scholarly journals Structural Design of Mechanical Property for Biodegradable Polymeric Stent

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Yunbo Wei ◽  
Minjie Wang ◽  
Danyang Zhao ◽  
Hongxia Li ◽  
Yifei Jin
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Design Method ◽  
Ring Structure ◽  
Mechanical Tests ◽  
Radial Force ◽  
Element Analysis ◽  
Stent Expansion ◽  
Supporting Ring

How to improve stent mechanical properties is a key issue for designing biodegradable polymeric stents (BPSs). In this study, a new design method of BPS was proposed based on the force analysis of supporting rings and bridges during stent implantation, and a novel BPS called open C-shaped stent (OCS) with superior comprehensive mechanical properties was developed accordingly. The key mechanical properties including radial force, radial recoil, and axial foreshortening of the OCS have been comprehensively studied and compared with those of the Abbott BVS using finite element analysis (FEA). In addition, the effects of the stent geometries on these mechanical properties have also been discussed in detail. Besides, in vitro mechanical tests including stent expansion and planar compression experiments have been performed to verify the simulation results. Based on the FEA results, it is found that the radial force and radial recoil of the designed OCS are 30% higher and 24% lower than those of the BVS, respectively. Meanwhile, the OCS is not shortened during expansion. Radial force and radial recoil are mainly dependent on the supporting ring structure, and the utilization of designed unequal-height supporting ring (UHSR) can effectively improve these two properties. Axial foreshortening is mainly determined by the bridge geometry as well as the connecting position of the bridge with the adjacent supporting rings. It is feasible to improve the axial foreshortening by using the bridges with a curved structure and locating the connecting position in the middle of the straight section of the supporting elements. The rationality of the proposed OCS and the effectiveness of the finite element method have been verified by in vitro experiments.

scholarly journals Validation of Finite Element Analysis of a selfexpanding polymeric microstent for treatment of Fallopian tube occlusions

2021 ◽  
Vol 7 (2) ◽  
pp. 700-703
Author(s):  
Ariane Dierke ◽  
Thomas Kuske ◽  
Hagen Frank ◽  
Eric Bohne ◽  
Christoph Brandt-Wunderlich ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fallopian Tube ◽  
Mechanical Performance ◽  
Material Model ◽  
Radial Force ◽  
Experimental Investigations ◽  
Element Analysis ◽  
Fea Model

Abstract Proximal occlusion of the Fallopian tube is one of the most common causes of female infertility. Due to the occlusion, the passage of the fallopian tubes is no longer given. Basically, there are two options for patients affected by this condition: cost-intensive in vitro fertilization (IVF) or surgery. The pregnancy rates of approximately 50% achieved with current treatment options are not satisfying. In this work, we present a Finite Element Analysis (FEA) model of a previously reported optimized microstent design for minimally invasive therapy of proximal tubal occlusion. Based on experimental investigations, the material model was set up and the simulation was validated. Comparison of the mechanical performance as an application related critical load case was in a good agreement. In this work, the proof of concept for the FEA model and the material model were carried out. In the future, the simulation will be used for further load cases such as the investigation of the bending stiffness and radial force and for the design optimization.

Importance of the Meshing Accuracy for Stress Evaluation in All-Ceramic Restored Teeth

2013 ◽  
Vol 404 ◽  
pp. 112-117
Author(s):  
Sorin Porojan ◽  
Florin Topală ◽  
Liliana Porojan
Keyword(s):  
Finite Element ◽  
Design Method ◽  
In Vitro Study ◽  
Material Behavior ◽  
Element Analysis ◽  
All Ceramic ◽  
Distribution Of Stress ◽  
Ceramic Restorations

The fracture resistance of all-ceramic restorations is one of the major concerns in clinical applications of these materials. An in vitro study can help to estimate the in vivo behavior of a new dental material and design method. The FEM (finite element method) seems to be a proper tool to study material behavior in relation to their composition, relationship and geometry, by analyzing the distribution of stress. The purpose of this study was to evaluate, by finite element analysis, the importance of meshing accuracy on stresses induced in all-ceramic restored teeth during protrusion loading. For the experimental analysis, a 3D model of a central incisor was achieved: intact teeth, unrestored teeth with chamfer marginal preparation, the same tooth restored with full pressed ceramic crown. Stress analysis was performed on the restored incisor during protrusion. To evaluate the importance of the meshing accuracy for stresses in all-ceramic restored teeth three kinds of meshing options were chosen: coarse, medium and fine. For the analysis choosing of the proper meshing options is essential for accurate results. The medium meshing is enough to obtain favorable results.

scholarly journals Experimental evaluation of stent retrievers’ mechanical properties and effectiveness

2016 ◽  
Vol 9 (3) ◽  
pp. 257-263 ◽  
Author(s):  
Paolo Machi ◽  
Franck Jourdan ◽  
Dominique Ambard ◽  
Cedric Reynaud ◽  
Kyriakos Lobotesis ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Vessel Wall ◽  
Large Diameter ◽  
Mechanical Tests ◽  
Radial Force ◽  
Functional Tests ◽  
Clot Removal ◽  
Stent Retrievers ◽  
Thrombus Removal

BackgroundFive randomized controlled trials recently appeared in the literature demonstrating that early mechanical thrombectomy in patients with acute ischemic stroke is significantly related to an improved outcome. Stent retrievers are accepted as the most effective devices for intracranial thrombectomy.ObjectiveTo analyze the mechanical properties of stent retrievers, their behavior during retrieval, and interaction with different clots and to identify device features that might correlate with the effectiveness of thrombus removal.Materials and methodsAll stent retrievers available in France up to June 2015 were evaluated by mechanical and functional tests aimed at investigating the variation of their radial force and their behavior during retrieval. Devices were also tested during in vitro thrombectomies using white and red experimental thrombi produced with human blood. Functional tests and in vitro thrombectomies were conducted using a rigid 3D printed vascular model.ResultsMechanical tests showed a variation in radial force during retrieval for each stent. A constant radial force during retrieval was related to continuous cohesion over the vessel wall and a higher rate of clot removal efficacy. All stent retrievers failed when interacting with white large thrombi (diameter ≥6 mm).ConclusionsNone of the tested devices were effective in removing white clots of large diameter (≥6 mm). Constant radial force during retrieval allows constant cohesion to the vessel wall and pressure over the clot; such features allow for a higher rate of clot removal.

Finite Element Analysis of Nonuniformity of Tires with Imperfections5

2007 ◽  
Vol 35 (3) ◽  
pp. 226-238 ◽  
Author(s):  
K. M. Jeong ◽  
K. W. Kim ◽  
H. G. Beom ◽  
J. U. Park
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Radial Force ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Dimensional Finite Element ◽  
Force Variation ◽  
Three Dimensional Finite Element

Abstract The effects of variations in stiffness and geometry on the nonuniformity of tires are investigated by using the finite element analysis. In order to evaluate tire uniformity, a three-dimensional finite element model of the tire with imperfections is developed. This paper considers how imperfections, such as variations in stiffness or geometry and run-out, contribute to detrimental effects on tire nonuniformity. It is found that the radial force variation of a tire with imperfections depends strongly on the geometrical variations of the tire.

Finite Element Analysis of Reinforced Concrete Beams with Exterior FRP Shell

2011 ◽  
Vol 243-249 ◽  
pp. 1461-1465
Author(s):  
Chuan Min Zhang ◽  
Chao He Chen ◽  
Ye Fan Chen
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Test Results ◽  
Contact Interface ◽  
Accurate Calculation ◽  
Element Analysis

The paper makes an analysis of the reinforced concrete beams with exterior FRP Shell in Finite Element, and compares it with the test results. The results show that, by means of this model, mechanical properties of reinforced concrete beams with exterior FRP shell can be predicted better. However, the larger the load, the larger deviation between calculated values and test values. Hence, if more accurate calculation is required, issues of contact interface between the reinforced concrete beams and the FRP shell should be taken into consideration.

Finite Element Analysis and Optimization of Long-Span Gantry NC Machining Center Structure

2011 ◽  
Vol 346 ◽  
pp. 379-384
Author(s):  
Shu Bo Xu ◽  
Yang Xi ◽  
Cai Nian Jing ◽  
Ke Ke Sun
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Design Method ◽  
Dynamic Performance ◽  
Plate Thickness ◽  
Element Model ◽  
Wall Structure ◽  
Characteristic Analysis ◽  
Element Analysis ◽  
Dynamic Performance Analysis

The use of finite element theory and modal analysis theory, the structure of the machine static and dynamic performance analysis and prediction using optimal design method for optimization, the new machine to improve job performance, improve processing accuracy, shorten the development cycle and enhance the competitiveness of products is very important. Selected for three-dimensional CAD modeling software-UG NX4.0 and finite element analysis software-ANSYS to set up the structure of the beam finite element model, and then post on the overall structure of the static and dynamic characteristic analysis, on the basis of optimized static and dynamic performance is more superior double wall structure of the beam. And by changing the wall thickness and the thickness of the inner wall, as well as the reinforcement plate thickness overall sensitivity analysis shows that changes in these three parameters on the dynamic characteristics of post impact. Application of topology optimization methods, determine the optimal structure of the beam ultimately.

The equivalent method of double V-wing honeycombs on the in-plane dynamic impact

2021 ◽  
pp. 073168442199086
Author(s):  
Yunfei Qu ◽  
Dian Wang ◽  
Hongye Zhang
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Elastic Modulus ◽  
Energy Absorption ◽  
Width Ratio ◽  
Size Factor ◽  
Dynamic Impact ◽  
Element Analysis ◽  
Equivalent Method

The double V-wing honeycomb can be applied in many fields because of its lower mass and higher performance. In this study, the volume, in-plane elastic modulus and unit cell area of the double V-wing honeycomb were analytically derived, which became parts of the theoretical basis of the novel equivalent method. Based on mass, plateau load, in-plane elastic modulus, compression strain and energy absorption of the double V-wing honeycomb, a novel equivalent method mapping relationship between the thickness–width ratio and the basic parameters was established. The various size factor of the equivalent honeycomb model was denoted as n and constructed by the explicit finite element analysis method. The mechanical properties and energy absorption performance for equivalent honeycombs were investigated and compared with hexagonal honeycombs under dynamic impact. Numerical results showed a well coincidence for each honeycomb under dynamic impact before 0.009 s. Honeycombs with the same thickness–width ratio had similar mechanical properties and energy absorption characteristics. The equivalent method was verified by theoretical analysis, finite element analysis and experimental testing. Equivalent honeycombs exceeded the initial honeycomb in performance efficiency. Improvement of performance and weight loss reached 173.9% and 13.3% to the initial honeycomb. The double V-wing honeycomb possessed stronger impact resistance and better load-bearing capacity than the hexagonal honeycomb under impact in this study. The equivalent method could be applied to select the optimum honeycomb based on requirements and improve the efficiency of the double V-wing honeycomb.

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