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In the paper, results of research concerning new measuring equipment for evaluation of cutting properties of superhard grinding wheels under production conditions are described. The results presented are focused on the selection of conditions for measurement and repeatability of the measurement. The sensitivity of the parameters being measured to variation of dressing conditions of CBN grinding wheels...
The analysis of safety of composite prestressed concrete bridges in terms of cracking is presented. The analysis of the standard-based requirements was carried out. The assessment of safety is based on Cornell’s reliability index taking into consideration two random factors: the tensile strength of concrete and the values of normal stresses at the bottom edge of girder. As random variables which affect...
The methodology of determination of strain-rate sensitivity index was developed based on rolling of a set of samples with the same draught but different speed at a defined temperature. It was shown that an initial grain size has nearly negligible influence on the variable investigated, in contrast to phase compo-sition whose influence is considerable.
The P/M low-alloy steel with sintered density of 7.0 g/cm3 was surface hardened by means of vacuum carburizing method. The fatigue strength of steel in case-hardened and sintered state was determined. Fatigue tests were conducted in the axial loading mode (R = –1, f = 25 Hz) on unnotched specimens. Comparing the S–N curves obtained for case-hardened and sintered specimens, the influence of vacuum...
Spring-back is the main defect of the U-shaped parts. After removal of tools, the U-shaped part undergoes significant modification of the angles between the bottom, the sidewall and the flange, and also a curvature of the sidewall appears. The blankholder force is an important factor in controlling the size of spring-back parameters. The present paper is an experimental study of how blankholder force...
This paper presents the MANPRESS robot: a simple, low-cost and newly developed industrial device primarily devoted to press feeding. This robot exhibits two major features: great flexibility to accommo-date different machines and products, and optimal performance in loading/unloading one or more machines. The first is due to the usage of modular, off-the-shelf and easy to control system components...
Algorithms using wavelet-packet bases for solving initial-value problems described by systems of linear differential equations with constant or variable coefficients have been demonstrated. Algorithms which use expansions of the derivative of state variables and expansions of the state variables in any wavelet-packet basis were described and compared. The results of the analyses were compared with...
Reliability of bridge beams with hybrid cross-sections is considered. The beams made of elastoplastic material and loaded quasistatically are regarded as failure-free. Dead load and the load caused by a tram described by random variables are taken into account. Furthermore, material capacity and the dimensions of the cross-sections are also described by random values. In order to calculate the reliability...
The possibility of using two models of geometry in the analysis of bridges consisting of a tubular frame combined with a concrete slab is presented. The first model is derived from the orthotropic plate theory and the second one is a discrete model including beam elements (the structure) and shell elements (the slab). This makes it possible to adopt some easy to model flat two-dimensional elements...
An algorithm for analysis of capacity and behaviour of steel-concrete beams prestressed with external cables has been presented. Nonlinear constitutive laws for concrete and constructional and reinforcing steel can be taken into account, in a way similar to that adopted in the case of nonlinear slip dependence and nonlinear studs' distribution along the beam. According to the method presented, completed...
The effect of different complex strain paths on the behaviour of silicon bronze CuSi5 has been examined. The strain paths contain various sequences of cyclic torsion and tension. The amplitude was changed in the range of 0.05-0.5, a temperature from 20 C to 800 C and the strain rate from 0.01 to 1S-1. The properties and structure obtained in complex strain paths are compared with those gained in monotonic...
A planar mechatronic system with three degrees of freedom (a link mechanism having a closed structure and controllable drives) can execute any trajectory. Owing to the third drive the workspace is increased, but at the same time the problem of selecting driving functions for the execution of a particular trajectory arises. This paper deals with the effect of drive setting accuracy on the deviations...
The paper deals with single-track, single-span, simply supported steel railway bridges with two plate steel girders and a ballasted closed platform; they are called stee/ beam bridges for short. A simplified model, i.e. a design model, of the bridge-track-moving train system is constructed that simulates dynamic processes with the accuracy acceptable in practice. A physical non-linear high-performance...
Development of computer technology enables implementation of expert tools supporting decision processes in the Bridge Management Systems. The proposed expert tools utilise both data base and knowledge base of the system. Decisions in bridge management are very often based on a mixture of accurate data and fuzzy or uncertain information. This requires a proper technology for information acquisition,...
In this paper, a new approximate method of determining fundamental solutions for thin plates on elastic foundation is considered. Various models of foundations (Winkler, Pasternak, elastic half-space) are analysed. The approximate fundamental solutions are obtained through the analysis of power series of their Fourier's transform images. In the inversion procedure from images to originals, the well-known...
In the paper, the measurement system of "crash-test" experiments was presented. The prototype system based on two laser transmitters (red light) with special detectors with electronic system was used as the sensor. The system became an option of much more expensive accelerometers. The advantage of the method presented is its simplicity as well as the possibility of high acceleration recording...
Spring-back is a phenomenon that seriously affects the quality of parts made by forming processes of metal sheets. The size of distortions of the formed part caused by spring-back depends on different factors, such as: material parameters and chemical composition, working conditions and tool accuracy. The present paper deals with an experimental research into the influence of such sheet material as...
The paper presents a mathematical model of impulse compacting of moulding sands developed at the Institute of Machine Engineering and Automation of Wrocław University of Technology. The model presented consists of a system of differential equations that describe the impulse head dynamics and the process of moulding sand deformation. This deformation is described by a viscoelastic rheological model...
The paper develops computer-aided design of reconfigurable/modular machine tools with rolling guideways, at the stage of conceptual design. The main static and dynamic stiffnesses in the tool-workpiece area are proposed for assessment of possible configurations of a machine tool. These stiffnesses are understood as reversals of the main relative compliances of the tool with the workpiece under static...
The influence of the temperature rise of a sample on relationship between the flow stress and strain determined in a hot torsion test was evaluated. Measurement of temperature was performed for samples of austenitic steel OH18N9 and titanium alloy WT22 deformed at temperature of 900 C at a rate of l0, 100 and 1000 rpm with partial radiation pyrometer and a thermovision system. It was proved that the...
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