Papers by Keyword: Scale Model

Abstract: Sometimes in open mining, it is economically expedient to extract and transport rock mass with the help of wheel tractors-scrapers. To improve the hopper filling with the rock mass operating with clay or loosened rocks, it is advisable to use scrapers equipped with loading intensifiers in the form of a raking wall located inside the hopper. The article presents the experimental filling study results of wheel tractor-scraper hopper models of different capacities with a standard and increased hopper length at the presence or absence of a raking wall. The investigations were carried out on an experimental rock removal bench equipped with a strain gauge measuring system to record forces that arise during the hopper model filling with rock mass. Data are given on the rock mass removal for various filling methods, as well as for the resistance values for the piling wall movement and the energy capacity of the hopper filling process for operating with sandy loam, loam, clay, and limestone crushed stone. There were realized the calculations of the operational productivity and the specific cost of works, depending on the rock mass transportation distance with elongated hopper scrapers equipped with a scraper wall, scrapers with standard hoppers and scrapers operating with a pusher bulldozer set. The rational application areas for each of the machines were revealed.

Abstract: This article focuses on the estimation of a proper logarithmic damping decrement in industrial boilers when flue gases travel in the vertical direction. The structure for this type of facility is quite unified worldwide. The structural conception is rather simple, and the response to any static loading is predictable. Nevertheless, with regard to dynamics and damping, some specifics in the detailed solution make this system unique. For the purpose of this analysis, a Plexiglas scale model was prepared at a geometric scale of 1:20. A set of experimental modal analyses was performed on the model. Each test focused on the damping effect of specific details and compared it with the common structure without a damping effect. Finally, a site modal analysis was conducted on an actual boiler located in the CHP Torun Plant in Poland. The upper part of the structure was reinforced to have a horizontal deflection of 8 mm and was suddenly released. The resulting movement was recorded with an HD camera linked to a theodolite. Experimental results on the scale model of the actual structure confirmed that damping of this type of structure is significantly higher than that considered for common steel structures.

Abstract: The primary objective of daylighting measurements, by means of physical models, is the experimental finding of daylight conditions in the interior (in case of scale model of a specific room), or their impact on the surrounding buildings (in case of models of whole buildings). If these measurements are carried out even at the early stage of the building design, they can be very helpful in revealing gross deficiencies of the design or optimization of window apertures. According to the purpose of the measurement, physical models can be placed either on site of the future building – which advantage is the possibility of a reliable reproduction of the actual shading conditions, respectively the amount of reflected light by the envelop of existing buildings – or in laboratory, under artificial sky. The advantage of measurements using artificial skies is mainly the possibility to imitate the conditions of CIE overcast sky, thus the disadvantages of the variability of natural daylight are eliminated, while there is also a potentiality to optimize different solutions at the same boundary conditions. On the other hand, if the luminance distribution of the artificial sky is does not correspond with the theoretical luminance distribution of CIE overcast sky, the results of the measurements can be incorrect. The aim of this contribution is to illustrate through a case study, the importance of ensuring the appropriate boundary conditions at scale model measurements.

Abstract: Based on the similarity theory, the horizontal tail scale model is designed and manufactured. Subsonic doublet lattice method is used to calculate unsteady aerodynamics, V-g method is used to solve the flutter determinant. Optimus software is used to optimize the thickness of the skin. The constraint condition is the frequency, MAC value and flexibility, and the objective function is flutter dynamic pressure. Flutter velocity of horizontal tail model optimized decreased 6%,and flutter frequency increased greatly. Horizontal tail scale model was test in wind tunnel. The finite element calculate results was very close with wind tunnel results, which verify the correctness of the finite element model and optimization models.

Abstract: This paper has been prototyped fine 1:20 scale model of the finite element numerical simulation analysis of each parameter sensitivity test conditions, based on similar principles of dynamics, through the production of about 1/20 the proportion of prototype scale model of the bridge, dynamic characteristics of research conducted scale model of finite element analysis, and study whether there are cracks in the presence of dynamic response mode model, summarized the structure of the bridge structure in a given period reflect the physical characteristics of the local sound voiceprint and bridges under the geometric structure of the physical parameters of a period of time to maintain the basic stability conditions, the "voiceprint" has a high probability of stability.

Abstract: Due to the constraints of the cost, the space and other factors, scale model of the building structure is commonly used in the study of blast effect on building structure experiment. However, in order to make the experimental results reflect the real prototype structure characteristics, the accuracy of the similarities between the prototype structure and the scale model must be ensured. Therefore, its important to study the way to solve the existing problems in the design of the experiment of RC model of frame structure under the influence of the loads of the internal explosion, which is designed to provide some references for the similar experiments in the future.

Abstract: This paper presents the experimental investigations into the seismic failure for high arch dam with shaking table test. The similitude scale of high arch dam was studied firstly. Then we developed a like concrete material to simulate the mechanical behavior of the structural concrete in high arch dam. The shaking table tests have been performed on the scale model. The experimental results reveal the failure process of high arch dam with respect to the different earthquake intensities.

Abstract: The subject of Foundation Excavation near the buried pipeline line. Compared with each other using a scale model of the buried pipeline foundation excavation factor of the vertical displacement, and connected with the buried pipeline displacement of both ends of the fixed elastic beam theory; analysis of the factors affecting the displacement of buried pipelines, the good agreement of the theoretical results with the scale model test value.

Abstract: RCS is an important indicator to evaluate the performance of an unmanned aircraft. It is often costly to measure the dynamic RCS of a large-electric-size unmanned aircraft. To solve the problem, a scale formula for RCS measurement is deducted from the Maxwell Equations. With the formula, the RCS of a large-electric-size unmanned aircraft can be calculated based on the RCS of a scale model. Furthermore, the method of calculation the dynamic RCS of an unmanned aircraft based on its static RCS and its flight paths is brought forward.

Abstract: According to the China Aviation Industry Standard HB6129 “The requirements of aircraft lightning protection and test method” and standards of foreign countries. The high voltage generator was used to make the lightning attachment point test on a scale model of airplane. The lightning attachment zone was determined, and the result was agreed with the actual lightning experience of F-4 aircraft. The technical factors such as test method, the model scale, gap spacing, and polar discharge relative positions in respect to the model are related to the laboratory test; the lightning discharging theory will be discussed in detail. The test method has been proved feasible and the experience of test research work has accumulated for future use.