A theoretically-based novel protocol for the analytic treatment of the glass failure stresses associated with coaxial double ring test method

2021 ◽  
Author(s):  
Giulio Castori ◽  
Gabriele Pisano ◽  
Emanuela Speranzini
Keyword(s):  
Test Method ◽  
Ring Test ◽  
Analytic Treatment ◽  
Double Ring

Effect of ultrasonic melt treatment on the tribological behavior of 7075 aluminum alloy

2020 ◽  
Vol 62 (12) ◽  
pp. 1243-1250
Author(s):  
Fahri Vatansever ◽  
Alpay Tamer Erturk ◽  
Erol Feyzullahoglu
Keyword(s):  
Surface Roughness ◽  
Aluminum Alloy ◽  
Tribological Properties ◽  
Lower Surface ◽  
Test Method ◽  
Ring Test ◽  
7075 Aluminum Alloy ◽  
Melt Treatment ◽  
Ultrasonic Melt Treatment ◽  
Worn Surfaces

Abstract In this study, the tribological properties of 7075 aluminum alloy produced by ultrasonic melt treatment (UST) are investigated. Tribological properties of untreated and ultrasonically treated samples under dry and lubricated sliding conditions were analyzed experimentally by the block on ring test method. Worn surfaces of untreated and ultrasonically treated samples were scanned by 3D optical profilometer and analyzed to search out wear characteristics in the material. Furthermore, microstructural examinations were conducted to investigate the beneficial effects of UST on the microstructural properties of the alloy using optical and scanning electron microscopy. According to the results obtained, UST refines the α-Al phase of the alloy and disperses precipitates to grain boundaries more uniformly. Also, hardness and density of the alloy increased through the effect of UST. Due to these favorable effects, the wear resistance of the alloy increased and the worn surfaces of the ultrasonically treated samples exhibited lower surface roughness according to 3D surface roughness measurements.

Restrained Shrinkage Behavior of Concrete under Different Environmental Conditions

2014 ◽  
Vol 941-944 ◽  
pp. 835-841 ◽  
Author(s):  
Zhi Tao Chen ◽  
Mao Guang Li ◽  
Ying Zi Yang ◽  
Qi Liu
Keyword(s):  
Relative Humidity ◽  
Environmental Conditions ◽  
Test Method ◽  
Mineral Admixtures ◽  
Ring Test ◽  
Test Duration ◽  
Restrained Shrinkage ◽  
Shrinkage Cracking ◽  
Higher Temperature ◽  
Shrinkage Behavior

The ring test method is used to evaluate the behavior of concrete under restrained shrinkage. Four kinds of environmental conditions (20±1°C, RH60±5%; 35±1°C, RH60±5%; 50±1°C, RH15±5%; 65±1°C, RH15±5%) were designed to investigate the effect the environmental condition on the shrinkage behavior of concrete prepared with different kinds of mineral admixtures. The results show that higher temperature and lower relative humidity can increase the risk of shrinkage cracking. The addition of different mineral admixtures increases the shrinkage of concrete at room conditions. In the case of higher temperature and lower relative humidity, the addition of mineral admixtures can delay the shrinkage cracking in the test duration.

scholarly journals Development of a test method to investigate mode II fracture and dissection of arteries

2020 ◽  
Author(s):  
Brian FitzGibbon ◽  
Patrick McGarry
Keyword(s):  
Crack Initiation ◽  
Test Method ◽  
Ring Test ◽  
Mode Ii ◽  
High Shear ◽  
Crack Initiation And Propagation ◽  
Mode Ii Fracture ◽  
Initiation And Propagation ◽  
Mode Ii Crack ◽  
Arterial Tissue

The current study presents the development and implementation of a bespoke experimental technique to generate and characterise mode II crack initiation and propagation in arterial tissue. The current study begins with a demonstration that lap-shear testing of arterial tissue results in mixed mode fracture, rather than mode II. We perform a detailed computational design of a bespoke experimental method (which we refer to as a shear fracture ring test (SFRT)) to robustly and repeatably generate mode II crack initiation and propagation in arteries. This method is based on generating a localised region of high shear adjacent to a cylindrical loading bar. Placement of a radial notch in this region of high shear stress is predicted to result in a kinking of the crack during a mode II initiation and propagation of the crack over a long distance in the circumferential (c)-direction along the circumferential-axial (c-a) plane. Fabrication and experimental implementation of the SFRT on excised ovine aorta specimens confirms that the bespoke test method results in pure mode II initiation and propagation. We demonstrate that the mode II fracture strength along the c-a plane is eight times higher than the corresponding mode I strength determined from a standard peel test. We also calibrate the mode II fracture energy based on our measurement of crack propagation rates. The mechanisms of fracture uncovered in the current study, along with our quantification of mode II fracture properties have significant implications for current understanding of the biomechanical conditions underlying aortic dissection.

Effect of Ion-Exchange Chemistry on the Fracture of Chemically Strengthened Sodium Aluminosilicate Glass

2019 ◽  
Author(s):  
Benedict O. Egboiyi ◽  
Trisha Sain
Keyword(s):  
Residual Stress ◽  
Ion Exchange ◽  
Fracture Strength ◽  
Critical Stress Intensity Factor ◽  
Consumer Electronics ◽  
Test Method ◽  
Aluminosilicate Glass ◽  
Ring Test ◽  
Stress Profile ◽  
Sodium Aluminosilicate

Abstract The widespread use of sodium aluminosilicate glass in many critical applications due to its hardness, weight, density and optical properties (transparency, dielectric etc.), instead of metals or plastics has become common in recent years. However, glass which is known to be a brittle material has its own vulnerability to fracture. Processes such as heat treatment (heat tempering) or chemical strengthening, through ion-exchange have been deployed to create residual stress profile on the glass, in a bid to improve its strength for applications such as in the automobile windshield design, consumer electronics mobile communication devices e.g. smartphones and tablet etc. However, failure still occurs which is mostly catastrophic and expensive to repair. Therefore, understanding, predicting and eventually improving the resistance to damage or fracture of chemically strengthened glass is significant to designing new glasses that would be tougher, while retaining their transparency. The relationship between the glass residual stress parameters, compressive stress (CS), depth of layer (DOL), center tension (CT) and fracture strength was investigated in this study using a grit particle blast plus ring on ring test method, based on IEC standard for retained biaxial flexural strength measurements. This technique can be used to measure both the surface and edge fracture strength of the glass. Preliminary results showed that for a reasonable level of CS, and CT, high DOL are beneficial to resisting fracture due to severe surface damage, while a high CS and low CT are beneficial to resisting fractures due to shallower flaws. The correlation of critical stress intensity factor versus DOL and CT for various level of CS were also determined and discussed. These results provide a valuable piece of information in the design of a more robust glass in engineering applications.

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