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31.
R.A. Alashti G.H. Rahimi E. Poursaeidi 《International Journal of Pressure Vessels and Piping》2008,85(7):498-506
In this paper, the results of limit analyses of thin-walled cylindrical shells with a circular hole under the action of a pure bending moment are presented in dimensionless form for a wide range of geometric parameters. Analytical estimation of lower bound limit load is carried out using the feasible sequential quadratic programming (FSQP) technique. The finite element calculations of limit load consist of elastic–plastic and lower and upper bound predictions by elastic compensation methods. A testing device was made to perform experiments to obtain limit bending moment of cylinders with circular openings. The analytical and finite element calculations are compared with experimental results and their correlation is discussed. The finite element calculation results were found to be in good agreement with lower bound estimations by the nonlinear mathematical programming (FSQP) method and the formula proposed by Shu. 相似文献
32.
This paper deals with the identification of concrete fracture parameters through indirect methods based on size effect experiments. These methods utilize the size effect curve (structural strength versus structural size), associated with a certain specimen geometry, to identify the tensile strength and the initial fracture energy. These two parameters, in turn, are typically used to characterize the peak and the initial post-peak slope of the cohesive crack law. In the literature, two different approaches can be found for the calculation of the size effect curve: (a) an approach based on the polynomial interpolation of numerically calculated structural strengths of geometrically similar specimens of different sizes, and (b) the classical approach based on equivalent elastic fracture mechanics, which gives rise to the well-known Bažant’s size effect law (SEL). In this paper, the two approaches are first reviewed, the relationship between them is investigated, and a new procedure to identify the tensile strength using the SEL is proposed. Then several sets of experimental results, recently performed at the Politecnico di Milano, are analyzed with both approaches in order to assess their range of applicability and accuracy in the identification of the two fracture parameters specified above. 相似文献
33.
I. Cullis M. Hinton S. Gilbert P. Church D. Porter T. Andrews W. Proud A. Pullen 《International Journal of Impact Engineering》2008
Simulations are becoming an increasingly important part of the weapon design cycle allowing the investigation of more parameters in warhead concepts. This relies on a thorough verification and validation process for the simulation tools, which enables a cost effective approach to down-selecting concepts for full-scale experiments. A key factor in this process applied to the design of warheads to defeat hard (structural) targets is the development of truly physically based material models for geological materials where constants are either derived or measured. The paper describes this general approach and highlights aspects of its initial application to kinetic energy (KE) penetration and suggests areas for future investigation. 相似文献
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35.
Zinedine Khatir Joe PatonHarvey Thompson Nik KapurVassili Toropov Malcolm LawesDaniel Kirk 《Applied Energy》2012,89(1):89-96
Experimental and computational fluid dynamics (CFD) analyses of the thermal air flow distribution in a 3-zone small scale forced convection bread-baking oven are undertaken. Following industrial bread-making practise, the oven is controlled at different (constant) temperatures within each zone and a CFD model is developed and validated against experimental data collected within the oven. The CFD results demonstrate that careful selection of the flow model, together with implementation of realistic boundary conditions, give accurate temperature predictions throughout the oven. The CFD model is used to predict the flow and thermal fields within the oven and to show how key features, such as regions of recirculating flow, depend on the speeds of the impinging jets. 相似文献
36.
《Calphad》2021
Decades of scientific work dedicated to the investigation of phase diagrams gave significant benefit to industry and science. After all those years of phase diagram investigation still there is missing information about phase diagram of some ternary systems. One of those systems is Cu-Ge-Pb. It is known importance of Cu-based alloys and Ge-based alloys in electro industry. Since such combination is not tested before this work will provide information about phase diagram of ternary Cu-Ge-Pb system. In this work ternary Cu-Ge-Pb system has been tested experimentally and analytically by using Calphad model. Two isothermal sections at 600 and 400 °C and three vertical sections are experimentally tested and results were compared with calculated corresponding phase diagrams. None of the ternary compound and large solubility of third element in binary compound is not confirmed. Liquidus projection, invariant reaction and scheme of invariant reaction are presented. Scheil and Lever simulation of solid phases for Cu80Ge10Pb10 alloy were calculated. 相似文献
37.
探讨草鱼鱼鳞明胶的提胶条件及其特性。采用正交试验研究pH值、温度和时间对鱼鳞明胶品质的影响,利用物性仪、高效液相色谱仪和红外光谱仪等对制备的明胶特性进行分析研究。得到最佳提胶条件:提胶液pH值为6、提胶温度为55℃和时间为6h。得到的明胶提取率为35.56%,黏度为6.04mPa·s,凝胶强度为478.58g,等电点为pH值7.6,亚氨基酸(脯氨酸和羟脯氨酸)含量达21.6%。所得鱼鳞明胶结构稳定,为较高品质的明胶。 相似文献
38.
Stretching dominated Kagome lattices reinforced by carbon fibers were designed and manufactured. The sandwich panels were assembled with bonded laminate skins. The mechanical behaviors of the sandwich panels were tested by out-of-plane compression, in-plane compression and three-point bending. Different failure modes of the sandwich structures were revealed. The experimental results showed that the carbon fiber reinforced lattice grids are much stiffer and stronger than foams and honeycombs. It was found that buckling and debonding dominate the mechanical behavior of the sandwich structures, and that more complaint skin sheets might further improve the overall mechanical performance of the sandwich panels. 相似文献
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40.
This paper is concerned with the finite element modeling of the experiments on cone–cylinder–skirt–ring transition junctions in steel silos under simulated bulk solid loading presented in the companion paper. Before presenting the finite element results, the issue of modeling the interaction between the stored solid and the shell wall throughout the loading process is first examined. Results from nonlinear bifurcation analyses using the perfect shapes and nonlinear analyses using the measured imperfect shapes are then presented and compared with the experimental results. These comparisons show that despite the structural complexity of steel silo transition junctions, their behavior can be satisfactorily predicted by finite element analyses taking into account a number of important factors including geometric imperfections, effects of welding and the interaction between the junction and the stored solid. Next, the paper presents results of nonlinear analyses of these junctions with assumed eigenmode-affine imperfections. These results shed considerable light on the effect of ring buckling on the load-carrying capacity of transition junctions. Finally, the implications of the experimental and finite element results for the design of steel silo transition junctions are discussed. 相似文献