Evaluating Toughness as a Parameter to Determine the Fatigue Life of Wollastonite Microfiber Reinforced High Flow Pavement Quality Concrete

Author(s):  
Shashi Kant Sharma ◽  
K. P. Marisarla Chaitanya
Keyword(s):  
Author(s):  
Akihiko Hirano ◽  
Katsumi Sakaguchi ◽  
Tetsuo Shoji

Fatigue tests in simulated LWR environment of carbon and stainless steels were performed under high water flow rates between 7 to 10 m/s. For carbon steel, high flow rate of water clearly mitigated the environmental effect on the fatigue life at the high sulfur concentration of 0.016% which caused high environmental effect on a fatigue life. On the contrary, high flow rate of water slightly enhanced the environmental effect at the low sulfur concentration at or less than 0.008% which caused very low environmental effect. These results suggested that the environmental fatigue life under various flow rate conditions should be determined by the combination between the mitigating effect caused by flushing of the severe local environment and the enhancing effect caused by increase in corrosion potential. Low alloy steel showed the similar behavior as carbon steel. For stainless steel, flow rate had little effect on the fatigue life of type 316NG stainless steel. It suggested that there was no role of water flushing. For type 304 and 304L stainless steel, fatigue life has a tendency to decrease with increase in water flow rate. Fatigue lives of type 304 stainless steel under high flow rate of 7 to 10 m/s were shorter than those predicted by proposed fatigue life prediction equation by the Japanese EFT committee. This effect should be considered in an evaluation of environmental fatigue. No water flow effect was found in cast stainless steel.


Author(s):  
Akihiko Hirano ◽  
Michiyoshi Yamamoto ◽  
Katsumi Sakaguchi ◽  
Tetsuo Shoji

Fatigue tests in simulated LWR environment of carbon and stainless steels were performed under high water flow rates between 7 to 10 m/s. For carbon steel, high flow rate of water clearly mitigated the environmental effect on a fatigue life at the high sulfur concentration of 0.016 wt% which caused high environmental effect on a fatigue life. On the contrary, high flow rate of water slightly enhanced the environmental effect at the low sulfur concentration at or less than 0.008 wt% which caused very low environmental effect. These results suggested that the environmental fatigue life under various flow rate conditions should be determined by the combination between the mitigating effect caused by flushing of locally severe environment and the enhancing effect caused by increase in corrosion potential. To understand those effects, effects of sulfur concentration on fatigue life for various DO condition were formulated. And corrosion potential under low and high flow rate condition was measured during the fatigue test. Environmental correction factor, Fen, which is the ratio of fatigue lives derived from the fatigue life at room temperature in air divided by that in water to be used for the fatigue life prediction at high flow rate condition was assumed based on the MITI guideline equation and considering the hypothetical fatigue life under sulfur free condition and high corrosion potential condition. This assumption was agreed very well with the test data. For stainless steel, flow rate had little effect on a fatigue life of type 316 stainless steel. It suggested that there was no role of water flushing. For type 304 stainless steel, fatigue life has a tendency to decrease with increase in water flow rate. Fatigue lives of type 304 stainless steel under high flow rate of 7 to 10 m/s were shorter than those predicted by MITI guideline equation. This effect should be considered in an evaluation of environmental fatigue.


Author(s):  
Thomas P. Turnbull ◽  
W. F. Bowers

Until recently the prime purposes of filters have been to produce clear filtrates or to collect particles from solution and then remove the filter medium and examine the particles by transmission electron microscopy. These filters have not had the best characteristics for scanning electron microscopy due to the size of the pores or the surface topography. Advances in polymer chemistry and membrane technology resulted in membranes whose characteristics make them versatile substrates for many scanning electron microscope applications. These polysulphone type membranes are anisotropic, consisting of a very thin (0.1 to 1.5 μm) dense skin of extremely fine, controlled pore texture upon a much thicker (50 to 250μm), spongy layer of the same polymer. Apparent pore diameters can be controlled in the range of 10 to 40 A. The high flow ultrafilters which we are describing have a surface porosity in the range of 15 to 25 angstrom units (0.0015-0.0025μm).


2020 ◽  
Vol 5 (4) ◽  
pp. 1006-1010
Author(s):  
Jennifer Raminick ◽  
Hema Desai

Purpose Infants hospitalized for an acute respiratory illness often require the use of noninvasive respiratory support during the initial stage to improve their breathing. High flow oxygen therapy (HFOT) is becoming a more popular means of noninvasive respiratory support, often used to treat respiratory syncytial virus/bronchiolitis. These infants present with tachypnea and coughing, resulting in difficulties in coordinating sucking and swallowing. However, they are often allowed to feed orally despite having high respiratory rate, increased work of breathing and on HFOT, placing them at risk for aspiration. Feeding therapists who work with these infants have raised concerns that HFOT creates an additional risk factor for swallowing dysfunction, especially with infants who have compromised airways or other comorbidities. There is emerging literature concluding changes in pharyngeal pressures with HFOT, as well as aspiration in preterm neonates who are on nasal continuous positive airway pressure. However, there is no existing research exploring the effect of HFOT on swallowing in infants with acute respiratory illness. This discussion will present findings from literature on HFOT, oral feeding in the acutely ill infant population, and present clinical practice guidelines for safe feeding during critical care admission for acute respiratory illness. Conclusion Guidelines for safety of oral feeds for infants with acute respiratory illness on HFOT do not exist. However, providers and parents continue to want to provide oral feeds despite clinical signs of respiratory distress and coughing. To address this challenge, we initiated a process change to use clinical bedside evaluation and a “cross-systems approach” to provide recommendations for safer oral feeds while on HFOT as the infant is recovering from illness. Use of standardized feeding evaluation and protocol have improved consistency of practice within our department. However, further research is still necessary to develop clinical practice guidelines for safe oral feeding for infants on HFOT.


1995 ◽  
Vol 05 (C8) ◽  
pp. C8-1223-C8-1228
Author(s):  
N. Hagemeister ◽  
L'H. Yahia ◽  
E. Weynant ◽  
T. Lours

2020 ◽  
Vol 117 (6) ◽  
pp. 615
Author(s):  
Ping Shen ◽  
Lei Zhou ◽  
Qiankun Yang ◽  
Zhiqi Zeng ◽  
Kenan Ai ◽  
...  

In 38MnVS6 steel, the morphology of sulfide inclusion has a strong influence on the fatigue life and machinability of the steel. In most cases, the MnS inclusions show strip morphology after rolling, which significantly affects the steel quality. Usually, the MnS inclusion with a spherical morphology is the best morphology for the steel quality. In the present work, tellurium was applied to 38MnVS6 micro-alloyed steel to control the MnS inclusion. Trace tellurium was added into 38MnVS6 steel and the effect of Te on the morphology, composition, size and distribution of MnS inclusions were investigated. Experimental results show that with the increase of Te content, the equivalent diameter and the aspect ratio of inclusion decrease strikingly, and the number of inclusions with small aspect ratio increases. The inclusions are dissociated and spherized. The SEM-EDS analysis indicates that the trace Te mainly dissolves in MnS inclusion. Once the MnS is saturated with Te, MnTe starts to generate and wraps MnS. The critical Te/S value for the formation of MnTe in the 38MnV6 steel is determined to be approximately 0.075. With the increase of Te/S ratio, the aspect ratio of MnS inclusion decreases and gradually reaches a constant level. The Te/S value in the 38MnVS6 steel corresponding to the change of aspect ratio from decreasing to constant ranges from 0.096 to 0.255. This is most likely to be caused by the saturation of Te in the MnS inclusion. After adding Te in the steel, rod-like MnS inclusion is modified to small inclusion and the smaller the MnS inclusion, the lower the aspect ratio.


2020 ◽  
Vol 2 (04) ◽  
pp. 327-335
Author(s):  
Markus Bald ◽  
Carl Josef Hocke
Keyword(s):  

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