scholarly journals Investigation on Microstructural Damage Properties of Asphalt Mixture Using Linear and Damage-Coupled Viscoelastic Model

2019 ◽  
Vol 9 (2) ◽  
pp. 303
Author(s):  
Wenke Huang ◽  
Zhibin Ren ◽  
Xiaoning Zhang ◽  
Jiangmiao Yu
Keyword(s):  
Stress Distribution ◽  
Viscoelastic Model ◽  
Asphalt Mixture ◽  
Viscoelastic Behavior ◽  
Von Mises Stress ◽  
Micromechanical Modeling ◽  
Fe Model ◽  
Asphalt Mastic ◽  
Simulation Results ◽  
Von Mises

This paper presents an image-based micromechanical modeling approach for simulating the damage-couple viscoelastic response of asphalt mixture. Details of the numerical damage-couple viscoelastic constitutive formulation implemented in a finite element code are presented and illustrated by using the ABAQUS user material subroutine (UMAT). Then, an experimental procedure based on the Linear Amplitude Sweep test for obtaining the viscoelastic and damage parameters at a given temperature was conducted. An improved morphological multi-scale algorithm was employed to segment the adhesive coarse aggregate images. We developed a pixel-based digital reconstruction model of asphalt mixture with the X-ray CT image after being processed. Finally, the image-based FE model incorporated with damage-coupled viscoelastic asphalt mastic phase and elastic aggregates was used for the compressive test simulations successfully in this study. Simulation results showed that the damaged simulation results have a larger stress distribution compared with the undamaged simulation due to the irregularity of the coarse aggregates. The von Mises stress distribution is smaller as the loading time increases due to the viscoelastic behavior of asphalt mastic. It can also provide insight on the damaged mechanisms and the possible location in asphalt mixture where microscopic cracking would most likely occur.

DYNAMIC STRESS DISTRIBUTION IN A MODEL OF IMPLANTED MANDIBLE: NUMERICAL ANALYSIS OF VISCOELASTIC BONE

2015 ◽  
Vol 15 (04) ◽  
pp. 1550050 ◽  
Author(s):  
H. MOTALLEBZADEH ◽  
M. TAFAZZOLI-SHADPOUR ◽  
M. M. KHANI
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Cortical Bone ◽  
Dynamic Loading ◽  
Viscoelastic Behavior ◽  
Element Model ◽  
Von Mises Stress ◽  
Dental Implantation ◽  
Trabecular Bones ◽  
Von Mises

To determine the success of dental implants, mechanical stress distribution in the implant-bone interface is considered to be a determinant. Many researchers have used finite element modeling of implant-bone through applying static loading on the implant; however, dynamic loading has not extensively been investigated specially considering viscoelastic behavior of the bone. The aim of this study is to analyze effects of viscoelasticity of bone and dynamic loading comparable to mastication conditions on stress distribution in an implanted mandible. A three-dimensional finite-element model of an implanted mandible in the first molar region was constructed from computerized tomography data. Effects of several parameters, such as material properties including viscoelastic behavior of the cortical and trabecular bones, load amplitude, duration and direction on the instantaneous and long-term von Mises stress distribution of an implanted mandible were evaluated. In all loading conditions, the maximum von Mises stress occurred in cortical bone surrounding the neck of implant. Stress distribution was not noticeably affected by viscoelastic behavior during the first loading cycles, however, after 100 s periodic loading, the differences between stress magnitudes (especially in the cortical bone) became noticeable. In addition, sensitivity analysis showed that both cortical and trabecular bones were more sensitive to axial load than buccalingual and mesiodistal forces. The results of this study contribute to analysis of parameters involved in success of dental implantation.

scholarly journals Which is the better posterior lumbar dynamic device: Dynesys or BioFlex?

2020 ◽  
Author(s):  
Konghe Hu ◽  
Jianjun Li ◽  
Sujun Qiu ◽  
Yingmin Xie ◽  
Kaiqin Gong ◽  
...  
Keyword(s):  
Stress Distribution ◽  
Simulation Models ◽  
Middle Part ◽  
Von Mises Stress ◽  
Fe Model ◽  
Surgery Simulation ◽  
Intact Group ◽  
3D Ct Scan ◽  
Von Mises

Abstract Objective: The purpose of this study was to analyze the biomechanical characteristics of the lumbar posterior dynamic devices: the Dynesys system and the BioFlex system. Methods: We validated the FE model of an lumbar spine (L3-S1) established by transferring the data, collected by 3D CT scan, to the FE software ABAQUS and comparing these data with the data from published studies. Then, were reconstructed by the lumbar posterior dynamic devices to analyze the range of motion (ROM) and stress distribution on the lumbar posterior dynamic devices. Results: The current lumbar FE model was able to measure the biomechanical changes in a follow-up surgery simulation. The total ROM of the surgery simulation models was substantially decreased compared with the total ROM of the intact group, and the Dynesys system group had the closest total ROM to the intact group. The maximal von Mises stress concentrate at the middle part of the screws in Dynesys system, but at the Nitinol memory loop in BioFlex system. The maximal stress level was only 49 MPa in Dynesys system, but 164 MPa in BioFlex system. Conclusion: Through the comparison of ROM and the stress distribution of the prosthesis, we find that the Dynesys system maybe has a better theoretical outcome.

Biomechanical Evaluation of an Endplate-Conformed Polycaprolactone-Hydroxyapatite Intervertebral Fusion Graft and Its Comparison With a Typical Nonconformed Cortical Graft

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Aakash Agarwal ◽  
Vivek Palepu ◽  
Anand K. Agarwal ◽  
Vijay K. Goel ◽  
Eda D. Yildirim
Keyword(s):  
Stress Distribution ◽  
Case Studies ◽  
Posterior Instrumentation ◽  
Von Mises Stress ◽  
Fe Model ◽  
Stress Distributions ◽  
Functional Spinal Unit ◽  
Thoracolumbar Region ◽  
Von Mises

In the thoracolumbar region, between 7% and 30% of spinal fusion failures are at risk for pseudarthrosis. From a biomechanical perspective, the nonconformity of the intervertebral graft to the endplate surface could contribute to pseudarthrosis, given suboptimal stress distributions. The objective of this study was to quantify the effect of endplate-graft conformation on endplate stress distribution, maximum Von Mises stress development, and stability. The study design used an experimentally validated finite element (FE) model of the L4–L5 functional spinal unit to simulate two types of interbody grafts (cortical bone and polycaprolactone (PCL)-hydroxyapatite (HA) graft), with and without endplate-conformed surfaces. Two case studies were completed. In Case Study I, the endplate-conformed grafts and nonconformed grafts were compared under without posterior instrumentation condition, while in Case Study II, the endplate-conformed and nonconformed grafts were compared with posterior instrumentation. In both case studies, the results suggested that the increased endplate-graft conformity reduced the maximum stress on the endplate, created uniform stress distribution on endplate surfaces, and reduced the range of motion of L4–L5 segments by increasing the contact surface area between the graft and the endplate. The stress distributions in the endplate suggest that the load sharing is greater with the endplate-conformed PCL-HA graft, which might reduce the graft subsidence possibility.

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.

scholarly journals DESAIN DAN ANALISIS TEGANGAN STRUKTUR CRANE KAPASITAS 10 TON MENGGUNAKAN METODE ELEMEN HINGGA

2020 ◽  
Vol 4 (2) ◽  
pp. 201
Author(s):  
Lasinta Ari Nendra Wibawa
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Mild Steel ◽  
Von Mises Stress ◽  
Assembly Process ◽  
Heavy Equipment ◽  
Steel Material ◽  
Simulation Results ◽  
Heavy Loads ◽  
Von Mises

Crane is one of the heavy equipment that is widely used in the industry. The crane functions as a tool for lifting heavy loads and moving them from one place to another vertically and horizontally. In the LAPAN Garut office, it is used for the rocket assembly process. The study investigates the design and analysis of von Mises stress of crane structure with a capacity of 10 tons using mild steel material. The investigation was carried out numerically using Autodesk Inventor Professional 2017. The simulation results showed the Crane structure had a von Mises stress, deformation, mass, and safety factor respectively 63.73 MPa; 2,173 mm; 1.508,53 kg; and 3.25.Keywords: autodesk inventor 2017; finite element method; mild steel; stress analysis; von Mises stressABSTRAKCrane merupakan salah satu alat berat yang banyak digunakan dalam suatu industri. Crane berfungsi sebagai alat untuk mengangkat beban berat dan memindahkannya dari satu tempat ke tempat lain secara vertikal maupun horisontal. Di LAPAN Garut, Crane digunakan untuk proses perakitan roket. Penelitian ini meneliti tentang perancangan dan analisis tegangan von Mises struktur Crane dengan kapasitas 10 Ton menggunakan material mild steel. Analisis dilakukan secara numerik dengan menggunakan perangkat lunak Autodesk Inventor Professional 2017. Hasil simulasi menunjukkan struktur Crane memiliki tegangan von Mises, deformasi, massa, dan factor keamanan berturut-turut sebesar 63,73 MPa; 2,173 mm; 1.508,53 kg; dan 3,25.

Altered Load Transfer in the Pelvis in the Presence of Periprosthetic Osteolysis

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
Jacob T. Munro ◽  
Justin W. Fernandez ◽  
James S. Millar ◽  
Cameron G. Walker ◽  
Donald W. Howie ◽  
...  
Keyword(s):  
Cortical Bone ◽  
Load Transfer ◽  
Von Mises Stress ◽  
Patient Specific ◽  
Fe Model ◽  
Stress Concentrations ◽  
Periprosthetic Osteolysis ◽  
Total Hip ◽  
Long Term Follow Up ◽  
Von Mises

Periprosthetic osteolysis in the retroacetabular region with cancellous bone loss is a recognized phenomenon in the long-term follow-up of total hip replacement. The effects on load transfer in the presence of defects are less well known. A validated, patient-specific, 3D finite element (FE) model of the pelvis was used to assess changes in load transfer associated with periprosthetic osteolysis adjacent to a cementless total hip arthroplasty (THA) component. The presence of a cancellous defect significantly increased (p < 0.05) von Mises stress in the cortical bone of the pelvis during walking and a fall onto the side. At loads consistent with single leg stance, this was still less than the predicted yield stress for cortical bone. During higher loads associated with a fall onto the side, highest stress concentrations occurred in the superior and inferior pubic rami and in the anterior column of the acetabulum with larger cancellous defects.

scholarly journals Study on the biomechanical responses of the loaded bone in macroscale and mesoscale by multiscale poroelastic FE analysis

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
WeiLun Yu ◽  
XiaoGang Wu ◽  
HaiPeng Cen ◽  
Yuan Guo ◽  
ChaoXin Li ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Fluid Velocity ◽  
Fluid Pressure ◽  
Biological Information ◽  
Von Mises Stress ◽  
Fe Model ◽  
Heterogeneous Distribution ◽  
Material Parameters ◽  
Mesoscopic Models ◽  
Von Mises

Abstract Background Bone is a hierarchically structured composite material, and different hierarchical levels exhibit diverse material properties and functions. The stress and strain distribution and fluid flow in bone play an important role in the realization of mechanotransduction and bone remodeling. Methods To investigate the mechanotransduction and fluid behaviors in loaded bone, a multiscale method was developed. Based on poroelastic theory, we established the theoretical and FE model of a segment bone to provide basis for researching more complex bone model. The COMSOL Multiphysics software was used to establish different scales of bone models, and the properties of mechanical and fluid behaviors in each scale were investigated. Results FE results correlated very well with analytical in macroscopic scale, and the results for the mesoscopic models were about less than 2% different compared to that in the macro–mesoscale models, verifying the correctness of the modeling. In macro–mesoscale, results demonstrated that variations in fluid pressure (FP), fluid velocity (FV), von Mises stress (VMS), and maximum principal strain (MPS) in the position of endosteum, periosteum, osteon, and interstitial bone and these variations can be considerable (up to 10, 8, 4 and 3.5 times difference in maximum FP, FV, VMS, and MPS between the highest and the lowest regions, respectively). With the changing of Young’s modulus (E) in each osteon lamella, the strain and stress concentration occurred in different positions and given rise to microscale spatial variations in the fluid pressure field. The heterogeneous distribution of lacunar–canalicular permeability (klcp) in each osteon lamella had various influence on the FP and FV, but had little effect on VMS and MPS. Conclusion Based on the idealized model presented in this article, the presence of endosteum and periosteum has an important influence on the fluid flow in bone. With the hypothetical parameter values in osteon lamellae, the bone material parameters have effect on the propagation of stress and fluid flow in bone. The model can also incorporate alternative material parameters obtained from different individuals. The suggested method is expected to provide dependable biological information for better understanding the bone mechanotransduction and signal transduction.

Thermal-Mechanical Study of 3D Printing Technology for Rail Repair

2018 ◽  
Author(s):  
Ershad Mortazavian ◽  
Zhiyong Wang ◽  
Hualiang Teng
Keyword(s):  
Thermal Analysis ◽  
Thermal Expansion ◽  
3D Printing ◽  
Stress Distribution ◽  
Temperature Gradient ◽  
Initial Temperature ◽  
Mechanical Analysis ◽  
Von Mises Stress ◽  
Additive Materials ◽  
Von Mises

The complicated steel wheel and rail interaction on curve causes side wear on rail head. Thus, the cost of maintenance for the track on curve is significantly higher than that for track on a tangent. The objective of this research is to develop 3D printing technology for repairing the side wear. In this paper, the study examines induced residual thermal stresses on a rail during the cooling down process after 3D printing procedure using the coupled finite volume and finite element method for thermal and mechanical analysis respectively. The interface of the railhead and additive materials should conserve high stresses to prevent any crack initiation. Otherwise, the additive layer would likely shear off the rail due to crack propagation at the rail/additive interface. In the numerical analysis, a cut of 75-lb ASCE (American Society of Civil Engineers) worn rail is used as a specimen, for which a three-dimensional model is developed. The applied residual stresses, as a result of temperature gradient and thermal expansion coefficient mismatch between additive and rail materials, are investigated. At the beginning, the worn rail is at room temperature while the additive part is at a high initial temperature. Then, additive materials start to flow thermal energy into the worn rail and the ambient. The thermal distribution results from thermal analysis are then employed as thermal loads in the mechanical analysis to determine the von-Mises stress distribution as the decisive component. Then, the effect of preheating on residual stress distribution is studied. In this way, the thermo-mechanical analysis is repeated with an increase in railhead’s initial temperature. In thermal analysis, the temperature contours at different time steps for both the non-preheated and preheated cases indicate that preheating presents remarkably lower temperature gradient between rail and additive part and also represents a more gradual cooling down process to allow enough time for thermal expansion mismatch alignment. In mechanical analysis, the transversal von-Mises stress distribution at rail/additive interface is developed for all cases for comparison purposes. It is shown that preheating is a key factor to significantly reduce residual stresses by about 40% at all points along transversal direction of interface.

Consequences of Viscoelastic Behavior in the Human Temporomandibular Joint Disc

2007 ◽  
Vol 86 (12) ◽  
pp. 1198-1202 ◽  
Author(s):  
J.H. Koolstra ◽  
T.M.G.J. van Eijden
Keyword(s):  
Temporomandibular Joint ◽  
Viscoelastic Behavior ◽  
Material Model ◽  
Von Mises Stress ◽  
Joint Movement ◽  
Temporomandibular Joint Disc ◽  
Apparent Stiffness ◽  
Linear Viscoelastic Material ◽  
Masticatory System ◽  
Von Mises

The consequences of the viscoelastic behavior of the temporomandibular joint disc were analyzed in simulated jaw open-close cycles. It was hypothesized that viscoelasticity helps protect the underlying bone, while augmenting the smoothness of articular movements. Simulations were performed with a dynamic model of the masticatory system, incorporating the joints’ cartilaginous structures as Finite Element Models. A non-linear viscoelastic material model was applied for the disc. The apparent stiffness of the disc to principal stress was largest when the jaw was closed, whereas, with the Von Mises’ stress, it appeared largest when the jaw was open. The apparent stiffnesses appeared to be dependent on both the speed of the movements and the presence of a resistance between the teeth. It was concluded that the disc becomes stiffer when load concentrations can be expected. During continued cyclic motion, it softens, which favors smoothness of joint movement at the cost of damage prevention.

scholarly journals Effect of Fiber Posts on Stress Distribution of Endodontically Treated Upper Premolars: Finite Element Analysis

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1708 ◽  
Author(s):  
Maciej Zarow ◽  
Mirco Vadini ◽  
Agnieszka Chojnacka-Brozek ◽  
Katarzyna Szczeklik ◽  
Grzegorz Milewski ◽  
...  
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Resin Composite ◽  
Von Mises Stress ◽  
Stress Distributions ◽  
Stress Concentrations ◽  
Element Analysis ◽  
Endodontically Treated Tooth ◽  
Maxillary Premolars ◽  
Von Mises

By means of a finite element method (FEM), the present study evaluated the effect of fiber post (FP) placement on the stress distribution occurring in endodontically treated upper first premolars (UFPs) with mesial–occlusal–distal (MOD) nanohybrid composite restorations under subcritical static load. FEM models were created to simulate four different clinical situations involving endodontically treated UFPs with MOD cavities restored with one of the following: composite resin; composite and one FP in the palatal root; composite and one FP in the buccal root; or composite and two FPs. As control, the model of an intact UFP was included. A simulated load of 150 N was applied. Stress distribution was observed on each model surface, on the mid buccal–palatal plane, and on two horizontal planes (at cervical and root-furcation levels); the maximum Von Mises stress values were calculated. All analyses were replicated three times, using the mechanical parameters from three different nanohybrid resin composite restorative materials. In the presence of FPs, the maximum stress values recorded on dentin (in cervical and root-furcation areas) appeared slightly reduced, compared to the endodontically treated tooth restored with no post; in the same areas, the overall Von Mises maps revealed more favorable stress distributions. FPs in maxillary premolars with MOD cavities can lead to a positive redistribution of potentially dangerous stress concentrations away from the cervical and the root-furcation dentin.

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