Applied Mechanics and Materials Vol. 732

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: The article deals with problems of high temperature strain gauge measurements. A preliminary experimental work for purpose of mastery of this technique after a longer break has been kicked off in VZLÚ. Initially, possibilities of usage of commercial products and two means of strain gauge attachment were verified.

Abstract: Force interaction between a railway track and a vehicle affects the safety, comfort, and last but not least, economical maintenance. Train of wagons incidence on track in both transversal and vertical direction is simplified by qualifying of force wheel (F_Q), guiding (F_Y) and perpendicular and transverse acceleration. An experimental basis for dynamic determination of vertical, F_Q, and lateral, F_Y, forces at the wheel using strain measures in the foot of the rail is given. Measurements of the dynamic forces during passing train are normally very costly and uneasy. These method consists of measuring strains at selected points of the rail profile is very simple and therefore interesting.

Abstract: In the presented paper the system for determination of pits due to alloy corrosion in steam turbines is described. For two-dimensional task the number of pits in different areas is determined by microscopy technique with image analysis.

Abstract: This paper describes the design verification process of a new bus roof. The aim was to obtain a roof with comparable or better mechanical properties and likely dropped weight. The sandwich roof is developed in the framework of the project when properties matching real roof were compared to test samples. Different core materials and faces have been investigated. The experimental results serve to verify the suitability of the proposed FEM modelling for the future use on global structure roof numerical model.

Abstract: This paper demonstrates the operational stress analysis, performed on the strip mine conveyer drive after the damage has occurred at the second installed gear box. According the long term test it has been found; that the damage was probably caused due to the different breaking moment, introduced on both drives. The examples of measured time histories as well as the evaluation and comparison of measured data are presented, too.

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: During working of tram the chassis are dynamically loaded through acceleration, deceleration, passage curves and evidently by the roughness of the rail track. These added dynamic loads can significantly increase wearing of the chassis components and drive. In the case of tested tram problems with bearing housing into gear box occurred. Too rigid hinge bedding can cause additional parasitic load to bearings. It is desirable to investigate its stress state during acceleration, deceleration and other common drive regimes. For this purpose, strain gauges are used. Moreover, for the verification and better description of gearbox suspension behaviour, the Qualisys system for capturing and evaluating motion is used. Acquired data are processed in software Matlab and in user interface of the Qualisys software.

Abstract: Aircraft Propeller Testing Laboratory of VZLÚ Praha-Letňany has been performed strain measuments on rotating parts, especially on aircraft propellers, for more than five decades. The means of signal recording and its processing have been changed during this age, following technical trends in electrical enginering, but a resistance strain gauge has remained the only one sensor easy practicable for the measurement. The article describes the contemporary state-of-the art and presents some examples of signal evaluation to obtain the data required for purpose of design and certification.

Abstract: This paper is focused on examination of teeth loading in rotating gears during standard operation and describes the applied approach and device developed. One of the closely examined items in planetary transmission testing is the gearing. The tooth load of each wheel in planetary transmission is monitored individually. In large devices, also the load across the width of the tooth is assessed by the K_hβ coefficient.