scholarly journals MODELING PULL-OUT TEST OF DENTAL IMPLANTS

2003 ◽  
Vol 15 (04) ◽  
pp. 133-142 ◽  
Author(s):  
ANNA DOLLAR ◽  
KEVIN P. MEADE
Keyword(s):  
Continuous Distribution ◽  
Singular Integral Equations ◽  
Analytical Techniques ◽  
Relative Displacement ◽  
Interface Failure ◽  
Bony Tissue ◽  
Bone Implant ◽  
Pull Out ◽  
Edge Dislocations ◽  
Quantities Of Interest

The objective of this paper is to investigate bone-implant interface failure using analytical techniques of fracture mechanics. The implant usually is anchored to the surrounding bone by growth of bony tissue into the surface of the implant. A mechanical interlock is formed between the implant and the bone. Plane strain conditions are imposed. By using a continuous distribution of edge dislocations to represent interfacial debonding, the problem reduced to a system of singular integral equations that was solved numerically using standard collocation techniques. Quantities of interest are the extent of the debonded zone, the relative displacement between the implant and the bone and the stresses at the bone-implant interfaces, all of which depend on the load in a nonlinear fashion.

On Branched, Interface Cracks

1981 ◽  
Vol 48 (3) ◽  
pp. 529-533 ◽  
Author(s):  
K. Hayashi ◽  
S. Nemat-Nasser
Keyword(s):  
Integral Equations ◽  
Contact Region ◽  
Continuous Distribution ◽  
Singular Integral Equations ◽  
Potential Method ◽  
Intensity Factors ◽  
Interface Cracks ◽  
Branch Lengths ◽  
Interface Contact ◽  
Edge Dislocations

The problem of branched, external cracks in the interface between two elastic materials is considered under the plane strain condition. A small interface contact region is introduced in the vicinity of each crack tip in order to remove oscillatory singularities. The branches are replaced by continuous distribution of edge dislocations, and, with the aid of Muskhelishvili’s potential method, the problem is reduced to a system of singular integral equations which are defined on the branches and the perfectly bonded region of the interface. The unknown functions of these integral equations are the shear stress acting on the bonded region, and the density functions of the edge dislocations. Stress-intensity factors of the interface cracks and branches are obtained numerically for several branch angles and branch lengths. Finally, the question of kinking from a tip of an interface crack is discussed with the aid of the results.

Comparison of Push-In versus Pull-Out Tests on Bone-Implant Interfaces of Rabbit Tibia Dental Implant Healing Model

2011 ◽  
Vol 15 (3) ◽  
pp. 460-469 ◽  
Author(s):  
Wook-Jin Seong ◽  
Shahrzad Grami ◽  
Soo Cheol Jeong ◽  
Heather J. Conrad ◽  
James S. Hodges
Keyword(s):  
Dental Implant ◽  
Bone Implant ◽  
Pull Out ◽  
Rabbit Tibia ◽  
Healing Model

Behavior of a Horizontal Fluid Filled Crack Under Moving Hertzian Load

2005 ◽  
Author(s):  
X. Jin ◽  
L. M. Keer ◽  
E. L. Chez
Keyword(s):  
Half Plane ◽  
Continuous Distribution ◽  
Contact Stresses ◽  
Hertzian Contact ◽  
Subsurface Crack ◽  
Intensity Factors ◽  
Crack Volume ◽  
Rolling Body ◽  
Soft Inclusion ◽  
Edge Dislocations

Numerical analysis is presented for a fluid filled subsurface crack in an elastic half plane loaded by Hertzian contact stresses. The opening volume of the horizontal Griffith crack is fully occupied by an incompressible fluid. In the presence of friction, a moving Hertzian line contact load is applied at the surface of the half plane. The stress intensity factors at the tips of the fluid filled crack are analyzed on condition that the change of the opening crack volume vanishes due to the fluid incompressibility. The method used is that of replacing the crack by a continuous distribution of edge dislocations. As a cycle of rolling can be viewed as shifting the Hertzian contact stresses across the surface of the half plane, the results of this analysis may prove useful in the prediction of rolling fatigue of an elastic rolling body containing a soft inclusion.

scholarly journals Multiscale Design and Multiobjective Optimization of Orthopedic Hip Implants with Functionally Graded Cellular Material

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Sajad Arabnejad Khanoki ◽  
Damiano Pasini
Keyword(s):  
Bone Resorption ◽  
Relative Density ◽  
Titanium Implant ◽  
Functionally Graded ◽  
Interface Instability ◽  
Interface Failure ◽  
Bone Implant ◽  
Multiscale Mechanics ◽  
Cellular Microstructure ◽  
Dense Titanium

Revision surgeries of total hip arthroplasty are often caused by a deficient structural compatibility of the implant. Two main culprits, among others, are bone-implant interface instability and bone resorption. To address these issues, in this paper we propose a novel type of implant, which, in contrast to current hip replacement implants made of either a fully solid or a foam material, consists of a lattice microstructure with nonhomogeneous distribution of material properties. A methodology based on multiscale mechanics and design optimization is introduced to synthesize a graded cellular implant that can minimize concurrently bone resorption and implant interface failure. The procedure is applied to the design of a 2D left implanted femur with optimized gradients of relative density. To assess the manufacturability of the graded cellular microstructure, a proof-of-concept is fabricated by using rapid prototyping. The results from the analysis are used to compare the optimized cellular implant with a fully dense titanium implant and a homogeneous foam implant with a relative density of 50%. The bone resorption and the maximum value of interface stress of the cellular implant are found to be over 70% and 50% less than the titanium implant while being 53% and 65% less than the foam implant.

New Concept in Preventive Orthopedics. The Prevention of Pathological Fractures of the Proximal Hip Through Prophylactic Reinforcement

2015 ◽  
Vol 22 (4) ◽  
pp. 39-46
Author(s):  
Минасов ◽  
T. Minasov ◽  
Минасов ◽  
B. Minasov ◽  
Дубров ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Cortical Layer ◽  
Low Energy ◽  
Design Quality ◽  
Pathological Fractures ◽  
Bony Tissue ◽  
Bone Implant ◽  
Bench Tests ◽  
Type Design ◽  
Definition Of

The paper is dedicated to the pilot study of the surgical ways of preventing fractures of the hip among elderly patients suffering from various diseases that cause destructive‐dystrophic changes of the bony tissue (osteoporosis, cancer, cartilage and fibrous dysplasia, etc.) and are the cause of pathological fractures. The research involves the identification of people at risk, the development of preventive techniques and original reinforcement implant designs, the definition of a methodology for mathematical modeling and bench tests to determine the strength of the original implant reinforced hip. Studies have shown that the index of strain in the bone is considerably lower than on its surface (closer to longer‐term cortical layer), and when the load increases, it results in the development of a fracture. As a result of the reinforcement of the bone with different implants the index of strain at critical points is increases up to 11.6% ‐12.1. The bench tests proved that the preventive reinforcement to prevent fractures in low‐energy trauma can increase the strength of bone‐implant, depending on the type, design, quality, implant and method of its introduction up to 23‐93%.

scholarly journals Nanointerfacial strength between non-collagenous protein and collagen fibrils in antler bone

2014 ◽  
Vol 11 (92) ◽  
pp. 20130993 ◽  
Author(s):  
Fei Hang ◽  
Himadri S. Gupta ◽  
Asa H. Barber
Keyword(s):  
Volume Fraction ◽  
Interfacial Strength ◽  
Collagen Fibrils ◽  
Interface Failure ◽  
Force Microscopy ◽  
Microscopy Technique ◽  
Rate Dependent ◽  
Pull Out ◽  
Atomic Force ◽  
Small Volume Fraction

Antler bone displays considerable toughness through the use of a complex nanofibrous structure of mineralized collagen fibrils (MCFs) bound together by non-collagenous proteins (NCPs). While the NCP regions represent a small volume fraction relative to the MCFs, significant surface area is evolved upon failure of the nanointerfaces formed at NCP–collagen fibril boundaries. The mechanical properties of nanointerfaces between the MCFs are investigated directly in this work using an in situ atomic force microscopy technique to pull out individual fibrils from the NCP. Results show that the NCP–fibril interfaces in antler bone are weak, which highlights the propensity for interface failure at the nanoscale in antler bone and extensive fibril pullout observed at antler fracture surfaces. The adhesion between fibrils and NCP is additionally suggested as being rate dependent, with increasing interfacial strength and fracture energy observed when pullout velocity decreases.

Pull-out test and discrete spring model of fibre-reinforced polymer perfobond rib shear connector

2012 ◽  
Vol 39 (12) ◽  
pp. 1311-1320 ◽  
Author(s):  
Jeong-Rae Cho ◽  
Sung Yong Park ◽  
Keunhee Cho ◽  
Sung Tae Kim ◽  
Byung-Suk Kim
Keyword(s):  
Constitutive Equation ◽  
Relative Displacement ◽  
Displacement Curve ◽  
Spring Model ◽  
Analysis And Design ◽  
Shear Connectors ◽  
Pull Out ◽  
Reinforced Polymer ◽  
Dowel Action ◽  
Fibre Reinforced Polymer

In this study, a series of pull-out tests on fibre-reinforced polymer (FRP) perfobond rib shear connectors were conducted to investigate their shear behavior. The test specimens were designed to examine only the effects of the resistance by rib holes. The test variables were the size and number of rib holes. In the tests, the resistance by concrete dowel action was practically linearly proportional to the area of the rib hole. However, the resistance appeared to be nonlinearly proportional to the number of rib holes with a slight loss for a larger number of the rib holes, due to the sequential failure of the rib holes. The constitutive equation of the discrete spring model representing the concrete dowel including post-failure frictional effects, adopting the diameter of the rib hole as parameter, was derived through regression analysis of the load – relative displacement curve obtained for specimens with a single rib hole. The proposed discrete spring model resulted in good correlation with the experimental results for specimens with a larger number of rib holes. It is expected that the derived constitutive equation would be useful for the analysis and design of structures using FRP perfobond rib shear connectors.

Cracks Emanating From a Fluid Filled Void Loaded in Compression: Application to the Bone-Implant Interface

1987 ◽  
Vol 109 (1) ◽  
pp. 55-59 ◽  
Author(s):  
M. H. Santare ◽  
L. M. Keer ◽  
J. L. Lewis
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Numerical Scheme ◽  
Singular Integral Equations ◽  
Orthopedic Implants ◽  
Mode I ◽  
Quadratic Polynomials ◽  
Bone Implant ◽  
Cement Interface

Loosening of orthopedic implants is believed to be caused, in part, by fracture at the bone-cement interface. This loosening occurs even in regions where the interfacial load is primarily compressive. A model is developed whereby cracks can radiate from an elliptical fluid filled void. The incompressible fluid is allowed to penetrate into the cracks when the system is loaded compressively. The mode I stress intensity factor is calculated to test the feasibility of crack growth, and a numerical scheme which uses piecewise quadratic polynomials is used to solve the resulting singular integral equations. The results show the combinations of parameters for which cracks are likely to grow.

Stress Concentrations in an Intermingled Hybrid Composite

1997 ◽  
Vol 64 (4) ◽  
pp. 738-742
Author(s):  
H. A. Luo ◽  
Q. Wang
Keyword(s):  
Integral Equations ◽  
Hybrid Composite ◽  
Continuous Distribution ◽  
Singular Integral Equations ◽  
High Modulus ◽  
Stress Concentrations ◽  
Shear Lag Model ◽  
Lag Model ◽  
Low Modulus ◽  
Stress Concentration Factors

This paper studies the stress redistribution in a tensile hybrid composite sheet due to the breakage of a high modulus fiber. Employing a continuous distribution of dislocations, a set of singular integral equations is established to analyze the fiber crack impinging upon weakly bonded fiber-matrix interfaces. After solving the integral equations numerically, the stress concentration factors of both high modulus and low modulus fibers are evaluated as a function of loading stress and interfacial parameters. The results are compared with those obtained from shear-lag model solution.

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