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Abstract

Stability is one of the most critical problems in the design of welded metal structures, since in many cases instability causes failure or collapse of the structures. The present study aims to show the minimum mass design procedure for welded steel box columns loaded by a compression force. The normal stresses and overall stability are calculated for pinned columns. The dimensions of the box columns are optimized by using constraints on global stability, local buckling of webs and flanges. Different design rules and standards are compared: Eurocode 3, Japan Railroad Association, American Petroleum Institute, and American Institute of Steel Construction. The calculations are made for different loadings, column length and steel grades. The yield stress varies between 235 and 690 MPa. Optimization is carried out using the generalized reduced gradient method in Excel solver. Cost calculations and comparisons show the most economical structure.

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A natural occurrence of a silica/clay nanocomposite material was investigated by transmission electron microscopy (TEM) and X-ray powder diffraction (XRD). High-resolution images show that this nanocomposite material consists of 5–20 nm thick slabs of smectite and tridymite/cristobalite layers with coincident normals. In spite of the brittle glass-like appearance of the nanocomposite material its colloidal properties are similar to those of pure smectite but partial loss of expansion capacity was detected upon glycerol solvation. The structural relationship between smectite and silica is interpreted based on the smectite structure model of Edelman and Favejee (1940) which supposes reversed tetrahedra in the SiO4 layer of the TOT structure. This structure model explains the presence of silica impurities in bentonites used as raw material and several geological standard montmorillonites.

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. Test environment of the tensile test The mechanical properties were measured on standard flat tensile specimens. The results were evaluated according to the standard ISO 6892-1:2016 [ 11 ], method B, specimen class D

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Resolution and Discovery
Authors: Judit Babcsán, Shai Essel, Nahum Karni, György Számel, Sándor Beke, and Norbert Babcsán

conductivity (1–40 W/mK). Besides that, metal foam is nonflammable, nontoxic, affordable, and recyclable. The mechanical properties of the standard aluminum foam alloys of Aluinvent (EN43100 and EN6061) are listed in Table 1 . All values of the aluminum foams

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Resolution and Discovery
Authors: Alessandro Benedetti, Luis Miguel Sender, Ignacio Escapa, Rubén Cúneo, and José Bienvenido Diez

We applied the FIB–SEM technique to fragments of fossil conifer leafy twigs preserved as cutinized coalified compressions from the Early–Middle Jurassic deposits in central Argentina. In contrast with the standard SEM analysis, no previous chemical

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adhesion strength changes of Hap coatings deposited on commercial Ti substrates. Adhesion strength of coated samples was tested by the standard tensile adhesion test ISO 13779-4. 2. Materials and Methods 2

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the procedure of “terrestrial” loading have been investigated. Samples were ground and polished using a standard technique. Polished sections were etched by Nital (2–4 vol % HNO 3 solution in ethanol). Microstructure studies were accomplished

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Resolution and Discovery
Authors: Nada Žnidaršič, Polona Mrak, Eva Rajh, Kristina Žagar Soderžnik, Miran Čeh, and Jasna Štrus

in Agar 100 epoxy resin, and the 0.5 μm thick sections were prepared with a glass knife using a Reichert Ultracut S ultramicrotome (Leica). Hematoxylin–eosin staining of paraffin sections was performed in the standard procedure as described

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coating thickness (~700 nm). The hardness and the indentation modulus values were automatically calculated according to the measuring standards based on the work of Oliver and Pharr [ 36 ], and visibly aberrant data were neglected from the averaging

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solder interconnects used in commercial applications, reference test methods are specified by international standards and protocols. Thermal shock testing is performed to determine the ability of the tested product to consistently meet the criteria of a

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