scholarly journals Finite element analysis of cutting balloon expansion in a calcified artery model of circular angle 180°: Effects of balloon-to-diameter ratio and number of blades facing calcification on potential calcification fracturing and perforation reduction

PLoS ONE ◽  
2021 ◽  
Vol 16 (5) ◽  
pp. e0251404
Author(s):  
Xiaodong Zhu ◽  
Mitsuo Umezu ◽  
Kiyotaka Iwasaki
Keyword(s):  
Finite Element ◽  
Diameter Ratio ◽  
Principal Stresses ◽  
Element Analysis ◽  
Stent Restenosis ◽  
Calcified Lesion ◽  
Nominal Pressure ◽  
Vessel Injury ◽  
Different Diameters ◽  
Vessel Dissection

Calcified artery lesions cause stent under-expansion and increase the risk of in-stent restenosis and stent thrombosis. Cutting balloons facilitate the fracturing of calcification prior to stent implantation, although vessel dissection and perforation are potential issues. In clinical practice, calcifications having maximum calcium angles ≤ 180° are rarely fractured during conventional balloon angioplasty. We hypothesize that the lesion/device diameter ratio and the number of blades facing a non-circular calcified lesion may be crucial for fracturing the calcification while avoiding vessel injury. The geometries of the cutting balloons were constructed and their finite-element models were generated by folding and wrapping the balloon model. Numerical simulations were performed for balloons with five different diameters and two types of blade directions in a 180° calcification model. The calcification expansion ability was distinctly higher when two blades faced the calcification than when one blade did. Moreover, when two blades faced the calcification model, larger maximum principal stresses were generated in the calcification even when using undersized balloons with diameters reduced by 0.25 or 0.5 mm from the reference diameter, when compared with the case where one blade faced the calcified model and a balloon of diameter equal to the reference diameter was used. When two blades faced the calcification, smaller stresses were generated in the artery adjacent to the calcification; further, the maximum stress generated in the artery model adjacent to the calcification under the rated pressure of 12 atm when employing undersized balloons was smaller than that when only one blade faced the calcification and when lesion-identical balloon diameters were used under a nominal pressure of 6 atm. Our study suggested that undersized balloons of diameters 0.25 or 0.5 mm less than the reference diameter might be effective in not only expanding the calcified lesion but also reducing the risk of dissection.

Advancement in the Application of Finite Element Analysis to the Optimization of Composite Yacht Structures

2011 ◽  
Author(s):  
David Fornaro
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Composite Structures ◽  
State Of The Art ◽  
Load Case ◽  
Post Processing ◽  
Principal Stresses ◽  
Element Analysis ◽  
Current State ◽  
Case Development

Finite Element Analysis (FEA) is mature technology that has been in use for several decades as a tool to optimize structures for a wide variety of applications. Its application to composite structures is not new, however the technology for modeling and analyzing the behavior of composite structures continues to evolve on several fronts. This paper provides a review of the current state-of-the-art with regard to composites FEA, with a particular emphasis on applications to yacht structures. Topics covered are divided into three categories: Pre-processing; Postprocessing; and Non-linear Solutions. Pre-processing topics include meshing, ply properties, laminate definitions, element orientations, global ply tracking and load case development. Post-processing topics include principal stresses, failure indices and strength ratios. Nonlinear solution topics include progressive ply failure. Examples are included to highlight the application of advanced finite element analysis methodologies to the optimization of composite yacht structures.

Fatigue surviving, fracture resistance, shear stress and finite element analysis of glass fiber posts with different diameters

2015 ◽  
Vol 43 ◽  
pp. 69-77 ◽  
Author(s):  
Vinícius Felipe Wandscher ◽  
César Dalmolin Bergoli ◽  
Ariele Freitas de Oliveira ◽  
Osvaldo Bazzan Kaizer ◽  
Alexandre Luiz Souto Borges ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Shear Stress ◽  
Glass Fiber ◽  
Fracture Resistance ◽  
Element Analysis ◽  
Fiber Posts ◽  
Glass Fiber Posts ◽  
Different Diameters

scholarly journals Dynamic Behavior of Steel and Composite Ferry Subjected to Transverse Eccentric Moving Load Using Finite Element Analysis

2020 ◽  
Vol 10 (15) ◽  
pp. 5367 ◽  
Author(s):  
Mohamed N. Lotfy ◽  
Yasser A. Khalifa ◽  
Abdelrahim K. Dessouki ◽  
Elsayed Fathallah
Keyword(s):  
Finite Element ◽  
Dynamic Analysis ◽  
Load Capacity ◽  
Moving Load ◽  
Load Factor ◽  
Principal Stresses ◽  
Element Analysis ◽  
Software Analysis ◽  
Analysis System ◽  
Von Mises

The most important problems confronted by designers of floating structures are minimizing weight and increasing payload to get proper resistance to the applied loads. In the present study, the structural performance of a ferry is analyzed using both metallic and composite materials as a result of the dynamic load of the Military Load Capacity (MLC) 70 (tank load). The model is composed of sixteen floating pontoons. Finite element simulation and dynamic analysis were performed using ANSYS software (analysis system software), considering a moving MLC70 (tank load). Both concentric and eccentric cases of loading are considered. Draft, deformation, and stresses are obtained and investigated. For the steel ferry, the von-Mises stresses are investigated, while for the composite ferry, the maximum principal stresses are investigated. Furthermore, buckling analysis is performed on the composite ferry and the buckling load factor is determined. The results of the dynamic analysis illustrated that the transverse eccentricity of the moving tank MLC70 must not exceed 0.5 m for a steel ferry while it may reach up to 1.5 m for the composite ferry. This research can also be a useful tool in the design of floating composite and steel ferries.

A comparative study between zirconia and titanium abutments on the stress distribution in parafunctional loading: A 3D finite element analysis

2020 ◽  
Vol 28 (6) ◽  
pp. 603-613 ◽  
Author(s):  
Efe Can Sivrikaya ◽  
Mehmet Sami Guler ◽  
Muhammed Latif Bekci
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Von Mises Stress ◽  
Principal Stresses ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
3D Fea ◽  
Von Mises ◽  
Three Dimensional Finite Element

BACKGROUND: Zirconia has become a popular biomaterial in dental implant systems because of its biocompatible and aesthetic properties. However, this material is more fragile than titanium so its use is limited. OBJECTIVES: The aim of this study was to compare the stresses on morse taper implant systems under parafunctional loading in different abutment materials using three-dimensional finite element analysis (3D FEA). METHODS: Four different variations were modelled. The models were created according to abutment materials (zirconia or titanium) and loading (1000 MPa vertical or oblique on abutments). The placement of the implants (diameter, 5.0 × 15 mm) were mandibular right first molar. RESULTS: In zirconia abutment models, von Mises stress (VMS) values of implants and abutments were decreased. Maximum and minimum principal stresses and VMS values increased in oblique loading. VMS values were highest in the connection level of the conical abutments in all models. CONCLUSIONS: Using conical zirconia abutments decreases von Mises stress values in abutments and implants. However, these values may exceed the pathological limits in bruxism patients. Therefore, microfractures may be related to the level of the abutment.

Finite Element Modeling of Biodegradable Stents

2013 ◽  
Author(s):  
Nic Debusschere ◽  
Matthieu De Beule ◽  
Peter Dubruel ◽  
Patrick Segers ◽  
Benedict Verhegghe
Keyword(s):  
Finite Element ◽  
Mechanical Behavior ◽  
Mechanical Performance ◽  
Cost Effective ◽  
Minimal Invasive ◽  
Material Behavior ◽  
Element Analysis ◽  
Design And Optimization ◽  
Stent Restenosis ◽  
Biodegradable Stents

Biodegradable stents, which temporarily support a stenotic blood vessel and afterwards fully disappear, have recently gained a lot of interest. They avoid long-term complications associated with conventional stents such as late stent thrombosis and in-stent restenosis. Moreover, degradable stents allow for a restoration of vasomotion and vessel growth which makes them particularly suitable for pediatric applications [1]. Finite element simulations have proven to be an efficient and cost-effective tool to investigate and optimize the mechanical performance of minimal invasive devices such as stents [2]. Biodegradable stents have however created new challenges in their design and optimization via finite element analysis because of their complex time-varying material behavior. To correctly simulate the mechanical behavior of biodegradable stents, a model should be developed that incorporates the effect of degradation upon all material characteristics. By combining existing constitutive material models based on continuum damage theory we were able to create such a virtual environment in which the transitional mechanical behavior of biodegradable stents can be investigated.

ENGINEERING ANALYSIS OF A FAILED COMPASS PROXIMAL INTERPHALANGEAL (PIP) JOINT HINGE

2015 ◽  
Vol 27 (02) ◽  
pp. 1550013 ◽  
Author(s):  
M. M. Youssef ◽  
D. E. T. Shepherd ◽  
O. G. Titley
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Maximum Principal Stress ◽  
Engineering Analysis ◽  
Principal Stresses ◽  
Element Analysis ◽  
Pip Joint ◽  
Scanning Electron

A failed compass hinge external fixator for fingers has been analyzed. The device consists of polymer parts manufactured from polyetherimide. Finite element analysis (FEA) was used to investigate the principal stresses in the device under different loading conditions. Scanning electron microscopy (SEM) was used to investigate the fracture surfaces. The FEA showed that the maximum principal stress was greater than the fatigue strength of polyetherimide. The SEM fractographs confirm that failure was by brittle fatigue.

scholarly journals A Numerical Study on the Control of Horizontal Cracking at the Ends of BS22 Hollow-type PC-girders Utilizing Midas FEA

2021 ◽  
Vol 1996 (1) ◽  
pp. 012011
Author(s):  
Abdul Khaliq Karimi ◽  
Bashir Ahmad Aasim ◽  
Jun Tomiyama
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Numerical Study ◽  
Crack Size ◽  
Analysis Software ◽  
Principal Stresses ◽  
Element Analysis ◽  
Crack Penetration ◽  
Strand Debonding

Abstract When the prestressing forces transfer from PC-strands to concrete, a region of stress concentration develops at the ends of pretensioned girders, which often results in horizontal cracking during or just after the detensioning process. In this study, a hollow PC-girder was modeled utilizing a Finite Element Analysis software Midas FEA to identify the horizontal cracking locations in terms of the principal stresses at the end-zone of the hollow PC-girder. Strand-debonding and placing end-zone reinforcements were hired in this work by introducing four cases. The only strand-debonding method could not prevent horizontal end crack penetration. Though the end-zone reinforcements were placed alongside the strand-debonding, this combination could reduce principal stresses to a level that could bring the crack size to a negligible range.

scholarly journals Study on the characteristics of pipe buckling strength under pure bending and external stress using nonlinear finite element analysis

2021 ◽  
Vol 12 (2) ◽  
pp. 110-116
Author(s):  
Hartono Yudo ◽  
Wilma Amiruddin ◽  
Ari Wibawa Budi Santosa ◽  
Ocid Mursid ◽  
Tri Admono
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Bending Moment ◽  
Nonlinear Finite Element Analysis ◽  
External Pressure ◽  
Diameter Ratio ◽  
Nonlinear Finite Element ◽  
Pure Bending ◽  
Element Analysis ◽  
Buckling Strength

Buckling and collapse are important failure modes for laying and operating conditions in a subsea position. The pipe will be subjected to various kinds of loads, i.e., bending moment, external pressure, and tension. Nonlinear finite element analysis was used to analyze the buckling strength of the pipe under pure bending and external pressure. The buckling of elastic and elasto-plastic materials was also studied in this work. The buckling strength due to external pressure had decreased and become constant on the long pipe when the length-to-diameter ratio (L/D) was increased. The non-dimensional parameter (β), which is proportionate to (D/t) (σy/E), is used to study the yielding influence on the buckling strength of pipe under combined bending and external pressure loading. The interaction curves of the buckling strength of pipe were obtained, with various the diameter-to-thickness ratio (D/t) under combination loads of external pressure and bending moment. For straight pipes L/D = 2.5 to 40, D = 1000 to 4000 mm, and D/t = 50 to 200 were set. The curved pipes D/t = 200, L/D =2.5 to 30 have been investigated by changing the radius of curvature-to-diameter ratio (R/D) from 50 to ∞, for each one. With decreasing R/D, the buckling strength under external pressure decreases slightly. This is in contrast to the bending of a curved pipe. When the value of R/D was decreased, the flexibility of the pipe was increased. However, the buckling strength of the pipe during bending was decreased due to the oval deformation at the cross-section.

scholarly journals Application of finite element analysis on balloon expandable coronary stents: A review

2018 ◽  
Vol 7 (3) ◽  
pp. 1640
Author(s):  
Chandrakantha Bekal ◽  
Dr. Hiroshi Yamada ◽  
Dr. Ranjan Shetty ◽  
Dr. Satish Shenoy
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Coronary Stents ◽  
Product Development Process ◽  
Qualitative Assessment ◽  
Geometrical Parameters ◽  
Element Analysis ◽  
Major Drawback ◽  
Stent Restenosis

Numerical analysis of complex physical environment continues to be preferred over “build and test” approach in product development process. Finite Element Analysis (FEA) of coronary artery stenting is studied and researched worldwide for many years. Potential of using FEA for mimicking in-vivo is high as experimental test is ruled out for variety of reasons. This review aims at discussing issues and challenges of numerical simulation based on part of available literature on usage of FEA techniques for investigating behavior of balloon expandable (BE) coronary stents inside artery. Literatures of past 16 years of study on the structural analysis is summarized and potential issues for research is discussed. Study tries to investigate deployment characteristics and biomechanical response of artery post stenting and significance of non-physiological conditions induced. Effects of geometrical parameters, simulation strategies are summarized. Study mainly underscores the potential challenges of reliable numerical investigation. Scope of FEA in predicting contributor for in-stent restenosis (ISR), a major drawback of stenting procedure, by correlating the engineering aspect of stent design and its clinical significance supported by clinical trials are highlighted. Study is expected to serve as qualitative assessment for cardiologists to minimize procedural failure and quantitative tool for the designers for stent optimization.  

Evaluation of Stress in Tilted Implant Concept with Variable Diameters in the Atrophic Mandible: 3D Finite Element Analysis

2019 ◽  
pp. 0000-0000 ◽  
Author(s):  
Erdem Kilic ◽  
Ozge Doganay
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Longitudinal Axis ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Short Implants ◽  
Dimensional Finite Element ◽  
Von Mises ◽  
Different Diameters ◽  
Tilted Implant

The beneficial mechanical properties provided by greater diameter or short implants increased their usage in the tilted implant concept. The aim of the present study is to compare the stress distribution of four different treatment models including variable implant numbers and diameters under static loading protocol in the atrophic mandible using 3-dimensional finite element analysis. Three models included two tilted and two vertical positioned implants with different diameters, whereas distally placed two short implants were added to the fourth model. The von Mises stress, maximum and minimum principal stress values were evaluated after applying 200N bilateral oblique loads to the first molar teeth with the inclination of 450 to the longitudinal axis. Tilted implants were associated with higher stress values when compared with vertical implants in all models. The lowest stress values were obtained in the fourth model including short implants. Although all stress values showed slight increases by descending implant diameters, the stress values of the model including implants with 3.3 mm diameter were within physiologic limits. All in all, increasing number or diameter of implants may have a positive effect on implant survival. In addition, when narrow diameter implants need to be inserted in the tilted implant concept, combination with short implants may be recommended for long term success.

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