Papers by Keyword: Eccentricity

Abstract: In this contribution, the determination of loading forces in the joint of the floor structure and masonry is presented. The point is a subject being accompanied by designing multistorey masonry buildings.The problem of this apparently simple assignment is not so much a calculation of values from characteristic loading of both floors and walls or an actual numerical calculation of masonry carrying capacity, but a correct stipulation of the resultant force location at the spot under the floor structure.In the paper, the resting types of reinforced concrete floor structure on the masonry, influences on the resultant force magnitude, its position to the mid-masonry and consequences for the masonry construction design. The resting examples of floor structures, exhibitions of calculation, and schemas are given. Auxiliary tables and charts to specify the moments in the head of masonry were made up. In conclusion, a recommendation to the optimal span of floor structure destined for masonry construction is stated.

Abstract: This study aimed to investigate the influence of longitudinal steel embedded tubes located at the center of the column cross-section on the behavior of reinforced concrete (RC) columns. The experimental program consisted of 8 testing pin-ended square sectional columns of 150×150 mm, having a total height of 1400 mm, subjected to eccentric load. The considered variables were the steel square tube sizes of 25, 51 and 68 mm side dimensions and the load eccentricity (50 and 150) mm. RC columns were concealed steel tubes with hollow ratios of 3%, 12% and 20% depending on tube sizes used. The experimental results indicated an improvement in the overall behavior of eccentric columns when steel embedded tubes are used. The maximum gain in strength was about 59% for the hollow ratio of 20% with e/h=1. The test results show that the inserted steel pipe improves strength, ductility and enables these columns to absorb more energy than a similar solid column.

Abstract: The pocketed orifice structure for the air-nozzles of an aerostatic bearing is usually a particular pocketed orifice. This structure can not help the shaft to reach high stiffness in working process, so the applicability of the aerostatic bearing in machines with large centrifugal or horizontal force is not focused. A common pocketed orifice structure for the air-nozzles of the aerostatic bearing to meet the demand of high stiffness of the journal shaft has been developed.. Experimental results show that the stiffness of the aerostatic bearing increases, the eccentricity is only about 0.03 mm at a pressure of 2 to 2.5 bar compared to the structure of particular pocketed orifice. Besides operating at high pressure, a common pocketed orifice structure does not suffer from air congestion (blockage) as in a particular pocketed orifice structure. This results in reducing vibration and avoiding damage inside the aerostatic bearing.

Abstract: In the article the results of the eccentrically compressed reinforced concrete element calculation operating under the dynamic loading in fire conditions are shown. The calculation of the compressed reinforced concrete element was carried out, taking into account the conducted experimental studies. The calculation showed that, depending on the temperature effects, the curvature of the reinforced concrete element in stages I and II decreases while the class concrete, which varies from 28.9% to 55%, is increasing. When the temperature reaches 250⁰, the cracking moment and the moment of internal forces at the end of the stage II are reduced to 22% with respect to these forces at normal conditions. With increasing temperature, the dynamic stiffness of the element in the stage I is reduced by 29.3%.

Abstract: The efficiency of reinforced concrete columns with precompressed reinforcement is shown. It was proved that in the elements with mixed reinforcement, up to 50% from the total steel consumption can be economized.

Abstract: The paper focuses on the analysis of the eccentricity effect in the measurement of the hole-drilling residual stress. Relaxed strains were evaluated by computational simulation of the hole-drilling experiment using the finite element method. Errors induced by eccentricity were estimated for elastic and elastic-plastic states in area around the drilled hole due to the stress concentration. The invariance of the stress change with depth was assumed. The correction of eccentricity and plasticity effects in evaluation of residual stresses was realized within the EVAL 7 software (SINT Technology). The analysis shows that in elastic state the eccentricity and angular position of the drilled hole have a significant effect on relative residual stress errors. Correction according to the HDM method is very effective in this case. If the relative error of 5 % is allowed, which is in engineering practice acceptable, eccentricity of ±0.05 mm could be accepted without correction. When the combination of eccentricity and plasticity occurs, the correction of plasticity is more important in method 13-EXT-UN.

Abstract: An attempt is made here to join 2024 aluminum alloy plate by friction stir joining (FSJ) using tools with different eccentricity. Joint surface morphology was observed, and the sizes of both arc line spacing and flash were measured. Furthermore, study the effect of eccentricity of the tool on the surface topography of FSJ joint and analyze the formation of the joint surface topography. It is found that, the space trajectory of long axis of shoulder which formed by the eccentricity of the tool determine the morphology of the arc lines; the ratio between the feed speed and the rotation speed determine the arc line spacing; length of time that long axis of shoulder squeeze the edge of the joint line in the advancing side and the retreating side determines the size of flash in both sides of the joint line. Arc lines were regularly distributed in the joint lines and there are also regular texture structure distributed in the flash of each side. The flash in the advancing side is less than the retreating side. Increasing the amount of eccentricity, it has litter effect on the arc line spacing but will destroy the arc lines morphology in the joint surface and promote the formation of filamentous flash structure in the both sides of the joint.

Abstract: In the process of the oil and gas well construction work such as casing pressure test、fracturing, etc. Casing and cement ring induration will be resulted in stress and deformation response. Under the condition of high load, may be give rise to the body damage of cement ring, and cementing interface tear and other forms of structural failure, also the function of cement ring sealing was endangered. The casing-cement ring-strata finite element mechanics model was established by using the mechanics theory and finite element theory in this paper. The affect of casing eccentricity on stress at the cement ring interface was analyzed. The results showed that, the greater eccentricity, narrow gaps of cement stone was easier to be crushed after load when the load value was near to the in-situ stress.The greater the degree of the eccentricity, narrow gaps of cementation interface was easier to be tore after unload when the load value differ greatly with the in-situ stress.

Abstract: For the aspheric processing is complex , time consuming and difficult to guarantte the eccentricity ,this paper introduce a new method of aspheric processing --repairing and polishing methed and describe the principle . Best fit radius, removal function were computed by mathematical model method and the respective performance curves were given by simulation. This methed has the particular advantage of shortening the working time ,reducing the eccentric amount of the element and improving the processing efficiency. Through this processing method, do a series of processing experiments on the smaller aspheric tolerance single crystal silicon aspheric.As the result indicated , plane surface shape error PV 0.52 μm,surface roughness RMS value of single-crystal silicon 0.09 μm ,the center deviation was less than1μm and the surface smoothness meet the standard above the grade Π.

Abstract: The lubrication state of three-lobe bearing is simulated by using Reynolds equation. It concluded that the load-carrying capability of three-lobe bearing increases with the eccentric distance between the centers of axis and bearing with a nonlinear way. The largest bearing load-carrying capacity occurs in the eccentric direction of 30 °and making sure the eccentric direction can improve the stability of the system. To improve the rotation speed of the axis is beneficial to promote the load-carrying capacity.