Three-dimensional elastoplastic finite element and elastohydrodynamic analyses of journal bearings

1997 ◽  
Vol 211 (2) ◽  
pp. 143-152 ◽  
Author(s):  
H Bahai ◽  
H Xu
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Hydrodynamic Pressure ◽  
Cyclic Stress ◽  
Hoop Strain ◽  
Interference Fit ◽  
Lining Material ◽  
Von Mises ◽  
Fourier Type ◽  
Hoop Stresses

It is generally believed that cracks initiating from the surface of bearings with their line perpendicular to the circumferential direction of the shell are predominantly induced by the presence of cyclic hoop stresses in the bearing. A method is proposed in this paper where an elastohydrodynamic (EHD) analysis is combined with a full elastoplastic finite element (FE) stress analysis using a particular Fourier type of element which enables the application of non-uniform, non-axisymmetric hydrodynamic pressure loading to an axisymmetric bearing geometry. The analysis accounts for the effect of the initial interference fit and the three-dimensional pressure distribution which is obtained from the EHD analysis. Plasticity is incorporated into the analysis using the von Mises yield surface hardening rule. The analysis predicts the variation of cyclic stress and strain values in the lining material across the bearing width. It is seen from the analysis that a hoop strain variation changing from tensile in the loaded condition to compressive in the unloaded condition is responsible for the initiation of cracks at the surface of the bearing lining material.

Effects of occlusal scheme on All-on-Four abutments, screws and prostheses: A three-dimensional finite element study

2020 ◽  
Author(s):  
Nurullah Türker ◽  
Hümeyra Tercanlı Alkış ◽  
Steven J Sadowsky ◽  
Ulviye Şebnem Büyükkaplan
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Good Prognosis ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Group Function ◽  
Occlusal Contact ◽  
Maximum Deformation ◽  
Contact Points ◽  
Von Mises

An ideal occlusal scheme plays an important role in a good prognosis of All-on-Four applications, as it does for other implant therapies, due to the potential impact of occlusal loads on implant prosthetic components. The aim of the present three-dimensional (3D) finite element analysis (FEA) study was to investigate the stresses on abutments, screws and prostheses that are generated by occlusal loads via different occlusal schemes in the All-on-Four concept. Three-dimensional models of the maxilla, mandible, implants, implant substructures and prostheses were designed according to the All-on-Four concept. Forces were applied from the occlusal contact points formed in maximum intercuspation and eccentric movements in canine guidance occlusion (CGO), group function occlusion (GFO) and lingualized occlusion (LO). The von Mises stress values for abutment and screws and deformation values for prostheses were obtained and results were evaluated comparatively. It was observed that the stresses on screws and abutments were more evenly distributed in GFO. Maximum deformation values for prosthesis were observed in the CFO model for lateral movement both in the maxilla and mandible. Within the limits of the present study, GFO may be suggested to reduce stresses on screws, abutments and prostheses in the All-on-Four concept.

Optimization of the Wrist Pin End of an Automobile Engine Connecting Rod With an Interference Fit

1990 ◽  
Vol 112 (3) ◽  
pp. 406-412 ◽  
Author(s):  
Vijay Sarihan ◽  
Ji Oh Song
Keyword(s):  
Finite Element ◽  
Optimum Design ◽  
Three Dimensional ◽  
Stress Singularity ◽  
Design Strategy ◽  
Structural Components ◽  
Connecting Rod ◽  
Fem Model ◽  
Automobile Engine ◽  
Interference Fit

Current design procedures for complicated three-dimensional structural components with component interactions may not necessarily result in optimum designs. The wrist pin end design of the connecting rod with an interference fit is governed by the stress singularity in the region where the wrist pin breaks contact with the connecting rod. Similar problems occur in a wide variety of structural components which involve interference fits. For a better understanding of the problems associated with obtaining optimum designs for this important class of structural interaction only the design problems associated with the wrist pin end of the rod are addressed in this study. This paper demonstrates a procedure for designing a functional and minimum weight wrist pin end of an automobile engine connecting rod with an interference fit wrist pin. Current procedures for Finite Element Method (FEM) model generation in complicated three-dimensional components are very time consuming especially in the presence of stress singularities. Furthermore the iterative nature of the design process makes the process of developing an optimum design very expensive. This design procedure uses a generic modeler to generate the FEM model based on the values of the design variables. It uses the NASTRAN finite element program for structural analysis. A stress concentration factor approach is used to obtain realistic stresses in the region of the stress singularity. For optimization, the approximate optimization strategy in the COPES/CONMIN program is used to generate an approximate design surface, determine the design sensitivities for constrained function minimization and obtain the optimum design. This proposed design strategy is fully automated and requires only an initial design to generate the optimum design. It does not require analysis code modifications to compute the design sensitivities and requires very few costly NASTRAN analyses. The connecting rod design problem was solved as an eight design variable problem with five constraints. A weight reduction of nearly 27 percent was achieved over an existing design and required only thirteen NASTRAN analyses. It is felt that this design strategy can be effectively used in an engineering environment to generate optimum designs of complicated three-dimensional components.

scholarly journals Biomechanical assessment of different fixation methods in mandibular high sagittal oblique osteotomy using a three-dimensional finite element analysis model

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Charles Savoldelli ◽  
Elodie Ehrmann ◽  
Yannick Tillier
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Three Dimensional ◽  
Von Mises Stress ◽  
Analysis Model ◽  
Element Analysis ◽  
Fixation Methods ◽  
Oblique Osteotomy ◽  
Von Mises

AbstractWith modern-day technical advances, high sagittal oblique osteotomy (HSOO) of the mandible was recently described as an alternative to bilateral sagittal split osteotomy for the correction of mandibular skeletal deformities. However, neither in vitro nor numerical biomechanical assessments have evaluated the performance of fixation methods in HSOO. The aim of this study was to compare the biomechanical characteristics and stress distribution in bone and osteosynthesis fixations when using different designs and placing configurations, in order to determine a favourable plating method. We established two finite element models of HSOO with advancement (T1) and set-back (T2) movements of the mandible. Six different configurations of fixation of the ramus, progressively loaded by a constant force, were assessed for each model. The von Mises stress distribution in fixations and in bone, and bony segment displacement, were analysed. The lowest mechanical stresses and minimal gradient of displacement between the proximal and distal bony segments were detected in the combined one-third anterior- and posterior-positioned double mini-plate T1 and T2 models. This suggests that the appropriate method to correct mandibular deformities in HSOO surgery is with use of double mini-plates positioned in the anterior one-third and posterior one-third between the bony segments of the ramus.

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.

scholarly journals A 3-D Finite Element Study of the Influence of Crown-Implant Ratio on Stress Distribution

2013 ◽  
Vol 24 (6) ◽  
pp. 635-641 ◽  
Author(s):  
Sandra Lucia Dantas de Moraes ◽  
Fellippo Ramos Verri ◽  
Joel Ferreira Santiago Junior ◽  
Daniel Augusto de Faria Almeida ◽  
Caroline Cantieri de Mello ◽  
...  
Keyword(s):  
Finite Element ◽  
Bone Tissue ◽  
Three Dimensional ◽  
Maximum Principal Stress ◽  
Von Mises Stress ◽  
Bone Block ◽  
Crown Height ◽  
Oblique Loading ◽  
Von Mises ◽  
Three Dimensional Finite Element

The purpose of this study was to assess the influence of the crown height of external hexagon implants on the displacement and distribution of stress to the implant/bone system, using the three-dimensional finite element method. The InVesalius and Rhinoceros 4.0 softwares were used to generate the bone model by computed tomography. Each model was composed of a bone block with one implant (3.75x10.0 mm) with external hexagon connections and crowns with 10 mm, 12.5 mm and 15 mm in height. A 200 N axial and a 100 N oblique (45°) load were applied. The models were solved by the NeiNastran 9.0 and Femap 10.0 softwares to obtain the results that were visualized by maps of displacement, von Mises stress (crown/implant) and maximum principal stress (bone). The crown height under axial load did not influence the stress displacement and concentration, while the oblique loading increased these factors. The highest stress was observed in the neck of the implant screw on the side opposite to the loading. This stress was also transferred to the crown/platform/bone interface. The results of this study suggest that the increase in crown height enhanced stress concentration at the implant/bone tissue and increased displacement in the bone tissue, mainly under oblique loading.

scholarly journals A three - dimensional finite element study on the stress distribution pattern of two prosthetic abutments for external hexagon implants

2013 ◽  
Vol 07 (04) ◽  
pp. 484-491 ◽  
Author(s):  
Wagner Moreira ◽  
Caio Hermann ◽  
Jucélio Tomás Pereira ◽  
Jean Anacleto Balbinoti ◽  
Rodrigo Tiossi
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Three Dimensional ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
3D Fea ◽  
The One ◽  
Von Mises ◽  
Three Dimensional Finite Element

ABSTRACT Objective: The purpose of this study was to evaluate the mechanical behavior of two different straight prosthetic abutments (one- and two-piece) for external hex butt-joint connection implants using three-dimensional finite element analysis (3D-FEA). Materials and Methods: Two 3D-FEA models were designed, one for the two-piece prosthetic abutment (2 mm in height, two-piece mini-conical abutment, Neodent) and another one for the one-piece abutment (2 mm in height, Slim Fit one-piece mini-conical abutment, Neodent), with their corresponding screws and implants (Titamax Ti, 3.75 diameter by 13 mm in length, Neodent). The model simulated the single restoration of a lower premolar using data from a computerized tomography of a mandible. The preload (20 N) after torque application for installation of the abutment and an occlusal loading were simulated. The occlusal load was simulated using average physiological bite force and direction (114.6 N in the axial direction, 17.1 N in the lingual direction and 23.4 N toward the mesial at an angle of 75° to the occlusal plan). Results: The regions with the highest von Mises stress results were at the bottom of the initial two threads of both prosthetic abutments that were tested. The one-piece prosthetic abutment presented a more homogeneous behavior of stress distribution when compared with the two-piece abutment. Conclusions: Under the simulated chewing loads, the von Mises stresses for both tested prosthetic-abutments were within the tensile strength values of the materials analyzed which thus supports the clinical use of both prosthetic abutments.

Finite Element Analysis of Gold Bonding under Different Loading Conditions

2014 ◽  
Vol 607 ◽  
pp. 713-716
Author(s):  
Wen Liang Tang ◽  
Chun Yue Huang ◽  
Tian Ming Li ◽  
Ying Liang ◽  
Guo Ji Xiong ◽  
...  
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Simulation Software ◽  
Bonding Time ◽  
Von Mises Stress ◽  
Bonding Pressure ◽  
Element Analysis ◽  
Von Mises ◽  
Three Dimensional Finite Element

In this paper, ANSYS-LSDYNA simulation software is used to build the three-dimensional finite element model of the ball bond and to get the Von Mises stress. The change of stress about the bump is researched which base on the model in different bonding pressure, bonding power and bonding time. The result show that: The stress increase with bonding pressure increase within a certain bonding pressure range, and then the stress will maintain a table number, however, the stress will continue to increase when the bonding pressure reach a certain value; increasing the bonding power, the area of lager stress will grow; prolonging the bonding time, the stress of the pad will increase with time, but when time increase to a certain value, the stress of the pad will not increase over time.

scholarly journals Effect of Augmentation Material Stiffness on Adjacent Vertebrae after Osteoporotic Vertebroplasty Using Finite Element Analysis with Different Loading Methods

2015 ◽  
Vol 6;18 (6;11) ◽  
pp. E1101-E1110
Author(s):  
Ah-Reum Cho
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Bone Cement ◽  
Vertebral Fractures ◽  
Three Dimensional ◽  
Element Model ◽  
Element Analysis ◽  
Adjacent Vertebral Body ◽  
Von Mises ◽  
Von Mises Stresses

Background: Vertebroplasty is an effective treatment for osteoporotic vertebral fractures, which are one of the most common fractures associated with osteoporosis. However, clinical observation has shown that the risk of adjacent vertebral body fractures may increase after vertebroplasty. The mechanism underlying adjacent vertebral body fracture after vertebroplasty is not clear; excessive stiffness resulting from polymethyl methacrylate has been suspected as an important mechanism. Objectives: The aim of our study was to compare the effects of bone cement stiffness on adjacent vertebrae after osteoporotic vertebroplasty under load-controlled versus displacementcontrolled conditions. Study Design: An experimental computer study using a finite element analysis. Setting: Medical research institute, university hospital, Korea. Methods: A three-dimensional digital anatomic model of L1/2 bone structure was reconstructed from human computed tomographic images. The reconstructed three-dimensional geometry was processed for finite element analysis such as meshing elements and applying material properties. Two boundary conditions, load-controlled and displacement-controlled methods, were applied to each of 5 deformation modes: compression, flexion, extension, lateral bending, and torsion. Results: The adjacent L1 vertebra, irrespective of augmentation, revealed nearly similar maximum von Mises stresses under the load-controlled condition. However, for the displacementcontrolled condition, the maximum von Mises stresses in the cortical bone and inferior endplate of the adjacent L1 vertebra increased significantly after cement augmentation. This increase was more significant than that with stiffer bone cement under all modes, except the torsion mode. Limitations: The finite element model was simplified, excluding muscular forces and incorporating a large volume of bone cement, to more clearly demonstrate effects of bone cement stiffness on adjacent vertebrae after vertebroplasty. Conclusion: Excessive stiffness of augmented bone cement increases the risk of adjacent vertebral fractures after vertebroplasty in an osteoporotic finite element model. This result was most prominently observed using the displacement-controlled method. Key words: Bone cements, displacement-controlled method, finite element analysis, loadcontrolled method, osteoporosis, osteoporotic fracture, polymethyl methacrylate, vertebroplasty

scholarly journals Assessment of stress changes in dentoalveolar and skeletal structures of the mandible with the miniplate anchored Forsus: A three-dimensional finite element stress analysis study

2017 ◽  
Vol 7 ◽  
pp. 87-93
Author(s):  
Harshal Ashok Patil ◽  
Pawankumar Dnyandeo Tekale ◽  
Veerendra V. Kerudi ◽  
Jitendra S. Sharan ◽  
Ratnadip Arunrao Lohakpure ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Three Dimensional ◽  
Element Model ◽  
Von Mises Stress ◽  
Functional Appliance ◽  
3D Finite Element ◽  
Fixed Functional Appliance ◽  
Finite Element Stress Analysis ◽  
Von Mises

ObjectiveThe study conducted to assess the effects of a fixed functional appliance (Forsus Fatigue Resistant Device; 3M Unitek, Monrovia, CA, USA) on the mandible with three-dimensional (3D) finite element stress analysis.Materials and MethodsA 3D finite element model of mandible with miniplate at mandibular symphysis was prepared using SolidEdge software along with the plate geometry. The changes were deliberated with the finite element method, in the form of highest von Mises stress and maximum principal stress regions.ResultsMore areas of stress were seen in the model of the mandible at cortical bone in canine region at bone and miniplate interface.ConclusionsThis fixed functional appliance studied by finite element model analysis caused more von Mises stress and principal stress in both the cortical bone and the condylar region.

scholarly journals Comparative analysis of stress distribution in one-piece and two-piece implants with narrow and extra-narrow diameters: A finite element study

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0245800
Author(s):  
Fabricia Teixeira Barbosa ◽  
Luiz Carlos Silveira Zanatta ◽  
Edélcio de Souza Rendohl ◽  
Sergio Alexandre Gehrke
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Three Dimensional ◽  
In Vitro Study ◽  
Von Mises Stress ◽  
Axial Loads ◽  
Three Dimensional Model ◽  
The One ◽  
Von Mises

Objectives The aim of this in vitro study was to evaluate the stress distribution on three implant models with narrow and extra-narrow diameters using the finite element method (FEA). Materials and methods Dental implants of extra-narrow diameter of 2.5 mm for a one-piece implant (group G1), a narrow diameter of 3.0 mm for a one-piece implant (group G2) and a narrow diameter of 3.5 mm for a two-piece implant with a Morse taper connection (group G3). A three-dimensional model was designed with cortical and cancellous bone, a crown and an implant/abutment set of each group. Axial and angled (30°) loads of 150 N was applied. The equivalent von Mises stress was used for the implants and peri-implant bone plus the Mohr-Coulomb analysis to confirm the data of the peri-implant bone. Results In the axial load, the maximum stress value of the cortical bone for the group G1 was 22.35% higher than that the group G2 and 321.23% than the group G3. Whereas in angled load, the groups G1 and G2 showing a similar value (# 3.5%) and a highest difference for the group G3 (391.8%). In the implant structure, the group G1 showed a value of 2188MPa, 93.6% higher than the limit. Conclusions The results of this study show that the extra-narrow one-piece implant should be used with great caution, especially in areas of non-axial loads, whereas the one- and two-piece narrow-diameter implants show adequate behavior in both directions of the applied load.

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