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Srovnání stavby a vybraných vlastností dřeva douglasky tisolisté z různých stanovišť
Timko, Lukáš
The aim of this thesis was to analyse the macroscopic structure of the wood of Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) and determine selected physical and mechanical properties with an emphasis on the comparison of juvenile and mature wood zones. Additionally, the structure and selected properties of the wood from sites varying in the forest types (3K, 3B, 3A) were compared. Five sample trees were sampled in each of the three selected sites. Their rootstock parts were then worked into test specimens with dimensions of 20 x 20 x 30 mm a 20 x 20 x 300 mm. The selected wood properties were the density at moisture content of 0% and 12%, basic density, the total shrinkage in all three basic directions, the total volumetric shrinkage, strength in compression parallel to the grain, bending strength, and the modulus of elasticity in bending. Additionally, a tree-ring analysis was conducted. It was found out that the juvenile wood has wider rings, a lower proportion of earlywood and all the observed properties showed lower values. The properties determined and the structure of the wood from the selected groups of forest types is statistically significantly different in most cases. From the forestry perspective, the resulting material characteristics of wood of Douglas fir are greatly dependent on the site; however, the precise location of the sample within the stem (centre or periphery) has a more pronounced effect on the properties.
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Slisovatelnost dýh pro použití ve vrstvených lepených materiálech
Krejčíř, Michal
This bachelor work is based on studies of physical and mechanical properties of plywoods with various composition. The goal of research was to determine the influence of pre-pressed beech veneer on bending properties. There is also review of plywoods manufacturing in the work. The properties of plywood were tested according to EN standards and evalueted by descriptive statistics and Analysis of variance.
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Návrh, výroba a charakterizace překližované desky s využitím skelného vlákna v povrchových vrstvách
Svatoň, Kryštof
Bachelor thesis is dealing with manufacturing of plywood with fiberglass reinforcement. Therein fiberglass is propose to increase mechanical properties. Firstly short review of plywood production, common plywood properties characterization and plywood board properties is of interest. Furthermore the focus was on current possibilities of plywood board reinforcement considering plywood. Secondly the own plywood composition is designed and full method of production, sample preparation and panel testing is described. Density, swelling, bending properties and shear strength of central ply and bonding strength was specified according to EN standards. In the end the results are statistically evaluated, summarized and discussed.
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Návrh inovace konstrukční skladby dřevěného jádra snowboardu
Bátěk, Silvestr
This diploma thesis describes the comparison of two different kinds of structures of snowboard wooden core. One is a combination of ash and poplar (long known and reliable structure currently used by the company Hackboards Ltd.). The other is tested combination when abele is replaced by lighter balsa wood. For both types of core the same types of fibreglass, base and top sheet are used (triaxial fibreglass, sintered base, protective top sheet). The individual mouldings were cut to the required sample on which the tests were made for the determination of bending strength according to ČSN EN 310 and impact bending according to ČSN EN ISO 179-1. Then according to ČSN EN 322 and ČSN EN 323 the moisture and density of used wooden boards were set. The measured results were evaluated and presented in charts and tables in the experimental part of this work.
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Analýza mechanických vlastností balzového dřeva na mesoúrovni pomocí zkušebního stroje iErudio
Grossová, Olga
This thesis analysis the mechanical properties of balsa wood mesolevel using the test machine iErudio. The thesis aim is to experimentally determine the mechanical properties of balsa wood (Ochroma lagopus). On the prototype minimachine iErudio is a set of measurements. Specifically, tensile and bending tests. Another objective is to determine the Poisson ratio on measured levels. These properties will be obtained from image data recorded device iErudio and calculated using the digital image correlation. Another objective is to evaluate the work done with the prototype device, point out the advantages and disadvantages. To analyse data using a commercial computer program VIC 3D and Mercury RT, which process the results using digital image correlation. The work has provided us with confirmation of mechanical characteristics of balsa and the suitability of using "minimachine" iErudio the performed tests.
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Vliv variability stavby rezonančního dřeva na jeho akustické vlastnosti
Schwarzer, Martin
This work was the structure of resonant spruce wood devoted to. The tree-ring widths and summer wood measure were measured. By use of non - destructive methods their acoustic properties were measured - speed of sound, acoustic constant, logarithmic decrement of damping, acoustic wave resistance, wood - density and Young's modulus. Data were statistically analyzed and the wood structure coefficient of variation for each specimen was calculated. There were three different methodologies for verification of the wood structure variability effect formulated. Subsequently, it was found that it is possible to determine the effect on the acoustic properties of the wood macroscopic structure variability.
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Pevnost lepeného spoje vodáckých pádel
Jonáš, Martin
This work deals with the strength of the bond with paddles made of solid wood. The samples were made of solid wood blanks from spruce, alder and ash. There were used three types of adhesives in samples - polyvinyl acetate, melamine-urea-formaldehyde and epoxy resins. For these samples the effect of the species and different types of adhesive bonded joints for strength in bending was studied. Also described herein is cutting samples, bonding joints and their testing methodology. In the literature review are discussed various issues such as conditions affecting the adhesive bond, the adhesive film formation components adhesives etc., that are associated with this topic.
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Numerický model celodřevěného konstrukčního spoje
Staňková, Eliška
Part of bachelor's thesis is numeric simulation of several testing variants of wholewood carpentry joints during mechanical strain. As a type of test was used 3 and 4 spots bend for symmetric and asymmetric loaded joint.There were tested a joints with two different dimensions. Purpose of this test is elaboration, evaluation and comparison of joint behavior. For simulations is monitored the process of Ansys Workbench tool, that means, Individual steps from creation of geometric model trough networking, defining of material attributes, determination of boundary conditions solution to exportation of results. Basic joint designs were taken from destruction tests ongoing within "Design and evaluation of historical construction carpentry joints" project, which followed up the design of wholewood joints and destruction tests. This project is showing complex joint response by using a method based on finite element method. The results of the project will be used for comparison with experimental data and then used to examine alternatives joints.
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Inovace klasifikace a zkoušení podložních zemin pro realizaci lesních odvozních cest
Tvrdý, Daniel
Basic presumption of good functionality of forest roads is not only high quality of laminars in flexible pavement, but also right distribution of elasticity modules in soil plain and it's protection against degradation during the process of building. Materials used for TA ČR project, which were isolated from forest roads subsoil, were analyzed in soil mechanics laboratory of Geostar s.r.o. company for the purposes of diploma thesis. Basic laboratory tests were carried out in order to classify soils. Sub-component is to propose a simplified classification of soils for the implementation of forest haul routes. In this work are validated according to the static load tests ( SZZ ) and dynamic light boards ( LDD ) . The thesis includes evaluation of the quality of existing forest roads for faults and failure on forest roads classes 1L and 2L with different surfaces and ground covers .
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Analýza vlivu odklonu vláken v lamelách dřevěného lepeného nosníku na jeho tuhost
Klvač, Ondřej
This thesis deals with the analysis of the influence of deflection of grain in the single slats in the wooden glued beam on its stiffness by the finite element method. It is concerned with the deflection of the grains in single slats and a possible combination of changing these slats in the beam.The ascertainment of overal deformation, stiffness and tension placement in the beam cross- section. The thesis also contains general information from the technical literature regarding the issues of glued beams, manufacture technology, examples of use and a comparison and the measured outcomes of the finite element method. The result of the thesis is to evaluate the deflection laminated beams and determine the optimal arrangement the slats in terms of minimum deflection.
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