Natural vs. Artificial Aging

1930 ◽  
Vol 3 (1) ◽  
pp. 148-155
Author(s):  
Stanley Krall
Keyword(s):  
Oxygen Pressure ◽  
Artificial Aging ◽  
Natural Aging ◽  
First Grade ◽  
Pneumatic Tire ◽  
Oxygen Bomb ◽  
Short Period ◽  
Aging Properties ◽  
American Society

Abstract A CONSIDERABLE number of types of artificial aging are being used today in an endeavor to determine the aging properties of rubber stocks in a short period of time without waiting for natural aging results. The data reported here were taken from some that are being obtained by Sub-Committee XV, Committee D-11 of the American Society for Testing Materials. Experimental Three types of pneumatic tire stocks were aged by two natural and two artificial methods: (1) Slabs were hung separately in the dark. (2) Slabs were hung separately exposed to the weather. (3) One-inch (2.5-cm.) wide strips were hung separately in the Geer (2) oven at 158° F. (70° C.). (4) One-inch (2.5-cm.) wide strips were hung separately in the Bierer (1) oxygen bomb at 158° F. (70° C.) and 300 pounds (21 kg. per sq. cm.) oxygen pressure. The stocks tested were a pure gum stock, a first grade, and a reclaim tread stock as follows:

scholarly journals Clustering behavior during natural aging and artificial aging in Al-Mg-Si alloys with different Ag and Cu addition

2018 ◽  
Vol 732 ◽  
pp. 273-283 ◽  
Author(s):  
Yaoyao Weng ◽  
Zhihong Jia ◽  
Lipeng Ding ◽  
Shinji Muraishi ◽  
Qing Liu
Keyword(s):  
Artificial Aging ◽  
Natural Aging ◽  
Clustering Behavior

Effect of Non-Conventional Aging Treatments on the Tensile Properties of Non-Hipped Castings of Aluminum Alloy 354

2014 ◽  
Vol 875-877 ◽  
pp. 1397-1405 ◽  
Author(s):  
G. Dinesh Babu ◽  
M. Nageswara Rao
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Aluminum Alloy ◽  
Tensile Properties ◽  
Artificial Aging ◽  
Natural Aging ◽  
Single Step ◽  
Cast Aluminum Alloy ◽  
Cast Aluminum ◽  
Automobile Components

Cast aluminum alloy 354 is used extensively for production of critical automobile components, owing to its excellent castability and attractive combination of mechanical properties after heat-treatment. With the advent of higher performance engines, there has been a steady demand to further improve the mechanical behavior of the castings made of the alloy, among others, through improvements in processing. The present study explores the possibility of improving tensile properties of the alloy by adopting certain non-conventional aging treatments. The non-conventional treatments include aging cycles similar to T6I4 and T6I6 referred to in the published literature, artificial aging in two steps instead of in single step and artificial aging preceded by various natural aging times. The results show that none of these non-conventional treatments leads to improvement of all tensile properties compared to the standard T61 treatment. Significant hardening takes place in the alloy due to natural aging. Changing the time of natural aging preceding artificial aging was found to have little effect on tensile properties.

Effect of Non-Conventional Aging Treatments on the Tensile Properties and Quality Indices of Hipped Components Made of Cast Aluminum Alloy 354

2014 ◽  
Vol 875-877 ◽  
pp. 1429-1436 ◽  
Author(s):  
G. Dinesh Babu ◽  
M. Nageswara Rao
Keyword(s):  
Aluminum Alloy ◽  
Mechanical Behavior ◽  
Tensile Properties ◽  
Artificial Aging ◽  
Natural Aging ◽  
Single Step ◽  
Quality Level ◽  
Cast Aluminum Alloy ◽  
Cast Aluminum ◽  
Quality Indices

Cast aluminum alloy 354 is used extensively for production of critical automobile component, owing to its excellent castability and attractive combination of mechanical properties. With the advent of higher performance engines, there has been a steady demand to further improve the mechanical behavior of the alloy, among others, through improvements in processing. The present study explores the possibility of improving mechanical behavior and quality levels of the alloy by adopting certain non-conventional aging treatments. Quality indices Q and QC have been used for quality rating. The non-conventional treatments include aging cycles similar to T6I4 and T6I6 referred to in the published literature, artificial aging in two steps instead of in single step and artificial aging preceded by various natural aging times. The results show that none of the non-conventional treatments leads to improvement of all tensile properties compared to the standard T61 treatment. However, some specific treatments could be identified which lead to a comparable combination of tensile properties and a shade higher quality level. Increasing the time of preceding natural aging does not help in improving the tensile properties after artificial aging.

scholarly journals Effects of natural aging and reversion treatments on artificial aging behavior of 6000 series aluminum alloys

2009 ◽  
Vol 59 (3) ◽  
pp. 128-133 ◽  
Author(s):  
Takahiko Nakamura ◽  
Kazuto Morita ◽  
Masanori Nagai ◽  
Shin-ya Komatsu
Keyword(s):  
Aluminum Alloys ◽  
Artificial Aging ◽  
Natural Aging ◽  
Aging Behavior

The Influence of Prolonged Natural Aging on the Subsequent Artificial Aging Response of the AA6111 Automotive Alloy

2015 ◽  
Vol 46 (9) ◽  
pp. 4380-4393 ◽  
Author(s):  
Abdelhadi Abouarkoub ◽  
G. E. Thompson ◽  
X. Zhou ◽  
T. Hashimoto ◽  
G. Scamans
Keyword(s):  
Artificial Aging ◽  
Natural Aging ◽  
Aging Response

scholarly journals Gust Factors and Turbulence Intensities for the Tropical Cyclone Environment

2009 ◽  
Vol 48 (3) ◽  
pp. 534-552 ◽  
Author(s):  
Bo Yu ◽  
Arindam Gan Chowdhury
Keyword(s):  
Tropical Cyclone ◽  
Surface Wind ◽  
Monitoring Program ◽  
Near Surface ◽  
Wind Speeds ◽  
Flat Terrain ◽  
Short Period ◽  
Terrain Roughness ◽  
American Society ◽  
Gust Factors

Abstract Gust factors are used to convert peak wind speeds averaged over a relatively short period (e.g., 3 s) to mean wind speeds averaged over a relatively long reference period (e.g., 1 h) or vice versa. Such conversions are needed for engineering, climatological, or forecasting purposes. In this paper, gust factors in tropical cyclone (TC) winds are estimated from Florida Coastal Monitoring Program (FCMP) observations of near-surface TC wind speeds representative of flow over the sea surface and over open flat terrain in coastal areas. Comparisons are made with gust factors in extratropical winds over open flat terrain that are available in the literature. According to the results of the study, for gust durations of less than 20 s, the Durst model underestimates, and the Krayer–Marshall model overestimates, gust factors of TC winds over surfaces with roughness specified in the American Society of Civil Engineers (ASCE) 7 Standard Commentary as typical of open terrain. Consideration should be given to these findings when updating the gust factors provided in the ASCE 7 Standard Commentary. The study also compares gust factors in TC winds obtained from FCMP data with gust factors in extratropical winds obtained from near-surface wind data collected at eight Automated Surface Observing System (ASOS) stations and concludes that, depending upon terrain roughness, gust factors in TC winds can be higher by about 10%–15% than gust factors in extratropical winds. The study also presents FCMP-based estimates of turbulence intensities and their variability and shows that turbulence intensities in TC winds increase as the terrain roughness increases. The longitudinal turbulence intensity can vary from storm to storm and can exceed its typical value by as much as 20%. It is recommended that future TC wind measurement campaigns obtain temperature data usable for stratification estimation purposes, as well as information on waves and storm surge upwind of the anemometer towers.

The T5 Heat Treatment of Semi-Solid Metal Processed Aluminium Alloy F357

2009 ◽  
Vol 618-619 ◽  
pp. 365-368 ◽  
Author(s):  
Heinrich Möller ◽  
Gonasagren Govender ◽  
Waldo Stumpf
Keyword(s):  
Heat Treatment ◽  
Aluminium Alloy ◽  
Tensile Properties ◽  
Cooling Rate ◽  
Quality Index ◽  
Artificial Aging ◽  
Natural Aging ◽  
Solid Metal ◽  
Semi Solid

The T5 heat treatment of semi-solid metal (SSM) processed alloy F357 was investigated by considering the effects of cooling rate and natural aging after casting, as well as artificial aging parameters on tensile properties. In addition, the tensile properties of SSM-HPDC F357 in different temper conditions (F, T4, T5 and T6) are compared. The Quality Index (QI) is used to compare the influence of different T5 heat treatment parameters and different temper conditions.

scholarly journals Micronutrient Monitoring and Management in Parenteral Nutrition–Dependent Premature Neonates: A Case Series

2021 ◽  
Vol 26 (2) ◽  
pp. 200-204
Author(s):  
Kassandra L. Vettleson ◽  
Hannah J. Larson ◽  
Mohamed W. Mohamed ◽  
Carlina J. Grindeland ◽  
Julia D. Muzzy Williamson
Keyword(s):  
Parenteral Nutrition ◽  
Lipid Emulsion ◽  
Case Series ◽  
Gastrointestinal Complications ◽  
Premature Neonates ◽  
Short Period ◽  
Pediatric Nutrition ◽  
Prospective Case Series ◽  
American Society ◽  
Spontaneous Intestinal Perforation

We present a prospective case series of 3 premature neonates with abnormal vitamin A, vitamin E, and selenium levels after being managed on prolonged parenteral nutrition (PN). All 3 patients experienced gastrointestinal complications including spontaneous intestinal perforation, necrotizing enterocolitis, and/or short bowel syndrome. Additionally, all 3 patients developed PN-associated liver disease, which required the use of a mixed lipid emulsion and a fish oil–based lipid emulsion for a short period of time. We evaluated the micronutrient levels of these patients after they had been receiving PN for 1 to 2 months. After the early identification of these abnormalities, we promptly attempted to correct the levels through supplementation and restriction, as appropriate. One barrier we experienced in the treatment of these patients was the conflicting guidance of daily micronutrient dosing in PN and when to evaluate levels in premature infants from the European and American pediatric nutrition organizations, the European Society for Paediatric Gastroenterology Hepatology and Nutrition and the American Society for Parenteral and Enteral Nutrition. Additionally, after we assessed micronutrient levels, we experienced a lack of guidance on how to adjust dosing and when to monitor subsequent levels.

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