Papers by Keyword: Experimental Measurement

Abstract: The Triple Hybrid Hydrogen Bus project comprises research and development, implementation and a test operation of a city bus with hybrid electric propulsion using hydrogen fuel cells. The mass distribution and the total bus mass are rather different from common buses. This is, among others, the reason for investigating the bus driving stability. In order to obtain a tool for dynamic analysis, multibody models of the bus were created. Verification of multibody models was performed based on the comparison of simulation results and experimental measurements focused on handling behaviour of the bus. To perform the simulations two approaches were used. The first (original) one, at which the initial position of the bus multibody model at the beginning of the simulation of the manoeuvre depends on the bus motion trajectory, and the second (new) one, at which the initial position of the bus multibody model at the beginning of the simulation of the manoeuvre is set an equilibrium position.

Abstract: Residual stress is one of the important factors in thermally sprayed deposits which affects both processing and performances. In the present study, the hole-drilling method and moire interferometry were used to determine the residual stress of thermally sprayed coatings to overcome certain limitations of the strain rosette version of hole drilling. The methodology was established based on the elastic theory and finite element method. The residual displacement was measured by moire interferometry and the residual stress of the thermally sprayed coating was calculated. The results have demonstrated that moire interferometry for surface displacement caused by hole-drilling is high sensitive, reliable and stable.

Abstract: This article deals about experimental analysis of the operational loads on the agricultural machine in real conditions. The goal of this work is to gain boundary conditions which stress frame, joints, screw connections, bearings and other parts of agricultural machines.

Abstract: Numerical modelling and experimental measurements led to the assessment of stress of structural nodes of scissor lifting platform, which is used for relocation of cars from a production line. It also led to optimization of producing process. Immediate load of scissor lifting platform by a car on stand causes additional bending moment that must be captured in a scissor mechanism. At the beginning the experimental measurements on the real lifting platform were made for obtaining of dependence of displacement, velocity and acceleration on time which was almost 1.5±0.1 g. Then dynamical analysis using a numerical method Runge Kutta 4^th order of lifting platform were created. Model analysis showed that the initial immediate acceleration of lifting platform at start and immediate deceleration at stop lead to dynamic shocks. These dynamic shocks are due to long term operation dangerous because they permanently load not only pivots but also other parts – bearings and joining parts. A resonance may occur as well. In particular, dynamic shocks caused damage of structural nodes. Immediate load of scissor lifting platform by a car on stand causes additional bending moment. It is not appropriate in terms of long-term operation. Recommended load lifting platform should be symmetrical.

Abstract: Fibres, cables and wires can play an important role in design of many machines. One of the most interesting applications is replacement of chosen rigid elements of a manipulator or a mechanism by fibres. Dynamic behaviour of fibres in simplified mechanical systems was investigated. In the first step the computational investigation of a fibre dynamic behaviour in the system of an inverted pendulum attached to two fibres and driven by them was performed. Then experiments and computer simulations with two simple laboratory mechanical systems followed. The first system consisted of a weight moving on an inclined plane and of one fibre, the second one contained a drive and a pulley in addition to it. The results of experimental measurements serve for tuning the computational models. The simulation aim is to create a phenomenological model of a fibre.

Abstract: This paper deals with the hygrothermal performance of timber-frame external cladding in a passive house. The wall and roof assemblies were simulated and analyzed with regard to hygrothermal performance. Different boundary conditions and methods were used for the simulation calculations. The results of the simulations were compared with in-situ measurements, which were carried out at an experimental passive house at East Czech Republic. Due to the results of simulations and measurements, it should be possible to evaluate accuracy of simulation methods for prediction of the hygrothermal performance of the lightweight external cladding.

Abstract: This contribution deals with experimental determination of thermal properties needed for transient heat transfer calculation by conduction in highly viscous fluids; which are the density, thermal conductivity and specific heat capacity. Density was determined by direct method, heat capacity was measured with mixing calorimeter and thermal conductivity was studied with two different measuring equipments. Experimental set up for determination of thermal conductivity was designed and constructed by the author. Results were corrected by numerical simulations in CalA software. All measurement quantities were compared with calculations based on the chemical composition of the substance. The determined thermal properties can be used for calculation of energy performance of heating and cooling of highly viscous fluids.

Abstract: The aim of this article is analysis of energy performance of the timber-frame passive house. The analysis is made on the base of numerical simulation, analytical calculation and experimental measurement. Numerical simulation is solved by the Design Builder software which can determine thermal losses, thermal loads of buildings and other parameters of indoor microclimate - mean radiant temperature, operating temperature and indoor relative humidity, the Predicted Mean Vote (PMV) index, the Predicted Percentage Dissatisfied (PPD) index, concentration CO₂ (carbon dioxide). Analytical calculations are solved by the software Simulace. Boundary conditions of the exterior calculation are set with using standard values and the real hour meteorological values (from database of the software Design Builder for Ostrava town and from database of the real experimental measurement values). Experimental measurements of the indoor and exterior parameters (external and indoor air temperature) are realized at the passive timber-frame house of the Research and Innovation Centre of the Moravian-Silesian Wood Cluster in the area of the Faculty of Civil Engineering, VSB – Technical University of Ostrava. Results of theoretical analysis and experimental measurements are compared and evaluated.

Abstract: As a result of the trend towards lightweight construction in manufacturing, there has been a significant increase in the use of clinched joints in engineering structures and components. Mechanical structures assembled by clinching are expected to possess a high damping capacity. The aim of this paper is to provide an experimental measurement technique for the investigation of the forced vibration behavior of clinched joints. The dynamic test software and the data acquisition hardware were used in the experimental measurement of the dynamic response of the clinched joints. The frequency response functions of the clinched joints of different clinching point number were measured and compared.

Abstract: Clinching is a high-speed mechanical fastening technique which is suitable for point joining coated and pre-painted sheet materials. In this study, an experimental measurement technique was provided for the prediction of the free vibration behavior of single-lap cantilevered clinched beams. The dynamic test software and the data acquisition hardware were used in the experimental measurement of the dynamic response of the single-lap cantilevered clinched beams. The frequency response functions of the clinched beams of different clinching number were measured and compared. The main goal of the paper is to provide a basis for further research on vibration based non-destructive damage detection in clinched beams.