Laboratory assessment of the resistance to crack propagation in high-stiffness asphaltic materials

Microwave cutting glass and ceramics based on thermal controlled fracture method has gained much attention recently for its advantages in lower energy-consumption and higher efficiency than conventional processing method. However, the irregular crack-propagation is problematic in this procedure, which hinders the industrial application of this advanced technology. In this study, the irregular crack-propagation is summarized as the unstable propagation in the initial stage, the deviated propagation in the middle stage, and the non-penetrating propagation in the end segment based on experimental work. Method for predicting the unstable propagation in the initial stage has been developed by combining analytical models with thermal-fracture simulation. Experimental results show good agreement with the prediction results, and the relative deviation between them can be <5% in cutting of some ceramics. The mechanism of deviated propagation and the non-penetrating propagation have been revealed by simulation and theoretical analysis. Since this study provides effective methods to predict unstable crack-propagation in the initial stage and understand the irregular propagation mechanism in the whole crack-propagation stage in microwave cutting ceramics, it is of great significance to the industrial application of thermal controlled fracture method for cutting ceramic materials using microwave.

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POSTOPERATIVE COMPLIANCE OF BARIATRIC SURGERY PATIENTS REGARDING THE ASSESSMENT OF SERUM LEPTIN LEVELS AND INSULIN RESISTANCE

Medical Connections ◽

10.33311/medcon.2019.49.1.1 ◽

2019 ◽

Vol 49 (1/2019) ◽

Keyword(s):

Insulin Resistance ◽

Bariatric Surgery ◽

Serum Levels ◽

Medical Laboratory ◽

Leptin Resistance ◽

Obese Patients ◽

Laboratory Assessment ◽

Serum Leptin ◽

Before And After ◽

Bariatric Patients

Background and aims: Overweight and obese patients who undergo bariatric surgery require a rigorous clinical and paraclinical assessment both before and after the surgery at 3, 6, and 12 months.The present study aims the assessment of serum leptin levels and insulin resistance status in compliant bariatric patients to scheduled medical laboratory assessment at 6 months after surgery. Material and Method: The study included 109 eligible patients selected for bariatric surgery, 48 of whom attended the scheduled visit at 6 months after the surgery. Laboratory assessing regarded the insulin resistance by determining before meal the serum levels of leptin, glucose and insulin, as well as HOMA 1 and HOMA 2 indexes. Results: Patients who underwent bariatric treatment experienced a significant decrease in insulin resistance status. A higher percentage in the preoperative group was recorded in women, feature which was also recorded in the postoperative group that attended the scheduled visit at 6 months after surgery. Age is also an important factor that significantly influences the behavioral adherence to postoperative visits. Conclusions: Insulin resistance status improved significantly in 6 months after bariatric surgery among the fully compliant patients. The percentage of attendance at scheduled visits is higher among women, and decreases with age. Keywords: obesity surgery, leptin resistance, insulin resistance, HOMA index, compliance

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High Cycle Fatigue and Fatigue Crack Propagation Behaviors of Modified A7075-T73 Alloy

Korean Journal of Metals and Materials ◽

10.3365/kjmm.2014.52.4.283 ◽

2014 ◽

Vol 52 (4) ◽

pp. 283-291 ◽

Cited By ~ 4

Author(s):

Gwan Yeong Kim ◽

Kyu Sik Kim ◽

Joong Cheol Park ◽

Shae Kwang Kim ◽

Young Ok Yoon ◽

...

Keyword(s):

Fatigue Crack ◽

Crack Propagation ◽

Fatigue Crack Propagation ◽

High Cycle Fatigue ◽

Cycle Fatigue

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An Alternative Technique to Evaluate Crack Propagation Path in Hyperelastic Materials

Tire Science and Technology ◽

10.2346/1.3684484 ◽

2012 ◽

Vol 40 (1) ◽

pp. 42-58 ◽

Cited By ~ 6

Author(s):

R. R. M. Ozelo ◽

P. Sollero ◽

A. L. A. Costa

Keyword(s):

Constitutive Model ◽

Crack Propagation ◽

Experimental Tests ◽

Growth Direction ◽

Propagation Path ◽

J Integral ◽

Alternative Technique ◽

Crack Propagation Path ◽

Hyperelastic Materials ◽

Material Constitutive Model

Abstract REFERENCE: R. R. M. Ozelo, P. Sollero, and A. L. A. Costa, “An Alternative Technique to Evaluate Crack Propagation Path in Hyperelastic Materials,” Tire Science and Technology, TSTCA, Vol. 40, No. 1, January–March 2012, pp. 42–58. ABSTRACT: The analysis of crack propagation in tires aims to provide safety and reliable life prediction. Tire materials are usually nonlinear and present a hyperelastic behavior. Therefore, the use of nonlinear fracture mechanics theory and a hyperelastic material constitutive model are necessary. The material constitutive model used in this work is the Mooney–Rivlin. There are many techniques available to evaluate the crack propagation path in linear elastic materials and estimate the growth direction. However, most of these techniques are not applicable to hyperelastic materials. This paper presents an alternative technique for modeling crack propagation in hyperelastic materials, based in the J-Integral, to evaluate the crack path. The J-Integral is an energy-based parameter and is applicable to nonlinear materials. The technique was applied using abaqus software and compared to experimental tests.

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