scholarly journals A FEA-Based Methodology to Predict the Osteotome Wear Status during Nasal Bone Surgical Operations

Coatings ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 855 ◽  
Author(s):  
G. Skordaris ◽  
F. Stergioudi ◽  
A. Boumpakis ◽  
D. Stergioudi ◽  
H. Behrbohm
Keyword(s):  
Fatigue Strength ◽  
Nasal Bone ◽  
Bone Geometry ◽  
Test Results ◽  
Surgical Instrument ◽  
Preventive Replacement ◽  
Fea Model ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Surgical Operations

A FEA-based methodology was developed in order to predict the wear status of an osteotome (surgical instrument) during its use in a lateral nasal bone osteotomy considering its fatigue strength. The latter parameter was determined by appropriate FEM-evaluation of the perpendicular impact test results. For the simulation of the surgical procedure, two scenarios were examined: (i) when utilizing a brand new osteotome and (ii) when utilizing an already used osteotome characterized by decreased fatigue strength. The actual nasal bone geometry used in the FEA model was obtained from a high-resolution, maxillofacial, computed tomography (CT) scan of a single patient. In both cases examined, depiction of fracture patterns for the osteotome and the nasal bone were obtained. The wear of a new osteotome and an already used osteotome was also calculated and compared. The developed von Mises stresses in both the osteotome and nasal bone were depicted. The proposed methodology allowed an accurate prediction of the critical number of impacts that the osteotome can receive during the lateral nasal osteotomy which is followed in all rhinoplasties. Based on the developed methodology, a preventive replacement of the osteotome before its extensive fracture can be determined, thereby minimizing the risk of postoperative complications.

scholarly journals Reconstruction of Severe Acetabular Bone Defect with 3D Printed Ti6Al4V Augment: A Finite Element Study

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Jun Fu ◽  
Ming Ni ◽  
Jiying Chen ◽  
Xiang Li ◽  
Wei Chai ◽  
...  
Keyword(s):  
Finite Element ◽  
Yield Strength ◽  
Bone Defect ◽  
Cancellous Bone ◽  
Acetabular Bone ◽  
Fea Model ◽  
Acetabular Bone Defect ◽  
3D Printed ◽  
Von Mises ◽  
Von Mises Stresses

Purpose. The purpose of this study was to establish the finite element analysis (FEA) model of acetabular bone defect reconstructed by 3D printed Ti6Al4V augment and TM augment and further to analyze the stress distribution and clinical safety of augments, screws, and bones.Methods. The FEA model of acetabular bone defect reconstructed by 3D printed Ti6Al4V augment was established by the CT data of a patient with Paprosky IIIA defect. The von Mises stresses of augments, screws, and bones were analyzed by a single-legged stance loading applied in 3 increments (500 N, 2000 N, and 3000 N).Results. The peak von Mises stresses under the maximal loading in the 3D printed augments, screws, and cortical bone were less than the yield strength of the corresponding component. However, the peak stress in the bone was greater than the yield strength of cancellous bone under walking or jogging loading. And under the same loading, the peak compressive and shear stresses in bone contact with TM augment were larger than these with 3D printed augment.Conclusions. The FEA results show that all the components will be intact under single-legged standing. However, partial cancellous bone contacted with 3D printed augment and screws will lose efficacy under walking or jogging load. So we recommend that patients can stand under full bearing, but can not walk or jog immediately after surgery.

Impact of mandibular prognathism on morphology and loadings in temporomandibular joints

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Jingheng Shu ◽  
Quanyi Wang ◽  
Desmond Y.R. Chong ◽  
Zhan Liu
Keyword(s):  
Finite Element Analysis ◽  
Pearson Correlation ◽  
Morphological Parameters ◽  
Element Analysis ◽  
Mandibular Prognathism ◽  
Temporomandibular Joints ◽  
Pearson Correlation Analysis ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Asymptomatic Subjects

AbstractLoadings in temporomandibular joints (TMJs) are essential factors in dysfunction of TMJs, and are barely noticed in treatment of maxillofacial deformity. The only approach, which can access stresses in TMJs, could expend day’s even weeks to complete. The objective of the study was to compare the differences of the morphological and biomechanical characteristics of TMJs between asymptomatic subjects and patients with mandibular prognathism, and to preliminarily analyze the connection between the two kinds of characteristics. Morphological measurements and finite element analysis (FEA) corresponding to the central occlusion were carried out on the models of 13 mandibular prognathism patients and 10 asymptomatic subjects. The results indicated that the joint spaces of the patients were significantly lower than those of the asymptomatic subjects, while the stresses of patients were significantly greater than those of asymptomatic subjects, especially the stresses on discs. The results of Pearson correlation analysis showed that weak or no correlations were found between the von Mises stresses and the joint spaces of asymptomatic subjects, while moderate, even high correlations were found in the patients. Thus, it was shown to be a feasible way to use morphological parameters to predict the internal loads of TMJs.

scholarly journals Interior-stress fields produced by a general axisymmetric punch

Friction ◽  
2021 ◽  
Author(s):  
Longxiang Yang ◽  
Zhanjiang Wang ◽  
Weiji Liu ◽  
Guocheng Zhang ◽  
Bei Peng
Keyword(s):  
Hankel Transform ◽  
Elastic Half Space ◽  
Stress Fields ◽  
Dual Integral Equations ◽  
Total Load ◽  
Interior Stress ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Relationship Of ◽  
Analytical Expressions

AbstractThis work is a supplement to the work of Sneddon on axisymmetric Boussinesq problem in 1965 in which the distributions of interior-stress fields are derived here for a punch with general profile. A novel set of mathematical procedures is introduced to process the basic elastic solutions (obtained by the method of Hankel transform, which was pioneered by Sneddon) and the solution of the dual integral equations. These processes then enable us to not only derive the general relationship of indentation depth D and total load P that acts on the punch but also explicitly obtain the general analytical expressions of the stress fields beneath the surface of an isotropic elastic half-space. The usually known cases of punch profiles are reconsidered according to the general formulas derived in this study, and the deduced results are verified by comparing them with the classical results. Finally, these general formulas are also applied to evaluate the von Mises stresses for several new punch profiles.

Mechanics of Composite Layered Rough Medium in Contact

2013 ◽  
Vol 703 ◽  
pp. 200-203
Author(s):  
Shao Biao Cai ◽  
Yong Li Zhao
Keyword(s):  
Material Properties ◽  
Three Dimensional ◽  
Shear Stresses ◽  
Normal Loading ◽  
Layered Coatings ◽  
Pressure Profiles ◽  
Tangential Traction ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Tangential Friction

This study presents a first attempt to develop a numerical three-dimensional multilayered (more than 2 composite layered coatings) elasticperfectly plastic rough solids model to investigate the contact behavior under combined normal loading and tangential traction. Contact analyses are performed to study the effects composite thin film layers. Local contact pressure profiles, von Mises stresses, and shear stresses as a function of material properties and applied normal and tangential friction loads are calculated.

COMPARATIVE STRESS ANALYSIS OF LINGUALIZED AND CONVENTIONAL BALANCED OCCLUSION SCHEMES IN A FULL-ARCH FIXED IMPLANT PROSTHESIS USING FINITE ELEMENT ANALYSIS

2017 ◽  
Vol 17 (04) ◽  
pp. 1750074
Author(s):  
MD ABU HASAN ◽  
PANOS S. SHIAKOLAS
Keyword(s):  
Cortical Bone ◽  
Acrylic Resin ◽  
Element Analysis ◽  
Posterior Teeth ◽  
Failure Index ◽  
Biomechanical Behavior ◽  
Denture Teeth ◽  
Implant Prosthesis ◽  
Von Mises ◽  
Von Mises Stresses

This study compares the biomechanical behavior of a mandibular full-arch fixed implant prosthesis with four implants under lingualized and conventional balanced occlusion schemes. The acrylic resin denture was supported by four titanium cylindrical implants and connected via a titanium prosthetic rectangular bar. Orthotropic material was used for the cortical and cancellous bones. The applied loadings were vertical and bilateral: 100[Formula: see text]N on first molar and 50[Formula: see text]N on first and second premolars each. For the lingualized balanced occlusion, the loadings were applied in central fossae of the posterior teeth, whereas for the conventional balanced occlusion the loadings were applied in central fossae and buccal cusps. The maximum von-Mises stresses for the lingualized and conventional balanced schemes were 301[Formula: see text]MPa and 25[Formula: see text]MPa, respectively, and were located at the neck of the posterior implants. In the denture teeth, the highest stress was located at the beginning of the cantilever extension. In the cortical bone, according to Tsai–Wu criterion, the failure index for the lingualized balanced occlusion was 1.10 and for the conventional balanced occlusion was 0.83. Thus, the conventional balanced occlusion demonstrated more favorable stress distribution in the implants and the cortical bone than the lingualized balanced occlusion.

scholarly journals Finite element simulation of sink pass round tubes using Ansys

2012 ◽  
pp. 179-188 ◽  
Author(s):  
M.P. Nagarkar ◽  
R.N. Zaware ◽  
S.G. Ghalme
Keyword(s):  
Modeling And Simulation ◽  
Product Quality ◽  
Metal Forming ◽  
Cold Working ◽  
Ansys Software ◽  
Simulation Techniques ◽  
Element Simulation ◽  
Simulation Results ◽  
Von Mises ◽  
Von Mises Stresses

Modeling and simulation of metal forming processes are increasingly in demand from the industry as the resulting models are found to be valuable tools considering the optimization of the existing and development of new processes. By the application of modeling and simulation techniques, it is possible to reduce the number of time-consuming experiments such as prototyping. Seamless tubes of various sizes and shapes are manufactured by various processes like sinking, fixed plug, floating plug, moving mandrel, cold working and hot working. The present work deals with the simulation of round tubes while passing through the sink pass, using ANSYS software. The simulation results are the displacement and von Mises stresses. The procedure can be used to improve the product quality and to study the effect of various parameters like die angle on the product quality.

A Finite Element Analysis of the Human Temporomandibular Joint

1994 ◽  
Vol 116 (4) ◽  
pp. 401-407 ◽  
Author(s):  
J. Chen ◽  
Liangfeng Xu
Keyword(s):  
Finite Element ◽  
Temporomandibular Joint ◽  
Reaction Force ◽  
Element Model ◽  
Contact Stresses ◽  
Element Analysis ◽  
Tensile Stresses ◽  
Reaction Forces ◽  
Von Mises ◽  
Von Mises Stresses

A 2-D finite element model of the human temporomandibular joint (TMJ) has been developed to investigate the stresses and reaction forces within the joint during normal sagittal jaw closure. The mechanical parameters analyzed were maximum principal and von Mises stresses in the disk, the contact stresses on the condylar and temporal surfaces, and the condylar reactions. The model bypassed the complexity of estimating muscle forces by using measured joint motion as input. The model was evaluated by several tests. The results demonstrated that the resultant condylar reaction force was directed toward the posterior side of the eminence. The contact stresses along the condylar and temporal surfaces were not evenly distributed. Separations were found at both upper and lower boundaries. High tensile stresses were found at the upper boundaries. High tensile stresses were found at the upper boundary of the middle portion of the disk.

Discrete-Direct Model Calibration and Uncertainty Propagation Method Confirmed on Multi-Parameter Plasticity Model Calibrated to Sparse Random Field Data

2021 ◽  
Vol 7 (2) ◽  
Author(s):  
Vicente J. Romero ◽  
Justin G. Winokur ◽  
George E. Orient ◽  
James F. Dempsey
Keyword(s):  
Strain Rate ◽  
Model Calibration ◽  
Structural Model ◽  
Uncertainty Propagation ◽  
Material Strength ◽  
Rate Dependent ◽  
Direct Model ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Force Displacement

Abstract A discrete direct (DD) model calibration and uncertainty propagation approach is explained and demonstrated on a 4-parameter Johnson-Cook (J-C) strain-rate dependent material strength model for an aluminum alloy. The methodology's performance is characterized in many trials involving four random realizations of strain-rate dependent material-test data curves per trial, drawn from a large synthetic population. The J-C model is calibrated to particular combinations of the data curves to obtain calibration parameter sets which are then propagated to “Can Crush” structural model predictions to produce samples of predicted response variability. These are processed with appropriate sparse-sample uncertainty quantification (UQ) methods to estimate various statistics of response with an appropriate level of conservatism. This is tested on 16 output quantities (von Mises stresses and equivalent plastic strains) and it is shown that important statistics of the true variabilities of the 16 quantities are bounded with a high success rate that is reasonably predictable and controllable. The DD approach has several advantages over other calibration-UQ approaches like Bayesian inference for capturing and utilizing the information obtained from typically small numbers of replicate experiments in model calibration situations—especially when sparse replicate functional data are involved like force–displacement curves from material tests. The DD methodology is straightforward and efficient for calibration and propagation problems involving aleatory and epistemic uncertainties in calibration experiments, models, and procedures.

An Investigation of Shaft Relief Grooves in Tailshaft Assemblies

1969 ◽  
Vol 6 (03) ◽  
pp. 274-280
Author(s):  
Peter L. Caiamari
Keyword(s):  
Fatigue Strength ◽  
Notch Effect ◽  
Test Results

Various relief grooves, located in the shafts between the liners and the hubs, were investigated with regard to their effects on the fatigue strengths of conventional tailshaft assemblies. It was found that tailshaft assemblies could be designed which would fail in the groove, regardless of whether single or increment loads were used, and that the fatigue strength of these grooved assemblies was higher than the fatigue strength of comparable ungrooved tailshaft assemblies. The grooved assemblies which had the highest fatigue strengths failed predominantly under the fitted members. The notch fatigue factors obtained with these test results were considerably higher than the estimated combined fatigue notch factors, and it is speculated that this apparent intensification is due to the added notch effect from the fitted members.

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