scholarly journals Finite Element Analysis of Different Hip Implant Designs along with Femur under Static Loading Conditions

2019 ◽  
Author(s):  
K N Chethan ◽  
N Shyamasunder Bhat ◽  
M Zuber ◽  
B Satish Shenoy
Keyword(s):  
Hip Joint ◽  
Cross Sections ◽  
Von Mises Stress ◽  
Implant Design ◽  
Element Analysis ◽  
Early 19Th Century ◽  
Hip Implant ◽  
Design Life ◽  
Von Mises ◽  
Von Mises Stresses

Background: The hip joint is the largest joint after the knee, which gives stability to the whole human structure. The hip joint consists of a femoral head which articulates with the acetabulum. Due to age and wear between the joints, these joints need to be replaced with implants which can function just as a natural joint. Since the early 19th century, the hip joint arthroplasty has evolved, and many advances have been taken in the field which improved the whole procedure. Currently, there is a wide variety of implants available varying in the length of stem, shapes, and sizes.Material and Methods: Circular, oval, ellipse and trapezoidal-shaped stem designs are considered in the present study. The human femur is modeled using Mimics. CATIA V-6 is used to model the implant models. Static structural analysis is carried out using ANSYS R-19 to evaluate the best implant design.Results: All the four hip implants exhibited the von Mises stresses, lesser than its yielded strength. However, circular and trapezoidal-shaped stems have less von Mises stress compared to ellipse and oval.Conclusion: This study shows the behavior of different implant designs when their cross-sections are varied. Further, these implants can be considered for dynamic analysis considering different gait cycles. By optimizing the implant design, life expectancy of the implant can be improved, which will avoid the revision of the hip implant in active adult patients.

scholarly journals The Influence of Pelvic Tilt on Stress Distribution in the Acetabulum: Finite Element Analysis

2020 ◽  
Author(s):  
Kazuhiro Hasegawa ◽  
Tamon Kabata ◽  
Yoshitomo Kajino ◽  
Daisuke Inoue ◽  
Jiro Sakamoto ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Distribution ◽  
Hip Joint ◽  
Tilt Angle ◽  
Pelvic Tilt ◽  
Biomechanical Analysis ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Von Mises

Abstract Background Finite element analysis (FEA) has been previously applied for the biomechanical analysis of acetabular dysplasia and osteotomy. However, until now, there have been little reports on the use of FEA to evaluate the effects of pelvic tilt on stress distribution in the acetabulum. Methods We used the Mechanical Finder Ver. 7.0 (RCCM, Inc., Japan) to construct finite element models based on 3D-CT data of patients, and designed dysplasia, borderline, and normal pelvic models. For analysis, body weight was placed on the sacrum and the load of the flexor muscles of the hip joint was placed on the ilium. The pelvic tilt was based on the anterior pelvic plane, and the pelvic tilt angles were -20°, 0°, and 20°. The load of the flexor muscle of the hip joint was calculated using the moment arm equation.Results All three models showed the highest values of von Mises stress in the -20° pelvic tilt angle, and the lowest in the 20° angle. Stress distribution concentrated in the load-bearing area. The maximum values of von Mises stress in the borderline at pelvic tilt angles of -20° was 3.5Mpa, and in the dysplasia at pelvic tilt angles of 0° was 3.1Mpa. Conclusions The pelvic tilt angle of -20° of the borderline model showed equal maximum values of von Mises stress than the dysplasia model of pelvic tilt angle of 0°, indicating that pelvic retroversion of -20° in borderline is a risk factor for osteoarthritis of the hip joints, similar to dysplasia.

Gun Barrel Refurbishing Using a Shrink-Fitted Autofrettaged Liner

2018 ◽  
Vol 140 (2) ◽  
Author(s):  
J. Perry ◽  
M. Perl
Keyword(s):  
Cross Sections ◽  
Cost Effective ◽  
Von Mises Stress ◽  
Maximum Pressure ◽  
Internal Diameter ◽  
Original Performance ◽  
Gun Barrel ◽  
Von Mises ◽  
Von Mises Stresses ◽  
The Cost

During the firing of guns, the barrel undergoes two major damaging processes: wear of its inner surface and internal cracking. Barrel's are condemned based on either the increase of their internal diameter due to wear or the severity of their internal cracking. The cost of replacing such a damaged gun barrel runs in the tenth of thousands of U.S.$. Therefore, cost effective methods are sought for restoring such gun barrels. In the present analysis, a new method is proposed for refurbishing vintage gun barrels by machining their inner damaged layer and replacing it by an intact, autofrettaged, shrink-fit liner that will restore the barrel to its original performance. The design of the shrink-fitted liner is based on two design principles. First, the von-Mises residual stress distribution through the thickness of the barrel at each of its cross sections along the inserted liner should be at least equal in magnitude to von Mises stress, which prevailed in the original barrel. Second, once the maximum pressure is applied to the compound barrel, the von-Mises stresses at the inner surfaces of the liner machined barrel should be equal to their respective yield stresses. The preliminary results demonstrate the ability of this process to mend such barrels and bringing them back to their initial safe maximum pressure (SMP) and their intact conditions, rather than condemn them. Furthermore, from the authors' experience, based on a preliminary rough estimate, such an alternative seems to be cost effective.

Influence of Dental Implant Design on Stress Distribution and Micromotion of Mandibular Bone

2020 ◽  
Vol 899 ◽  
pp. 81-93
Author(s):  
Nur Faiqa Ismail ◽  
M. Saiful Islam ◽  
Solehuddin Shuib ◽  
Rohana Ahmad ◽  
M. Amar Shahmin
Keyword(s):  
Shear Stress ◽  
Dental Implant ◽  
Cancellous Bone ◽  
3D Models ◽  
Von Mises Stress ◽  
Implant Design ◽  
Element Analysis ◽  
Reconstruction Process ◽  
Mandibular Bone ◽  
Von Mises

This research was conducted to provide a feasible method for reconstructing the 3D model of mandibular bone to undergo finite element analysis to investigate von Mises stress, deformation and shear stress located at the cortical bone, cancellous one and neck implant of the proposed dental implant design. Dental implant has become a significant remedial approach but although the success rate is high, the fixture failure may happen when there are insufficient host tissues to initiate and sustain the osseointegration. Computerised Tomography scan was conducted to generate head images for bone reconstruction process. MIMICS software and 3-matic software were used to develop the 3D mandibular model. The reconstructed mandibular model was then assembled with five different 3D models of dental implants. Feasible boundary conditions and material properties were assigned to the developed muscle areas and joints. The highest performance design with the best responses was the design B with the value for the von Mises stress for the neck implant, cortical and cancellous bone were 7.53 MPa, 16.91 MPa and 1.34 MPa respectively. The values for the maximum of micromotion for the neck implant, cortical and cancellous bone of design B were 20.60 μm, 21.17 μm and 5.83 μm respectively. Shear stress for neck implant, cortical and cancellous bone for this design were 0.15 MPa, 4.74 MPa and 1.54 MPa respectively. The design with a cone shaped hole which is design B was the proper design when compared with other designs in terms of von Misses stress, deformations and shear stress.

Optimization of custom cementless stem using finite element analysis and elastic modulus distribution for reducing stress-shielding effect

2017 ◽  
Vol 231 (2) ◽  
pp. 149-159 ◽  
Author(s):  
Gurunathan Saravana Kumar ◽  
Subin Philip George
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Elastic Modulus ◽  
Stress Shielding ◽  
Von Mises Stress ◽  
Shielding Effect ◽  
Implant Design ◽  
Element Analysis ◽  
Von Mises ◽  
Reducing Stress

This work proposes a methodology involving stiffness optimization for subject-specific cementless hip implant design based on finite element analysis for reducing stress-shielding effect. To assess the change in the stress–strain state of the femur and the resulting stress-shielding effect due to insertion of the implant, a finite element analysis of the resected femur with implant assembly is carried out for a clinically relevant loading condition. Selecting the von Mises stress as the criterion for discriminating regions for elastic modulus difference, a stiffness minimization method was employed by varying the elastic modulus distribution in custom implant stem. The stiffness minimization problem is formulated as material distribution problem without explicitly penalizing partial volume elements. This formulation enables designs that could be fabricated using additive manufacturing to make porous implant with varying levels of porosity. Stress-shielding effect, measured as difference between the von Mises stress in the intact and implanted femur, decreased as the elastic modulus distribution is optimized.

scholarly journals Influence of sagittal root positions on the stress distribution around custom-made root-analogue implants: a three-dimensional finite element analysis

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Chunping Lin ◽  
Hongcheng Hu ◽  
Junxin Zhu ◽  
Yuwei Wu ◽  
Qiguo Rong ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Class I ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Custom Made ◽  
Root Position ◽  
Von Mises ◽  
Von Mises Stresses

Abstract Background Stress concentration may cause bone resorption even lead to the failure of implantation. This study was designed to investigate whether a certain sagittal root position could cause stress concentration around maxillary anterior custom-made root-analogue implants via three-dimensional finite element analysis. Methods The von Mises stresses in the bone around implants in different groups were compared by finite element analysis. Six models were constructed and divided into two groups through Geomagic Studio 2012 software. The smooth group included models of unthreaded custom-made implants in Class I, II or III sagittal root positions. The threaded group included models of reverse buttress-threaded implants in the three positions. The von Mises stress distributions and the range of the stresses under vertical and oblique loads of 100 N were analyzed through ANSYS 16.0 software. Results Stress concentrations around the labial lamella area were more prominent in the Class I position than in the Class II and Class III positions under oblique loading. Under vertical loading, the most obvious stress concentration areas were the labial lamella and palatal apical areas in the Class I and Class III positions, respectively. Stress was relatively distributed in the labial and palatal lamellae in the Class II position. The maximum von Mises stresses in the bone around the custom-made root-analogue implants in this study were lower than around traditional implants reported in the literature. The maximum von Mises stresses in this study were all less than 25 MPa in cortical bone and less than 6 MPa in cancellous bone. Additionally, compared to the smooth group, the threaded group showed lower von Mises stress concentration in the bone around the implants. Conclusions The sagittal root position affected the von Mises stress distribution around custom-made root-analogue implants. There was no certain sagittal root position that could cause excessive stress concentration around the custom-made root-analogue implants. Among the three sagittal root positions, the Class II position would be the most appropriate site for custom-made root-analogue implants.

scholarly journals Effects of the geometric shape and placing length of a fiber post on the stress distribution in a mandibular premolar tooth: A finite element analysis study

2018 ◽  
Vol 8 (3) ◽  
pp. 105-110
Author(s):  
Tuğrul Aslan ◽  
Emir Esim ◽  
Kerem Kılıç ◽  
Özgür Er ◽  
Şahin Yıldırım
Keyword(s):  
Stress Distribution ◽  
Von Mises Stress ◽  
Fiber Post ◽  
Stress Concentrations ◽  
Element Analysis ◽  
Fiber Posts ◽  
Luting Cement ◽  
Circular Fiber ◽  
Von Mises ◽  
Von Mises Stresses

Aim: The aim of this study was to evaluate the effects of two geometrically different fiber post systems and two different placing lengths on the stress distribution of endodontically treated teeth. Methodology: Four different mandibular premolar tooth models were created. These models were restored using oval or circular fiber posts with two different placing lengths. An oblique force of 300 N was applied to the top of the tooth, and von Mises stress evaluations were carried out on the dentin tissue, luting cement, and fiber posts. Results: The maximum von Mises stresses were observed in the 10-mm long circular fiber post model, while the minimum stresses were seen in the 5-mm long oval fiber post model. In general, the oval fiber post models presented more homogeneous stresses than the circular fiber post models. Moreover, the 10-mm long fiber post models generated greater von Mises stresses than the 5-mm long fiber post models in the dentin tissue and luting cement. Conclusion: According to the study findings, the use of oval fiber posts at both placing lengths is suggested for oval shaped root canals due to the lower stress concentrations.

scholarly journals FINITE ELEMENT ANALYSIS USING SHELL ELEMENTS ON RETICULATED STRUCTURES

2017 ◽  
Vol 2 (2) ◽  
Author(s):  
Alexandre Huberto Balbino Selhorst ◽  
Rafael Elias Meyer ◽  
Tatielen Pereira Costa ◽  
Liércio André Isoldi
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Von Mises Stress ◽  
The Finite Element Method ◽  
Element Analysis ◽  
Shell Elements ◽  
Final Weight ◽  
Verification Process ◽  
Von Mises ◽  
Von Mises Stresses

This paper studies the possibility of using SHELL elements on structures that are usually designed using BEAM or BAR elements. Using SHELL elements in such structures, named reticulated structures, opens the possibility to remove material from the structures’ members by adding holes. Once the members get holes, the final weight of the structure and material consumption will drop. In order to develop the study, a total of three different structures were analyzed using the software ANSYS®. This software uses the Finite Element Method to solve the equations originated from the designed structure upon it is meshed and the boundary conditions are set. Several results between SHELL and SOLID elements for each one of the structures were compared. The comparison of SHELL model with a SOLID model is used as a verification process, for SOLID elements are known to return accurate values. All of the meshes were tested by the independence mesh study to check its convergence. It is shown that the results are in a very good acceptable range with differences no bigger than 0.1 mm for displacements, and the map of von Mises stresses are pretty similar. Von Mises stresses for Finite Element Analysis for the C-Shaped Truss are shown in a figure comparing the results between the two finite elements used. This figure shows that there are no major differences between the SHELL and SOLID analyses. The Finite Element Analyses results were compared to analytical solutions, also. In this case, a noticeable difference in one structure for von Mises Stress was found. This difference, however, is understandable and reasonable, given the works presented on this paper.

scholarly journals Finite Element Analysis Comparison of Plate Designs in Managing Fractures Involving the Mental Foramen

2013 ◽  
Vol 6 (2) ◽  
pp. 93-97 ◽  
Author(s):  
Neralla Mahathi ◽  
Emmanuel Azariah ◽  
C. Ravindran
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Mental Foramen ◽  
Stress Generation ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Plate Design ◽  
Von Mises ◽  
Von Mises Stresses

Introduction The aim of the study was to propose an ideal plating design for fractures running through the mental foramen. Methods The study compared three plating designs—two four-hole miniplates, 2 × 2-hole three-dimensional (3D) plate, and modified 2 × 2-hole 3D plate (posterior strut removed)—using finite element analysis. Von Mises stresses generated around the plates and bone were measured, as well as the mobility that is generated between the fracture fragments by applying muscle forces to generate bite force in one test and applying a force of 500 N over the premolars and first molar region in the second test. Results Von Mises stress in bone with miniplates measured 9.24 MPa in test 1 and 131.99 MPa in test 2. The stress with unmodified 3D plates measured 34.9 MPa in test 1 and150.03 MPa in test 2. The stress with modified 3D plates measured 24.98 MPa in test 1 and 150.59 MPa in test 2. Von Mises stress on the plates and screws measured 28.23 MPa, 95.97 MPa, 72.93 MPa in test 1 and 458.63 MPa, 779.01 MPa, 742.39 MPa in test 2 on miniplates, unmodified 3D plates, and modified 3D plates, respectively. The fracture mobility generated in the model with miniplates measured 0.001 mm in test 1 and 0.01 mm in test 2 and 0.007 mm and 0.02 mm in the model with unmodified 3D plates in test 1 and in test 2, respectively. In the model with modified 3D plates, the value was 0.001 mm and 0.01 mm in tests 1 and 2, respectively. Conclusion The ideal plate design is the two-plate technique with minimal stress generation on the bone and the hardware. The modified 3D plate has adequate strength to be used in the region but needs to be studied in detail.

scholarly journals The Mechanical Behaviors of Various Dental Implant Materials under Fatigue

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Fatma Bayata ◽  
Cengiz Yildiz
Keyword(s):  
Surface Properties ◽  
Dental Implant ◽  
Mechanical Performance ◽  
Bone Structure ◽  
Von Mises Stress ◽  
Implant Design ◽  
Element Analysis ◽  
The Difference ◽  
Von Mises ◽  
Cp Ti

The selection of materials has a considerable role on long-term stability of implants. The materials having high resistance to fatigue are required for dental implant applications since these implants are subjected to cyclic loads during chewing. This study evaluates the performance of different types of materials (AISI 316L stainless steel, alumina and its porous state, CoCr alloys, yttrium-stabilized zirconia (YSZ), zirconia-toughened alumina (ZTA), and cp Ti with the nanotubular TiO2 surface) by finite element analysis (FEA) under real cyclic biting loads and researches the optimum material for implant applications. For the analysis, the implant design generated by our group was utilized. The mechanical behavior and the life of the implant under biting loads were estimated based on the material and surface properties. According to the condition based on ISO 14801, the FEA results showed that the equivalent von Mises stress values were in the range of 226.95 MPa and 239.05 MPa. The penetration analysis was also performed, and the calculated penetration of the models onto the bone structure ranged between 0.0037389 mm and 0.013626 mm. L-605 CoCr alloy-assigned implant model showed the least penetration, while cp Ti with the nanotubular TiO2 surface led to the most one. However, the difference was about 0.01 mm, and it may not be evaluated as a distinct difference. As the final numerical evaluation item, the fatigue life was executed, and the results were achieved in the range of 4 × 105 and 1 × 109 cycles. These results indicated that different materials showed good performance for each evaluation component, but considering the overall mechanical performance and the treatment process (implant adsorption) by means of surface properties, cp Ti with the nanotubular TiO2 surface material was evaluated as the suitable one, and it may also be implied that it displayed enough performance in the designed dental implant model.

scholarly journals Finite Element Analysis and Investigation on Spinning of Quadrilateral Parts with Hollow Cross-Sections Based on Hypocycloid Theory

2020 ◽  
Vol 10 (23) ◽  
pp. 8588
Author(s):  
Xibin Ou ◽  
Xianyong Zhu ◽  
Peng Gu ◽  
Baichao Wang ◽  
Jing Li ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
High Efficiency ◽  
Circular Cross Section ◽  
Forming Process ◽  
Element Analysis ◽  
Spinning Process ◽  
Specific Geometry ◽  
Von Mises ◽  
Von Mises Stresses

This paper presents research on a new high-efficiency, non-circular spinning method based on hypocycloid theory. The trajectory of the roller during the forming process was derived, and the non-circular spinning process was simulated in ABAQUS 2016/Explicit. The distribution of von Mises stresses and equivalent plastic strains after each spinning pass were analyzed. The spinning quality was also investigated. This research proves the feasibility of spinning the workpieces of a non-circular cross-section using hypocycloid theory. This new non-circular spinning method can be used in practice to produce workpieces with a specific geometry and to increase the rotational speed of the workpiece from 60–240 rpm to 600 rpm, thereby improving the efficiency by around 2.5 times while maintaining acceptable forming quality.

Sign in / Sign up

Export Citation Format

Share Document