Papers by Keyword: Static Load

Abstract: The article is devoted to improving the accuracy measuring hardness metals based on the principle similarity mechanical. Hardness test homogeneous solid by means indentation static tip rigid into its flat surface by a force normal to this plane is considered. Volumes that have experienced plastic and elastic deformation in the process of the indentation do not have distinct and definite boundaries. Deformation degree within these volumes is as variable as the stresses causing it. The application relationship empirical between the applied static load and the restored indent diameter indent is shown.

Abstract: This paper deals with the problem of a flexible pipe with internal diameter of 110 mm buried in laboratory soil box facilities for this study. The box is filled with sand reinforced by geogrid layer of different widths to investigate the effect of geogrid width layer on the performance of buried pipe subjected to static load. Two type of reinforcement used (geogrid and geocell). The geogrid location is kept constant at a depth of 0.5d (do is o the pipe o diameter) below the loading plate. The results show that the reduction in crown strain in loose sand, when the geogrid width equals 1B iso13% in comparison with results of tests excluding geogrid, this percent reduces to 11% when the geogrid width equals 2B, while the reduction percent in medium sand becomes 14% and 12% when the geogrid width was B and 2B, respectively and becomes in dense sand 15 % and 11% when the width of geogrid change from B to 2B.

Abstract: The problems of improving operating procedures and diagnosing the bearing capacity of metal structures designed and operating in the Arctic and subarctic regions of the country with a long period of low climatic temperatures remain unresolved. The paper notes that the development of digital methods of non-destructive testing, primarily X-ray diffractometry methods, can provide technical diagnostics of structures by identifying the features of the deformation of the crystalline structure of structural materials in an elastic stress-strain state. It is shown that the application of the method of X-ray diffractometry of complex polycrystalline structural steels has sufficient resolution to detect changes in the fine structure under the elastically stressed state of the samples. The broadening of the diffraction line (B) profile characterizes the effect of the elastically stressed state of steel samples 08 ps and 09Г2С on the course of microdeformation processes in the surface layers of the metal. The effect of periodic annual temperature fluctuations on the profile characteristics of the diffraction lines of 08 ps structural steel samples was studied experimentally. It is established that low climatic temperatures contribute to the elimination of individual instrumental errors due to the design conditions of the experiment. A sharp change in the true half-width of the profile of diffraction lines (В) at stresses σ ≥ 0.5 σ_т indicates the minimum possible value of the allowable stress [σ] for structural steel 08 ps.

Abstract: The dependence of strain on temperature in polyethylene under various static loads and exposure doses has been studied experimentally. After electron irradiation with doses of 10, 30, 50, 70, and 100 kGy, significant changes in the mechanical properties were observed, which are caused by the formation of nanodefects in the material’s structure. With increasing radiation dose, PE deformation at different temperatures decreases due to destruction in the structure of the polymer material. At the same time, the return deformation increases with increasing dose, indicating a change in the modulus of elasticity (E). The increase in E occurs due to the decrease in the distance between macromolecules in the irradiated structure of the sample. The obtained curves for both non-irradiated and irradiated material are described in an exponential model satisfactorily.

Abstract: Composite materials in structural applications that are subjected to static loads for several decades tend to change material performance over their lifetime. Classical creep tests with constant static loading are quite simple tests with low demands on the test equipment. Unfortunately, these tests require uneconomically long test times, which is why a shortening of the test times with various accelerated approaches is being researched. Within this work two approaches for reduction of the testing time were investigated. On the one hand a fatigue test with the variation of R-ratio and following extrapolation to an R-ratio of 1 was done. On the other hand a Stress Rate Accelerated Creep Rupture Test (SRCR) was developed, where a defined initial stress σ_i is applied at the beginning of the loading process, followed by an increase load with a constant rate instead of the static stress segment of the classic creep rupture tests. Changing the load rate in several individual tests leads to stress rate-dependent fracture strengths with associated fracture times, which allows extrapolation to a fracture time at a load rate of zero. In particular, the approach of the SRCR offers great potential for greatly reducing test times with an acceptable prediction quality.

Abstract: The peculiarities of influence of static load on strength characteristics of polymer concretes based on furfural acetone monomer (FAM) are considered in the article. Resistance of static load fatigue is an independent strength characteristic, which should enter into the practice of mechanical testing of materials possessing elastoplastic properties. The regression equation has been obtained as a result of the experiment on a polymer composite material (PCM), which allowed constructing the response surface of the static loading of the polymer composite material based on the resin FAM. A second-order plan for three factors studying static load of a tested composite material is also presented in the paper. It has been established that the ratio of the polymer component to the filler spreading factor is the fundamental ideas influencing the cyclic durability of polymer concretes, while the thickness of the polymer bonding layer and the coarse aggregate are an insignificant factor.

Abstract: The paper presents technological schemes of hybrid and combined operations performed through the action on a workpiece by several sources of loading (static and dynamic). Multiple or single dynamic action is performed during action of static loading. Use of pulsed magnetic fields is treated as the dynamic action. The brief description of the presented schemes, needed for understanding of the new technical decisions, their features and advantages, is available. The proposed technical decisions are innovative, they are protected by patents and are tested in respect of their reality and efficiency. Standard-type parts have been obtained which were made with the help of the proposed technologies of sheet stamping, assembling, welding, casting, rolling, etc. The paper defines a new scientific-technical direction in processing of metals which is aimed at increase in productivity of production processes.

Abstract: Upgrading the quality of compaction of powder materials is achieved by the use of hybrid technologies when the powders are acted upon by two or more sources of loading. The present paper describes compaction of a powder under the action of static and dynamic loads. A pulse-magnetic field is used as a dynamic load. The procedure and technique of experimental researches are described. Porosity (compactness) and structure of the material are evaluated for various combinations of loads, geometrical sizes and shapes of products. The conclusion is made about significant upgrading of quality of the powder material when used the hybrid technology compared to the static compaction.

Abstract: It is necessary to analyze the strength of STS crane with static load for assessing the safety of the STS crane. A case study of a STS crane with 28 ton capacity and 18 years of working time has been conducted. A testing system with signal sensing, signal conditioning, signal acquiring and signal analyzing has been established. After the field test, all the stresses of the test positions have been calculated and the strength of STS crane with static load is in the allowable range. As a result of this study, a systematic approach to analyze the strength of STS crane with static load is proposed.

Abstract: Ferro foam concrete is an alternative material which consist of a combination between wire mesh and foam concrete. The advantage of this material is in addition to its ability to carry the load, this type of material is lightweight, and easy to be produced. The objectives of this study are to study performance of ferro foam concrete girder beam subjected to static load, and to investigate the beam to be used as an alternative material for bridge girder. Six ferro foam concrete channel profile that is configured into three I profile with 300 mm, 450 mm, and 600 mm with four layer wire mesh were tested in Structural Laboratory of Syiah Kuala University. This profile has a span of 2000 mm, and 150 mm, 175 mm, and 300 mm wingspan. Foam concrete used in this research consist of cement, water, foam agent, and 10 % pozzolan. Material properties for concrete 32.47 MPa compression strength, and 421 MPa for yield strength of reinforcement with D8, and 421 MPa for wire mesh G 12.7. The specimens were tested using four point loading. Three units of LVDT placed at a distance of 250 mm and 1000 mm from the support. Based on test results, it was found that the maximum load that can be carried by the channel profile configuration I with 300 mm height is 17.45 tf on deflection of 23.32 mm, for a profile with a height of 450 mm is 20.72 tf on deflection of 14.85 mm, and for a profile with a height of 600 mm was 22.48 tf on deflection of 37.74 mm.