scholarly journals Zirconia ceramic fixed partial dentures after cyclic fatigue tests and clinical evaluation: a systematic review

2018 ◽  
Vol 118 (1-2) ◽  
pp. 62-69 ◽  
Author(s):  
Sonja Zarkovic Gjurin ◽  
Mutlu Özcan ◽  
Cedomir Oblak
Keyword(s):  
Systematic Review ◽  
Clinical Evaluation ◽  
Cyclic Fatigue ◽  
Fatigue Tests ◽  
Zirconia Ceramic

scholarly journals The Effects of Sterilization Procedures on the Cutting Efficiency of Endodontic Instruments: A Systematic Review and Network Meta-Analysis

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1559
Author(s):  
Mario Dioguardi ◽  
Enrica Laneve ◽  
Michele Di Cosola ◽  
Angela Pia Cazzolla ◽  
Diego Sovereto ◽  
...  
Keyword(s):  
Systematic Review ◽  
Selection Process ◽  
Meta Analysis ◽  
Indirect Comparison ◽  
Physical And Mechanical Properties ◽  
Surface Characteristics ◽  
Cyclic Fatigue ◽  
P Value ◽  
Cutting Efficiency ◽  
Dental Instruments

Sterilization processes guarantee the sterility of dental instruments but can negatively affect instrument features by altering their physical and mechanical properties. The endodontic instrumentation can undergo a series of alterations, ranging from corrosion to variation in the cutting angle and then changes in the torsional properties and torsional fatigue resistance. This systematic literature review and meta-analysis aims to investigate alterations to the cutting efficiency of endodontic instruments that are induced by procedures for their disinfection and sterilization. Methodologies adopted for this investigation follow the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines. The following were used as search terms on PubMed and Scopus: “endodontic sterilization”, “endodontic autoclave”, “cyclic fatigue”, “torsional”, “cutting efficiency”, “sterilization”, “surface characteristics”, and “corrosion”. At the end of the selection process, 36 articles were identified, and seven of them are included in this systematic review. The results of a meta-analysis conducted for the use of 10 autoclaving cycles shows a standardized mean difference (SMD) of 0.80 with a p-value equal to 0.04 with respect to effect on cutting efficiency. The network meta-analysis, through direct and indirect comparison between the different autoclave cycles (0, 1, 5, 10, and 15 cycles), revealed that treatment involving 15 autoclave cycles produced the most robust results in terms of having the greatest effects in terms of altered cutting efficiency with a probability of 57.7% and a SUCRA (surface under the cumulative ranking) of 80%. The alterations in the effects on cutting efficiency appear to be triggered after five cycles of sterilization by heat (autoclave). In conclusion, the meta-analysis of the data indicates that the autoclave sterilization protocol must not be repeated more than five times to preserve cutting efficiency. Within the limitations of this review, we can therefore establish that sterilization by autoclaving alone results in steel and NiTi instruments becoming less efficient in cutting after five cycles, as measured by a reduction in cutting efficiency.

scholarly journals FATIGUE TESTS OF METAL MATERIALS (review) Part 1. Main definitions, loading parameters, representation of results of tests

2020 ◽  
pp. 59-70
Author(s):  
V.S. Erasov ◽  
◽  
E.I. Oreshko ◽  
Keyword(s):  
Hysteresis Loop ◽  
Distinctive Feature ◽  
Main Crack ◽  
Elastoplastic Deformation ◽  
Cyclic Fatigue ◽  
Fatigue Tests ◽  
Surface Layers ◽  
Near Surface ◽  
Mechanical Hysteresis ◽  
Metal Materials

The article gives the review of techniques of fatigue tests of metal materials and presents the results of such tests . It has been shown that the low-cyclic fatigue occurs in conditions of elastoplastic deformation in material microvolume from the first cycles of loading. Its distinctive feature is influence on durability of the size and form of a mechanical hysteresis loop . Nucleation of fatigue microcracks and formation of the main crack occurs on the surface and in near-surface layers of a sample.

Nanostructured Strengthening of Springs and Spring Steels

2016 ◽  
Vol 870 ◽  
pp. 40-45
Author(s):  
O.I. Shavrin ◽  
A.N. Skvortsov
Keyword(s):  
Cyclic Loading ◽  
Thermal Strain ◽  
Cyclic Fatigue ◽  
Fatigue Tests ◽  
Dominant Effect ◽  
Grain Sizes ◽  
Limited Life ◽  
Spring Steels

The paper considers the problem of nanostructured strengthening of spring steels and springs, the idea of steel nanostructured strengthening determined not only by grain sizes but also by subgrain sizes is justified. Design schemes of thermal strain nanoscale substructure patterning in spring material produced by hot and cold coiling were implemented. Patterning of nanoscale substructure was experimentally proved. Strength analyses of spring steels and springs showed the dominant effect of nanoscale substructure on spring limited life increasing not less than 10 times at cyclic fatigue tests. Spring compression at cyclic loading decreases 10 times.

Fatigue Analysis of FRP Strengthened Masonry by Acoustic Emission Monitoring

2019 ◽  
Vol 817 ◽  
pp. 594-601 ◽  
Author(s):  
Alessandro Grazzini ◽  
Giuseppe Lacidogna
Keyword(s):  
Acoustic Emission ◽  
Cyclic Fatigue ◽  
Fatigue Tests ◽  
Fiber Reinforced Polymers ◽  
Test Duration ◽  
Time Behavior ◽  
Damage Growth ◽  
Reinforced Polymers ◽  
Safety Work ◽  
Long Time

The safety work of historical and monumental building heritage requires the use of innovative materials compatible with the high architectural value. The Fiber Reinforced Polymers (FRP) represent a valid alternative to traditional ones, and the carbon fiber sheets are very light and easy to glue to the masonry structures. However, the durability of the application of FRP sheets is still uncertain in the long time behavior, especially with regard to cyclic fatigue loads such as seismic ones. In this work an experimental analysis on a set of strengthened masonry walls under fatigue tests (loading and freezing-thawing test) has been carried out in order to evaluate creep effects. During cyclic tests in the laboratory it was possible to monitor the damage pattern through the acoustic emission (AE) technique. The AE monitoring is useful to estimate the amount of energy released from fracture propagation in the adherence surface between masonry and FRP sheet. The different phases of damage evolution are recognized through the analysis of AE data over time. In particular, the time dependence of AE counting number is useful to indicate the beginning of the unstable damage growth and predicts the possible failure of the specimens at the 80% of the test duration. Furthermore, a sudden decay in the AE frequency is detected during the last phase of the fatigue tests. These results illustrate the applicability and the advantages of AE technique for the monitoring of long-term damage growth in strengthened masonry.

scholarly journals Application of a √ area -Approach for Fatigue Assessment of Cast Aluminum Alloys at Elevated Temperature

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1033 ◽  
Author(s):  
Roman Aigner ◽  
Christian Garb ◽  
Martin Leitner ◽  
Michael Stoschka ◽  
Florian Grün
Keyword(s):  
Elevated Temperature ◽  
Fatigue Strength ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Damage Mechanism ◽  
Cyclic Fatigue ◽  
Fatigue Tests ◽  
Cast Aluminum ◽  
Fatigue Assessment ◽  
Cast Aluminum Alloys

This paper contributes to the effect of elevated temperature on the fatigue strength of common aluminum cast alloys EN AC-46200 and EN AC-45500. The examination covers both static as well as cyclic fatigue investigations to study the damage mechanism of the as-cast and post-heat-treated alloys. The investigated fracture surfaces suggest a change in crack origin at elevated temperature of 150 ∘ C. At room temperature, most fatigue tests reveal shrinkage-based micro pores as their crack initiation, whereas large slipping areas occur at elevated temperature. Finally, a modified a r e a -based fatigue strength model for elevated temperatures is proposed. The original a r e a model was developed by Murakami and uses the square root of the projected area of fatigue fracture-initiating defects to correlate with the fatigue strength at room temperature. The adopted concept reveals a proper fit for the fatigue assessment of cast Al-Si materials at elevated temperatures; in detail, the slope of the original model according to Murakami should be decreased at higher temperatures as the spatial extent of casting imperfections becomes less dominant at elevated temperatures. This goes along with the increased long crack threshold at higher operating temperature conditions.

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