Genetic Based Experimental Investigation on Finishing Characteristics of AlSiCp-MMC by Abrasive Flow Machining

Implementing non-conventional finishing methods in the aircraft industry by the abrasive flow machining (AFM) process depends on the production quality at optimal conditions. The optimal set of the process variables in metal-matrix-composite (MMC) for a varying reinforcement percentage removes the obstructions and errors in the AFM process. In order to achieve this objective, the resultant output functions of the overall process using every clustering level of variables in a model are configured by using genetic programming (GP). These functions forecast the data to vary the percent of silicon carbide particles (particles without experimentation obtaining the output functions for material removing rates and surface roughness changes of Al-MMCs machined with the AFM process by using GP. The obtained genetic optimal global models are simulated and, the results show a higher degree of accuracy up to 99.97% as compared to the other modeling techniques.

Determination of the Optimum Percentage of High Strength Bars in RC Beams with Combined Reinforcement Using Fem

In this work on the basis of the developed and tested mathematical model, the numerical experiment is conducted in order to study in more detail the specifics of performance of concrete beams` with combined reinforcement. For this purpose nine series of reinforced concrete beams with different combination of steel bars (A400C, At800, A1000) and ribbon reinforcement (C275) were modeled. In the developed series two classes of concrete were used: C50/60, C35/45. The functions derived on the basis of mathematical modeling allow us to determine the recommended percentage of high-strength reinforcement of common reinforced concrete structures with single reinforcement. Therefore, the possibility is obtained to reduce the total structures` reinforcement percentage, increasing their deformability by the specified value without affecting the bearing capacity.

TRAY RESEARCH OF THE STRAIN STATE OF SOIL BASES REINFORCED BY SOIL-CEMENT ELEMENTS UNDER THE STRIP STAMP

Experimental research of weak bases reinforced by vertical soil-cement elements are discribed in this article. Tray research ofweak clay bases and bases with percent of reinforcement from 2,1% to 7,1% under strip stamp were conduct. As a result ofthe experiment settlements for each of soil base models were obtained. Characteristic curves of the influence of the reinforcement percentage on the bearing capacity, deformability are given, character of settlements of the investigated soil massin time at step-increasing loading are shown. It was found that depending on the percentage of reinforcement the critical pressures increased linearly and the values of settlement at critical pressures were determined increased with the base reinforcement percentage. Empirical dependencies were obtained to determine the critical pressures depending on the percentage ofreinforcement for the investigated soil conditions. In conclusion, the effectiveness of reinforcing the base of the strip foundations by vertical soil-cement elements was proved.

Strength and Deformability of Reinforced Concrete Beams with Indirect Reinforcement in the Form of Welded Meshes in Compressed Zone

One of the ways to improve the strength and deformation characteristics of reinforced concrete structures is the use of indirect reinforcement. Such reinforcement, located perpendicular to the compressive force, by limiting transverse deformations creates a volumetric stress state and increases the efficiency of concrete in compression. The article presents a method for assessing the stress-strain state of structures, which allows to take into account the reserves of bearing capacity and apply more economical design solutions. The calculation of strength is considered and the diagram of concrete deformation reinforced by indirect reinforcement is obtained. It is shown that the relative deformations at the apex of the compression diagram depend mainly on the relative level of lateral reduction and concrete strength. It is shown that the lower the concrete class, the less indirect reinforcement affects its strength characteristics, but the limiting deformations increase more strongly, and therefore an almost horizontal section appears near the top of the diagram, the longer the concrete class and the higher the reinforcement percentage.

Reinforcement impact on the stress-deformation state of concrete faced rockfill dam

ABSTRACT Introduction. The article considers results of research of reinforced-concrete face stress-deformation state depending on availability of the reinforcement. At some ultra-high reinforced-concrete faced rockfill dams (CFRD) the transversal (horizontal) cracks were developed in the seepage-control element. It is supposed that the cause of the crack formation is high values of tensile stresses. In this connection, opinions are expressed about the necessity of strengthening the face reinforcement. However, in accordance with the experience gained, in real dams the reinforcement, as a rule, is arranged in one row with reinforcement percentage 0.35 to 0.5 %. The urgent issue of CFRD studies is assessment of impact of the concrete face strengthened reinforcement on enhancement of its reliability. Materials and methods. The studies were conducted for different variants of rock fill deformation properties on the example of 100 m high rockfill dam. The reinforced concrete face was adopted to be wide (1 m thick). The reinforcement was adopted to be two-row one, with reinforcement percentage of 1.5 %. The study was conducted using the finite element method. The reinforcement was simulated using bar finite elements. Results. To reveal the role of reinforcement, analyses of the stress-deformation state were conducted for two cases. In one case it was assumed that reinforcement is absent and in the other case consideration was made for the face with steel reinforcement. Stresses in concrete and steel reinforcement were analysed. Stresses acting along the upstream slope were considered. Conclusions. It was revealed that due to the reinforcement of steel-bar reinforced concrete face it was impossible to provide decrease of tensile stresses in the face concrete down to the permissible level. Reinforcement may play a significant role in the face stress-deformation state only at the moment of forming transversal cracks in the face concrete, but such a case is inadmissible.

The impact of the reinforcement percentage on the stress-strain state of the bending steel fiber reinforced concrete elements

The use of concrete with traditional reinforcement pose the problem of finding ways to increase the crack resistance, impact strength, frost resistance and other characteristics, which in turn depend on the strength properties of the material. One of the solution is the use of dispersion reinforced concrete steel fiber concrete (with short steel fibers of 30-50mm). The combination of rigid fibers with significant strength reserves and the concrete could increase the crack resistance of the matrix and other strength characteristics. The paper presents the results of theoretical studies of the reinforcement percentage effect on the stress-strain state of the rectangular cross-section elements of steel fiber reinforced concrete (SFRC) in bending from at repeated loads with levels of application η = 0.5 and η = 0.7 . It is found that the limit deformations of the SFRC cross-section in bending is recommended to calculate using a polynomial function, which gives the greatest convergence between the true values and approximations in comparison with the logarithmic and exponential functions.