Fatigue Behavior of Porous Coated and Uncoated Ti-6Al-4V Surgical Implant Material PDF Download

Author: Frederick Steven Georgette
Publisher:
ISBN:
Category : Orthopedic implants
Languages : en
Pages : 156

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Author: P. Ducheyne
Publisher:
ISBN:
Category : Fatigue
Languages : en
Pages : 11

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Porous coated Ti-6Al-4V has a bending fatigue strength that is approximately one-third that of the uncoated material. This reduction in strength is due primarily to stress concentrations caused by the interfacial geometry between the porous coating and the substrate. An unconventional interfacial geometry, the porous coated nodule, has been shown to reduce the stress concentration factor compared to conventional porous coatings in finite element modeling. We report here on bending fatigue testing to determine whether the fatigue strength of the new geometry is better than that of the conventional porous coating geometry. We also report on modeling of shear loading to determine whether the new geometry lowers stress concentrations under this mode of loading as well as under bending loading. The fatigue strength of the nodule geometry was found to be 305 (+/- 12) MPa, which is greater than the strength of conventional porous coated specimens. In addition, the porous coated nodule was seen to reconcile the differences in the results for modeling under shear and bending loads and can thus reduce stress concentrations under both modes of loading.

Author: Chandrasekaran Venkatesan
Publisher:
ISBN:
Category : Orthopedic implants
Languages : en
Pages : 148

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Author: Debra Wolfarth
Publisher:
ISBN:
Category :
Languages : en
Pages : 226

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Author: David H. Kohn
Publisher:
ISBN:
Category : Implants, Artificial
Languages : en
Pages : 486

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Author: AC. Fraker
Publisher:
ISBN:
Category : Biodegradation
Languages : en
Pages : 13

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The object of this work was to determine mechanical properties of implants with graded porous coatings without reference to the properties of the ingrown bone. Optimum strength of a bone/implant interface consisting of porous metal and ingrown bone requires a gradation from base metal to the original bone. The composite metal-bone interface can be obtained by applying a metal coating of graded porosity, varying from near zero at the substrate surface to more than 50% at the outermost layer, on the original implant. Graded porous coatings of titanium or Ti-6Al-4V were obtained by plasma spraying of selected particle size fractions in three layers of successively decreasing density, the top coat being made with 300 to 850 ?m powder. Tensile and shear strengths of the coatings were determined by cementing coated samples face to face with an adhesive resin to simulate ingrown bone. Data from these tests are given. Shear strength values ranged from 5.6 to 9.9 MPa (815 to 1430 psi) and tensile strength values were 5.1 to 25.5 MPa (745 to 3700 psi). Failure occurred within the porous coating and not at the interface between the substrate and the coating. Corrosion fatigue tests in Hanks' solution at 37°C (98.6°F) and a pH of 7.4, with a cyclic, fully reversed, peak torsional shear strain of ±0.01, gave lifetimes comparable to or better than those reported for mill-annealed Ti-6Al-4V, except for the samples that had been sintered.

Author: Ducheyne
Publisher: CRC Press
ISBN: 1351082876
Category : Science
Languages : en
Pages : 133

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The understanding of the in vivo performance of synthetic materials is largely dependent upon a profound knowledge of the properties of the materials in question. Analogous to materials science in its broadest sense, the basis for biomaterials science is formed by microstructural there. It is therefore, that in this series on structure property relationships in biomaterials a substantial part is devoted to the analysis of the basic properties of the various synthetic biomaterials. In addition, the effect of microstructural aspects on properties is considered at great length.

Author: Jaspal Singh Kamboj
Publisher:
ISBN: 9781321094008
Category :
Languages : en
Pages : 63

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It is key to consider a material's mechanical properties when determining its use for any given application, including biomaterial implantations. One such characteristic includes the fatigue life, which is determined by repeatedly cycling specified amounts of load on any given material [2]. The fatigue life is then measured according to how many cycles of load the material can undergo before fracture [2]. When a material is introduced to the human body it is usually expected that the life of the material will not match that of the patient. It is crucial to understand the fatigue life of the material before implantation to pre-diagnose how often and when the implant will need to be replaced. The purpose of this project is to help determine and compare the fatigue behaviors of a commonly used biocompatible coating on Titanium 6-4 metal alloy. The comparison will help identify how the material properties vary with the addition of calcium phosphate when compared to the bare alloy itself. Multiple, small rectangular samples were cut by electrical discharge machining (EDM) of which half were covered with calcium phosphate coating. Fatigue crack initiations and propagation would then be analyzed using scanning electron microscopy (SEM) to help determine the nature of the damage processes. It was found that the fatigue life of the coated samples varied at different stresses but was greater than the bare samples, and particularly high in the 900 MPa - 1000 MPa stress range.

Author: V. Chandrasekaran
Publisher:
ISBN:
Category : Crack nucleation
Languages : en
Pages : 14

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Book Description
Although Ti-6Al-4V has superior mechanical "properties" and corrosion resistance when compared to many other materials in implant applications, it is more susceptible to fretting initiated problems. This is because Ti-6Al-4V exhibits a greater tendency for material transfer when it slides over other materials or over itself. The insidious nature of fretting is more evident when it often leads to other degradation mechanisms such as pitting corrosion and crevice corrosion. To characterize the fretting fatigue behavior of Ti-6Al-4V fretting fatigue tests were conducted in a laboratory environment. The test parameters were selected to simulate the hip prostheses loading conditions. When the cyclic fatigue load of 3.30/0.33 kN (742/74 1bf) was applied to the fatigue specimen [producing the maximum fatigue stress of approximately 524 MPa (76 ksi) through the center section of the fatigue specimen] at a frequency of 6 HZ, the fatigue life of Ti-6Al-4V was reduced to a mere 69,660 cycles at a normal stress of 41.4 MPa (6 ksi). The test results showed that fretting reduced the fatigue life of Ti-6Al-4V when tested in laboratory environment simulating the hip prosthesis loading conditions. The reduction in fretting fatigue life was clearly evident from the fractographic analysis that can be interpreted as resulting from the production of mechanical surface damage that leads to numerous crack nucleation sites. Therefore, to enhance an understanding of fretting related problems in modular joints among the orthopaedic surgeons and researchers the parameters that influence fretting including the sensitivity of titanium to microstructure and the present state of knowledge on the mechanisms of fretting are discussed.

Author: Orthopaedic Research Society
Publisher:
ISBN:
Category : Orthopedics
Languages : en
Pages : 606

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Book Description
Consists of the transactions of the 22nd- annual meeting of the society.