Plain Geopolymer Concrete Cross-Section Surface Analysis After Creep and Shrinkage Tests in Compression and Tension

Author(s):  
Rihards Gailitis ◽  
Andina Sprince ◽  
Leonids Pakrastins ◽  
Kinga Korniejenko ◽  
Tomass Kozlovskis
Author(s):  
Tatsuya Nariyama ◽  
Kazuki Nakai ◽  
Masahiro Tsukamoto ◽  
Yuji Sato ◽  
Shinichiro Masuno ◽  
...  

Author(s):  
Frank Altmann ◽  
Jens Beyersdorfer ◽  
Jan Schischka ◽  
Michael Krause ◽  
German Franz ◽  
...  

Abstract In this paper the new Vion™ Plasma-FIB system, developed by FEI, is evaluated for cross sectioning of Cu filled Through Silicon Via (TSV) interconnects. The aim of the study presented in this paper is to evaluate and optimise different Plasma-FIB (P-FIB) milling strategies in terms of performance and cross section surface quality. The sufficient preservation of microstructures within cross sections is crucial for subsequent Electron Backscatter Diffraction (EBSD) grain structure analyses and a high resolution interface characterisation by TEM.


2021 ◽  
Vol 11 (9) ◽  
pp. 4272
Author(s):  
Stefano Invernizzi ◽  
Francesco Montagnoli ◽  
Alberto Carpinteri

The present paper investigates the influence of the specimen size of EN-AW6082 wrought aluminium alloy subjected to very high cycle fatigue (VHCF) tests. The hourglass specimens were tested under fully reversed loading condition, up to 109 cycles, by means of the ultrasonic fatigue testing machine developed by Italsigma® (Italy). Three specimens groups were considered, with a diameter in the middle cross-section ranging from 3 mm up to 12 mm. The stress field in the specimens was determined numerically and by strain gauge measurements in correspondence of the cross-section surface. The dispersion of experimental results has been accounted for, and data are reported in P-S-N diagrams. The decrease in fatigue resistance with increasing specimen size is evident. Theoretical explanation for the observed specimen-size effect is provided, based on Fractal Geometry concepts, allowing to obtain scale independent P-S*-N curves. The fatigue life expectation in the VHCF regime of the EN-AW6082 aluminium alloy full-scale components is rather overestimated if it is assessed only from standard small specimens of 3 mm in diameter. Experimental tests carried out on larger specimens, and a proper extrapolation, are required to assure safe structural design.


2019 ◽  
Vol 71 (20) ◽  
pp. 1070-1082 ◽  
Author(s):  
Amin Noushini ◽  
Arnaud Castel ◽  
Raymond Ian Gilbert

Author(s):  
Bin Li ◽  
Anastassios Mavrokefalos ◽  
Jianhua Zhou ◽  
Li Shi ◽  
Paul S. Ho ◽  
...  

A thermal nano-imprint method has been developed to pattern sub-40 nm polymer lines of Hydrogensilsesquioxane (HSQ) and electron beam resist ZEP 520A. The imprint template was the cross section surface of a selectively etched GaAs/AlGaAs heterostructure wafer. Silicon nanowires were formed using reactive ion etching (RIE) of a silicon-on-insulator wafer with the polymer nanolines as an etching mask. The obtained Si nanowires were well defined and continuous for a length up to hundreds of microns. Reaction of the silicon lines with a metal can lead to the formation of silicide interconnect lines, which is used to investigate the size effects on the transport and electromigration properties of interconnects for future microelectronics.


1996 ◽  
Vol 23 (1) ◽  
pp. 86-97 ◽  
Author(s):  
Amin Ghali ◽  
Gamil Tadras ◽  
Paul H. Langohr

The Northumberland Strait at the Atlantic coast of Canada will be crossed by a 13 km bridge. The major part of the superstructure will consist of 44 spans, each of length 250 m and a box cross section of variable depth 4.5–14 m. The superstructure, divided into units of maximum length 192 m, will be produced in a yard by segmental casting and multistage prestressing. These units will be assembled at their final position on top of the piers. Each pier is composed of two pieces, also produced in the yard and connected on site by cast in situ concrete. This paper describes selected analysis problems and their solutions employed in the structural design. The analysis problems are concerned with (i) dynamic response to ice forces; (ii) movements of pier footings and stiffness of the subgrade; (iii) variation of stresses and deformations during construction and during the life of the structure, considering the effects of creep and shrinkage of concrete and relaxation of the prestressed steel; and (iv) thermal stresses. Key words: bridges, concrete, creep, prestress relaxation, segmental construction, shrinkage, strait crossing.


Author(s):  
Norine George ◽  
Kiran Umachagi ◽  
Sunil Kumar Tengli

Time dependent variables such as temperature gradient, effective temperature, creep, and shrinkage lead to long term deflection in prestressed concrete girders. This in turn effects the serviceability and sustainability of the bridge in the long run. Therefore, research and analysis is of paramount importance before deciding the type of girder to be used. A parametric study was carried out in order to determine the most desirable and efficient type of box girder to be used for a prestressed concrete bridge having a continuous span. Three prestressed concrete box girder bridge models of single, multi-cell rectangular and multi-cell trapezoidal cross section, having similar span, width and depth were taken into consideration. The finite element models were analysed using MIDAS Civil. The behaviour of the box girder cell types under various time dependent properties such as temperature, creep and shrinkage are presented in this paper. The results show that the prestressed concrete box girder bridge of multi-cell rectangular cross section exhibits greater forces and moments due to time dependent variables in comparison to the other two box girder cell types.


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