Biomechanical evaluation of the screw preload values used in the plate placement for bone fractures

2020 ◽  
pp. 095441192096462
Author(s):  
Talip Çelik
Keyword(s):  
Finite Element ◽  
Bone Fractures ◽  
Bone Plate ◽  
Long Bone ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Biomechanical Evaluation ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Plate System

The purpose of this study is to examine the effects of screw preload values on the bone-plate system. The preload value was taken differently in the literature range from 50 N to 3000 N. These preload value were examined in this study. The finite element method was used to calculate the strain and stress on the models. The long bone, plate and screws were modeled as 3D using CAD software. The finite element models were created using Ansys Workbench software. The convergence and validation study were made for the correct results. The 400 N axial load was applied to the proximal end of bone. The distal end of the bone fixed for boundary condition. The preload values were applied to the screws differently. The results of the finite element analysis were compared and evaluated. The results showed that when the preload values increased, the von Mises stresses and strains on the bone and plate system increased. The critical preload value of the screw is the 500 N. The upper values of this critical value can be damaged bone and plate system. The critical region of the bone is the holes where the screw inserted. In conclusion, the preload values of the screw should not exceed the 500 N for the successful fixation.

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.

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 Assessing the Impact of Changes on Design and Material of Howe Bridges by Finite Element Analysis

2021 ◽  
Vol 3 (3) ◽  
pp. 33-37
Author(s):  
Jairo Aparecido Martins ◽  
Estaner Claro Romão
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Lateral Loads ◽  
Element Analysis ◽  
Design Changes ◽  
Minimal Design ◽  
Von Mises ◽  
Truss Bridge ◽  
Von Mises Stresses ◽  
The Impact

This paper presents an investigation of changes on design and material of a Howe bridge under vertical loads. Specifically, it aimed to find out how small changes on Howe bridge design and material affected von Mises stresses as well as stresses at Z direction. As a method, it was used a finite element analysis (linear-elastic) by Autodesk F-360. Half of a bridge was designed (one bridge side) and loaded with a central higher load and two equal smaller lateral loads. In essence, von Mises stresses (s) and stress at Z direction (sz) decreased on stresses values until a certain design change, which was proportional to a raise of mass due to beams added on the trusses. With a change of material to a lighter metal, from steel to aluminum, it was possible to overcome the mass drawback brought by steel and utterly possible to end up for a more effective design for a Howe truss bridge by applying minimal design changes.

scholarly journals Effects of Attraction of Vacuum Extractors of Different Materials and Pressures on the Fetal Head During Delivery

2021 ◽  
Author(s):  
Yu-Hsuan Chen ◽  
Kuo-Min Su ◽  
Ming-Tzu Tsai ◽  
Chi-Kung Lin ◽  
Cheng-Chang Chang ◽  
...  
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
Von Mises Stress ◽  
Reactive Force ◽  
Fetal Head ◽  
Element Analysis ◽  
Vacuum Extractor ◽  
The Finite Element Analysis ◽  
Von Mises ◽  
Analysis Models

Abstract PurposeIn some cases where operative deliveries are required with vacuum extractor, and obstetricians could choose the vacuum extractor to facilitate the process smoother and safer. However, there is no related biomechanical literature about the influences of vacuum extractors fabricated from different materials and pressures of vacuum on the fetal head. Hence, we utilized the finite element method to investigate the influences of vacuum extractors manufactured from different materials on the fetal head under various extractive pressures.MethodsFirst, the finite element analysis models of vacuum extractor and fetal head were established. The vacuum extractor model was designed as a hemispherical shape and we compared silicone rubber and stainless steel for the materials of vacuum extractor. Subsequently, four different vacuum pressures were applied as the factors for investigation—500-cm H2O, 600-cm H2O, 700-cm H2O, and 800-cm H2O. Finally, we observed and analyzed the reactive force on the fetal head, von Mises stress of vacuum extractor, and von Mises stress on the skull of fetal head to evaluate the influences of vacuum extractors of different materials under different pressures. ResultsThe results demonstrated that different vacuum pressures had only a slight difference of influences on the fetal head. The use of stainless-steel vacuum extractors caused a relatively larger reactive force (358.04–361.37 N) and stress (13.547–13.675 MPa) on the fetal head. ConclusionsNon-metallic or relatively softer materials could be selected when using a vacuum extractor for operative delivery to avoid complications such as scalp scratch, and even cephalohematoma and intracerebral hemorrhage.

scholarly journals Stress distribution in a mandibular premolar after separated nickel-titanium instrument removal and root canal preparation: a three-dimensional finite element analysis

2019 ◽  
Vol 47 (4) ◽  
pp. 1555-1564 ◽  
Author(s):  
Na Ni ◽  
Jing Ye ◽  
Liyuan Wang ◽  
Simin Shen ◽  
Lei Han ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Distribution ◽  
Three Dimensional ◽  
Cervical Region ◽  
Element Analysis ◽  
Straight Line ◽  
Mandibular First Premolar ◽  
Von Mises ◽  
Von Mises Stresses

Objective This study used finite element analysis (FEA) to assess the von Mises stresses of a mandibular first premolar after removing a separated instrument with an ultrasonic technique. Methods FEA models of the original and treated mandibular first premolar were reconstructed, and three models (the original canal, size 30/taper 0.04 canal, and separated instrument removal canal) were created. Two-direction (vertical and lateral) loading patterns were simulated with a 175-N force. The maximum von Mises stresses of the models within the roots from the apex to the cervical region were collected and summarized. Results Under vertical and lateral loads, all maximal values in the three models were localized in the straight-line access region. Compared with the original model (model 1), the treated models (models 2 and 3) had greater maximum stress values from the apex to the cervical region. Greater differences in the maximum von Mises stresses between models 2 and 3 were present in the straight-line access region. Conclusions Separated instrument removal caused changes in stress distribution and increases in stress concentration in the straight-line access region of roots.

Effect of Intramedullary Nailing Patterns On Interfragmentary Strain in a Mouse Femur Fracture: a Parametric Finite Element Analysis

2021 ◽  
Author(s):  
Gregory Lowen ◽  
Katherine Garrett ◽  
Moore-Lotridge Stephanie ◽  
Sasidhar Uppuganti ◽  
Scott A. Guelcher ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fracture Healing ◽  
Bone Repair ◽  
Bone Fractures ◽  
Fracture Site ◽  
Fracture Repair ◽  
Long Bone ◽  
Design Parameters ◽  
Element Analysis

Abstract Delayed long bone fracture healing and nonunion continue to be a significant socioeconomic burden. While mechanical stimulation is known to be an important determinant of the bone repair process, understanding how the magnitude, mode, and commencement of interfragmentary strain (IFS) affect fracture healing can guide new therapeutic strategies to prevent delayed healing or non-union. Mouse models provide a means to investigate the molecular and cellular aspects of fracture repair, yet there is only one commercially available, clinically-relevant, locking intramedullary nail (IMN) currently available for studying long bone fractures in rodents. Having access to alternative IMNs would allow a variety of mechanical environments at the fracture site to be evaluated, and the purpose of this proof-of-concept finite element analysis study is to identify which IMN design parameters have the largest impact on IFS in a murine transverse femoral osteotomy model. Using the dimensions of the clinically relevant IMN as a guide, the nail material, distance between interlocking screws, and clearance between the nail and endosteal surface were varied between simulations. Of these parameters, changing the nail material from stainless steel (SS) to polyetheretherketone (PEEK) had the largest impact on IFS. Reducing the distance between the proximal and distal interlocking screws substantially affected IFS only when nail modulus was low. Therefore, IMNs with low modulus (e.g., PEEK) can be used alongside commercially available SS nails to investigate the effect of initial IFS or stability on fracture healing with respect to different biological conditions of repair in rodents.

The Geometric and Material Nonlinear Analysis of the Bioprosthetic Heart Valve

2012 ◽  
Vol 157-158 ◽  
pp. 714-718
Author(s):  
Quan Yuan ◽  
Hai Bo Ma ◽  
Cheng Rui Zhang ◽  
Hua Cong ◽  
Xin Ye
Keyword(s):  
Finite Element ◽  
Heart Valve ◽  
Computer Aided Design ◽  
Mechanical Performance ◽  
Bioprosthetic Heart Valve ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Von Mises ◽  
Material Nonlinear ◽  
Aided Design

This paper constructs four types of bioprosthetic heart valve’s parametric model via computer aided design, a series of accurate parameters of the bioprosthetic heart valve, such as radius of the sutural ring, height of the supporting stent and inclination of the supporting stent are determined. The finite element method is used to analyze the mechanical properties of the bioprosthetic heart valve in which geometric non-linearity and material non-linearity are all taken into account. The finite element analysis results show that the shape of the bioprosthetic has a significant effect on the mechanical performance of the valve. The stress distribution of ellipsoidal valve leaflets is comparatively reasonable. It has lower peak von-Mises, smaller stress concentration area than the other three types of valve leaflets. This work is very helpful to manufacture valvular leaflets with reasonable shapes and to prolong the lifetime of the bioprosthetic heart valve.

scholarly journals Finite Element Method and Von Mises Investigation on Bone Response to Dynamic Stress with a Novel Conical Dental Implant Connection

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Luca Fiorillo ◽  
Marco Cicciù ◽  
Cesare D’Amico ◽  
Rodolfo Mauceri ◽  
Giacomo Oteri ◽  
...  
Keyword(s):  
Finite Element ◽  
Dynamic Stress ◽  
Force Distribution ◽  
Element Analysis ◽  
Occlusal Force ◽  
Bone Response ◽  
The Finite Element Analysis ◽  
New Type ◽  
Von Mises ◽  
Biomedical Fields

The bioengineering and medical and biomedical fields are ever closer, and they manage to obtain surprising results for the development of new devices. The field of simulations and studies in silica has undergone considerable development in recent years, favoring the advancement of medicine. In this manuscript, a study was carried out to evaluate the force distribution on the implant components (In-Kone® Universal) and on the peri-implant tissues subjected to loading. With the finite element analysis and the Von Mises method, it was possible to evaluate this distribution of forces both at 0 degrees (occlusal force) and at 30 degrees; the applied force was 800 N. The obtained results on this new type of connection and on all the implant components are satisfactory; the distribution of forces appears optimal even on the peri-implant tissues. Surely, studies like this help to obtain ever more performing devices, improving both the clinic and the predictability of rehabilitations.

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