The Structural Efficiency of Wing Covers

1945 ◽  
Vol 12 (1) ◽  
pp. A8-A12
Author(s):  
A. F. Donovan ◽  
Martin Goland ◽  
J. N. Goodier
Keyword(s):  
Yield Stress ◽  
Weight Ratio ◽  
High Strength ◽  
Limited Range ◽  
Structural Efficiency ◽  
Better Than ◽  
The Ideal

Abstract The paper seeks to establish rational criteria for evaluating the structural efficiencies of sheet-stiffener combinations and alternative constructions used for wing and other surfaces, and to determine the suitability of the available materials for panels of various proportions. The efficiency criteria require the determination of the ideal construction for such panels, and this is carried out. It is found that the primary requirement of the “best” material for the ideal design is a high strength-weight ratio (yield stress-density). A diagram (Fig. 5) is given to determine readily the weights of panels of ideal design made of various materials, all to carry the same load. In general one material is better than another only for a limited range of panel proportions.

scholarly journals DETERMINATION OF LIGHT QUARK MASSES IN QCD

2010 ◽  
Vol 25 (29) ◽  
pp. 5223-5234 ◽  
Author(s):  
C. A. DOMINGUEZ
Keyword(s):  
Strange Quark ◽  
Sum Rules ◽  
Standard Procedure ◽  
Light Quark ◽  
Qcd Sum Rules ◽  
Quark Masses ◽  
Systematic Uncertainties ◽  
Better Than ◽  
The Ideal

The standard procedure to determine (analytically) the values of the quark masses is to relate QCD two-point functions to experimental data in the framework of QCD sum rules. In the case of the light quark sector, the ideal Green function is the pseudoscalar correlator which involves the quark masses as an overall multiplicative factor. For the past thirty years this method has been affected by systematic uncertainties originating in the hadronic resonance sector, thus limiting the accuracy of the results. Recently, a major breakthrough has been made allowing for a considerable reduction of these systematic uncertainties and leading to light quark masses accurate to better than 8%. This procedure will be described in this talk for the up-, down-, strange-quark masses, after a general introduction to the method of QCD sum rules.

Metallographic Analysis of ECAP Processed Selected Magnesium Alloys

2014 ◽  
Vol 782 ◽  
pp. 404-407 ◽  
Author(s):  
Stanislav Rusz ◽  
Michal Salajka ◽  
Lubomír Čížek ◽  
Stanislav Tylšar ◽  
Jan Kedroň
Keyword(s):  
Heat Treatment ◽  
Magnesium Alloys ◽  
Weight Ratio ◽  
High Strength ◽  
Metallographic Analysis ◽  
Low Density ◽  
Ecap Processing ◽  
Experimental Part ◽  
Composition Study

Magnesium alloys has been used for a wide variety of applications, namely from the reason of their low density and high strength–to–weight ratio. The properties of magnesium alloys are connected with microstructure that is influenced by metallurgical and technological aspects. Scope of utilisation of foundry magnesium alloys is continuously being extended, so if we want to operate as competitive producers, it is necessary to investigate very actively properties of individual alloys, optimise their chemical composition, study issues of their metallurgical preparation, verify experimentally their casting properties and conditions of successful casting of castings by individual methods, including heat treatment. Recently, however, increases also utilisation of formed magnesium alloys namely application of SPD methods. The experimental part deals with hardness and structure determination of selected magnesium alloys after ECAP processing.

scholarly journals Design and Development of Dental Implant Using Bio Ceramics

2021 ◽  
pp. 30-45
Author(s):  
Koushik Alapati ◽  
Bheemisetty Saibaba ◽  
M. Amarnath
Keyword(s):  
Composite Materials ◽  
Dental Implant ◽  
Weight Ratio ◽  
High Strength ◽  
Viable Option ◽  
Design And Development ◽  
Gold Silver ◽  
Conducting Research ◽  
Number Of Cycles ◽  
The Ideal

Generally, dental tooth fixtures are made of conventional metals like titanium, gold, silver etc and also some other materials like Acrylic and porcelain. These fixtures are either too expensive to make or are delicate and would deteriorate after a certain number of cycles. Therefore, a possibility of using composite materials was looked at owing to its high strength to weight ratio under compressive conditions, durability and cost. On conducting research on various materials available, Hydroxyapatite in combination with Zirconia was chosen to be the ideal material. This pair was tested for the weaker one among them and the results are established conclusively which confirmed that it is indeed a viable option to go for.

Determinant of Critical Distance of Bolt on Bamboo Connection

2014 ◽  
Vol 69 (6) ◽  
Author(s):  
Astuti Masdar ◽  
Bambang Suhendro ◽  
Suprapto Siswosukarto ◽  
Djoko Sulistyo
Keyword(s):  
Shear Strength ◽  
Construction Material ◽  
Tensile Force ◽  
Weight Ratio ◽  
High Strength ◽  
Critical Distance ◽  
Structural Elements ◽  
Bearing Failures ◽  
Connection System

Bamboo is a construction material that has great potential to be utilized as structural material on building construction. Bamboo available in variety length and high strength-weight ratio that make it ideal to be used as main structural component of buildings, such as column, beam, floor, partitions or trusses structural elements. High strength bamboo material can not be fully utilized due to the constraints in the connection system. The connection system adopted in joining bamboo elements on bamboo construction significantly influences the strength as well as behavior of the structure. The existence of nodes at the end of bamboo culms may improve the strength of connection. In practice, however, it is nearly impossible to have all bamboo element with nodes at the end of bamboo culms. Therefore in design of strength bamboo connection should be based on condition of end bamboo culms without nodes. In this research, analytical method considering two strength criterions is verified with result from experimental work. Results of research show that shear strength is the smallest strength among others. As bolt is used as connector in bamboo connections, shear strength commonly serves as critical criterion that determines the connection strength. This paper presents the result of study aiming at determination of minimum distance of bolt to the end of bamboo culms without node. Tests conducted by giving tensile force on the bolt with certain distance based on the analysis of shear strength and bearing strength of bamboo. The results showed that the critical distance of bolt to end of bamboo culms without node is 4-5 times the diameter of bamboo. Two main criterion of connection failure, namely shear and bearing failures are considered.

Time and Latitude in South Africa

1972 ◽  
Vol 1 ◽  
pp. 27-38
Author(s):  
J. Hers
Keyword(s):  
South Africa ◽  
Cape Town ◽  
Astronomical Observations ◽  
Royal Observatory ◽  
The Republic ◽  
Astronomical Determination ◽  
Limited Accuracy ◽  
Better Than

In South Africa the modern outlook towards time may be said to have started in 1948. Both the two major observatories, The Royal Observatory in Cape Town and the Union Observatory (now known as the Republic Observatory) in Johannesburg had, of course, been involved in the astronomical determination of time almost from their inception, and the Johannesburg Observatory has been responsible for the official time of South Africa since 1908. However the pendulum clocks then in use could not be relied on to provide an accuracy better than about 1/10 second, which was of the same order as that of the astronomical observations. It is doubtful if much use was made of even this limited accuracy outside the two observatories, and although there may – occasionally have been a demand for more accurate time, it was certainly not voiced.

Precipitation in Al-Li-Zr alloys

1992 ◽  
Vol 50 (1) ◽  
pp. 186-187
Author(s):  
D.M. Vanderwalker
Keyword(s):  
Fracture Toughness ◽  
Precipitation Hardening ◽  
Weight Ratio ◽  
High Strength ◽  
Transmission Electron ◽  
Water Quench ◽  
Aluminum Lithium ◽  
Aluminum Lithium Alloys ◽  
Lithium Alloys ◽  
Zr Alloys

Aluminum-lithium alloys have a low density and high strength to weight ratio. They are being developed for the aerospace industry.The high strength of Al-Li can be attributed to precipitation hardening. Unfortunately when aged, Al-Li aquires a low ductility and fracture toughness. The precipitate in Al-Li is part of a sequence SSSS → Al3Li → AlLi A description of the phases may be found in reference 1 . This paper is primarily concerned with the Al3Li phase. The addition of Zr to Al-Li is being explored to find the optimum in properties. Zirconium improves fracture toughness and inhibits recrystallization. This study is a comparision between two Al-Li-Zr alloys differing in Zr concentration.Al-2.99Li-0.17Zr(alloy A) and Al-2.99Li-0.67Zr (alloy B) were solutionized for one hour at 500oc followed by a water quench. The specimens were then aged at 150°C for 16 or 40 hours. The foils were punched into 3mm discs. The specimens were electropolished with a 1/3 nitric acid 2/3 methanol solution. The transmission electron microscopy was conducted on the JEM 200CX microscope.

Green Synthesis and Enhanced CO2 Capture Performance of Perfluorinated Cerium-Based Metal-Organic Frameworks with UiO-66 and MIL-140 Topology

2018 ◽  
Author(s):  
Roberto D’Amato ◽  
Anna Donnadio ◽  
Mariolino Carta ◽  
Claudio Sangregorio ◽  
Riccardo Vivani ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Metal Organic Frameworks ◽  
Isosteric Heat ◽  
Experimental Conditions ◽  
Cerium Ammonium Nitrate ◽  
Ideal Adsorbed Solution Theory ◽  
Metal Organic ◽  
Adsorbed Solution ◽  
Better Than ◽  
The Ideal

Reaction of cerium ammonium nitrate and tetrafluoroterephthalic acid in water afforded two new metal-organic frameworks with UiO-66 [F4_UiO-66(Ce)] and MIL-140 [F4_MIL-140A(Ce)] topologies. The two compounds can be obtained in the same experimental conditions, just by varying the amount of acetic acid used as crystallization modulator in the synthesis. Both F4_UiO-66(Ce) and F4_MIL-140A(Ce) feature pores with size < 8 Å, which classifies them as ultramicroporous. Combination of X-ray photoelectron spectroscopy and magnetic susceptibility measurements revealed that both compounds contain a small amount of Ce(III), which is preferentially accumulated near the surface of the crystallites. The CO<sub>2</sub> sorption properties of F4_UiO-66(Ce) and F4_MIL-140A(Ce) were investigated, finding that they perform better than their Zr-based analogues. F4_MIL-140A(Ce) displays an unusual S-shaped isotherm with steep uptake increase at pressure < 0.2 bar at 298 K. This makes F4_MIL-140A(Ce) exceptionally selective for CO<sub>2</sub> over N<sub>2</sub>: the calculated selectivity, according to the ideal adsorbed solution theory for a 0.15:0.85 mixture at 1 bar and 293 K, is higher than 1900, amongst the highest ever reported for metal-organic frameworks. The calculated isosteric heat of CO<sub>2 </sub>adsorption is in the range of 38-40 kJ mol<sup>-1</sup>, indicating a strong physisorptive character.

TUNGUM ALLOY

Alloy Digest ◽  
2012 ◽  
Vol 61 (5) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Physical Properties ◽  
Tensile Properties ◽  
Weight Ratio ◽  
High Strength ◽  
Fatigue Properties ◽  
Excellent Corrosion Resistance

Abstract Tungum alloy combines an unusually high strength-to-weight ratio, with ductility, excellent corrosion resistance, and good fatigue properties. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming. Filing Code: Cu-806. Producer or source: Tungum Ltd.

SANDVIK Ti-3Al-2.5V GRADE 9

Alloy Digest ◽  
1997 ◽  
Vol 46 (9) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Endurance Limit ◽  
Weight Ratio ◽  
High Strength ◽  
Strain Ratio ◽  
Bend Strength ◽  
Aerospace Applications ◽  
Excellent Corrosion Resistance ◽  
Titanium Aluminum ◽  
Fatigue Endurance

Abstract Sandvik Ti-3Al-2.5V Grade 9 titanium-aluminum alloy offers excellent corrosion resistance, especially to chloride media, and has a high strength-to-weight ratio, which is especially suitable for use in aerospace applications. Tubing can be produced having a CSR (contractile strain ratio) that enhances the fatigue endurance limit. This datasheet provides information on composition, physical properties, elasticity, tensile properties, and bend strength as well as fatigue. It also includes information on corrosion resistance as well as forming, machining, and joining. Filing Code: TI-109. Producer or source: Sandvik.

DONEGAL DC-50

Alloy Digest ◽  
1954 ◽  
Vol 3 (8) ◽  
Keyword(s):  
Fracture Toughness ◽  
Stainless Steel ◽  
Corrosion Resistance ◽  
Physical Properties ◽  
Surface Treatment ◽  
Tensile Properties ◽  
Precipitation Hardening ◽  
Weight Ratio ◽  
High Strength ◽  
Heat Treating

Abstract Donegal DC-50 is a precipitation hardening stainless steel having high strength-weight ratio. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as casting, heat treating, machining, joining, and surface treatment. Filing Code: SS-17. Producer or source: Donegal Manufacturing Corporation.

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