Papers by Keyword: Cross Section

Abstract: The article presents and describes the methodology for determining the fire resistance limit state of loaded thermally stressed steel floor beams. The article describes the methodology for taking into account the uneven temperature distribution along the height of the cross-section of a fireproofed steel floor beam. The author presents a method for refining the stiffness characteristics of an I-beam after exposure to high temperatures from a fire and compares the results with the results of field tests.

Abstract: Equal Channel Angular Extrusion (ECAE) is used as a top down process to produce bulk nano/ultrafine grain structured materials by inducing high amount of strain with less experimental set up. In the present study AA 5083 alloy with circular and square cross sections are extruded at room temperature using two dies having cannels with circular and square cross sections respectively. Both the dies used in this study are having same channel angle (Φ)120⁰ and outer corner angle (Ψ) 20⁰. The circular and square billets are extruded for four times in route B_C. The objective of this work is to study the effect of cross section of the billet, number of passes on grain refinement, mechanical properties and wear behaviour of AA 5083. Significant reduction in grain size is observed in extruded material using Field Emission Scanning Electron Microscope (FE-SEM) in the range of 80nm to 600nm after four passes. The microhardness in extruded materials is improved with no. of passes in both cross sectioned billets and it is more predominant for square billets even after two passes. The effect of dead zone is less in case of square billets and hence they have shown more structural homogeneity. The dry sliding wear tests are conducted to study the wear behaviour of the ECAEd materials. It is observed that the wear rate and coefficient of friction are reduced with number of passes in both the cases and rate of decrease is more in case of square billets.

Abstract: The objective of the present study is to analyze the progressive collapse of VLCC hull girder with damages subjected to longitudinal bending. For the simple case, the cross-section is assumed to be remained plane and the vertical bending moment is applied to the cross section. The residual stress, initial imperfection, and crack are not considered. The damages scenarios are located at the center part and asymmetric position of the cross section. To analyze the progressive collapse including its behavior of VLCC ship hull, the simply supported is imposed to the cross section and taking the hogging and sagging condition into account. The results obtained for intact and damages condition by the analytical solution is compared and summarized with one another.

Abstract: Results of obtaining of ¹⁸⁶Re for nuclear medicine using 13 MeV deuterons were presented. Cross section and yield of ¹⁸⁶W(d,2n)¹⁸⁶Re reaction were experimentally measured in the deuterons energy range from the threshold up to 13 MeV. The total yield of ¹⁸⁶Re in the energy range 12.5/6.43 MeV from natural tungsten was measured as (2.3 ± 0.15) MBq/(uA·h). The yield of the ¹⁸⁶Re from enriched ¹⁸⁶W for deuteron energy 12.5 MeV was evaluated as (8.2 ± 0.13)MBq/(uA·h). Possibility of ¹⁸⁶Re obtaining in sufficient quantities for a radiopharmaceuticals synthesis was established. On the basis of data on the yield ¹⁸⁶Re it is confidently expected that using of Tomsk Polytechnic University cyclotron can produce enough amount of ¹⁸⁶Re for using in nuclear medicine

Abstract: The size dependence becomes more significant as the devices scale down from micro-to nanodimensions, which is generally attributed to surface effects due to the very high surface-to-bulk ratios in nanoscale structures. However, significant discrepancies between experimental measurements and computational studies indicate that there could be other influences besides surface effects, such as the influences of native oxide layer, fabrication-induced defects and boundary conditions. In this paper, our purpose is to investigate mainly the influence of fabrication-induced defects on the elasticity of [110] silicon nanowires (SiNWs) with different cross sections. We accomplish this by using the molecular dynamics (MD) simulation. Our MD results show that the H-passivated [110] SiNWs without surface defects is slightly elastically softer than bulk, which is in good agreement with other literature MD values. However, the effective Young’s modulus of SiNWs with surface defects can significantly decreases as the defects increase. This softening behavior of [110] SiNWs is severe, which indicates the importance of surface defects. It is noted that the influence of defects on the Young's Modulus of SiNWs strongly depended on the distribution and morphology of defects as well as the cross-sectional shapes of SiNWs. It is observed that the influence of defects on square SiNWs is significantly different from those of hexagonal and triangle SiNWs. Our work reveals that fabrication-induced surface defects could be one of the important origins of the reduced effective Young’s modulus experimentally observed in ultra-thin SiNWs. Therefore, the effect of defects on the characterization of the mechanical properties of nanowire must be carefully considered.

Abstract: Microstructures and mechanical properties of melt spinning spandex were studied in this article.Cross section and longitudinal surface were observed and analyzed by JSM-5610LV scanning electron microscopy. Q2000 DSC differential scanning calorimeter was used to test the glass transition temperature and melting temperature which indicated glass transition temperature is about 44°C and melting temperature is about 200°C. We employed JSM-5610LV scanning electron microscopy to observe adhesion of melt spinning spandex with nylon filament after different time and temperature processing. It concluded that after 150°C90s、160°C60s、160°C90s、170°C30s heat treatment, the adhesive of melt spinning spandex with nylon is good. At the same time,tensile strength and elastic properties of melt spinning spandex which was processed under different time and temperature were tested, tensile strength and elastic recovery of melt spinning spandex after160°C 90s heat treatment is the best.

Abstract: Using the empirical formula with three free parameters recently proposed, ionization cross sections are given for the representation of cross sections for single ionization of free atoms from the ground stages by electron impact. Almost all experimental results can be approximated by this formula with 20% over the whole energy range between the threshold and 1 . All experimental results can be approximated with experimental error. The formula proposed is not suitable to regenerate the exact contour of fine structure in the ionization cross section curve. The probable error is estimated to be approximately 20%, but the error is larger than 40% and no fine structures are accounted for near the threshold.

Abstract: Mountainous freeway goes through complex geographic and geological regions and causes safety problem. Making clear of the inner relationship of the crash occurrence and the geometric factors is the most fundamental prerequisite to solve the problem. This paper reveals the contributing geometric factors through analyzing the crash data from Changjin Freeway, a typical mountainous freeway located in Jiangxi Province, China. Based on crash records and designed alignment data, contributing geometric factors are generally classified into three categories: vertical alignment, horizontal alignment, and cross section. And then detailed effects of geometric variables are separately discussed and quantified through the relation with crash rate (CR).

Abstract: Different temperature joint treatments in Changchun International Trade Center are discussed in detail in this thesis, and meanwhile the structure treatment of 25.5m-tall non-lateral support that is formed during the design of temperature joint structure is introduced in detail. The treatment introduced in this thesis has already been applied in the real construction practice.

Abstract: Based on the finite element analysis software ANSYS/LS-DYNA, this paper numerically analyzed the dynamic performance of MTCCCs with different cross sections under blast load, followed by the study and comparison on the differences of the detonation wave propagation and failure modes between the columns in circular cross section and square cross section. The results show: The blast resistant performance of the circular component is more superior than the square component for its better aerodynamic shape that can greatly reduce the impact of the detonation wave on the column; The main difference of the failure modes between the circular and square cross-sectional components under blast load lies in the different failure mode of the outer steel tube. The simulation results in this paper can provide some references for the blast resisting design of MTCCCs.