External Factors Impact on Basic Properties of Hovercraft Skirt Materials

2017 ◽  
Vol 265 ◽  
pp. 615-619
Author(s):  
A.K. Yakimov ◽  
Ye.N. Butusova ◽  
A.V. Tumanin
Keyword(s):  
Temperature Variation ◽  
Fresh Water ◽  
Operation Time ◽  
Strength Properties ◽  
External Factors ◽  
Strength Characteristics ◽  
Reliable Prediction ◽  
Air Cushion ◽  
The Impact ◽  
Air Cushion Vehicles

The article is devoted to the research of the most common materials for air-cushion vehicles skirt (ACV, hovercraft). The paper presents the results of the impact various external factors have on hovercraft operational properties. The impact of temperature and operation time of the ACV on strength characteristics of these materials are investigated. The influence of prolonged soaking in fresh water on the adhesion of the coating was researched. It is noted that temperature variation strongly affects the tear resistance of the materials. It is shown that the strength properties and adhesion are significantly changed during the operation of the ACV. It is noticed that such changes are intrinsic to both materials. It is recommended to use the obtained results in the design of hovercraft skirts for the reliable prediction of their life.

scholarly journals The Effect of Mixing Technique and Prolonged Mixing Time on Strength Characteristics of Concrete

Proceedings ◽  
2018 ◽  
Vol 2 (20) ◽  
pp. 1290
Author(s):  
Karol Urban ◽  
Alena Sicakova
Keyword(s):  
Compressive Strength ◽  
Mixing Time ◽  
Strength Properties ◽  
Recycled Concrete ◽  
Strength Characteristics ◽  
Concrete Aggregate ◽  
Splitting Strength ◽  
Mixing Method ◽  
Tensile Splitting Strength ◽  
The Impact

The experiment aims to test the triple mixing (3M) technique to produce the concrete with recycled concrete aggregate (RCA). Then, the impact prolonged mixing, representing the influence of delivery and discharge time in praxis, is analysed by the change in strength properties. Both the 28-day compressive strength and tensile splitting strength are evaluated in two aspects: the prolonged mixing time (0, 45 and 90 min after initial mixing), and the mixing method (normal and triple). Prolonged mixing time brought both the positive and negative changes in strength characteristics however the worst difference between initial mixing (0′) and 90′ minutes of mixing was only 8.4% for compressive strength and 8.5% for tensile splitting strength.

scholarly journals Sheet metal with variable mechanical properties over its thickness

2019 ◽  
Vol 62 (8) ◽  
pp. 587-593
Author(s):  
A. B. Maksimov ◽  
I. P. Shevchenko ◽  
I. S. Erohina
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Rupture Strength ◽  
Strength Properties ◽  
Deformation Resistance ◽  
Strength Characteristics ◽  
Load Application ◽  
Bending Test ◽  
Accelerated Cooling ◽  
The Impact

The influence of one-sided accelerated cooling of A32 plate shipbuilding steel with thickness of 10·10–3 m on structure and mechanical properties was investigated. As a result of such cooling, continuous spectrum of microstructures from ferrite-bainite on the rapidly cooled surface to ferrite-perlite on the opposite surface is formed along the billet thickness. Therefore, over the billet thickness strength properties are reduced from rapidly cooled surface to the opposite one. Thus, the gradient of strength characteristics (hardness, yield strength and rupture strength) along the billet thickness is directed to rapidly cooled surface. For comparative analysis, other batches of billets were subjected to normalization and hardening with high tempering. The analysis of mechanical properties has shown that strength and plastic properties of the samples at unilateral accelerated cooling are at level of heat-strengthened state. Testing on impact strength of the samples with variable distribution of mechanical properties over their thickness has shown that the impact depends on correlation of gradient directions of strength properties and load application. In impact bending test at the temperature of –40 °C, if the direction of load application is opposite to gradient of strength properties, the impact work was more than 300 J (the sample did not collapse). At coincidence of directions of the gradient deformation resistance and load, energy of the blow was 262 J. Thus, if the direction of deformation resistance gradient coincides with the direction of external applied load, then it leads to an increase in plasticity of steel. It is shown that, knowing distribution of strength characteristics over the sample thickness, it is possible to calculate integral values of yield strength and rupture strength of the sample. Value of relative through-thickness elongation increases from the rapidly cooled surface to the opposite one. Integral elongation of the billet is less than the smallest relative through-thickness elongation. With changing thickness strength of the billet during bending, displacement of the neutral deformation line relative to the geometrically average line in the direction of the strength properties gradient is inevitable. The position of neutral line of deformation during bending is proposed to be determined by the value of experimental integral yield strength (rupture strength).

Does kraft hardwood and softwood pulp viscosity correlate to paper properties?

TAPPI Journal ◽  
2016 ◽  
Vol 15 (10) ◽  
pp. 643-651 ◽  
Author(s):  
ROBERT J. OGLESBY ◽  
HUMPHREY J. MOYNIHAN ◽  
RICARDO B. SANTOS ◽  
ASHOK GHOSH ◽  
PETER W. HART
Keyword(s):  
Physical Properties ◽  
Strength Loss ◽  
Strength Properties ◽  
Clear Correlation ◽  
Paper Properties ◽  
Physical Strength ◽  
Pulp Viscosity ◽  
Softwood Pulp ◽  
The Impact ◽  
Related Paper

The impact of commercially prepared, fully bleached pulp viscosity variation on handsheet physical properties was evaluated at different levels of pulp refining. Hardwood pulps from the same brownstock species mix, cooking parameters, and kappa numbers were processed through two different commercial bleach plants: one with a D0(EP)D1D2 sequence and the second with an OD0(EOP)D1 sequence. Additionally, a commercial softwood (predominately Scotts pine) brownstock pulp bleached by an OD0(EP)D1D2 sequence was employed in this study. Pulps with viscosities ranging from 14 to 21 mPa∙s were refined in a Valley beater to two freeness levels, and the associated handsheet physical properties were measured in this study. Over the pulp viscosity range of 14 to 21 mPa∙s, no clear correlation was found to exist between pulp viscosity and related paper physical properties. Finally, a series of laboratory prepared bleached pulps were purposely prepared under non-ideal conditions to reduce their final viscosities to lower values. Handsheets made from these pulps were tested in their unbeaten condition for physical strength properties. Significant and rapid strength loss occurred when the measured pulp viscosity dropped below 12 mPa∙s; overall strength properties showed no correlation to viscosity above the critical 12 mPa∙s value.

Some reflections on social structure: Theoretical and practical aspects

2020 ◽  
Vol 18 (6) ◽  
pp. 1063-1078
Author(s):  
T.N. Skorobogatova ◽  
I.Yu. Marakhovskaya
Keyword(s):  
Service Industry ◽  
External Factors ◽  
Infrastructure Development ◽  
Social Infrastructure ◽  
Social Sphere ◽  
The Social ◽  
Study Results ◽  
The Republic ◽  
Internal And External Factors ◽  
The Impact

Subject. This article discusses the role of social infrastructure in the national economy and analyzes the relationship between the notions of Infrastructure, Service Industry and Non-Productive Sphere. Objectives. The article aims to outline a methodology for development of the social infrastructure of Russia's regions. Methods. For the study, we used the methods of statistical and comparative analyses. The Republic of Crimea and Rostov Oblast's social infrastructure development was considered as a case study. Results. The article finds that the level of social infrastructure is determined by a number of internal and external factors. By analyzing and assessing such factors, it is possible to develop promising areas for the social sphere advancement. Conclusions. Assessment and analysis of internal factors largely determined by the region's characteristics, as well as a comprehensive consideration of the impact of external factors will help ensure the competitiveness of the region's economy.

Evaluation of Hydraulic Fracturing Models and Their Limitations to Predict No-Drill Zones for Horizontal Directional Drilling

2018 ◽  
Author(s):  
Saeed Delara ◽  
Kendra MacKay
Keyword(s):  
Hydraulic Fracturing ◽  
Safety Factor ◽  
Standard Procedure ◽  
Accurate Determination ◽  
Strength Properties ◽  
Analytical Models ◽  
Alternative Methods ◽  
Directional Drilling ◽  
Horizontal Directional Drilling ◽  
The Impact

Horizontal directional drilling (HDD) has become the preferred method for trenchless pipeline installations. Drilling pressures must be limited and a “no-drill zone” determined to avoid exceeding the strength of surrounding soil and rock. The currently accepted industry method of calculating hydraulic fracturing limiting pressure with application of an arbitrary safety factor contains several assumptions that are often not applicable to specific ground conditions. There is also no standard procedure for safety factor determination, resulting in detrimental impacts on drilling operations. This paper provides an analysis of the standard methods and proposes two alternative analytical models to more accurately determine the hydraulic fracture point and acceptable drilling pressure. These alternative methods provide greater understanding of the interaction between the drilling pressures and the surrounding ground strength properties. This allows for more accurate determination of horizontal directional drilling limitations. A comparison is presented to determine the differences in characteristics and assumptions for each model. The impact of specific soil properties and factors is investigated by means of a sensitivity analysis to determine the most critical soil information for each model.

scholarly journals Evaluation of the Impact of Organic Fillers on Selected Properties of Organosilicon Polymer

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1103
Author(s):  
Sara Sarraj ◽  
Małgorzata Szymiczek ◽  
Tomasz Machoczek ◽  
Maciej Mrówka
Keyword(s):  
Tensile Strength ◽  
Natural Fiber ◽  
Accelerated Aging ◽  
Strength Properties ◽  
Visual Observation ◽  
Walnut Shell ◽  
Pistachio Shell ◽  
Thermoplastic Matrix ◽  
Static Tensile ◽  
The Impact

Eco-friendly composites are proposed to substitute commonly available polymers. Currently, wood–plastic composites and natural fiber-reinforced composites are gaining growing recognition in the industry, being mostly on the thermoplastic matrix. However, little data are available about the possibility of producing biocomposites on a silicone matrix. This study focused on assessing selected organic fillers’ impact (ground coffee waste (GCW), walnut shell (WS), brewers’ spent grains (BSG), pistachio shell (PS), and chestnut (CH)) on the physicochemical and mechanical properties of silicone-based materials. Density, hardness, rebound resilience, and static tensile strength of the obtained composites were tested, as well as the effect of accelerated aging under artificial seawater conditions. The results revealed changes in the material’s properties (minimal density changes, hardness variation, overall decreasing resilience, and decreased tensile strength properties). The aging test revealed certain bioactivities of the obtained composites. The degree of material degradation was assessed on the basis of the strength characteristics and visual observation. The investigation carried out indicated the impact of the filler’s type, chemical composition, and grain size on the obtained materials’ properties and shed light on the possibility of acquiring ecological silicone-based materials.

scholarly journals Water Influence on the Uniaxial Tensile Behavior of Polytetrafluoroethylene-Coated Glass Fiber Fabric

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 846
Author(s):  
Hastia Asadi ◽  
Joerg Uhlemann ◽  
Natalie Stranghoener ◽  
Mathias Ulbricht
Keyword(s):  
Mechanical Properties ◽  
Glass Fiber ◽  
Operation Time ◽  
Uniaxial Tensile ◽  
Membrane Structures ◽  
Strength Deterioration ◽  
Coated Glass ◽  
Reversible Loss ◽  
The Impact ◽  
Loss Of Strength

Polytetrafluoroethylene (PTFE)-coated glass fiber fabrics are used for long-lasting membrane structures due to their outstanding mechanical properties, chemical stabilities, and satisfying service life. During their operation time, different environmental impacts might influence their performance, especially regarding the mechanical properties. In this contribution, the impact of water on the tensile strength deterioration was assessed experimentally, providing evidence of considerable but partially reversible loss of strength by up to 20% among the various types of investigated industrially established fabrics.

scholarly journals Investigation of the Influence of Open-Die Forging Parameters on the Flow Kinetics of AZ91 Magnesium Alloy

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4010
Author(s):  
Grzegorz Banaszek ◽  
Teresa Bajor ◽  
Anna Kawałek ◽  
Tomasz Garstka
Keyword(s):  
Magnesium Alloy ◽  
Operation Time ◽  
Strength Properties ◽  
Hydraulic Press ◽  
Az91 Alloy ◽  
Az91 Magnesium Alloy ◽  
Numerical Tests ◽  
Az91 Magnesium ◽  
Product Manufacturing ◽  
Open Die Forging

This paper presents the results of numerical tests of the process of forging magnesium alloy ingots (AZ91) on a hydraulic press with the use of flat and proprietary shaped anvils. The analysis of the hydrostatic pressure distribution and the deformation intensity was carried out. It is one of the elements used for determining the assumptions for the technology of forging to obtain a semi-finished product from the AZ91 alloy with good strength properties. The aim of the research was to reduce the number of forging passes, which will shorten the operation time and reduce the product manufacturing costs. Numerical tests of the AZ91 magnesium alloy were carried out using commercial Forge®NxT software.

scholarly journals Competitiveness Determinants of Moroccan Exports: Quantity-Based Analysis

2016 ◽  
Vol 8 (7) ◽  
pp. 140 ◽  
Author(s):  
Bilal Lotfi ◽  
Mohamed Karim
Keyword(s):  
European Union ◽  
Literature Review ◽  
Econometric Analysis ◽  
External Factors ◽  
The European Union ◽  
Export Competitiveness ◽  
Main Determinants ◽  
Internal And External Factors ◽  
The Impact ◽  
Relative Concept

<p>The term competitiveness is a relative concept whose perception changes with the level of conducted analysis (nation, sector, company). Thus, a variety of internal and external factors can have deep effects on the competitiveness of a given entity. This paper aims to evaluate the competitiveness of Moroccan exports by identifying the main determinants that explain their performance. This is particularly dealing with the impact of customs’ tariff, the tariff of import, foreign demand, the share of the non-residents in the capital of domestic enterprises and the investment rate compared to the value of exporters.</p><p>Moreover, this paper presents a literature review on competitiveness and examines the main results of our econometric analysis regarding the determinants of export competitiveness applied to the top ten branches most exporters in Morocco. The gained results allow confirming the sensitivity of exports by branch to the situation of Morocco’s main trading partner namely the European Union while emphasizing, quantitatively, on the role played by the investment effort undertaken by Moroccan exporting companies in improving the competitiveness of national exports.</p>

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