Papers by Keyword: Static Loading

Abstract: This work presents the analysis of damage assessment for dangerous industrial objects of acoustic emission method. Samples of low carbon and low alloy steels were researched. The aim of this work is to experimentally determine damage assessment for the state of developed and unacceptable sources of acoustic emission. Cracks of various lengths have been obtained by low-cycle loading. According to research, it is necessary to use several criteria simultaneously to increase the reliability of inspection of each growing crack.

Abstract: In order to determine the failure mode of high-voltage transmission tower materials under the condition of ice-coating load in an actual line. The Qidian-Luoping 500kV wine glass type transmission tower is selected as the prototype, and the one tower with two lines model of the whole beam unit is established by using the ANSYS finite element software. The loading mode is static load considering icing load and wind load. The most unfavorable wind direction of the transmission tower is obtained by comparing and analyzing the maximum displacement and the stress of the rod under different directions of wind load in the transmission tower. Then the failure mode of transmission tower is studied by the variable ice thickness of the tower line system. The results show that the direction parallel to the cross arm is the most unfavorable direction in the transmission tower. And under the most unfavorable wind direction, with the increase of ice thickness, it is found that the tower head part is more sensitive to icing load than the tower body part. When the thickness of ice coating reaches 30mm, the weak load-bearing rod will appear locally in the transmission tower and the position of the rod is mainly distributed on the outer upper crank arm, the outer side of the ground bracket and the upper side of cross arm of the transmission tower.

Abstract: The article reflects the results of experimental studies of carbon-fiber reinforced concrete under compression and tension. Qualitative change of concrete strength and stress-strain properties at its dispersed reinforcement with carbon fibers is fixed. As a result of the statistic processing of experimental data, analytical dependencies for determination of carbon-fiber reinforced concrete main strength and stress-strain characteristics under compression and tension are suggested. Calculation diagram of non-linear straining of carbon-fiber reinforced concrete at static effect is presented.

Abstract: In this study, the alkali treatment of sawdust using different concentration of sodium hydroxide (NaOH) is performed. The purpose of this treatment is to improve the filler-matrix compatibility, thus, enhance the properties of tested specimens under various strain rate condition. The outcome shows the alkali treated sawdust did improve its surface roughness through reduction of sawdust diameter. With this increasing of surface roughness, it will enhance the compatibility between sawdust filler and HDPE matrix. For comparison purpose, the treated and untreated sawdust filler were reinforce in High Density Polyethylene (HDPE) matrix and have been test under static and dynamic loading using Universal Testing Machine (UTM) and Split Hopkinson Pressure Bar (SHPB) apparatus. The results indicate that the stiffness and compression strength properties were improved on treated sawdust composites for both static and dynamic loading compare to untreated sawdust composites.

Abstract: The objective of the present paper is to carry out the numerical studies on the buckling characteristics of unstiffened and anisogrid aluminium conical structures under axial static loading conditions. This study emphasizes the importance of lattice structures in space application wherein the minimization of weight of the principal part is given greater importance. Lattice structures are preferred in space applications due to their extremely low weight and high structural performance. Both unstiffened and anisogrid aluminium conical shell structures were modelled using Solidworks^®. The finite element computations were done using LS-Dyna^® under static loading conditions. The results of unstiffened and anisogrid shell structures are compared. Based on these studies, it has been asserted that there exists more energy absorption in case of anisogrid conical shell structures than the unstiffened counterpart. The results also reveal about 70% weight reduction in anisogrid conical shell structures.

Abstract: The paper deals with the problems of the actual behaviour, failure mechanism and load-carrying capacity of the special bolt connection developed and intended for the assembly joints of the truss main girders chords of perspective railway steel temporary bridges. Within the framework of this problem solution, several types of structural details of assembly joints have been considered as the conceptual structural design. Based on the preliminary evaluation of advantages or disadvantages of these ones, in principle two basic structural configurations – so-called “tooth” and “splice plate” connections have been selected for the subsequent detailed investigation. This investigation is mainly based on the experimental verification of the actual behaviour, strain and failure mechanism and corresponding strength of the connection, and on its numerical modelling using FEM. This paper is focused only on the static loading tests results of the splice plate connections and their evaluation, which have already been finished. Simultaneously with the static tests, the fatigue loading tests are being realized, too, but they have not been finished so far, as well as the FEM numerical modelling.

Abstract: Dual phase (DP), interstitial free (IF) and advanced high strength low alloy steel (HSLA)sheets have been successfully used for different components of car body. DP and HSLA are used ascrash resistant and IF as cover or “skin” of car body. The development of new vehicles nowadays isbeing driven by the need to simultaneously reduce mass and increase of passenger and pedestriansafety as well as costs saving through cold forming instead of hot forming. Limited publishedinformation is available on the changes in microstructure of these steel grades at different highstrain rates [1-3].This paper deals with changes of mechanical properties, microstructure and fractography of threesteel grades, which were tested at quasi static (10-3 s-1) and high strain rate (3000 s-1). Themicrostructures were characterized in terms of ferrite grain size, aspect ratio of ferrite andelongation of constituent phases. Deformed and undeformed specimens were compared to assess thechanges in the microstructure. The fracture appearance analysis indicates that the fracture patternunder high strain rates is mainly ductile, regardless of steel grades. The microstructure changessignificantly during the deformation process under both quasi-static and dynamic tension in allinvestigated steels. The plastic deformation in ferrite dominates in this process.

Abstract: In case of laminated glass strips, the mechanical characteristics of the composite element are different from the values that are obtained for the same element from a homogeneous and isotropic material. The experimental tests presented in the paper aims to determine the mechanical characteristics of laminated glass strips used to make a staircase. For the experiment, quasi-static and dynamic tests were conducted on different glass stair steps, made from normal and tempered glass, with different number and thicknesses glass sheets. The paper presents the carrying out conditions for the experiments, the synthesis of data processing and comments on the experimental results. Experimental test results led to the constructive solution of the glass staircase steps. For staircase building up, tempered glass was chosen and the values obtained for the mechanical properties, strength and deformation capacity of the system were used in its design. Whole set of experimental tests led to a successful design and build-up of the glass staircase.

Abstract: The work is dedicated to the experimental study of micromechanics process of unidirectional composite materials’ specimens under static loading till its fracture using acoustic emission method compared with the strain-load deformation curve. An attempt is made to identify subtle effects of the failure process of the composite material which is impossible using the traditional methods of the strain measurement. The prospect of applying the method of acoustic emission (AE) for the development and improvement of existing methods of model tense- analysis is shown. The characteristic stages of the damage accumulation for unidirectional composites’ specimens and the effect of training on these processes are shown experimentally. It’s shown that the AE-deformation diagram have three stages in contrast to commonly used load-strain deformation curve with one stage. So it become possible to investigate the physical process of composite unit’s fracture under static load.

Abstract: The force required to shell melon seed by static loading techniques was investigated with an experimental rig machine. Melon seeds were categorized based on their moisture content into 4 sub-samples by soaking. Ten seeds from each sample were randomly selected and loaded in three different loading orientations x, y and z. The mean force required to crack the seeds was determined. Results showed variations in force, while analysis of variance showed significant difference in the loading orientation and no significant difference in the interaction of moisture content, at 95% level of confidence.