Papers by Keyword: Test

Abstract: Methods for determining the actual limit of fire resistance of reinforced concrete building structures in case of fire are analyzed. On the basis of the offered methods the technique which gives the chance to receive data of temperature distributions on a surface of a fragment of a wall and in its section is created. The method of conducting a fire test to calculate the limit of fire resistance of a small fragment of the load-bearing wall and verify the reproducibility of experimental data is described. The distribution of temperatures over the entire area of the fire furnace, the studied fragment was checked and the obtained results were analyzed. According to the results of this work, the following was established: the aim of the work was to obtain the results of temperature distributions on the surface, in the points of integration in the cross sections of fragments of reinforced concrete walls for further calculation of their fire resistance limit and check reproducibility of experimental data. It is established that the temperature obtained as a result of the fire test corresponds to the standard temperature of the fire and this method of fire test to determine the temperature distributions of a small fragment of the load-bearing wall in fire conditions is acceptable for use. The error between the experimentally determined and theoretically calculated limit of fire resistance is not more than 3%.

Abstract: This research has been made a simple method for the detection of potassium iodate (KIO₃) in a kitchen salt using cassava starch (Manihot esculenta). The process of making this test kits using acid solvent as the reagent, KIO₃ solution, and indicator of cassava starch. The used cassava starch is in two conditions are dry starch for H₂SO₄ and wet starch for H₃PO₄. Based on the two solvents are then made a standard color series based on KIO₃ levels of 10, 20, 30, 40, and 50 ppm. Validation of this method has analyzed using Spectrophotometer UV-Vis. From the results of this analysis obtained calibration curve of each standard with both solvent. Coefficients determination for linearity using H₃PO₄ and H₂SO₄ solution is 0.9874 and 0.9656. From that results from the H₃PO₄ solution applied to the detection of potassium iodate (KIO₃) in a kitchen salt using cassava starch (Manihot esculenta) with a concentration in the range 30-40 ppm.

Abstract: The paper briefly describes the methods for testing soils by triaxial compression. Among the many mechanical characteristics of the soil, deformation and strength properties remain as the main and widely used ones, the determination of which is an important experimental task. In recent years, new test schemes, more advanced designs of instruments and equipment for the study of various soils have been proposed. Like any material, the soil has limited strength, and under certain external influences the soil massifs collapse, as a result of which their individual parts get unlimitedly large displacements. Triaxial soil compression is becoming more widespread in the production of engineering and geological studies to justify the construction projects of various engineering structures. Based on the results of this work, recommendations for the practical application of the obtained soil characteristics for the geotechnical geoinformational database of the city of Nur-Sultan are made.

Abstract: A new characterisation method based on free-bulge tests is proposed to find the characteristic parameters of the strainstress relation in superplastic alloys. The method is applied to experimental tests found in the literature and to new adhoc tests performed on aluminium, magnesium and titanium alloys. The parameters are then compared to independent values obtained from tensile test and computer-aided simulations. The characterisation of the material is evaluated as an apparent viscosity function of the strain-rate and is extracted from the height evolution at the apex dome during the forming process. Results show a good agreement between parameter estimation using this method and independent values. Moreover, this characterisation method exposes the non-newtonian fluid behaviour of these materials during superplastic processes known as shear-thinning or pseudoplasticity.

Abstract: The weld of T-joint segments is the weakest link during the excavation of a metro crossing passage tunnel with the shield method. The stress on the weld is one of the key factors and should be given special attention. This paper aims to monitor the stress and strain of the weld of the T-joint segments during the construction process of the metro crossing passage tunnel of Ningbo Metro Line 3, the world first metro crossing passage tunnel by the shield method. A finite element model of the metro crossing passage tunnel is established. The CAE (Computer Aided Engineering) simulation is conducted by the sub-model approach. The calibration analysis between test data and CAE results for the strain of the weld under several key cases is performed. Based on this, the vary regulation of the stress and strain of the weld seam at various positions of the steel tube sheet under critical working conditions is obtained. Consequently, an authentic, reliable and advanced simulation process is established, and the weld strength of the T-joint segments of such kind constructions can be well assessed and predicted.

Abstract: Nowaday´s trend is the effort to replace metal materials with the polymers, which already have the irreplaceable place in the field of the construction of various applications. Development offices effort is to achieve the best polymer quality for which various ways of modification are used. Besides common fillers and e.g. modification using beta radiation, there is a possibility to modify these properties (creep resistance, hardness, tensile strength) with the nanofillers, which have also the irreplaceable place in the field of development. This article deals with the possibilities of use of the nanofillers in HDPE material and primarily with the influence on creep properties of thus modified matrix. The influence of nanofillers shows a considerable influence in various materials, which should contribute to better resistance during these long-term tests.

Abstract: The braking performance of large-scale freight vehicle is an important influencing factor to braking safety. Presently, the utility ratio of disk brake in large-scale freight vehicle is low. In this paper, comparative test study on disk and drum brake mounted in semitrailer is conducted, including building and installing methods of the test system, test method and evaluation of test result. The test result shows that the disk brake can provide semitrailer with larger brake torque and better thermal stability. It is of more obvious advantages than drum brake.

Abstract: To study the low temperature liquefaction characteristics of SF₆ for the operation security of electric equipments in cold area, the writer carries out the low temperature liquefaction test of SF₆ respectively in laboratory and outdoors by using SF₆ gas low temperature experimental apparatus. According to the results of the test and the Beattie-Bridgman SF₆ empirical formula, SF₆ gas state parameter curve is plotted and a concise practical SF₆ gas state parameter formula is got. This formula is more applicable to electric equipments outdoors. The results show that SF₆ gas is easier to liquefy in cold area, and the liquefaction temperature of SF₆ gas is in proportion to gas pressure. So the liquefaction temperature of electric equipments operated in cold area should not be higher than the lowest area temperature. Otherwise, measures must be taken to prevent SF₆ gas from liquefaction.

Abstract: Based on the characteristics of domestic hemp cultivation and the previous designs and research, a hemp harvester that is suitable for Chinese hemp-growing areas was designed. The optimal cutting parameters of hemp stalks, which can provide a reference for prototypes, are obtained by the bench test: the average cutting speed is 1.5m/s and the stalks feeding speed 0.5m/s. It is showed by the field trials of prototypes that the cutting rate of prototypes can reach 92.0%, and the stalks conveying rate can reach 85.0%, and the average production rate is 0.22 hm²/h. All the performance indicators have reached the design requirements.

Abstract: The basic mechanical performance of glue laminated timber (GLT) reinforced with glass fiber reinforced plastic (GFRP) for structural materials was studied. The differences of mechanical performance of the GLT reinforced with GFRP and the common GLT were compared by the test, and the quantitative influence of reinforcement ratio and arrangement pattern of GFRP on the mechanical performance was investigated. The test results showed that the static bending strength of GLT increased with the increasing of GFRP reinforcement ratio, and the reasonable arrangement pattern of GFRP could improve the internal bonding strength of GLT. The influence of reinforcement ratio and arrangement pattern of GFRP on the elastic modulus was relatively small. Finally, a mathematical model of static bending strength for GLT reinforced with GFRP was proposed, which can consider the influence of reinforcement ratio and GFRP arrangement pattern