scholarly journals Study Effect of Silver Oxide Addition on Mechanical Properties of Epoxy Composites

2018 ◽  
Vol 3 (7) ◽  
pp. 38 ◽  
Author(s):  
Ismail Ibrahim Marhoon ◽  
Dalia Adil Rasool ◽  
Kawther Ali Dhumad ◽  
Younis Swadi Tlaiaa ◽  
Mohammed Ali Abdulrehman
Keyword(s):  
Mechanical Properties ◽  
Applied Load ◽  
Silver Oxide ◽  
Volume Fraction ◽  
Wear Test ◽  
Epoxy Composites ◽  
Oxide Addition ◽  
Before And After ◽  
Relationship Of ◽  
The Relationship

This study included the preparation of specimens of epoxy reinforced by silver oxide. Some of their mechanical properties been studied such as hardness, compression strength and wear rate with volume fraction 2%,4%,6%. The results showed that the mechanical properties hardness and compressive were affected directly by the increase of the volume fraction of the reinforcement material. The samples with the highest volume fraction had the highest hardness and compressive strength. As for the wear test was conducted in the circumstances of changing the applied load 40,60,80 N were approved, respectively, results shown that the rate of wear increases with load increasing of all samples before and after the reinforcement. For the relationship of the rate of wear with the increasing of the volume fraction, the results showed that there is a decrease in the rate of wear with the increasing of the volume fraction.

Mechanical properties of the living dog aorta

1962 ◽  
Vol 202 (4) ◽  
pp. 619-621 ◽  
Author(s):  
Robert L. Evans ◽  
Eugene F. Bernstein ◽  
Evelyn Johnson ◽  
Carl Reller
Keyword(s):  
Mechanical Properties ◽  
Cross Section ◽  
Cross Sections ◽  
Hooke’S Law ◽  
Before And After ◽  
Hooke's Law ◽  
Pressure Changes ◽  
Relationship Of ◽  
The Relationship ◽  
Propagation Velocities

The variation of living dog aortic cross sections with volemic pressure changes is given for states before and after thoracotomy. The relationship of vessel cross section to pressure is approximately linear, does not follow Hooke's law, and is roughly the same for both dynamic and relatively static changes. The implied and directly measured propagation velocities are comparable to each other.

Sunlight exposure: the effects on the performance of paragliding fabric

2018 ◽  
Vol 69 (05) ◽  
pp. 381-389
Author(s):  
MENGÜÇ GAMZE SÜPÜREN ◽  
TEMEL EMRAH ◽  
BOZDOĞAN FARUK
Keyword(s):  
Mechanical Properties ◽  
Aging Process ◽  
Air Permeability ◽  
Sunlight Exposure ◽  
Test Results ◽  
Coating Materials ◽  
Strength Tests ◽  
Before And After ◽  
The Relationship ◽  
Dark Blue

This study was designed to explore the relationship between sunlight exposure and the mechanical properties of paragliding fabrics which have different colors, densities, yarn counts, and coating materials. This study exposed 5 different colors of paragliding fabrics (red, turquoise, dark blue, orange, and white) to intense sunlight for 150 hours during the summer from 9:00 a.m. to 3:00 p.m. for 5 days a week for 5 weeks. Before and after the UV radiation aging process, the air permeability, tensile strength, tear strength, and bursting strength tests were performed. Test results were also evaluated using statistical methods. According to the results, the fading of the turquoise fabric was found to be the highest among the studied fabrics. It was determined that there is a significant decrease in the mechanical properties of the fabrics after sunlight exposure. After aging, the fabrics become considerably weaker in the case of mechanical properties due to the degradation in both the dyestuff and macromolecular structure of the fiber

Monitoring of mechanical properties of prestressed glass fiber epoxy composites over 12 months after fabrication

2021 ◽  
pp. 002199832110047
Author(s):  
Mahmoud Mohamed ◽  
Siddhartha Brahma ◽  
Haibin Ning ◽  
Selvum Pillay
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Flexural Strength ◽  
Compressive Residual Stress ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Epoxy Composites ◽  
Flexural Properties ◽  
Initial Increase ◽  
Fiber Volume

Fiber prestressing during matrix curing can significantly improve the mechanical properties of fiber-reinforced polymer composites. One primary reason behind this improvement is the generated compressive residual stress within the cured matrix, which impedes cracks initiation and propagation. However, the prestressing force might diminish progressively with time due to the creep of the compressed matrix and the relaxation of the tensioned fiber. As a result, the initial compressive residual stress and the acquired improvement in mechanical properties are prone to decline over time. Therefore, it is necessary to evaluate the mechanical properties of the prestressed composites as time proceeds. This study monitors the change in the tensile and flexural properties of unidirectional prestressed glass fiber reinforced epoxy composites over a period of 12 months after manufacturing. The composites were prepared using three different fiber volume fractions 25%, 30%, and 40%. The results of mechanical testing showed that the prestressed composites acquired an initial increase up to 29% in the tensile properties and up to 32% in the flexural properties compared to the non-prestressed counterparts. Throughout the 12 months of study, the initial increase in both tensile and flexural strength showed a progressive reduction. The loss ratio of the initial increase was observed to be inversely proportional to the fiber volume fraction. For the prestressed composites fabricated with 25%, 30%, and 40% fiber volume fraction, the initial increase in tensile and flexural strength dropped by 29%, 25%, and 17%, respectively and by 34%, 26%, and 21%, respectively at the end of the study. Approximately 50% of the total loss took place over the first month after the manufacture, while after the sixth month, the reduction in mechanical properties became insignificant. Tensile modulus started to show a very slight reduction after the fourth/sixth month, while the flexural modulus reduction was observed from the beginning. Although the prestressed composites displayed time-dependent losses, their long-term mechanical properties still outperformed the non-prestressed counterparts.

Richard Scheringer, the KPD and the Politics of Class and Nation in Germany, 1922–1969

2005 ◽  
Vol 14 (3) ◽  
pp. 317-346 ◽  
Author(s):  
TIMOTHY S. BROWN
Keyword(s):  
Interwar Period ◽  
Third Reich ◽  
Radical Right ◽  
High Profile ◽  
Army Officer ◽  
Modern Germany ◽  
Before And After ◽  
The Third Reich ◽  
Relationship Of ◽  
The Relationship

This article examines the life and times of Richard Scheringer, an army officer and supporter of Adolf Hitler who became famous during the early 1930s for his high-profile conversion to communism. Known in the closing years of the Weimar Republic as a point-man for Communist efforts to win support from the radical right, Scheringer survived the Third Reich to become a leading figure in the postwar Communist Party. His well-documented but little-studied career, bridging critical caesurae of modern Germany history, highlights the unique political constellation of the interwar period, demonstrating fundamental continuities in the relationship of German communism to the nation before and after 1945.

Evaluating Mechanical Properties of Ceramics by Relative Methods

2007 ◽  
Vol 336-338 ◽  
pp. 2406-2410
Author(s):  
Yi Wang Bao ◽  
Xiao Xue Bu ◽  
Yan Chun Zhou ◽  
Li Zhong Liu
Keyword(s):  
Mechanical Properties ◽  
Material Properties ◽  
Ceramic Coatings ◽  
Relative Method ◽  
Tempered Glass ◽  
Theoretic Analysis ◽  
Surface Strength ◽  
Indirect Approach ◽  
Before And After ◽  
The Relationship

A relative method, defined as indirect approach to evaluate the material properties via the relationship between unknown properties and a known property, is proposed to estimate some properties that could not be measured by the traditional methods for ceramics. Experiments and theoretic analysis based on the relative method were carried out in this study to estimate the properties in following aspects: determining the temperature dependence of elastic modulus of some machineable ceramics by comparing the deflections; obtaining the modulus and strength of ceramic coatings supported by substrates, from the variation in properties of the rectangular beam samples before and after coating; estimating the residual stresses in tempered glass by comparing the change in the surface strength after strengthening.

Limitations to prediction of maximal oxygen intake

1964 ◽  
Vol 19 (5) ◽  
pp. 919-927 ◽  
Author(s):  
Loring B. Rowell ◽  
Henry L. Taylor ◽  
Yang Wang
Keyword(s):  
Metabolic Rate ◽  
Pulse Rate ◽  
Oxygen Intake ◽  
Physical Conditioning ◽  
Maximal Oxygen Intake ◽  
Before And After ◽  
Normal Men ◽  
Accuracy Of Prediction ◽  
Relationship Of ◽  
The Relationship

The predictability of maximal O2 intake (max Vo2) was studied in four groups of normal men, 18–24 years of age. Prediction of max Vo2 was made from pulse rate and Vo2 at a single submaximal workload at an ambient temperature of 78 F by use of the nomogram of Åstrand and Ryhming (1954) and underestimated actual max Vo2 by 27 ± 7% and 14 ± 7% in a sedentary group, before and after 2frac12–3 months of physical training, and by 5.6 ȁ 4% in a group of ten endurance athletes. Accuracy of prediction in all groups varied with approximation of pulse rate to 128 beats/min at 50% of max Vo2. Nonspecific stresses increased predictive errors in all groups. Constants b (slope) and A (intercept) in the regression equation Vo2 = bP – A (where P is pulse rate), were determined from Vo2 and pulse measured at four submaximal workloads requiring 13–28 ml O2/kg min. Prediction of max Vo2 by extrapolation of the slope to maximal pulse rate resulted in underestimation of 700–800 ml O2/min. Removal of 14% of circulating hemoglobin decreased max Vo2 by 4% but there was no change in pulse rates or predicted max Vo2. The relationship of RQ to V22 during work provided no reliable basis for prediction of max Vo2. exercise pulse rate, oxygen intake, relationship; pulse rate, oxygen intake relationship in exercise; metabolic rate, maximal aerobic prediction of; aerobic metabolic rate, maximal, prediction of; phlebotomy, effect on maximal oxygen intake, pulse rate; blood loss, effect on maximal oxygen intake, pulse rate; training, effect on maximal oxygen intake, pulse rates; physical conditioning, effect on maximal oxygen intake, pulse rates Submitted on October 4, 1963

Impact of cigarette package warnings on attitudes towards sharing and gifting cigarettes in China: a nationwide study of smokers and non-smokers

2021 ◽  
pp. tobaccocontrol-2020-056160
Author(s):  
Yanhui Liao ◽  
Jinsong Tang ◽  
Ann McNeill ◽  
Brian C Kelly ◽  
Joanna E Cohen
Keyword(s):  
Cross Sectional Study ◽  
Social Practices ◽  
Sectional Study ◽  
Health Warnings ◽  
Cross Sectional ◽  
Percentage Points ◽  
Before And After ◽  
Relationship Of ◽  
The Relationship ◽  
Cigarette Package

BackgroundSharing and gifting cigarettes are common in China. These social practices promote cigarette consumption, and consequently may reduce quit rates in China. This study investigated sharing and gifting cigarettes, and the relationship of observing pictorial health warnings to attitudes towards sharing and gifting cigarettes in China.MethodsWe conducted an online nationwide cross-sectional study of 9818 adults in China. Experiences of sharing and gifting cigarettes, and attitudes towards sharing and gifting cigarettes before and after viewing text and pictorial health warnings on the packages were assessed, and compared between smokers and non-smokers.ResultsMost current smokers reported experiences of sharing (97%) and gifting (around 90%) cigarettes. Less than half of non-smokers reported sharing cigarettes and receiving gifted cigarettes, but over half (61.4%) gave cigarettes as a gift to others. More than half of non-smokers but less than 10% of smokers disagreed with sharing and gifting cigarettes. After observing both text and pictorial health warnings on the packages, disagreement with sharing and gifting cigarettes increased by more than 10 percentage points among both smokers and non-smokers.ConclusionHaving pictorial health warnings on cigarette packages may reduce sharing and gifting cigarettes in China.

scholarly journals The Development of Snow and Glacier Research in Switzerland

1948 ◽  
Vol 1 (04) ◽  
pp. 192-201 ◽  
Author(s):  
R. Haefeli
Keyword(s):  
Mechanical Properties ◽  
Snow Cover ◽  
Laboratory Experiments ◽  
Relationship Of ◽  
The Relationship ◽  
Research Institute

The evolution of snow and glacier research in Switzerland is outlined. The settling, creep, viscosity and slipping of the snow cover are discussed in detail and the relationship of these comparatively simple processes to the more complex movements in a glacier are described. The importance of further research in glacier physics in connection with the crystallographic and mechanical properties of ice is stressed; certain preliminary laboratory experiments and some subjects for further research in the field are suggested. The Great Aletsch Glacier is recommended for this owing to the proximity of the Jungfraujoch Research Institute and facilities for transport by the Jungfraujoch Railway.

Performance Changing Regularity of No.70 Road Asphalt with Different Aging Time

2013 ◽  
Vol 723 ◽  
pp. 136-140
Author(s):  
Yi Hua Nie ◽  
Ping Liu ◽  
Li Xin Xu ◽  
Jie Ding
Keyword(s):  
Thin Film ◽  
Aging Time ◽  
Resin Content ◽  
Change Processes ◽  
Road Asphalt ◽  
Performance Indexes ◽  
Before And After ◽  
Asphalt Performance ◽  
Relationship Of ◽  
The Relationship

In this paper, rolling thin film oven is used to heat No.70 road asphalt to simulate asphalt aging. Six aging time tests of 0min, 40min, 85min, 180min, 240min and 300min were carried and the relationship of asphalt performance indexes before and after aging was got as well as four components. The analysis results indicate that: as the aging time increases, change processes of all performance indexes followed curve of index and the correlation coefficient reached significant level. Changing regularity of asphalt four components are also got: the contents of saturate and aromatic both decrease with the aging time increasing, while asphaltene content and resin content increased and the increasing speed of resin is faster. Key words: No.70 road asphalt; four components; performance index; aging.

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