scholarly journals The Effect of Implant Length and Diameter on Stress Distribution around Single Implant Placement in 3D Posterior Mandibular FE Model Directly Constructed Form In Vivo CT

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7344
Author(s):  
Akikazu Shinya ◽  
Yoshiki Ishida ◽  
Daisuke Miura ◽  
Akiyoshi Shinya
Keyword(s):  
High Stress ◽  
Three Dimensional ◽  
Clinical Situation ◽  
Mechanical Analysis ◽  
Fe Model ◽  
High Stress Concentration ◽  
Implant Placement ◽  
Implant Therapy ◽  
Mandibular First Molar

A three-dimensional (3D) finite element (FE) model of the mandibular bone was created from 3D X-ray CT scan images of a live human subject. Simulating the clinical situation of implant therapy at the mandibular first molar, virtual extraction of the tooth was performed at the 3D FE mandibular model, and 12 different implant diameters and lengths were virtually inserted in order to carry out a mechanical analysis. (1) High stress concentration was found at the surfaces of the buccal and lingual peri-implant bone adjacent to the sides of the neck in all the implants. (2) The greatest stress value was approximately 6.0 MPa with implant diameter of 3.8 mm, approx. 4.5 MPa with implant diameter of 4.3 mm, and approx. 3.2 MPa with implant diameter of 6.0 mm. (3) The stress on the peri-implant bone was found to decrease with increasing length and mainly in diameter of the implant.

scholarly journals Modelling human skull growth: a validated computational model

2017 ◽  
Vol 14 (130) ◽  
pp. 20170202 ◽  
Author(s):  
Joseph Libby ◽  
Arsalan Marghoub ◽  
David Johnson ◽  
Roman H. Khonsari ◽  
Michael J. Fagan ◽  
...  
Keyword(s):  
Computational Model ◽  
Three Dimensional ◽  
Basic Knowledge ◽  
Fe Model ◽  
Adult Size ◽  
Fe Method ◽  
Percentage Difference ◽  
Skull Growth

During the first year of life, the brain grows rapidly and the neurocranium increases to about 65% of its adult size. Our understanding of the relationship between the biomechanical forces, especially from the growing brain, the craniofacial soft tissue structures and the individual bone plates of the skull vault is still limited. This basic knowledge could help in the future planning of craniofacial surgical operations. The aim of this study was to develop a validated computational model of skull growth, based on the finite-element (FE) method, to help understand the biomechanics of skull growth. To do this, a two-step validation study was carried out. First, an in vitro physical three-dimensional printed model and an in silico FE model were created from the same micro-CT scan of an infant skull and loaded with forces from the growing brain from zero to two months of age. The results from the in vitro model validated the FE model before it was further developed to expand from 0 to 12 months of age. This second FE model was compared directly with in vivo clinical CT scans of infants without craniofacial conditions ( n = 56). The various models were compared in terms of predicted skull width, length and circumference, while the overall shape was quantified using three-dimensional distance plots. Statistical analysis yielded no significant differences between the male skull models. All size measurements from the FE model versus the in vitro physical model were within 5%, with one exception showing a 7.6% difference. The FE model and in vivo data also correlated well, with the largest percentage difference in size being 8.3%. Overall, the FE model results matched well with both the in vitro and in vivo data. With further development and model refinement, this modelling method could be used to assist in preoperative planning of craniofacial surgery procedures and could help to reduce reoperation rates.

On the Axisymmetric Response of a Damaged Flexible Pipe

2014 ◽  
Author(s):  
José Renato M. de Sousa ◽  
Carlos Magluta ◽  
Ney Roitman ◽  
George C. Campello
Keyword(s):  
Finite Element ◽  
Analytical Model ◽  
Load Capacity ◽  
High Stress ◽  
Experimental Tests ◽  
Theoretical Models ◽  
Experimental Measurements ◽  
Fe Model ◽  
Flexible Pipe ◽  
High Stress Concentration

This work focuses on the structural analysis of a damaged 9.13″ flexible pipe to pure and combined axisymmetric loads. A set of experimental tests was carried out considering one up to ten broken wires in the outer tensile armor of the pipe and the results obtained are compared to those provided by a previously presented finite element (FE) model and a traditional analytical model. In the experimental tests, the pipe was firstly subjected to pure tension and, then, the responses to clockwise and anti-clockwise torsion superimposed with tension were investigated. In these tests, the induced strains in the outer armor were measured. Moreover, the axial elongation of the pipe was monitored when the pipe is subjected to tension, whilst the twist of the pipe was measured when torsion is imposed. The experimental results pointed to a slight decrease in the stiffness of the pipe with the increasing number of broken wires and, furthermore, a redistribution of forces among the intact wires of the damaged layer with high stress concentration in the wires close to the damaged ones. Both theoretical models captured these features, but, while the results obtained with the FE model agreed well with the experimental measurements, the traditional analytical model presented non-conservative results. Finally, the results obtained are employed to estimate the load capacity of the pipe.

Numerical Analysis of a Flexible Pipe With Damaged Tensile Armor Wires

2009 ◽  
Author(s):  
Jose´ Renato M. de Sousa ◽  
Aline Nacif Pinho ◽  
Gilberto Bruno Ellwanger ◽  
Edison C. P. Lima
Keyword(s):  
Mechanical Response ◽  
High Stress ◽  
Three Dimensional ◽  
Element Model ◽  
Axial Rotation ◽  
Flexible Pipe ◽  
High Stress Concentration ◽  
Flexible Pipes ◽  
Localized Defects ◽  
Nonlinear Finite Element Model

This paper focus on the structural analysis of a 2.5″ flexible pipe with one up to five broken wires in its outer tensile armor. The pipe is supposed to be under pure tension and the effect of the number of ruptured wires on its response is discussed. A three-dimensional nonlinear finite element model devoted to analyze the local mechanical response of flexible pipes is proposed and employed in all performed analyses. This model is capable of representing each wire of the tensile armors and, therefore, localized defects, including total rupture, may be adequately represented. The obtained results pointed to high stress concentration in the wires near the damaged ones as well as a significant increase in the axial rotation of the pipe. Moreover, the stresses in the inner carcass and the pressure armor are also affected by the rupture of wires in the outer tensile armor.

An Experimental and Numerical Study on the Axial Compression Response of Flexible Pipes

2010 ◽  
Author(s):  
Jose´ Renato M. de Sousa ◽  
Paula F. Viero ◽  
Carlos Magluta ◽  
Ney Roitman
Keyword(s):  
Axial Compression ◽  
Failure Modes ◽  
Mechanical Response ◽  
Numerical Study ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Mechanical Analysis ◽  
Fe Model ◽  
Flexible Pipe ◽  
Flexible Pipes

This paper deals with a nonlinear three-dimensional finite element (FE) model capable of predicting the mechanical response of flexible pipes subjected to axisymmetric loads focusing on their axial compression response. Moreover, in order to validate this model, experimental tests carried out at COPPE/UFRJ are also described. In these tests, a typical 4″ flexible pipe was subjected to axial compression until its failure is reached. Radial and axial displacements were measured and compared to the model predictions. The good agreement between all obtained results points that the proposed FE model is efficient to estimate the response of flexible pipes to axial compression and, furthermore, has potential to be employed in the identification of the failure modes related to excessive axial compression as well as in the mechanical analysis of flexible pipes under other types of loads.

The Effect of Pedicle Screw Thread Shape on the Stress Concentration Under Lateral Bending

2019 ◽  
Author(s):  
Yucheng Yang ◽  
Qin Ma
Keyword(s):  
Stress Concentration ◽  
Maximum Stress ◽  
High Stress ◽  
Three Dimensional ◽  
Spinal Column ◽  
Pedicle Screws ◽  
Screw Thread ◽  
Lateral Bending ◽  
High Stress Concentration ◽  
Stress Patterns

Abstract Pedicle screws (PS) are frequently used in medical spinal column fixation. Despite 7 out of 100 pedicle screws fracture inside of the patients’ body and under the claim that lateral bending is the main failure mode, little research has addressed the stress characteristics and the fracture location of the PS under lateral bending. This study focuses on the effect of thread design on the magnitude and location of maximum stress concentration. Four types of thread shapes are considered including V-shape, square-shape, buttress, and reverse buttress. Three-dimensional (3D) finite element (FE) methods are used in this investigation. A load of 150 Newton is applied at the screw head to simulate lateral bending. The models are created in SolidWorks. The 3D FE analysis is performed using the standard coding of ANSYS Workbench 19.1. Based on this study, it is found that the high stress concentration is located at the cortical bone region rather than at the cancellous bone region. Although the general stress patterns are similar, the PS thread shape design and the thread fillet radius may significantly affect on the magnitude and location of maximum stress concentration.

scholarly journals Regional Variations of HR-pQCT Morphological and Biomechanical Measurements of Bone Segments and Their Associations With Whole Distal Radius and Tibia Mechanical Properties

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Bin Zhou ◽  
Zhendong Zhang ◽  
Yizhong Jenny Hu ◽  
Ji Wang ◽  
Y. Eric Yu ◽  
...  
Keyword(s):  
Distal Radius ◽  
Imaging Modality ◽  
Quantitative Computed Tomography ◽  
Three Dimensional ◽  
Peripheral Quantitative Computed Tomography ◽  
Distal Segment ◽  
Mechanical Analysis ◽  
Bone Stiffness ◽  
Microstructural Parameters

High-resolution peripheral quantitative computed tomography (HR-pQCT) is a promising imaging modality that provides an in vivo three-dimensional (3D) assessment of bone microstructure by scanning fixed regions of the distal radius and tibia. However, how microstructural parameters and mechanical analysis based on these segment scans correlate to whole distal radius and tibia mechanics are not well-characterized. On 26 sets of cadaveric radius and tibia, HR-pQCT scans were performed on the standard scan segment, a segment distal to the standard segment, and a segment proximal to the standard segment. Whole distal radius and tibia stiffness were determined through mechanical testing. Segment bone stiffness was estimated using linear finite element (FE) analysis based on segment scans. Standard morphological and individual trabecula segmentation (ITS) analyses were used to estimate microstructural properties. Significant variations in microstructural parameters were observed among segments at both sites. Correlation to whole distal radius and tibia stiffness was moderate for microstructural parameters at the standard segment, but correlation was significantly increased for FE-predicted segment bone stiffness based on standard segment scans. Similar correlation strengths were found between FE-predicted segment bone stiffness and whole distal radius and tibia stiffness. Additionally, microstructural parameters at the distal segment had higher correlation to whole distal radius and tibia stiffness than at standard or proximal segments. Our results suggest that FE-predicted segment stiffness is a better predictor of whole distal radius and tibia stiffness for clinical HR-pQCT analysis and that microstructural parameters at the distal segment are more highly correlated with whole distal radius and tibia stiffness than at the standard or proximal segments.

A FE Model to Predict the Stress Concentration Factors in the Tensile Armor Wires of Flexible Pipes Inside End Fittings

2013 ◽  
Author(s):  
José Renato M. de Sousa ◽  
George C. Campello ◽  
Fabiano Bertoni ◽  
Gilberto B. Ellwanger
Keyword(s):  
Stress Concentration ◽  
High Stress ◽  
Axial Stiffness ◽  
Fe Model ◽  
Acceptance Test ◽  
Stress Distributions ◽  
High Stress Concentration ◽  
Flexible Pipes ◽  
The Wire ◽  
Stress Concentration Factors

In this work, a bidimensional finite element (FE) approach is proposed to estimate the stresses induced in the tensile armor wires inside end fittings (EF) of flexible pipes. This approach accounts for the residual stresses caused by the mounting procedure and the deformed configuration of the wire. The resin and its interaction with the wires are also addressed. A parametric study was performed aiming at investigating the influence of three parameters on the stress state along the wire, i. e., the contact conditions between the resin and the wire inside the EF, the stress levels induced during the factory acceptance test (FAT) or the offshore leak test (OLT) and the resin elastic properties. The study pointed that high stress concentration is induced in the transition between the flexible pipe’s body and the EF and the stress distribution along the wire may be significantly affected by these parameters. Moreover, the apparent axial stiffness of the wire is also modified by its anchoring conditions, which may lead to non-uniform stress distributions among the wires of the tensile armor layers.

An Experimental and Numerical Study on the Axial Compression Response of Flexible Pipes

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
José Renato M. de Sousa ◽  
Paula F. Viero ◽  
Carlos Magluta ◽  
Ney Roitman
Keyword(s):  
Axial Compression ◽  
Failure Modes ◽  
Mechanical Response ◽  
Numerical Study ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Mechanical Analysis ◽  
Fe Model ◽  
Flexible Pipe ◽  
Flexible Pipes

This paper deals with a nonlinear three-dimensional finite element (FE) model capable of predicting the mechanical response of flexible pipes subjected to axisymmetric loads focusing on their axial compression response. Moreover, in order to validate this model, experimental tests are also described. In these tests, a typical 4 in. flexible pipe was subjected to axial compression until its failure is reached. Radial and axial displacements were measured and compared to the model predictions. The good agreement between all results points out that the proposed FE model is effective to estimate the response of flexible pipes to axial compression and; furthermore, has potential to be employed in the identification of the failure modes related to excessive axial compression as well as in the mechanical analysis of flexible pipes under other types of loads.

scholarly journals A Flapless Surgical Placement of Implants in Mandibular Arch Using Computer-Guided Surgical Stent

2018 ◽  
Vol 9 (1-2) ◽  
pp. 55-60
Author(s):  
Chirag Gajjar ◽  
Vidhi Ajmera ◽  
Darshana Shah ◽  
Chirag Chauhan ◽  
Paras Doshi
Keyword(s):  
Three Dimensional ◽  
Clinical Situation ◽  
Cone Beam ◽  
Prosthetic Rehabilitation ◽  
Virtual Planning ◽  
Operative Trauma ◽  
Three Dimensional Printing ◽  
Mandibular Arch ◽  
Implant Placement ◽  
Dimensional Printing

The loss of teeth is always challenging for the patients. It is not only a functional loss but also a psychological and social loss. But with the advent of dental implants, this clinical situation can be dealt with tactfully. In an edentulous arch, prosthetic rehabilitation by all on 6 implants require accurate placement of implants for a successful result. A computer-guided surgical stent can be advantageous over arbitrary placement of implants and can overcome the difficulties associated with arbitrary placement. Using the cone beam computed tomography of the patient, virtual planning of implant is done. The exact implant angulations can be visualized to achieve the best possible esthetics and occlusion. This information is then converted to fabricate a stent using three-dimensional printing. Using this stent, a flapless surgical implant placement can be done which will reduce the post-operative trauma. This case report describes a case of a patient having an edentulous mandibular arch. The prosthetic rehabilitation of the mandibular arch was done by flapless surgical placement of six implants using a computer-guided surgical stent.

An Analysis Model of the Dynamic Characteristics of Brake Pads in Response to Changes in Material Properties

2017 ◽  
Vol 730 ◽  
pp. 601-606
Author(s):  
Myeong Jae Han ◽  
Tae Won Park ◽  
Ink Yeong Hwang ◽  
Jung Min Park
Keyword(s):  
Material Properties ◽  
Three Dimensional ◽  
Mechanical Analysis ◽  
Thickness Variation ◽  
Fe Model ◽  
Brake Pad ◽  
Analysis Model ◽  
Brake Pads ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

The sense of stability during vehicle braking is largely related to brake performance. Among the brake parts, the brake pad must be working properly to ensure the braking performance and stability of the vehicle. That is, brake pads are required to maintain a uniform pressure distribution during braking. In addition, brake pads must maintain a proper braking force during rapid increases in temperature. In this study, the three-dimensional finite element (FE) model was developed to determine the distribution of the contact pressure of the brake pad. The temperature distribution on the pad surface was confirmed. The sensitivity to changes in material properties was verified using the developed model. Pad wear due to friction can be predicted by confirming the thickness variation due to heat. A fully coupled thermo-mechanical analysis of the developed FE model was performed using ABAQUS.

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