scholarly journals Development of anatomically based customizable three-dimensional finite-element model of pelvic floor support system: POP-SIM1.0

2019 ◽  
Vol 9 (4) ◽  
pp. 20190022 ◽  
Author(s):  
Mark T. Gordon ◽  
John O. L. DeLancey ◽  
Aaron Renfroe ◽  
Andrew Battles ◽  
Luyun Chen
Keyword(s):  
Finite Element ◽  
Magnetic Resonance ◽  
Pelvic Floor ◽  
Support System ◽  
Structural Parameters ◽  
Vaginal Wall ◽  
Abdominal Pressure ◽  
Fe Model ◽  
Vaginal Length ◽  
Pelvic Floor Support

To develop an anatomically based customizable finite-element (FE) model of the pelvic floor support system to simulate pelvic organ prolapse (POP): POP-SIM1.0. This new simulation platform allows for the construction of an array of models that objectively represent the key anatomical and functional variation in women with and without prolapse to test pathomechanism hypotheses of the prolapse formation. POP-SIM1.0 consists of anatomically based FE models and a suite of Python-based tools developed to rapidly construct FE models by customizing the base model with desired structural parameters. Each model consists of anatomical structures from three support subsystems which can be customized based on magnetic resonance image measurements in women with and without prolapse. The customizable structural parameters include presence of levator ani (LA) avulsion, hiatus size, anterior vaginal wall dimension, attachment fascia length and apical location in addition to the tissue material properties and intra-abdominal pressure loading. After customization, the FE model was loaded with increasing intra-abdominal pressure (0–100 cmH 2 O) and solved using ABAQUS explicit solver. We were able to rapidly construct anatomically based FE models with specific structural geometry which reflects the morphology changes often observed in women with prolapse. At maximum loading, simulated structural deformations have similar anatomical characteristics to those observed during clinical exams and stress magnetic resonance images. Simulation results showed the presence of LA muscle avulsion negatively impacts the pelvic floor support. The normal model with intact muscle had the smallest exposed vaginal length of 11 mm, while the bilateral avulsion produced the largest exposed vaginal length at 24 mm. The unilateral avulsion model had an exposed vaginal length of 18 mm and also demonstrated a tipped perineal body similar to that seen in clinical observation. Increasing the hiatus size, vaginal wall length and fascia length also resulted in worse pelvic floor support, increasing the exposed vaginal length from 18 mm in the base model to 33 mm, 54 mm and 23.5 mm, respectively. The developed POP-SIM1.0 can simulate the anatomical structure changes often observed in women with prolapse. Preliminary results showed that the presence of LA avulsion, enlarged hiatus, longer vaginal wall and fascia length can result in larger prolapse at simulated maximum Valsalva.

scholarly journals Relationship Between High Intra-Abdominal Pressure and Compliance of the Pelvic Floor Support System in Women Without Pelvic Organ Prolapse: A Finite Element Analysis

2021 ◽  
Author(s):  
Xiaode Liu ◽  
Qiguo Rong ◽  
Jianliu Wang ◽  
Bing Xie ◽  
Shuang Ren
Keyword(s):  
Finite Element ◽  
Pelvic Organ Prolapse ◽  
Finite Element Model ◽  
Pelvic Floor ◽  
Support System ◽  
Element Model ◽  
Pelvic Organ ◽  
Abdominal Pressure ◽  
Pelvic Support ◽  
Pelvic Floor Support

Abstract Background: The objective of this study was to study the relationship between high intra-abdominal pressure and the compliance of the pelvic floor support system in a normal woman without pelvic organ prolapse (POP), using a finite element model of the whole pelvic support system.Methods: A healthy female volunteer (55 years old) was scanned using magnetic resonance imaging (MRI) during the Valsalva maneuver. According to the pelvic structure contours traced by a gynecologist and anatomic details measured from dynamic MRI, a finite element model of the whole pelvic support system was established, including the uterus, vagina with cavity, cardinal and uterosacral ligaments, levator ani muscle, rectum, bladder, perineal body, pelvis, and obturator internus and coccygeal muscles. This model was imported into ANSYS software, and an implicit iterative method was employed to simulate the biomechanical response with increasing intra-abdominal pressure.Results: Stress and strain distributions of the vaginal wall showed that the posterior wall was more stable than the anterior wall under high intra-abdominal pressure. Displacement at the top of the vagina was larger than that at the bottom, especially in the anterior–posterior direction.Conclusion: These results imply potential injury areas with high intra-abdominal pressure in non-prolapsed women, and provide insight into clinical managements for the prevention and surgical repair plans of POP.

An Effective Method for Determining Finite Element Model Parameters of Rotor Elastic Support System

2011 ◽  
Vol 141 ◽  
pp. 191-197
Author(s):  
Yong Xing Wang ◽  
Jiang Yan ◽  
Sheng Ze Wang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Support System ◽  
Structural Parameters ◽  
Element Model ◽  
Elastic Support ◽  
Asymmetric Structure ◽  
Model Parameters ◽  
Equivalent Stiffness ◽  
Rolling Ball

A finite element model of the elastic support rotor system based on the corresponding experimental model was established. According to the principle of two types of model with an equal first order critical speed, the equivalent stiffness and damping of a rolling ball bearing support system with rubber rings determined by experiment were transferred into the finite element model. Then, the dynamic behavior of rotor systems with symmetric and asymmetric structure, different support system stiffness and support span were calculated and analyzed respectively. At last, the influence of the rotor structural parameters on the equivalent stiffness of elastic bearing support system obtained by experiment was pointed out.

Bayesian Probabilistic Approach to FE Model Updating of Vehicle Typical Spot Weld Structure

2013 ◽  
Vol 690-693 ◽  
pp. 2601-2607
Author(s):  
Chun Zhu Yao ◽  
Hong Yan Wang ◽  
Qiang Rui
Keyword(s):  
Finite Element ◽  
Model Updating ◽  
Structural Parameters ◽  
Probabilistic Approach ◽  
Spot Weld ◽  
Statistical Characteristics ◽  
Fe Model ◽  
Finite Element Program ◽  
Distribution Ranges ◽  
Weld Structure

Finite element (FE) modeling of laser welds for dynamic analysis is a research issue because of the complexity and uncertainty of the welds and thus formed structures. A Bayesian probabilistic framework incorporating MCMC for updating the parameters of a spot weld structure model was presented, cooperation of finite element program and multiple chains sampling technology was realized, and statistical characteristics of structural parameters were obtained. Distribution ranges of the three frequencies were predicted based on parameter estimation. Numerical simulation indicates that there are little changes in standard deviations of posterior distribution compared to prior distribution, the posterior mean values are in good agreement with the corresponding measured average values. The convergence indicates the techniques feasibility and effectiveness. The present work offers an alternative approach to updating the spot weld structure parameters.

scholarly journals Finite Element Model Updating in Bridge Structures Using Kriging Model and Latin Hypercube Sampling Method

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Jie Wu ◽  
Quansheng Yan ◽  
Shiping Huang ◽  
Chao Zou ◽  
Jintu Zhong ◽  
...  
Keyword(s):  
Finite Element ◽  
Sampling Method ◽  
Model Updating ◽  
Structural Parameters ◽  
Latin Hypercube Sampling ◽  
Kriging Model ◽  
Computational Time ◽  
Fe Model ◽  
Latin Hypercube ◽  
Fe Model Updating

Computational cost reduction and best model updating method seeking are the key issues during model updating for different kinds of bridges. This paper presents a combined method, Kriging model and Latin hypercube sampling method, for finite element (FE) model updating. For FE model updating, the Kriging model is serving as a surrogate model, and it is a linear unbiased minimum variance estimation to the known data in a region which have similar features. To predict the relationship between the structural parameters and responses, samples are preselected, and then Latin hypercube sampling (LHS) method is applied. To verify the proposed algorithm, a truss bridge and an arch bridge are analyzed. Compared to the predicted results obtained by using a genetic algorithm, the proposed method can reduce the computational time without losing the accuracy.

Parameter Estimation of FE Model of a Bridge Using Identification System Assisted by Paris Software

2017 ◽  
Vol 21 ◽  
pp. 122-128
Author(s):  
Lăzărică Teșu ◽  
Gabriela Maria Atanasiu ◽  
Cristian Claudiu Comisu
Keyword(s):  
Finite Element ◽  
Parameter Estimation ◽  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Model Updating ◽  
Structural Parameters ◽  
Identification System ◽  
Fe Model ◽  
Bridge Structure ◽  
Bridge Structures

Recent studies in the field of Structural Health Monitoring SHM using nondestructive test NDT have shown promising applications for parameter estimation methods based on finite element FE models of bridge structures. Using measurements data, carried out during the experiment on real bridge structures, in situ, one can estimate the structural parameters of the bridge. These parameters can be used further in the process of model updating, model verification, structural evaluation and damage assessment. This paper aims to determine the structural parameters using the PARIS approach from a simulated FE model of a real bridge structure subjected to a typical bridge damage scenario. The MATLAB computer based program, entitled PARIS PARmeter Identification System used for the study case illustrated in this paper is applied for the Finite Element FE model updating of a reinforced concrete bridge, located in Iași municipality. PARIS software takes advantage of the Application Programming Interface API of a standalone structural computing software allowing to perform the necessary computational steps for the model updating process. In the same time the application of this software, recently developed by Prof. Masoud Sanayei permits the use of static and modal measurements, as input data, for the estimation of stiffness and mass parameters at the element level of the bridge. The obtained results of the updated model are useful in the process of further validation of a simulated damage test data. Finally, the results based on FE model parameter estimation can be useful for the structural health monitoring and condition assessment process of the bridge structure.

scholarly journals Do Measures of Muscular Fitness Modify the Effect of Intra-abdominal Pressure on Pelvic Floor Support in Postpartum Women?

2020 ◽  
Vol Publish Ahead of Print ◽  
Author(s):  
Ingrid E. Nygaard ◽  
Janet M. Shaw ◽  
Jie Wang ◽  
Xiaoming Sheng ◽  
Meng Yang ◽  
...  
Keyword(s):  
Pelvic Floor ◽  
Abdominal Pressure ◽  
Postpartum Women ◽  
Muscular Fitness ◽  
Pelvic Floor Support

THE INFLUENCE OF PELVIC ORGAN PROLAPSE ON THE PASSIVE BIOMECHANICAL PROPERTIES OF PELVIC FLOOR MUSCLES

2017 ◽  
Vol 17 (06) ◽  
pp. 1750090 ◽  
Author(s):  
M. E. T. SILVA ◽  
S. BRANDÃO ◽  
M. P. L. PARENTE ◽  
T. MASCARENHAS ◽  
R. M. NATAL JORGE
Keyword(s):  
Finite Element ◽  
Pelvic Organ Prolapse ◽  
Magnetic Resonance ◽  
Constitutive Model ◽  
Pelvic Floor ◽  
Constitutive Models ◽  
Biomechanical Properties ◽  
Pelvic Organ ◽  
Magnetic Resonance Images ◽  
Pelvic Floor Muscles

The biomechanical properties of the female pelvic floor tissues, such as muscles, fascia or ligaments are relevant when explaining pelvic disorders, since these may result from changes in the properties of those tissues. The aim of this study is to understand the influence of pelvic organ prolapse (POP) on the passive biomechanical properties of the pelvic floor muscles. For this purpose, magnetic resonance images at Valsalva maneuver were used, and an inverse finite element analysis technique was applied. The numerical models of the pubovisceralis muscle and pelvic bones were built from axial magnetic resonance images acquired at rest. The numerical simulation was based on the finite element method (FEM), by which the material constants were determined for three different constitutive models (Neo-Hookean, Mooney–Rivlin and Yeoh). The ratio between the values of the material constants for women with and without prolapse was approximately 43% for the parameter [Formula: see text] in the Neo-Hookean constitutive model, 57% and 24% for [Formula: see text] and [Formula: see text] in the Mooney–Rivlin constitutive model, and 35%, 21% and 14% for [Formula: see text], [Formula: see text] and [Formula: see text] in the Yeoh constitutive model. For the three constitutive models, the mean values of the material properties related with stiffness were higher for the muscles of women with POP. These increases in stiffness are in line with other experimental works involving vaginal tissue, which showing that the elasticity module is significantly higher in the prolapsed tissue when compared with normal tissue. The present work presents a noninvasive methodology based on the application of the FEM, which allows the establishment of a relationship between the stiffness of the pelvic floor muscles of women with POP and without this pathology.

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