Stress distribution analysis of novel dental mini-implant designs to support overdenture prosthesis

2021 ◽  
Author(s):  
Mariana Lima da Costa Valente ◽  
Ana Paula Macedo ◽  
Andréa Reis
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Axial Load ◽  
Static Load ◽  
Maximum Shear Stress ◽  
Load Application ◽  
Distribution Analysis ◽  
Mini Implants ◽  
Photoelastic Analysis

This study aimed to test and compare two novel dental mini-implant designs to support overdentures with a commercial model, regarding the stress distribution, by photoelastic analysis. Three different mini-implant designs (Ø 2.0 mm × 10 mm) were tested: G1—experimental threaded (design with threads and 3 longitudinal and equidistant self-cutting chamfers), G2—experimental helical (design with 2 long self-cutting chamfers in the helical arrangement), and G3—Intra-Lock® System. After including the mini-implants in a photoelastic resin, they were subjected to a static load of 100 N under two situations: axial and inclined model (30°). The fringe orders (n), that represents the intensity of stresses were analyzed around the mini-implants body and quantified using Tardy's method that calculates the maximum shear stress (τ) value in each point selected. In axial models, less stress was observed in the cervical third mini-implants, mainly in G1 and G2. In inclined models (30°), higher stresses were generated on the opposite side of the load application, mainly in the cervical third of G2 and G3. All mini-implant models presented lower tensions in the cervical third compared with the middle and apical third. The new mini-implants tested (G1 and G2) showed lower stresses than the G3 in the cervical third under axial load, while loading in the inclined model generated greater stresses in the cervical of G2.

Photoelastic Analysis on Different Retention Methods of Implant-Supported Prosthesis

2015 ◽  
Vol 41 (3) ◽  
pp. 258-263 ◽  
Author(s):  
Angélica Castro Pimentel ◽  
Marcello Roberto Manzi ◽  
Cristiane Ibanhês Polo ◽  
Claudio Luiz Sendyk ◽  
Maria da Graça Naclério-Homem ◽  
...  
Keyword(s):  
Stress Distribution ◽  
Axial Load ◽  
Testing Machine ◽  
Compressive Load ◽  
Lower Intensity ◽  
Photoelasticity Method ◽  
Universal Testing ◽  
Isochromatic Fringes ◽  
Photoelastic Analysis ◽  
Compressive Axial Load

The aim of this study was to evaluate the stress distribution of different retention systems (screwed, cemented, and mixed) in 5-unit implant-supported fixed partial dentures through the photoelasticity method. Twenty standardized titanium suprastructures were manufactured, of which 5 were screw retained, 5 were cement retained, and 10 were mixed (with an alternating sequence of abutments), each supported by 5 external hexagon (4.0 mm × 11.5 mm) implants. A circular polariscope was used, and an axial compressive load of 100 N was applied on a universal testing machine. The results were photographed and qualitatively analyzed. We observed the formation of isochromatic fringes as a result of the stresses generated around the implant after installation of the different suprastructures and after the application of a compressive axial load of 100 N. We conclude that a lack of passive adaptation was observed in all suprastructures with the formation of low-magnitude stress in some implants. When cemented and mixed suprastructures were subjected to a compressive load, they displayed lower levels of stress distribution and lower intensity fringes compared to the screwed prosthesis.

scholarly journals Shear Stress Distribution in the Opening Chords of Hybrid R/C T-Beams with Opening

2018 ◽  
Vol 147 ◽  
pp. 01005
Author(s):  
Jonie Tanijaya
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Shear Force ◽  
Maximum Shear Stress ◽  
Shear Stress Distribution ◽  
Shear Stresses ◽  
Web Openings ◽  
The Right ◽  
Lower Corner ◽  
T Beam

This study is carried out to evaluate the potential of three hybrid T-beams with web openings theoretical shear stresses distribution. The shear stresses at the opening edges were plotted at the working stage, yielding stage and collapse stage for these three tested beams. The available experimental results from the previous research was compared to the finite element results as well as the developed analytical. The shear stress distribution at the middle of the top and bottom chords of the opening in pure bending region are zero. At the upper and lower corners of the opening occurs the maximum shear stresses. The maximum shear stress occurs at the right lower corner chord at the high moment edge and at the left upper corner chord at the low moment edge in beams with openings at high shear and high flexural – shear region. Furthermore, an extensive parametric study is performed on these beams to find the distributing ratio of the shear force between the opening chords. The shear force at an opening in hybrid R/C T-beam is carried by the top and bottom chords of the opening according to the area – moment of inertia root ratio with the correction factor 0.70.

Numerical Study of the Shear Stress Distribution in an I-Beam in the Load Application Zone

2019 ◽  
Vol 974 ◽  
pp. 659-664 ◽  
Author(s):  
Sergey Saiyan ◽  
Alexander Paushkin
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Software Package ◽  
Numerical Study ◽  
Shear Stress Distribution ◽  
Load Application ◽  
Tangential Stresses

A study on the Saint-Venant principle implementation for a rigidly clamped I-beam loaded with various loads at the free end was carried out. When using the software package LIRA SAPR, the tangential stresses perturbations zones are determined in order to compare their distribution with the materials resistance solution.

Internal Stresses in Elastohydrodynamic Lubrication of Rolling/Sliding Contacts

1989 ◽  
Vol 111 (1) ◽  
pp. 180-187 ◽  
Author(s):  
Farshid Sadeghi ◽  
Ping C. Sui
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Internal Stress ◽  
Maximum Shear Stress ◽  
Elastohydrodynamic Lubrication ◽  
Normal Pressure ◽  
Internal Stresses ◽  
Stress Distributions ◽  
Principal Stresses ◽  
Dimensionless Velocity

The internal stress distribution in elastohydrodynamic lubrication of rolling/sliding line contact was obtained. The technique involves the full EHD solution and the use of Lagrangian quadrature to obtain the internal stress distributions in the x, y, z-directions and the shear stress distribution as a function of the normal pressure and the friction force. The principal stresses and the maximum shear stress were calculated for dimensionless loads ranging from (2.0452 × 10−5) to (1.3 × 10−4) and dimensionless velocity of 10−10 to 10−11 for slip ratios ranging from 0 to pure sliding condition.

Effect of the Strain Rate on the Twisting of Trabecular Bone from Women with Hip Fracture

2013 ◽  
Vol 135 (12) ◽  
Author(s):  
Ana C. Vale ◽  
Jennifer Faustino ◽  
Luís Reis ◽  
Ana Lopes ◽  
Bruno Vidal ◽  
...  
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Hip Fracture ◽  
Shear Modulus ◽  
Strain Rate ◽  
Trabecular Bone ◽  
Axial Load ◽  
Angular Displacement ◽  
Maximum Shear Stress ◽  
Lower Limbs

As one of the major functions of bone is to provide structural support for the musculoskeletal system, it is important to evaluate its mechanical strength. Bones may be subjected to multiaxial stresses due to bone pathologies, accidental loads which may lead to hip, wrist fracture, or to a prosthetic joint replacement. Twist loading may lead to fractures, especially involving long bones from lower limbs. The aim of this work was to study the effect of the strain rate on the shear properties of trabecular bone samples from women with hip fracture (from 65 to 100 years). Cylindrical samples were core drilled from human femoral heads along the primary trabecular direction. The cylinder's ends were polished and embedded in blocks of polymeric material which fit the grips of the testing device. Deformation rates of 0.005, 0.01, 0.015, and 0.05 s−1 were applied. Twisting tests were conducted with or without an applied axial load of 500 N. From the torque-angular displacement curves, the shear stress–strain curves were obtained. The maximum shear strength and the shear modulus (i.e. the slope of the linear region) were determined. A large scatter of the results of the shear strength and the shear modulus was found, which is probably related to the heterogeneity of nonhealthy human bone samples. There is no significant effect of the strain rate on the maximum shear stress and the shear modulus, either in tests undertaken with or without the application of an axial load. The effect of strain rate on nonhealthy bone trabecular twisting properties did not follow the trend observed on the effect of strain rate in healthy bone, where an increase is detected.

Contact Stress Analysis of NCD Coating on Cemented Carbide

2010 ◽  
Vol 431-432 ◽  
pp. 98-101
Author(s):  
Jia Jing Yuan ◽  
Wen Zhuang Lu ◽  
Dun Wen Zuo ◽  
Feng Xu
Keyword(s):  
Shear Stress ◽  
Elastic Modulus ◽  
Stress Distribution ◽  
Film Thickness ◽  
Contact Stress ◽  
Maximum Shear Stress ◽  
Shear Stress Distribution ◽  
Cemented Carbide ◽  
Low Elastic Modulus ◽  
Film Layer

The contact stress of cemented carbide with NCD coating in elastic contact was analyzed using ANSYS. Factors such as elastic modulus and thickness of NCD film and elastic modulus of interlayer which affect the shear stress distribution of NCD film on cemented carbide substrate were investigated. The results show that the maximum shear stress point moves towards the interface with the increase of film elastic modulus. Film thickness has a significant effect on shear stress distribution of NCD film. High shear stress develops in the film layer with the increase of film thickness. Interlayer with low elastic modulus will cause shear stress concentration in NCD film.

Stresses in a Reinforced Monocoque Cylinder Under Concentrated Symmetric Transverse Loads

1944 ◽  
Vol 11 (4) ◽  
pp. A235-A239
Author(s):  
N. J. Hoff
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Cross Section ◽  
Maximum Shear Stress ◽  
Circular Cross Section ◽  
Bending Moment ◽  
Normal Stress Distribution ◽  
Transverse Loads ◽  
Conventional Analysis ◽  
Analysis Application

Abstract The stresses in the sheet covering, stringers, and rings of a reinforced monocoque cylinder of circular cross section are calculated for the case of a loading consisting of concentrated symmetric forces applied to the rings in the planes of the rings. The conventional assumptions of a linear normal stress distribution and a corresponding shear-stress distribution in the bent cylinder are replaced by a least-work analysis. Application of the theory to the numerical example of a cantilever monocoque cylinder yields a maximum shear stress in the sheet covering and a maximum bending moment in the ring amounting to 900 per cent and 33 per cent, respectively, of the values obtained by the conventional analysis.

scholarly journals Stress Distribution in Co-Cr Implant Frameworks after Laser or TIG Welding

2013 ◽  
Vol 24 (2) ◽  
pp. 147-151 ◽  
Author(s):  
Gabriela Cassaro de Castro ◽  
Cleudmar Amaral de Araújo ◽  
Marcelo Ferraz Mesquita ◽  
Rafael Leonardo Xediek Consani ◽  
Mauro Antônio de Arruda Nóbilo
Keyword(s):  
Shear Stress ◽  
Maximum Shear Stress ◽  
Tig Welding ◽  
Edentulous Mandible ◽  
Significant Difference ◽  
Photoelastic Model ◽  
Group A ◽  
Photoelastic Analysis ◽  
The Right ◽  
Control Laser

Lack of passivity has been associated with biomechanical problems in implant-supported prosthesis. The aim of this study was to evaluate the passivity of three techniques to fabricate an implant framework from a Co-Cr alloy by photoelasticity. The model was obtained from a steel die simulating an edentulous mandible with 4 external hexagon analog implants with a standard platform. On this model, five frameworks were fabricated for each group: a monoblock framework (control), laser and TIG welding frameworks. The photoelastic model was made from a flexible epoxy resin. On the photoelastic analysis, the frameworks were bolted onto the model for the verification of maximum shear stress at 34 selected points around the implants and 5 points in the middle of the model. The stresses were compared all over the photoelastic model, between the right, left, and center regions and between the cervical and apical regions. The values were subjected to two-way ANOVA, and Tukey's test (α=0.05). There was no significant difference among the groups and studied areas (p>0.05). It was concluded that the stresses generated around the implants were similar for all techniques.

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