Papers by Keyword: Experimental Research

Abstract: The paper considers the material for the protective coating of building structures made of wood. The possibility of chemical processes occurring in the material leading to its expansion has been studied. The coefficient of expansion of the material when heated is practically established. It has been established that the material can swell, both under the influence of flame and when the temperature rises at a low speed. Swelling coefficient at the same time it reaches 8. The temperature range of swelling is 150–250 С, which is confirmed by thermodynamic calculations and experimentally. The temperature at which the material begins to swell is lower than the temperature of thermal destruction of wood.

Abstract: The processes of phase formation in a fire retardant composition based on liquid glass and potassium carbonate have been investigated. The mechanism of the process has been studied. It was found that the use of potassium carbonate provides controlled gas evolution during heat treatment of the composition, as a result of which the integrity of the fire retardant coating is preserved.

Abstract: Aiming at the problems of large temperature differences and inconsistent baking speeds at different positions in the tobacco chamber of the tobacco baking room, this paper proposes a complex structure processing technology of fan vent. according to the structure and drying principle of the baking room, ANSYS fluent simulation software was used to analyze the processing parameters of the heat flow field inside the baking room. combining the characteristics of positive and negative air supply baking, the processing and manufacturing parameters of the baking room were optimized, and then the baking comparison test was performed. The results show that: the forward and reverse air-baking method and the complex structure reduces the temperature difference in the interior of the smoke chamber; the forward and reverse air-bake method reduces the baking time by 11 hours, and reduces the coal consumption and power consumption by 12.6%, 48.5%, the standard deviation of temperature monitoring points in the baking room decreased by 44%.

Abstract: The paper analyzes the scientific work on fire protection, fire resistance, mathematical modeling of fire-proof properties, mathematical planning of experiments. The factors determining the efficiency of fire-proof coating have been determined. The experimental technique for determining fire-proof efficiency as an output parameter was selected. A factor space was constructed, and an experimental plan was drawn up. Experimental studies of the fire-proof effect of the coating based on the xerogel of the gel-forming system at all points of the factor space were carried out. A regression equation was obtained that describes the effect of the qualitative and quantitative composition of the coating on its fire-proof efficiency.

Abstract: With the deepening of marine development activities, human-related sea-related behavior has gradually moved from shallow sea to deep sea. In this paper, the deep sea environment of the thruster bearing of the deep sea space station is characterized by high pressure, high corrosion, large amount of microorganisms and sediment. The Modified UHMWPE is developed, and the friction under simulated seawater conditions is studied by using different proportions of samples. The experimental results show that the materials developed in this study have lower friction coefficient and better wear resistance than Thordon and Feroform materials, and are very suitable for deep sea environment.

Abstract: To provide reasonable guidance for CFST practical structures in design and construction, shrinkage test of concrete-filled steel tube (CFST) members in natural environments was presented. In order to acquire some knowledge regarding the influence of the interaction between the steel tube and core concrete during concrete shrinkage, ordinary concrete (OC) specimens exposed to the atmosphere were also performed in this test. The experimental results have been compared with predicted shrinkage strains obtained from the CEB-FIP1990 model, B3 model, GL2000 model, ACI 209 model. The research results show that the measured shrinkage strains of CFST specimens presents characteristics of seasonal variation under the influence of natural environments. Although expansive additive is added in the concrete mix, there is still strain difference between the steel tube and core concrete. The influence of steel ratio on the shrinkage behavior of CFST is unclear. The value of CFST shrinkage strain is about 50% of the OC shrinkage strain. For the early-age shrinkage of CFST, the predicted result by the ACI209 model is better than the other three models. The CEB-FIP1990 model is recommended to be used to predict the long-term shrinkage behavior of CFST.

Abstract: In order to understand heat transfer of the shell condenser in the closed-loop thermal propulsion system of the unmanned underwater Vehicles, the one-dimensional thermal model based on the hull-integrated condenser with helix channels is developed. After this, experimental research is conducted. Through the experiment data and theoretical calculation results compared, the accuracy of the heat transfer mathematical model is verified, and the correlation formulas about heat transfer are developed. In addition, the impacts of three factors on the performance of the shell condenser are investigated, including cross-sectional area of the cooling channel, flow rate and temperature of inlet steam. The research results indicate that the model and the correlation formulas about heat transfer is reliability and accuracy, which can provide a theoretical basis for simulation and optimization design of the shell condenser.

Abstract: Rotational molding is a manufacturing method which supposes the rotation of the mold, during the solidification of the liquid phase material, so that finally a part having a hollow could be obtained. The method could be applied in manufacturing of metallic and nonmetallic parts. Usually, the equipment for rotational molding ensures slow speed rotating of the mold around two axes placed perpendicularly each other and this fact led to relatively complex equipment for achieving rotational molding. The capacity of the liquid material to entirely cover the internal walls of the mold depends essentially on the liquid material viscosity, on the rotation speed and on the movements applied to the mold. Simplified equipment including a single rotation movement could be materialized. In order to test such a solution, a preliminary experiment was designed and materialized, by using a device adapted on universal lathe. Thus, the objective of the research presented in the paper was to study if it is possible to achieve plastic parts made by rotational molding using a single rotation movement. A polyurethane resin obtained from two liquid components was used in order to obtain the liquid material that could be introduced in the mold. The research results proved the possibility to use simplified equipment for achieving a rotational molding process, at least in certain cases and with some technological limits.

Abstract: The article deals with the analysis of the problem of the load-bearing capacity of reinforcing bars placed above the columns in slab-column connections of reinforced concrete structures. Failure of the support zone by punching and lack of proper structural integrity reinforcement can lead to a progressive collapse. The EC2 standard guidelines recommend the use of integrity reinforcement, however, they lack any instructions concerning the amount of necessary reinforcement. The article presents a theoretical calculation model that permits a more detailed analysis of internal forces in reinforcing bars located directly above the column. Adopting a solution in the form of exact equations makes it possible to take into account the influence of a non-linear change of the bar stiffness and considerable deflections. The calculation model is based on the results of experimental investigations. On the basis of a theoretical model it is possible to estimate the tensile force of the bar at which the bars located directly in the support zone are ruptured.

Abstract: In the paper the results of laboratory tests performed on a simplified model of a slab-column connection were presented. The aim of investigations was to find out at which value of the load the destruction of such a connection occurs due to a rupture of the bars above the column. In respective models the column was situated axially or eccentrically with respect to span of bars. In each case the reinforcement passing above the column consisted of bars with a diameter of ø8 mm, ø12 mm or ø16 mm. The obtained results of laboratory tests and calculations permitted to determine the relations between the exerted load and the displacement of the column in time and also were compared with the guidelines contained in the standards CSA A23.3 and ACI 352R. Based on the results, the reduction of the load bearing capacity of the reinforcement bars due to bending was determined.