scholarly journals Effects of Pentagonal Pore Sizes in the Zinc Hydroxyapatite Parietal-Temporal Implant

2021 ◽  
Vol 11 (11) ◽  
pp. 76-85
Author(s):  
Wan Nur Fatini Syahirah W. Dagang ◽  
◽  
Nik Harisha Qistina Nik Hamdi ◽  
Shahrul Hisyam Marwan ◽  
Jamaluddin Mahmud ◽  
...  
Keyword(s):  
Pore Size ◽  
Mechanical Performance ◽  
Biomechanical Properties ◽  
Biomechanical Analysis ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Pore Sizes ◽  
Alloplastic Materials ◽  
Cranial Implant ◽  
Von Mises

To reconstruct the fractured skull, affected patients are advised to undergo cranioplasty, which is a surgical procedure to repair the cranial defect by implanting materials such as autologous bone grafts or synthetic alloplastic materials. The use of synthetic alloplastic materials such as hydroxyapatite (HA) has been widely accepted due to their biocompatibility and suitability for larger cranial defects. The zinc hydroxyapatite (ZnHA) material is favourable as HA mimics 60% of the actual human bone, whereas zinc helps to improve its biomechanical properties. The purpose of this study is to construct the ZnHA cranial implant with different pore sizes of 600, 900, and 1200 µm in pentagonal shapes and to study its mechanical performance. At the end of the research, it was found that the implant with a pore size of 900 µm is the most appropriate implant to be utilized without affecting its mechanical performance. Aspects such as the deformation and von Mises stress are discussed to assist on the development of the ZnHA cranial implant. Keywords — Biomechanical analysis, cranial implant, finite element analysis, pore size, zinc hydroxyapatite

scholarly journals Mechanical Strength Study of a Cranial Implant Using Computational Tools

2022 ◽  
Vol 12 (2) ◽  
pp. 878
Author(s):  
Pedro O. Santos ◽  
Gustavo P. Carmo ◽  
Ricardo J. Alves de Sousa ◽  
Fábio A. O. Fernandes ◽  
Mariusz Ptak
Keyword(s):  
Structural Integrity ◽  
Mechanical Performance ◽  
Skull Fracture ◽  
Human Head ◽  
Element Model ◽  
Von Mises Stress ◽  
Cranial Implant ◽  
Von Mises ◽  
Two Parameters ◽  
The Brain

The human head is sometimes subjected to impact loads that lead to skull fracture or other injuries that require the removal of part of the skull, which is called craniectomy. Consequently, the removed portion is replaced using autologous bone or alloplastic material. The aim of this work is to develop a cranial implant to fulfil a defect created on the skull and then study its mechanical performance by integrating it on a human head finite element model. The material chosen for the implant was PEEK, a thermoplastic polymer that has been recently used in cranioplasty. A6 numerical model head coupled with an implant was subjected to analysis to evaluate two parameters: the number of fixation screws that enhance the performance and ensure the structural integrity of the implant, and the implant’s capacity to protect the brain compared to the integral skull. The main findings point to the fact that, among all tested configurations of screws, the model with eight screws presents better performance when considering the von Mises stress field and the displacement field on the interface between the implant and the skull. Additionally, under the specific analyzed conditions, it is observable that the model with the implant offers more efficient brain protection when compared with the model with the integral skull.

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.

Dynamic Analysis of Three Types of Bioprosthetic Heart Valves

2011 ◽  
Vol 71-78 ◽  
pp. 2683-2688
Author(s):  
Xin Ye ◽  
Quan Yuan ◽  
Hua Cong ◽  
Hai Bo Ma ◽  
Dong Liang Wei
Keyword(s):  
Stress Distribution ◽  
Heart Valve ◽  
Computer Aided Design ◽  
Heart Valves ◽  
Mechanical Performance ◽  
Bioprosthetic Valve ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Diastolic Phase ◽  
Von Mises

This paper constructs three types of bioprosthetic valve leaflets’ parametric model via computer aided design, a series of accurate parameters of the bioproshtetic heart valve, such as radius of the sutural ring, height of the supporting stent and inclination of the supporting stent, are determined. Numerical simulation is used to determine the effect of different shape designs on the mechanical performance of the bioprosthetic valve leaflet. The dynamic behavior of the valve during diastolic phase is analyzed. The finite element analysis results show the stress distribution of the ellipsoidal and spherical valve leaflets are comparatively reasonable. The ellipsoidal and spherical valve leaflets have the following advantages over the cylindrical leaflet valve, lower peak von-Mises stress, smaller stress concentration area, and relatively uniform stress distribution. The ellipsoidal and spherical valve leaflets may contribute to the long term durability of the valve. This work is very helpful to manufacture valvular leaflets with reasonable shapes and to prolong the lifetime of the bioprosthetic heart valve.

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 Effects of Bone Cement Distribution On Adjacent Endplates After Percutaneous Vertebroplasty For Thoracolumbar Fractures: A Finite Element Analysis

2021 ◽  
Author(s):  
Ye Han ◽  
Jincheng Wu ◽  
Xiaodong Wang ◽  
Wenshan Gao ◽  
Jianzhong Wang ◽  
...  
Keyword(s):  
Vertebral Body ◽  
Percutaneous Vertebroplasty ◽  
Compression Fracture ◽  
Biomechanical Analysis ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Cement Injection ◽  
Thoracolumbar Region ◽  
Cement Distribution ◽  
Von Mises

Abstract BACKGROUND: Percutaneous vertebroplasty (PVP) is a common surgical method for the treatment of thoracolumbar compression fractures. Currently, no biomechanical analysis has been performed examining the effects of cement distribution and positioning on the overall thoracolumbar range of motion (ROM) and the stress applied to adjacent endplates.METHODS: A model of PVP following vertebral compression fracture was established based on computed tomography data. Cement was injected into the T12 vertebral body. Depending on the location of the injection site, the model was divided into a median cement model, a left cement model, an upper-left cement model, and a lower-left cement model. The postoperative thoracolumbar ROM and biomechanical changes to the adjacent endplates were analyzed.RESULTS: After cement injection, the overall ROM for the thoracolumbar region increased compared with that before cement injection. The maximum ROM of flexion was 9.28° for the left model; the maximum ROM of extension was 10.90° for the upper-left model; the maximum left and right rotations were 8.47° and 8.52°, respectively, for the left model; the maximum left bending was 13.10° for the left model; and the maximum right bending was 13.43° for the left model. The stress applied to the adjacent vertebral endplate in the median cement model increased compared with the intact model, and the von Mises stress (VMS) value changed with different cement positions.CONCLUSION: After cement injection, the overall stress value of the endplate adjacent to the vertebral body increased, and when the position of the cement shifts, the maximum VMS increased further for some positions, and the stress value for the endplate adjacent to the vertebral body increased, which may cause fractures in the relative position.

scholarly journals The influence of pelvic tilt on stress distribution in the acetabulum: finite element analysis

2021 ◽  
Vol 22 (1) ◽  
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.

scholarly journals Head to head: the case for fighting behaviour in Megaloceros giganteus using finite-element analysis

2019 ◽  
Vol 286 (1912) ◽  
pp. 20191873 ◽  
Author(s):  
Ada J. Klinkhamer ◽  
Nicholas Woodley ◽  
James M. Neenan ◽  
William C. H. Parr ◽  
Philip Clausen ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cervus Elaphus ◽  
Mechanical Performance ◽  
Fallow Deer ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Deer Species ◽  
Von Mises ◽  
Fighting Behaviour

The largest antlers of any known deer species belonged to the extinct giant deer Megaloceros giganteus . It has been argued that their antlers were too large for use in fighting, instead being used only in ritualized displays to attract mates. Here, we used finite-element analysis to test whether the antlers of M. giganteus could have withstood forces generated during fighting. We compared the mechanical performance of antlers in M. giganteus with three extant deer species: red deer ( Cervus elaphus ), fallow deer ( Dama dama ) and elk ( Alces alces ). Von Mises stress results suggest that M. giganteus was capable of withstanding some fighting loads, provided that their antlers interlocked proximally, and that their antlers were best adapted for withstanding loads from twisting rather than pushing actions, as are other deer with palmate antlers. We conclude that fighting in M. giganteus was probably more constrained and predictable than in extant deer.

scholarly journals To Evaluate the Influence of Implant Length on Stress Distribution of Osseointegrated Implant: A Three-Dimensional Finite Element Analysis: An In Vitro Study

2018 ◽  
Vol 6 (02/03) ◽  
pp. 097-105
Author(s):  
Neha Jindal ◽  
Manjit Kumar ◽  
Shailesh Jain ◽  
Navjot Kaur ◽  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Distribution ◽  
Biomechanical Analysis ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Von Mises ◽  
The Impact ◽  
Implant Length ◽  
Nonsignificant Decrease

AbstractFinite element analysis is a technique for obtaining a solution to a complex mechanical problem by dividing the problem domain into a collection of much smaller and simpler domains (elements) in which the field variables can be interpolated with the use of shape functions. An overall approximated solution to the original problem is determined based on variational principles. Finite element analysis can provide a nondestructive system for quantifying stresses generated at the various interfaces of similar or dissimilar material. The finite element method also allows the study of the internal state of stress of components as well as stress patterns in two or more dissimilar materials adjacent to each other without affecting their independent behavior. This method is therefore ideally suitable for the biomechanical analysis of orthopedic, cardiovascular, and dental structures. In this study, implants of different length were numerically analyzed using bone-implant models developed from computed tomography-generated images of the mandible with osseointegrated implants. The impact of various lengths on stress distribution was examined using implants with a length of 8, 10, and 13 mm in mandibular first molar region under axial load of 100 N and buccolingual load of 50 N. All materials were assumed to be linearly elastic and isotropic. The Statistical Package for the Social Sciences software package was used for statistical analysis. Maximum von Mises stresses were located around the implant neck. It was demonstrated that there was statistically nonsignificant decrease in von Mises stress as the implant length increased. Within the limitations of this study, there was statistically nonsignificant decrease in von Mises stress as the implant length increased.

scholarly journals Finite Element Analysis of Cornea and Lid Wiper During Blink, With and Without Contact Lens

2020 ◽  
Author(s):  
Vivek R ◽  
Meenatchi S ◽  
Rinu Thomas ◽  
Ramesh Ve ◽  
Raghuvir Pai ◽  
...  
Keyword(s):  
Finite Element ◽  
Contact Lens ◽  
Element Model ◽  
Biomechanical Properties ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Biomechanical Changes ◽  
Von Mises

Abstract Contact Lens-related Discomfort (CLD) is one of the major problems in about 50% of contact lens users. It is a symptom of a variety of conditions such as Lid Wiper Epitheliopathy (LWE), Superior Epithelial Arcuate Lesion (SEAL), Limbal Stem Cell Deficiency (LSCD), Superior Limbic Keratoconjunctivitis (SLK) and dry eye disease; which affect the quality of life. Hence, it is essential to investigate the underlying cause of CLD. During a blink, the under surface of the eyelid tends to interact with the cornea and the conjunctiva. The presence of a contact lens can add to the biomechanical changes on these surfaces. To estimate these changes with and without a contact lens, a Finite Element Model (FEM) of the eyelid wiper, eyeball and contact lens was developed using COMSOL Multiphysics®. Biomechanical properties such as von Mises stress and displacement were calculated. Our study concluded that large stress formed in the lid wiper could be the reason for the occurrence of LWE and SLK without contact lens in the eye. When the contact lens was in situ, large stress was found in the superior 1.3mm of the cornea which could be responsible for the development of SEAL and superior LSCD.

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