Applied Methods of the Analysis of Static and Dynamic Loads of Structures and Machines II

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作者: Karel Doubrava, Ctirad Novotný
摘要: Lightweight and safe roof of the bus was solved within the MIT CR: FR-TI4/349 project. Several variants of sandwich roof were tested on samples in a prior period. Several errors of adhesive joints occurred during the production of the bus roof. Methyl methacrylate adhesive was tested with respect to the declared adhesive ability for arbitrary surfaces. Standardised shear test of the adhesive joints were made for tuning of the numerical model. The obtained parameters are used forthe numerical model of sandwich roof segment. Roof segments were loaded by four points bending and experimentally obtained data were compared with the results of numerical simulations. Several specimens were subjected to cyclic loading in order to get approximate fatigue life of tested variants.
作者: Valery V. Kuzin, Sergey N. Grigoriev, Sergey Fedorov
摘要: This paper describes approaches developed for the using of indentation method for evaluating the effectiveness of traditional and innovative kinds of ceramic parts manufacturing. Experimental studies revealed relationship between conditions of the grinding and pulse laser machining with the number and length of cracks, as well as local fracture area during indentation. Essential impact of regimes of these technological processes on the nature of cracks and local fracture formation during indentation of oxide-carbide ceramic surface was disclosed. The analysis of effectiveness of different methods of forming the surface of ceramic parts using the revealed effects was done.
作者: Lubomír Pešík, Ondřej Kohl
摘要: By destructive car tests are used acceleration sensors for the determination of a time courses of kinematic variables. The main task is to determine the velocity of measured points of selected objects. The fundamental problem in the solution of this problem is the fact that the acceleration sensor simultaneously record two mechanical movements. One of them is the movement of the object as a rigid body and the other is damped vibration of the object itself as a flexible body which is characterized by its dynamic parameters.
作者: Aleš Lufinka, Jaroslav Votoček
摘要: A drilling process quality and a drill life depend on the cutting conditions optimal setting. Research in the area of cutting fluid composition and drilling tools parameters for nonstandard material setting is performed at Technical university of Liberec. Real drilling parameters monitoring is essential during this research. Axial force and torque are two basic parameters describing this process. The measuring device for these parameters monitoring which was built at Technical university of Liberec is described in this paper.
作者: Klára Machalická, Martina Eliášová
摘要: Load-bearing joints of glass structures belong to the one of new applications of adhesive connections in civil engineering. They provide several important benefits particularly even stress distribution along the contact depending on geometry and stiffness of the glue joint, which is crucial for brittle glass. There is a lack of knowledge about semi-flexible or semi-rigid adhesive connections in the structural glass field and durability is one of the essential properties that have to be assessed during design-process of bonded connection. An extensive research focused on shear glued joints in glass structures was performed at CTU in Prague, which also comprised environmental effect simulation on the glued specimens in laboratory accelerated conditions. The paper is dedicated to impact of ageing to the specimens and their mechanical properties together with brief overview of available laboratory ageing methods.
作者: Pavel Malý, František Lopot, Vojtěch Dynybyl, Jiří Sojka
摘要: This paper describes the experimental shear test of clinched connection of two sheet metal plates. The force-displacement characteristic was obtained using the set of six testing specimens. Also the properties of the clinched joint were identified and were used in the following work including simulation methods and calculations.
作者: Diana Šimić Penava, Željko Penava, Marijana Tkalec
摘要: Coated fabrics have complex composite structure whose mechanical properties are considerably improved in relation with the initial basic material. They are obtained by applying a certain number of coatings to raw fabrics. In this paper the practical application of uniaxial testing of coated fabrics for determining its breaking properties and Poisson’s ratio is presented. Due to the anisotropy of woven and coated fabrics, Poisson's ratio changes over the fabric sample stretching. Experimental testing were carried out on two samples of plain weave cotton fabrics. The fabrics were tested before coating, and after one, two and three coatings. Samples are stretched with tensile force in the weft and warp direction, and based on different measured values of fabric stretching, warp and weft Poisson's ratio is calculated. The values of tensile force and relative extension of coated fabrics were measured, and breaking force values, elongation at break, contractions at break.
作者: Radka Pernicová, Jindřich Zeman
摘要: Measuring of the non-elastic deformation of wide range of materials under extreme environments, such as high temperature, underwater or lack of space, is described in this paper. Method, called Predictive Instant Defect Analysis of Constructions for short PIDAC, is based on precise indication of defined distance change between two points before and after loading. Distance is mechanical imprinted into an indication specimen and consequently measured by microscopy analysis. The technology solves not only problem of measuring plastic length deformations but also offers the capability of predicting catastrophic failure due to the breaking, tearing, or deforming of materials.
作者: Jiří Šmejkal, František Plánička
摘要: The article deals with damping design for steel platform with sorters for limestone. The steel platform has very small damping for two vibration sorters. The sorters are situated in the third floor of old reinforced concrete frame building. The sorters (Fig. 1) are supported by rubber springs (Fig. 2), bud the rest energy from vibration of sorters excite the supporting platform. The response of the platform is unacceptable for both service people and for technology. Therefore vibration absorber for minimization of the response of the steel platform was developed