scholarly journals Investigating The Fracture Resistance Of Bioactive Glass Coatings On Metallic Implants

2021 ◽  
Author(s):  
Ali (Mike) Matinmanesh
Keyword(s):  
Bioactive Glass ◽  
Coating Thickness ◽  
Strain Energy Release ◽  
Mode I ◽  
Pure Mode ◽  
Glass Coating ◽  
Testing Methodology ◽  
Bacterial Proliferation ◽  
Quantitative Studies ◽  
Borate Bioactive Glass

Bioactive glasses have been used experimentally as coatings for medical implants because of their good osseointegration properties and ability to inhibit bacterial proliferation. However, the available literature lacks quantitative studies for characterizing their mechanical properties. This research postulates two fracture mechanics testing methodologies that facilitate measuring the nearly pure mode I (opening) and mode II (shearing) critical strain energy release rate (GIC, GIIC) of the coating/substrate system. Using these methodologies, the effects of coating thickness, glass composition and degradation on the GIC and GIIC of the system were evaluated. The developed mode I testing methodology was applied on a silicate bioactive glass/Ti6Al4V substrate system and it was found that increasing the coating thickness from 90 to 390 μm, decreased the measured GIC of the system significantly, from 6.2 to 2.5 J/m2. This decrease was found to be due to the increase in the residual stresses in the thicker coatings. The mode I testing methodology was then applied on two series of silica-based and borate-based glass coating, with increasing amounts of TiO2 incorporated, and it was observed that an increase in the content of TiO2 in the glasses resulted in an increase in the GIC for both the bulk glass and for the coating/substrate system. The borate-based series was found to have a closer CTE to the substrate compared to the silica counterpart, suggesting that use of such glasses as coatings can minimize the chances of delamination and cracking. Incorporating SrCO3 in a series of borate bioactive glass coating also proved to significantly increase the GIC and GIIC of the system. In order to study the effect of degradation, the borate bioactive glass coatings on Ti6Al4V substrates were immersed in deionized water for different time periods, dried and tested. It was found that after 17% weight loss of the glass, the GIC and GIIC of the coating/substrate system for all compositions decreased by at least 80%.

scholarly journals Investigating The Fracture Resistance Of Bioactive Glass Coatings On Metallic Implants

2021 ◽  
Author(s):  
Ali (Mike) Matinmanesh
Keyword(s):  
Bioactive Glass ◽  
Coating Thickness ◽  
Strain Energy Release ◽  
Mode I ◽  
Pure Mode ◽  
Glass Coating ◽  
Testing Methodology ◽  
Bacterial Proliferation ◽  
Quantitative Studies ◽  
Borate Bioactive Glass

Bioactive glasses have been used experimentally as coatings for medical implants because of their good osseointegration properties and ability to inhibit bacterial proliferation. However, the available literature lacks quantitative studies for characterizing their mechanical properties. This research postulates two fracture mechanics testing methodologies that facilitate measuring the nearly pure mode I (opening) and mode II (shearing) critical strain energy release rate (GIC, GIIC) of the coating/substrate system. Using these methodologies, the effects of coating thickness, glass composition and degradation on the GIC and GIIC of the system were evaluated. The developed mode I testing methodology was applied on a silicate bioactive glass/Ti6Al4V substrate system and it was found that increasing the coating thickness from 90 to 390 μm, decreased the measured GIC of the system significantly, from 6.2 to 2.5 J/m2. This decrease was found to be due to the increase in the residual stresses in the thicker coatings. The mode I testing methodology was then applied on two series of silica-based and borate-based glass coating, with increasing amounts of TiO2 incorporated, and it was observed that an increase in the content of TiO2 in the glasses resulted in an increase in the GIC for both the bulk glass and for the coating/substrate system. The borate-based series was found to have a closer CTE to the substrate compared to the silica counterpart, suggesting that use of such glasses as coatings can minimize the chances of delamination and cracking. Incorporating SrCO3 in a series of borate bioactive glass coating also proved to significantly increase the GIC and GIIC of the system. In order to study the effect of degradation, the borate bioactive glass coatings on Ti6Al4V substrates were immersed in deionized water for different time periods, dried and tested. It was found that after 17% weight loss of the glass, the GIC and GIIC of the coating/substrate system for all compositions decreased by at least 80%.

scholarly journals Experimental and Numerical Failure Analysis of Adhesive Composite Joints

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Farhad Asgari Mehrabadi
Keyword(s):  
Adhesive Bonding ◽  
Strain Energy Release ◽  
Lap Joints ◽  
Mode I ◽  
Pure Mode ◽  
Bonded Joints ◽  
Lap Joint ◽  
Stress Concentrations ◽  
Adhesively Bonded ◽  
Mode I Loading

In the first section of this work, a suitable data reduction scheme is developed to measure the adhesive joints strain energy release rate under pure mode-I loading, and in the second section, three types of adhesive hybrid lap-joints, that is, Aluminum-GFRP (Glass Fiber Reinforced Plastic), GFRP-GFRP, and Steel-GFRP were employed in the determination of adhesive hybrid joints strengths and failures that occur at these assemblies under tension loading. To achieve the aims, Double Cantilever Beam (DCB) was used to evaluate the fracture state under the mode-I loading (opening mode) and also hybrid lap-joint was employed to investigate the failure load and strength of bonded joints. The finite-element study was carried out to understand the stress intensity factors in DCB test to account fracture toughness using J-integral method as a useful tool for predicting crack failures. In the case of hybrid lap-joint tests, a numerical modeling was also performed to determine the adhesive stress distribution and stress concentrations in the side of lap-joint. Results are discussed in terms of their relationship with adhesively bonded joints and thus can be used to develop appropriate approaches aimed at using adhesive bonding and extending the lives of adhesively bonded repairs for aerospace structures.

Towards pure mode I loading in dissimilar adhesively bonded double cantilever beams

2021 ◽  
Vol 107 ◽  
pp. 102826
Author(s):  
M. Moazzami ◽  
M.R. Ayatollahi ◽  
S. Teixeira de Freitas ◽  
L.F.M. da Silva
Keyword(s):  
Mode I ◽  
Pure Mode ◽  
Cantilever Beams ◽  
Adhesively Bonded ◽  
Mode I Loading ◽  
Double Cantilever Beams

scholarly journals Comparison of Borate Bioactive Glass and Calcium Sulfate as Implants for the Local Delivery of Teicoplanin in the Treatment of Methicillin-Resistant Staphylococcus aureus-Induced Osteomyelitis in a Rabbit Model

2015 ◽  
Vol 59 (12) ◽  
pp. 7571-7580 ◽  
Author(s):  
Wei-Tao Jia ◽  
Qiang Fu ◽  
Wen-Hai Huang ◽  
Chang-Qing Zhang ◽  
Mohamed N. Rahaman
Keyword(s):  
Staphylococcus Aureus ◽  
Bioactive Glass ◽  
Calcium Sulfate ◽  
Rabbit Model ◽  
Local Delivery ◽  
Methicillin Resistant ◽  
Content Type ◽  
Borate Bioactive Glass ◽  
Phosphate Buffered Saline

ABSTRACTThere is growing interest in biomaterials that can cure bone infection and also regenerate bone. In this study, two groups of implants composed of 10% (wt/wt) teicoplanin (TEC)-loaded borate bioactive glass (designated TBG) or calcium sulfate (TCS) were created and evaluated for their ability to release TECin vitroand to cure methicillin-resistantStaphylococcus aureus(MRSA)-induced osteomyelitis in a rabbit model. When immersed in phosphate-buffered saline (PBS), both groups of implants provided a sustained release of TEC at a therapeutic level for up to 3 to 4 weeks while they were gradually degraded and converted to hydroxyapatite. The TBG implants showed a longer duration of TEC release and better retention of strength as a function of immersion time in PBS. Infected rabbit tibiae were treated by debridement, followed by implantation of TBG or TCS pellets or intravenous injection with TEC, or were left untreated. Evaluation at 6 weeks postimplantation showed that the animals implanted with TBG or TCS pellets had significantly lower radiological and histological scores, lower rates of MRSA-positive cultures, and lower bacterial loads than those preoperatively and those of animals treated intravenously. The level of bone regeneration was also higher in the defects treated with the TBG pellets. The results showed that local TEC delivery was more effective than intravenous administration for the treatment of MRSA-induced osteomyelitis. Borate glass has the advantages of better mechanical strength, more desirable kinetics of release of TEC, and a higher osteogenic capacity and thus could be an effective alternative to calcium sulfate for local delivery of TEC.

scholarly journals Mixed-Mode Interlaminar Fracture Toughness of Glass and Carbon Fibre Powder Epoxy Composites—For Design of Wind and Tidal Turbine Blades

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2103
Author(s):  
Christophe Floreani ◽  
Colin Robert ◽  
Parvez Alam ◽  
Peter Davies ◽  
Conchúr M. Ó. Brádaigh
Keyword(s):  
Fracture Toughness ◽  
Carbon Fibre ◽  
Composite Structures ◽  
Mixed Mode ◽  
Epoxy Composites ◽  
Mode I ◽  
Mode Ii ◽  
Pure Mode ◽  
Interlaminar Fracture Toughness ◽  
Interlaminar Fracture

Powder epoxy composites have several advantages for the processing of large composite structures, including low exotherm, viscosity and material cost, as well as the ability to carry out separate melting and curing operations. This work studies the mode I and mixed-mode toughness, as well as the in-plane mechanical properties of unidirectional stitched glass and carbon fibre reinforced powder epoxy composites. The interlaminar fracture toughness is studied in pure mode I by performing Double Cantilever Beam tests and at 25% mode II, 50% mode II and 75% mode II by performing Mixed Mode Bending testing according to the ASTM D5528-13 test standard. The tensile and compressive properties are comparable to that of standard epoxy composites but both the mode I and mixed-mode toughness are shown to be significantly higher than that of other epoxy composites, even when comparing to toughened epoxies. The mixed-mode critical strain energy release rate as a function of the delamination mode ratio is also provided. This paper highlights the potential for powder epoxy composites in the manufacturing of structures where there is a risk of delamination.

Pre-Strain Effects on Mixed-Mode Fatigue Crack Propagation Behaviour of the P355NL1 Pressure Vessels Steel

2018 ◽  
Author(s):  
João Ferreira ◽  
José A. F. O. Correia ◽  
Grzegorz Lesiuk ◽  
Sergio Blasón González ◽  
Maria Cristina R. Gonzalez ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Mixed Mode ◽  
Pressure Vessels ◽  
Mode I ◽  
Pure Mode

Pressure vessels and piping are commonly subjected to plastic deformation during manufacturing or installation. This pre-deformation history, usually called pre-strain, may have a significant influence on the resistance against fatigue crack growth of the material. Several studies have been performed to investigate the pre-strain effects on the pure mode I fatigue crack propagation, but less on mixed-mode (I+II) fatigue crack propagation conditions. The present study aims at investigating the effect of tensile plastic pre-strain on fatigue crack growth behavior (da/dN vs. ΔK) of the P355NL1 pressure vessel steel. For that purpose, fatigue crack propagation tests were conducted on specimens with two distinct degrees of pre-strain: 0% and 6%, under mixed mode (I+II) conditions using CTS specimens. Moreover, for comparison purposes, CT specimens were tested under pure mode I conditions for pre-strains of 0% and 3%. Contrary to the majority of previous studies, that applied plastic deformation directly on the machined specimen, in this work the pre-straining operation was carried out prior to the machining of the specimens with the objective to minimize residual stress effects and distortions. Results revealed that, for the P355NL1 steel, the tensile pre-strain increased fatigue crack initiation angle and reduced fatigue crack growth rates in the Paris region for mixed mode conditions. The pre-straining procedure had a clear impact on the Paris law constants, increasing the coefficient and decreasing the exponent. In the low ΔK region, results indicate that pre-strain causes a decrease in ΔKth.

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