Gore-Tex stretch grafts. A retrospective analysis included eleven systemic to pulmonary artery shunts with diminished flow which were stented with the aim of increasing the original Nominal Diameter of the shunts. During bench testing, the grafts could be expanded to 4.5 mm and 5.8 mm, respectively. Fourteen stents were implanted in 11 stretch grafts a median of 18.9 months (3.2; 21.6 months) after shunt surgery. There was a median increase in Diameter of 1.4 mm (0.9; 1.7 mm) [P = 0.001, 95% CI: 0.47; 1.7) from original Nominal to final stented Diameter of the shunts with a median gain of 28%. A simultaneous improvement in saturations from a median of 73% (66; 77%) to 87% (84; 89%) [P = 0.015; 95% CI: 3; 22] was observed. No complications were experienced during the procedures. In our limited experience, stretch Gore-Tex vascular grafts can be safely expanded beyond Nominal Diameters using high pressure vascular stents. This leads to improvement in saturation and pulmonary blood flow. It allows the clinician to tailor pulmonary flow in relation to pulmonary artery size and growth, ensuring best possible timing for the next surgical procedure. Copyright 2010 Wiley-Liss, Inc.

  • Stent expansion of stretch Gore-Tex grafts in children with congenital heart lesions
    Catheterization and Cardiovascular Interventions, 2010
    Co-Authors: Stephen C. Brown, Ruth Heying, M Gorenflo, Filip Rega, Benedicte Eyskens, Bart Meyns, Derize E. Boshoff, Marc Gewillig
    Abstract:

    Objective: To evaluate the efficacy and safety of expanding vascular shunt grafts beyond original Nominal Diameter using stents. Methods: Bench testing confirmed the expandability of 3.5 mm and 4.0 mm vascular Gore-Tex(R) stretch grafts. A retrospective analysis included eleven systemic to pulmonary artery shunts with diminished flow which were stented with the aim of increasing the original Nominal Diameter of the shunts. Results: During bench testing, the grafts could be expanded to 4.5 mm and 5.8 mm, respectively. Fourteen stents were implanted in 11 stretch grafts a median of 18.9 months (3.2; 21.6 months) after shunt surgery. There was a median increase in Diameter of 1.4 mm (0.9; 1.7 mm) [P = 0.001, 95% CI: 0.47; 1.7) from original Nominal to final stented Diameter of the shunts with a median gain of 28%. A simultaneous improvement in saturations from a median of 73% (66; 77%) to 87% (84; 89%) [P = 0.015; 95% CI: 3; 22] was observed. No complications were experienced during the procedures. Conclusion: In our limited experience, stretch Gore-Tex vascular grafts can be safely expanded beyond Nominal Diameters using high pressure vascular stents. This leads to improvement in saturation and pulmonary blood flow. It allows the clinician to tailor pulmonary flow in relation to pulmonary artery size and growth, ensuring best possible timing for the next surgical procedure. (c) 2009 Wiley-Liss, Inc.status: publishe

M Gorenflo - One of the best experts on this subject based on the ideXlab platform.

  • Stent expansion of stretch Gore‐Tex grafts in children with congenital heart lesions
    Catheterization and cardiovascular interventions : official journal of the Society for Cardiac Angiography & Interventions, 2010
    Co-Authors: Stephen C. Brown, Derize Boshoff, Ruth Heying, M Gorenflo, Filip Rega, Benedicte Eyskens, Bart Meyns, Marc Gewillig
    Abstract:

    To evaluate the efficacy and safety of expanding vascular shunt grafts beyond original Nominal Diameter using stents. Bench testing confirmed the expandability of 3.5 mm and 4.0 mm vascular Gore-Tex stretch grafts. A retrospective analysis included eleven systemic to pulmonary artery shunts with diminished flow which were stented with the aim of increasing the original Nominal Diameter of the shunts. During bench testing, the grafts could be expanded to 4.5 mm and 5.8 mm, respectively. Fourteen stents were implanted in 11 stretch grafts a median of 18.9 months (3.2; 21.6 months) after shunt surgery. There was a median increase in Diameter of 1.4 mm (0.9; 1.7 mm) [P = 0.001, 95% CI: 0.47; 1.7) from original Nominal to final stented Diameter of the shunts with a median gain of 28%. A simultaneous improvement in saturations from a median of 73% (66; 77%) to 87% (84; 89%) [P = 0.015; 95% CI: 3; 22] was observed. No complications were experienced during the procedures. In our limited experience, stretch Gore-Tex vascular grafts can be safely expanded beyond Nominal Diameters using high pressure vascular stents. This leads to improvement in saturation and pulmonary blood flow. It allows the clinician to tailor pulmonary flow in relation to pulmonary artery size and growth, ensuring best possible timing for the next surgical procedure. Copyright 2010 Wiley-Liss, Inc.

  • Stent expansion of stretch Gore-Tex grafts in children with congenital heart lesions
    Catheterization and Cardiovascular Interventions, 2010
    Co-Authors: Stephen C. Brown, Ruth Heying, M Gorenflo, Filip Rega, Benedicte Eyskens, Bart Meyns, Derize E. Boshoff, Marc Gewillig
    Abstract:

    Objective: To evaluate the efficacy and safety of expanding vascular shunt grafts beyond original Nominal Diameter using stents. Methods: Bench testing confirmed the expandability of 3.5 mm and 4.0 mm vascular Gore-Tex(R) stretch grafts. A retrospective analysis included eleven systemic to pulmonary artery shunts with diminished flow which were stented with the aim of increasing the original Nominal Diameter of the shunts. Results: During bench testing, the grafts could be expanded to 4.5 mm and 5.8 mm, respectively. Fourteen stents were implanted in 11 stretch grafts a median of 18.9 months (3.2; 21.6 months) after shunt surgery. There was a median increase in Diameter of 1.4 mm (0.9; 1.7 mm) [P = 0.001, 95% CI: 0.47; 1.7) from original Nominal to final stented Diameter of the shunts with a median gain of 28%. A simultaneous improvement in saturations from a median of 73% (66; 77%) to 87% (84; 89%) [P = 0.015; 95% CI: 3; 22] was observed. No complications were experienced during the procedures. Conclusion: In our limited experience, stretch Gore-Tex vascular grafts can be safely expanded beyond Nominal Diameters using high pressure vascular stents. This leads to improvement in saturation and pulmonary blood flow. It allows the clinician to tailor pulmonary flow in relation to pulmonary artery size and growth, ensuring best possible timing for the next surgical procedure. (c) 2009 Wiley-Liss, Inc.status: publishe