Papers by Keyword: Experimental Investigation

Abstract: This paper is intended to reveal possibilities of defects finding in the wire ropes using dynamic properties of the tensed wire rope using specially designed test rig. The subject of the research is the tensioned wire rope with broken wires, located on surface of the rope.Fragment of steel rope (4 mm diameter and 1.35 m length) was tested experimentally in order to find mentioned defects. A measurement of vibrations of the wire fragment on this test rig was performed using contactless vibration sensors. Fragment of the rope, installed in the test rig was excited with electrodynamics vibrator, which created sinusoidal excitement indirectly, i.e. through own frame. Research of vibrations of the rope was performed in wide ranges of frequencies and desired dynamic properties of the rope fragment as a dynamic system was obtained. Finally, results of the experimental research are presented and conclusions are drawn.

Abstract: The aim of this paper is to explore new approaches of monitoring, diagnosis, condition evaluation, and possibility of extending the life of transformers. Research, emphasizing to experimental work, is conducted on a 1.5 KVA single-phase transformer to measure the internal temperature of the primary and secondary winding, using reliable instruments. Special consideration is given to the convenience in the acquisition and management of experimental data, so that the proposed monitoring system can be exploited for all kinds of thermal tests and various loading conditions. The transformer under study is designed and constructed from scratch, according to particular technical specifications. Having completed the transformer construction with the temperature sensors linked in each coil, our aim is to apply various types of loads and record the temperature variation inside the transformer. A process of acquisition and processing of data related to various parameters of transformers is developed so as to predict the behavior and prevent the failure of a transformer.

Abstract: As oil & gas exploration and production is moving increasingly towards offshore and deeper water, and then the demand for lighter and stronger material for deep water structures is growing. Fibre reinforced plastic (FRP) is a potential alternate. However, such application has low tolerance for accidental impact loads. This paper presents an experimental investigation on the behaviour of hollow glass fibre reinforced plastic (GFRP) pipes subjected to transverse impact. Drop weight impact tests were adopted. The GFRP pipe specimens were simply supported at two ends. The variations of strain, deflection and impact force were recorded. Different failure modes were observed and the critical factors affecting the damage of GFRP pipes were discussed. Their structural performance under transverse impact was assessed.

Abstract: Carrying capacity and fracture modes of concrete beams reinforced by different types of fiber reinforced plastic (FRP) bars are analyzed experimentally and numerically. The four-point-bending test is used as a typical loading case for this purpose. Synchronous registration of loading level, displacements and strains is performed by using InstronTM servohydraulic machine, LVDT sensors, strain gauges and digital image correlation Vic3DTM system. The experimental data and results of finite element simulations are compared and discussed.

Abstract: This paper investigates experimentally the effects of spacer geometry on temperature difference ratio downstream of pressure side split of trailing edge film cooling. The internal pin fins arrayed staggered and pin fins in the last row face to the cooling hole one by one. The geometric parameters include relative length of trailing edge l/b, ratio of length to span of split a/c, ratio of length to width a/b, angle of split α. And the effects of blowing ratio and Reynolds number are also researched specially. The correlation of temperature difference ratio vs. Reynolds number, blowing ratio, and geometric parameters respectively was induced.

Abstract: An experiment was performed about the bearing capacity of cold-formed thin-walled steel-OSB composite floor by the sand heap. The strain and deflection response of OSB board and steel beam is analyzed under the load; then the test process is simulated by ANSYS, the results of simulation are agreed with the experiment basically. Through the analysis of experiment and finite element simulation, the results indicate that the composite floor has enough bearing capacity and meets the requirement of the residential building completely.

Abstract: Large landslides usually dam lakes that may easily fail and then result in catastrophic flood threatening the population downstream. The grain size composition within landslide dams is considered as a vital factor that impacts the timing of failure and the resulting magnitude of flood. Therefore, experiments were conducted to investigate the features of size distribution in accumulation bodies. The results indicate that the grain size distribution varies in different parts of the deposits. The inverse grading phenomenon can be observed. Grains in the front of the deposit are coarser, while grains in the rear are finer. For the front of the deposit, the grains in the middle are finer than the other two sides. The grain size segregation is believed to be the governing mechanism that contributes to this special distribution. The speculations of the grain size distribution inside the landslide dam are presented.

Abstract: The external post-tensioning technique has been commonly used in the construction field because it facilitates the analysis of structures and is widely applicable for many types of structures. In this research, 12 steel H-beams were built and tested in terms of the amount of tendon or prestressing force. The results show that the externally prestressing method can increase ultimate bearing capacity of the beams. The prestressing force is the significant factor that influence the strengthening of steel H-beams. However, the amount of deviators cannot significantly influence the bearing capacity.

Abstract: Thermal expansion of ball screw system affects the machining accuracy of machine tools significantly. The objective of this paper is to analyze the thermal behavior and predict the temperature variation pattern of a ball screw based on finite element analysis and experimental investigation. Wireless temperature sensors are used to monitor the temperature variation of the ball screw system under different thermal conditions during both the warm-up and cooldown phases, so as to investigate its temperature variation pattern. Then an exponential algorithm is proposed to analyze and predict the temperature variation of the ball screw based on finite element analysis, and the actual thermal boundary conditions of the ball screw system are exactly defined according to the proposed algorithm and the experimental results. Finally, it was found that the simulation based on the thermal boundary conditions identified herein could match quite well with the experimental results.

Abstract: An analytically based calculation tool for the stress-strain analysis of multilayer composite plate structures with cut-outs is developed which offers high potential to be used in a sense as an analytical sub-model in combination with FE-Analysis Systems. For its validation extensive numerical and experimental investigations have to be carried out. Especially the examination of structures loaded by in-plane compression does not seem to be realizable by conventional testing techniques. That is why a novel testing device for the experimental stress concentration analysis of notched thin plate structures under in-plane compressive load is developed and its application in combination with an adapted optical measurement system is demonstrated.