Influence of Implant-Abutment Contact Surfaces and Prosthetic Screw Tightening on the Stress Concentration, Fatigue Life and Microgap Formation: A Finite Element Analysis

The purpose of this in silico study was to investigate the effect of abutment screw torque and implant-abutment contact surfaces on the stress generation, microgap formation and simulated fatigue life of an external hexagon connection under oblique loading. Three-dimensional numerical models of the external hexagon implant were modeled containing two different implant-abutment contact surfaces (with and without contacting the hexagon axial walls) as well as using screw torques of 20 Ncm or 30 Ncm. Following the ISO 14801, an oblique load of 100 N was applied to the prosthesis. The von Mises stress, microgap formation, safety factor and fatigue life were obtained. The stresses in the abutment screw and implant were minimally influenced by the screw torque. However, this minimal stress in the screw with a 30 Ncm torque reduced the calculated fatigue life in comparison with 20 Ncm when the external hexagon axial walls were not in contact at the implant-abutment interface. The safety factor for the implant was higher when using minimal surfaces at the abutment-interfaces; however, it compromised the screw safety factor increasing its failure probability. The higher the screw torque, the lower was the microgap formation at the implant-abutment interface. However, the calculated residual stress is proportional to the applied torque, reducing the fatigue life in the screw. This effect can be attenuated using an implant-abutment system with more contacting surfaces.

Download Full-text

Fatigue Failure Behaviour Study of Automotive Lower Suspension Arm

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.462-463.796 ◽

2011 ◽

Vol 462-463 ◽

pp. 796-800 ◽

Cited By ~ 1

Author(s):

Nawar A. Kadhim ◽

Shahrum Abdullah ◽

Ahmad Kamal Ariffin ◽

S.M. Beden

Keyword(s):

Finite Element ◽

Fatigue Life ◽

Numerical Models ◽

Good Alternative ◽

Analysis Tool ◽

Element Analysis ◽

Finite Element Software ◽

Life Model ◽

Experimental Process ◽

Behaviour Study

Fatigue life of automotive lower suspension arm has been studied under variable amplitude loadings. In simulation, the geometry of a sedan car lower suspension arm has been used. To obtain the material monotonic properties, tensile test has been carried out and to specify the material mechanical properties of the used material, a fatigue test under constant amplitude loading has been carried out using the ASTM standard specimens. Then, the results used in the finite element software to predict fatigue life has been evaluated later to show the accuracy and efficiency of the numerical models which they are appreciated. The finite element analysis tool is therefore proved to be a good alternative prior to the further experimental process. The predicted fatigue life from the simulation showed that Smith-Watson-Topper model provides longer life than Morrow and Coffin-Manson models. This is due to the different consideration for each strain-life model during life calculations.

Download Full-text

Biomechanical Evaluation of the Effects of Implant Neck Wall Thickness and Abutment Screw Size: A 3D Nonlinear Finite Element Analysis

Applied Sciences ◽

10.3390/app10103471 ◽

2020 ◽

Vol 10 (10) ◽

pp. 3471 ◽

Cited By ~ 2

Author(s):

Ming-Dih Jeng ◽

Yang-Sung Lin ◽

Chun-Li Lin

Keyword(s):

Finite Element ◽

Wall Thickness ◽

Alveolar Bone ◽

Nonlinear Finite Element ◽

Bone Strain ◽

Concentrated Force ◽

Element Analysis ◽

Implant Abutment ◽

Implant System ◽

Abutment Screw

In this study, we evaluate the influence of implant neck wall thickness and abutment screw size on alveolar bone and implant component biomechanical responses using nonlinear finite element (FE) analysis. Twelve internal hexagon Morse taper implant–abutment connection FE models with three different implant sizes (diameters 4, 5, and 6 mm), secured with 1.4, 1.6, and 1.8 mm abutment screws to fit with three unilateral implant neck wall thicknesses of 0.45, 0.50, and 1.00 mm, were constructed to perform simulations. Nonlinear contact elements were used to simulate realistic interface fixation within the implant system. A 200 N concentrated force was applied toward the center of a hemispherical load cap and inclined 30° relative to the implant axis as the loading condition. The simulation results indicated that increasing the unilateral implant neck wall thickness from 0.45 to 1.00 mm can significantly decrease implant, abutment, and abutment screw stresses and bone strain, decreased to 58%, 48%, 54%, and 70%, respectively. Variations in abutment screw size only significantly influenced abutment screw stress, and the maximum stress dissipation rates were 10% and 29% when the diameter was increased from 1.4 to 1.6 and 1.8 mm, respectively. We conclude that the unilateral implant neck wall thickness is the major design factor for the implant system and implant neck wall thickness in effectively decreasing implant, abutment, and abutment screw stresses and bone strain.

Download Full-text

New Triaxial Connection Safety Factor for Tubular Design

SPE Drilling & Completion ◽

10.2118/204130-pa ◽

2021 ◽

pp. 1-11

Author(s):

Malcolm A. Goodman

Keyword(s):

Finite Element Analysis ◽

Safety Factor ◽

American Petroleum Institute ◽

Von Mises Stress ◽

Element Analysis ◽

Threaded Connections ◽

Shear Component ◽

Physical Tests ◽

The Mean ◽

Von Mises

Summary The American Petroleum Institute (API) equation for internal leak of API connections is uniaxial because it ignores axial force and external backup pressure. The ISO 13679 (2002) standard for qualification of premium connections is biaxial at best. It includes tension/compression but ignores backup pressure for both internal and external leak tests. For tubular design, this paper introduces a new fully triaxial safety factor for threaded connections with dependence on thread shear and hydrostatic pressure. Triaxial hydrostatic behavior is modeled with the mean normal stress, and thread shear behavior is modeled with the shear component of the von Mises stress. A leak line for use like the pipe body ellipse is proposed for quick leak assessment. Leak ratings and correlation with finite element analysis (FEA) results are presented for an example case of a 7-in.35-ppf N80 long-thread-casing (LTC) connection. The new triaxial safety factor with two connection constants applies to all types of threaded connections, including tubing, casing, and drillpipe, so long as the two constants are evaluated with appropriate but simple physical tests.

Download Full-text

Partial Threading of Pedicle Screws in a Standard Construct Increases Fatigue Life: A Biomechanical Analysis

Applied Sciences ◽

10.3390/app11041503 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1503

Author(s):

Fon-Yih Tsuang ◽

Chia-Hsien Chen ◽

Lien-Chen Wu ◽

Yi-Jie Kuo ◽

Yueh-Ying Hsieh ◽

...

Keyword(s):

Finite Element ◽

Fatigue Life ◽

Pedicle Screw ◽

Pedicle Screws ◽

Biomechanical Analysis ◽

Von Mises Stress ◽

Shaft Length ◽

Element Analysis ◽

Screw Design ◽

Screw Length

This study proposed a pedicle screw design where the proximal 1/3 of the screw is unthreaded to improve fixation in posterior spinal surgery. This design was also expected to reduce the incidence of mechanical failure often observed when an unsupported screw length is exposed outside the vertebra in deformed or degenerated segments. The aim of this study was to evaluate the fatigue life of the novel pedicle screw design using finite element analysis and mechanical testing in a synthetic spinal construct in accordance with American Society for Testing and Materials (ASTM) F1717. The following setups were evaluated: (i) pedicle screw fully inserted into the test block (EXP-FT-01 and EXP-PU-01; full thread (FT), proximal unthread (PU)) and (ii) pedicle screw inserted but leaving an exposed shaft length of 7.6 mm (EXP-FT-02 and EXP-PU-02). Corresponding finite element models FEM-FT-01, FEM-FT-02, FEM-PU-01, and FEM-PU-02 were also constructed and subjected to the same loading conditions as the experimental groups. The results showed that under a 220 N axial load, the EXP-PU-01 group survived the full 5 million cycles, the EXP-PU-02 group failed at 4.4 million cycles on average, and both EXP-FT-01 and EXP-FT-02 groups failed after less than 1.0 million cycles on average, while the fatigue strength of the EXP-FT-02 group was the lowest at 170 N. The EXP-FT-01 and EXP-FT-02 constructs failed through fracture of the pedicle screw, but a rod fractured in the EXP-PU-02 group. In comparison to the FEM-FT-01 model, the maximum von Mises stress on the pedicle screw in the FEM-PU-01 and FEM-PU-02 models decreased by −43% and −27%, respectively. In conclusion, this study showed that having the proximal 1/3 of the pedicle screw unthreaded can reduce the risk of screw fatigue failure when used in deformed or degenerated segments.

Download Full-text

STUDI NUMERIK UMUR KELELAHAN (FATIGUE LIFE) PADA PROPELLER KAPAL PENANGKAP IKAN DENGAN KAPASITAS MESIN 24 HP

JTT (Jurnal Teknologi Terapan) ◽

10.31884/jtt.v6i1.245 ◽

2020 ◽

Vol 6 (1) ◽

Author(s):

Rizqi Ilmal Yaqin ◽

Angger Bagus Prasetiyo ◽

Pritiansyah Pritiansyah ◽

Muhammad Haritsah Amrullah ◽

Binsar Maruli Tua Pakpahan

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Fatigue Life ◽

Rapid Development ◽

Von Mises Stress ◽

Element Analysis ◽

Fishing Boat ◽

Finite Element Analysis Simulation ◽

Von Mises ◽

Model Affect

Propeller is part of a key component in fishing boat propulsion. Propeller can provide momentum to the fluid which can be a thrust on the ship. However, The failure of the propeller found prematurely. The failure of the propeller maybe because of overload on the propeller model so the fatigue life of the propeller becomes low. On the other hand, the rapid development of technology can simulate a design model to look for failures that occur. Finite Element Analysis is one of the designer solutions to determine the age of failure of a model and failure-prone areas in a model. This study uses propeller model data from fishing boat with engine 24HP in Dumai City TPI that always fail prematurely. The material used is copper alloy. While the drawing model uses Autodesk Inventor and Finite Element Analysis simulation using ANSYS R17.2 software with the number of model nodes is 51108 and the number of elements of the model is 26268. The results obtained from this study are Von Mises stress on the simulation model that is equal to 613.33 MPa to 0.01164 MPa. While the deformation value due to the effect of loading on the model is 5,3657 mm to 0 mm. These results affect the age of fatigue (fatigue life) on the model with the highest value 109 and the lowest 0. The results of the fatigue life value on the model affect the results of the level of damage and the safety number of the model with successive values of 1032 to 1 and 15 to 0.32446. The conclusion of the result is the propeller will fail prematurely.

Download Full-text

Influence of the Realistic Artery Geometry Parameters on a Coronary Stent Fatigue Life

International Journal of Computational Methods ◽

10.1142/s0219876218420069 ◽

2019 ◽

Vol 16 (03) ◽

pp. 1842006 ◽

Cited By ~ 1

Author(s):

Xinyang Cui ◽

Qingshuai Ren ◽

Gaoyang Li ◽

Zihao Li ◽

Aike Qiao

Keyword(s):

Fatigue Life ◽

Fatigue Resistance ◽

Safety Factor ◽

Geometric Model ◽

Von Mises Stress ◽

Stress Distributions ◽

Goodman Diagram ◽

Von Mises ◽

Geometry Parameter ◽

Artery Geometry

The stents’ adaptability and safety in realistic and idealized stenotic coronary model were compared to investigate the influence of artery geometry parameter on stent fatigue life. The stents’ fatigue resistance ability was calculated using Goodman diagram, and the cycle to failure, the fatigue life, and the fatigue safety factor (FSF) were analyzed. Although the peak top of the von Mises stress was located at the bending area of crowns, the stress distributions were different in the two models. Considering the safety and accuracy, it is necessary to use a realistic geometric model to calculate the stent fatigue performance.

Download Full-text

Biomechanical evaluation of different implant–abutment connections, retention systems, and restorative materials in the implant-supported single crowns using 3D finite element

Journal of Oral Implantology ◽

10.1563/aaid-joi-d-20-00328 ◽

2021 ◽

Author(s):

Cleidiel Aparecido Araujo Lemos ◽

Fellippo Ramos Verri ◽

Pedro Yoshito Noritomi ◽

Victor Eduardo Souza Batista ◽

Ronaldo Silva Cruz ◽

...

Keyword(s):

Finite Element ◽

Cortical Bone ◽

Bone Tissue ◽

Von Mises Stress ◽

Element Analysis ◽

Biomechanical Behavior ◽

Retention System ◽

Implant Abutment ◽

Fixation Screw ◽

Metal Ceramic

This is an in silico study aimed to evaluate the biomechanical influence of different implant–abutment interfaces (external hexagon and Morse taper implants), retention systems (cement- and screw-retained), and restorative crowns (metal–ceramic and monolithic) using three-dimensional finite element analysis (3D-FEA). Eight 3D models were simulated for the maxillary first molar area using InVesalius, Rhinoceros, and SolidWorks and processed using the Femap and NEi Nastran softwares. Axial and oblique forces of 200 N and 100 N, respectively, were applied on the occlusal surface of the prostheses. Microstrain and von Mises stress maps were used to evaluate the deformation (cortical bone tissue) and stress (implants/fixation screws/crowns), respectively for each model. For both loadings, Morse taper implants had lower microstrain values than the external hexagon implants. The retention system did not affect microstrain on the cortical bone tissue under both loadings. However, the cemented prosthesis displayed higher stress with the fixation screw than the external hexagon implants. No difference was observed between the metal–ceramic and zirconia monolithic crowns in terms of microstrain and stress distribution on the cortical bone, implants or components. Morse taper implants can be considered as a good alternative for dental implant rehabilitation because they demonstrated better biomechanical behavior for the bone and fixation screw as compared to external hexagon implants. Cement-retained prosthesis increased the stress on the fixation screw of the external hexagon implants, thereby increasing the risk of screw loosening/fracture in the posterior maxillary area. The use of metal–ceramic or monolithic crowns did not affect the biomechanical behavior of the evaluated structures.

Download Full-text

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

Craniomaxillofacial Trauma & Reconstruction ◽

10.1055/s-0033-1343789 ◽

2013 ◽

Vol 6 (2) ◽

pp. 93-97 ◽

Cited By ~ 4

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.

Download Full-text