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Abstract

The article describes the system approach to simulation the process of machining hard-to-cut materials using tools with wear-resistant coatings. In addition to increasing the wear resistance of the tool, factors such as thermal state model, load parameters and friction behavior at the tool-chip interface have been analyzed. A comparative analysis of these parameters is described in the article. It has been proven that the greatest wear of the cutting edge does not occur on the top of the tool, but in the area where the chip speed along the rake face of the cutting insert is greatest.

Abstract

The objective measurement of intraocular pressure (IOP) represents the identification of the symptoms of some diseases, e.g. glaucoma. This objective measurement can only be achieved by correct calibration of tonometers. Today, there is no uniform methodology for this calibration. Therefore, we introduce potential sources of error and try to quantify their contributions in this paper. Subsequently, a calibration standard containing an artificial cornea with similar properties to the human one should be designed.

Abstract

The paper deals with identifying the condition of bearings on a truss bridge with a reinforced concrete bridge deck by means of repeated dynamic tests. Interferometric radar was used to record the dynamic response of the bridge. This device measures the dynamic displacements of several points of the structure simultaneously. In addition to displacements, the values of eigenfrequencies in the vertical direction were also compared. The frequency values were also determined from acceleration records for purposes of comparison.

Abstract

The present work addresses the physical and mechanical properties of banana and palmyra fiber reinforced epoxy composites with the aim of study on the effect of weight ratio and fiber percentage. The banana and palmyra fibers were arranged with different weight ratios (1:1, 1:3, and 3:1) and then mixed with the epoxy matrix by hand lay-up technique to prepare the hybrid composites with various fiber percentages (10%, 20%, 30% and 40%). The properties are measured by testing its density, water absorption, tensile strength, impact strength, hardness and flexural strength and compared. From the results, it was indicated that addition of banana and palmyra fiber in to the matrix material up to 30% by fiber percentage results in increasing the mechanical properties and slightly variation with weight ratios. Interfacial analysis of the hybrid composites were also observed by using scanning electron microscope (SEM) to study the internal failures and micro structure of the tested specimen.

Abstract

The Friction Stir Welding process usually produces weld members of good quality compared to composite weld made with a standard welding process. However, there is a possibility of the formation of various defects if the input parameters are not properly selected. In the recent case study, an image-based feature recognition system using the Fourier conversion method which is a computer visual recognition tool is developed. Five types of filters like Ideal Filter, Butterworth Filter, Low Filter, Gaussian Filter, and High Pass Filter. The results showed that the high pass filter has more ability to detect surface defects compared to the other four filters. It has also been observed that the Ideal filter has a lot of distortions compared to the Gaussian Filter and the Butterworth Filter.

Abstract

The purpose of this work is to examine the microstructure, mechanical and sand abrasive properties of friction stir welded joints of aluminium alloy AA6061-T6 with and without nickel coating. A total eighteen samples, six samples of AA6061-T6 plates, six samples of 10 μm thick Ni coated AA6061-T6 plates and six samples of 15 μm thick Ni coated AA6061-T6 plates were friction stir welded by using different tool rotation speed (710 rpm, 1000 rpm, 1400 rpm) and different welding speed (28 mm/min, 56 mm/min). The joints manufactured using 1400 rpm tool rotation speed and 56 mm/min welding speed generated the highest tensile strength and percent elongation with joint efficiency of 69.05% with 15 μm Ni-coated AA6061-T6 plates and joints manufactured from 10 μm Ni-coated AA6061-T6 plates using 1000 rpm tool rotation speed and 28 mm/min welding speed generated the highest impact energy and higher hardness in NZ compared to the other joints. The 15 μm Ni-coated AA6061-T6 plates exhibited better abrasive wear resistant properties than the 10 15 μm Ni-coated plates. Microstructure investigation showed the precipitate size variations and their distributions and after friction stir welding, these precipitates became slightly coarser in the HAZ but finer in the nugget region.

Abstract

The selection of a composite material for any application will involve selection of reinforcing fibre and matrix, and their fractional volume in the resulting material. A properly selected combination will give a composite material high strength and stiffness, low weight, excellent fatigue and corrosion resistance. The present experimental work is a contribution to the study of the mechanical fatigue behaviour under 3-point bending stress, of aramid/aluminium composite panel with honeycomb core. The tests were performed on four specimens for three cyclic loadings (90%, 80% and 70%), and imposed deformation with a load ratio of 0.2 and a frequency of 5 Hz. The results show that the optimal load ensuring better service resistance of the experimented sandwich panel is 0.7 of the material elastic limit (720 N). Observation using optical microscope of fracture faces in static and cyclic flexion showed the different damage modes of skins and core.

Abstract

Method of predicting the strength of thin-walled tubes under a complex stress state, taking into account changes in the initial dimensions, is proposed. Uniform plastic deformation of a thin-walled tube under short-term static load by internal pressure and axial tension is considered. The tube material is considered to be homogeneous, isotropic and incompressible. The principle of maximum load is used to derive analytical dependences. The main decisions and conclusions were made using the Considere scheme.

Abstract

The aim of this study was to describe an experimental process, of which the main part is the preparation of apple batches and monitoring of the fermentation process. The batch was created from pulped apples to which special yeast cultures were added. Different process parameters of the fermentation were monitored during the experiments, depending on the yeast type and the fermentation temperature conditions. The fermented batch was later used in the distillation process of apple yeast.

Abstract

Friction Stir Welding (FSW) is one of the modern and constantly evolving technologies of solid state joining and is used for welding a wide range of materials. The main parameters of friction stir welding such as rotational speed of the tool, movement speed and the angle of a tilt are analyzed in this article. 6XXX aluminium alloys have been investigated. The examined mechanical properties of the welds include hardness and strength, which are both important sources of information about quality of welding of the materials used in constructions.