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The dreadnought rib guitar innovation
Hoffman, Pavel ; Nop, Patrik (referee) ; Jirásek, Ondřej (advisor)
This diploma thesis deals with the spectrum analysis, frequency characteristics, Chladni figures and simulation of modal and harmonic analysis of an acoustic guitar in ANSYS program interface. In the acoustic guitar analysis, various details that can influence the instrument spectrum are discussed. Especially on its performance over time, the number of generated harmonic components and their performance. Then the guitar bracing innovation of the dreadnought guitar was created from the measured, simulated and calculated data. Four acoustic guitars with the innovation were then made. These innovated instruments were further analyzed and compared with the acoustic guitar before the innovation and with a competitor’s guitar. Furthermore, the thesis describes parts of an acoustic guitar, wood properties, theoretical background and measurement methods.
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Využití materiálů na bázi dřeva pro výrobu umělých CubeSat satelitů na nízké oběžné dráze
Mládek, Martin
This bachelor thesis focuses on the use of wood and wood‑based materials in new potential industries such as space engineering, more specifically the production of panels for CubeSat satellites. Using a literature search, the historical and current use of wood and wood‑based materials in space engineering was summarized, while low Earth orbit, factors affecting low Earth orbit, wood, wood properties and wood‑based materials were described. The different acting factors in low orbit were compared with the properties of wood using sensitivity analysis. The resulting values of physical and mechanical properties were recalculated according to the described acting factors in low orbit. The resulting overstrains and applied thermal stresses were calculated using the relationships found. Based on the literature search, a suitable group of woods was selected, and the material index results were used to select suitable wood species. The suitable wood‑based material was selected using the observed criteria. From the results obtained, a potential panel composition of CubeSat satellite was proposed.
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Influence of Wood Density on Measured Values when Working with a Kučera's Drill
Černý, Pavel
Diagnostics of wooden structures is still a widely used field in construction. The measured values during testing in wood diagnostics are always influenced by the properties of the wood. One of the most important roles in wood diagnostics is moisture, which affects a wide range of physical and mechanical properties. This was not the case when testing with the Kučera`s drill, which is standardly used for masonry diagnostics. For research purposes, the drill had to be transformed for use on wooden structures. The transformation was performed on the basis of a special reduction.
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The dreadnought rib guitar innovation
Hoffman, Pavel ; Nop, Patrik (referee) ; Jirásek, Ondřej (advisor)
This diploma thesis deals with the spectrum analysis, frequency characteristics, Chladni figures and simulation of modal and harmonic analysis of an acoustic guitar in ANSYS program interface. In the acoustic guitar analysis, various details that can influence the instrument spectrum are discussed. Especially on its performance over time, the number of generated harmonic components and their performance. Then the guitar bracing innovation of the dreadnought guitar was created from the measured, simulated and calculated data. Four acoustic guitars with the innovation were then made. These innovated instruments were further analyzed and compared with the acoustic guitar before the innovation and with a competitor’s guitar. Furthermore, the thesis describes parts of an acoustic guitar, wood properties, theoretical background and measurement methods.
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Vlastnosti měsíčního dřeva
Zlámal, Jan
Jan Zlámal: Moon wood properties Bachelor thesis, Mendel University in Brno, 2017. 36 pages. This thesis summons the knowledge about the moon wood especially about its physical and mechanical properties. It compars the results of scientifical studies and experiments which were so far performed. So this thesis contains general knowledge about moon wood topic and chapters sorted according wood properties based on real experiments with moon influence on wood. The monitored properties are humidity, density, dimension changes, compression strength, combustibility and resistence. The most commonly observed tree species were Norway Spruce (Picea abies L. Karst) and Sweet Chestnut (Castanea sativa Mill.). The thesis also gives the overview of examined hypothesis, methodology of the experiments, time periods etc. This compilation can serve as a base for following experimental research.
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Wood impregnation
Pařil, Petr
Wood impregnation is one of the oldest and the most frequently used techniques to protect the wood. This treatment offers a wide range of protection depending on used impregnants (preservatives). Impregnation can make the wood more resistant to decay, less flammable, more dimensionally stable, harder, stronger, more UV stable resistant and many more. Generally, the aims of this thesis is to give a new and modern approaches to already known technologies. The experimental part have been carried out using laboratory vacuum-pressure impregnation plant and many other devices. Almost all treatments and measurement have been done in laboratories of Research centre in Útěchov. The different wood species e.g. European beech (Fagus sylvatica L.) and hybrid poplar (Populus hybrids) have been studied. The patented solution shows the method of the treatment and colouring of wood containing tannins, characterized by impregnation with a product containing iron oxide nanoparticles, in a concentration of 0.4 g/l to 42 g/l, an average particle size in the range of 1 to 100 nm, and a liquid medium. Impregnation can be performed as pressure impregnation, followed by soaking, or the product can be applied by brushing or spraying. This method is an alternative to wood ammonification. The tests (Paper I) shows following results. Both nanoiron and ammonia treatments tested induced darker colouring of oak wood, more intensive darkening was observed in case of the nano-iron treatment. The native oak showed a steep drop in lightness ca 25-50 hours of exposure followed by gradual re-increase during further exposure to the artificial sunlight. The darker surfaces generated by tannin reacting chemically with iron and ammonia evidently faded in the course of light exposure. In case of chromatic parameters a* and b*, the AT (ammonia treatment) oak more or less copied the colour change progress of native oak. On the contrary, the NIT (nanoiron treatment) wood showed a double increase in both parameters. The colour of NIT wood after light exposure was more or less equivalent to the original colour of the ammonium-treated. Distinct reddening of NIT oak may be caused by oxidation of non-precipitated iron particles. The antifungal effects of copper and silver nanoparticles against two wood-rotting fungi were investigated with following results (Paper II). The highest value of retention was observed for pine sapwood (~ 2 kg/m3) for both nanoparticle solutions. The amount of nanoparticles in the wood did not increase proportionally with an increasing concentration, but only 1.5-2 times increase was reached. An average leaching of 15% to 35% was observed for copper nanoparticles, depending on used wood species and concentration. Significantly lower leaching (max. 15 %) was observed for pine sapwood impregnated by silver nanoparticles with a concentration of 3 g/l. The highest antifungal effect (under 5 % of mass loss) against both tested fungi was found for nano-copper treatment at the concentration of 3 g/l. However, this effect of treatment seems to be almost negligible after the leaching test. Therefore, this study aims to present fundamental material properties of wood treated with copper and silver nanoparticles, and provide groundwork for further research (e.g. fixation of substances in the wood structure, etc.). In this study (Paper III), selected physical and mechanical properties, i.e., density profile, bending strength, hardness and moisture absorption were investigated for Lignamon (i), which was obtained from the Czech industrial production. Selected properties were also investigated using steam-densified beech (ii) and native beech (iii) and compared with each other. Densitometry of Lignamon showed a large variability of the density profile compared to the density profile of only densified beech. It is affected by the degree of densification, temperature and moisture gradients, and their relationship to the glass transition of the wood cell wall. Modulus of elasticity, hardness, moisture exclusion and anti-swelling efficiency of Lignamon are enhanced compared to densified beech. The enhanced dimension stability and lower hygroscopicity of Lignamon are probably caused by heat treatment during the process. Further investigation will be carried out with self-produced Lignamon samples. The paper IV deals with the effect of vacuum-pressure impregnation of poplar wood (Populus alba L.) by aqueous solutions of sucrose and sodium chloride on its physical properties. The most satisfying final properties were achieved in impregnation of sucrose with concentration of 6.25 g/100 ml H2O. The retention was 31 kg/m3 (WPG around 8 %). The values of ASE (anti-swelling efficiency) reached to 36 % and MEE (moisture exclusion efficiency) was reduced by 33 %. In Paper V, MW and conventional acetylation of wood was carried out to determine its efficacy on the material properties. Both MW and conventional heating positively affected the selected material properties. The results showed that no significant differences were found between MW and conventional heating; therefore, MW heating can be used as a valid replacement in the acetylation process. MW power of 2 kW and 0.1 m/min conveyor speed were the optimum conditions for MW acetylation. These process parameters resulted in 39.4 % ASE (T) and 35.2 % ASE (R) for beech and 38.0 % ASE (T) and 16.3 % ASE (R) for poplar samples. This work provides insight into the details of wood acetylation using MW heating. The study (Paper VI) aims to evaluate the antifungal activity of extractive compounds obtained with fexIKA accelerate extraction process. Results showed that the extractive compounds obtained from black locust heartwood were able to increase the native durability of European beech from class 5 (i.e. not durable with an average mass loss of 43.6 %) to class 3 (i.e. moderately durable with an average mass loss of 12.7 %). The final Paper VII shows following results. After impregnation with residual liquids and leaching, high amounts of TT (thermal treatment) and HTC (hydrothermal carbonisation) solution were washed out, whereas Pyrolysis liquids stayed with 25 % to 40 % remaining in the wood. Volumetric swelling in 65 % relative humidity at 20 °C was reduced from 6.5 % in untreated poplar to 5 % in impregnated samples with process residues of thermal treatment using 180 °C or 200 °C. The processes using HTC liquids from Miscanthus sp. (Misc.) or Sawdust showed reduction to 3-3.5 % and Pyrolysis liquid treatment to 2.5 %. After exposure to fungi, the mass loss of untreated Beech (30-35 %) and Poplar (40-50 %) was reduced to 2 % in case of Pyrolysis- and 4 % in case of TT-treatment.
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Bio-based composites from agricultural residues and other waste materials
Klímek, Petr
The main goal of the dissertation is to suggest several types of bio-based composites, notably particleboards, made from alternative materials (bio-waste, waste, plants´ residues) as an alternative to the currently produced wooden particleboards. The thesis provides a review and synthesis of the state-of-the-art literature. In the first part the literature is summarized and basic economical and ecological aspects of wood replacements for particleboards by using alternative materials are discussed. Further, mechanical properties data of suggested alternative particleboards are compiled, to give state-of-art insights in alternative particleboards developments. In the state-of-art, the compiled literature data are analysed through Ashby plots and give suggestions on what particleboards properties should be optimized. This evauationhave also proved that particleboards made from plants stalks, wood prunings and other wastes eg. waste tea leaves, peanut hulls, walnut shells could be economically viable alternative for the industry. The second part of this dissertation is concerned with designing and developing particleboards from the alternative resources available in Central Europe: (1) In total, 16 types of particleboards were produced from stalks coming from cup plants, Miscanthus, sunflower and topinambour. These particleboards are specified by standard mechanical tests and the effects of resin content and resin type were studied. Also chemical analysis were performed to determine the cellulose, hemicellulose and lignin contents. Structure of the Miscanthus particleboard were characterized by scanning electron microscopy (SEM). (2) Particleboards were also made and evaluated with different wastes. Particleboard made from BSG (Brewer´s spent grain) were characterized by their mechanical properties, chemical comosition and microscopic structure (SEM). Further, polyethylene terephtalate (PET) waste was added to wooden particleboards. Here, in addition to mechanical properties also microscopic structure and bond failures were analysed using SEM, with air-plasma treated PET particles studied by chemiluminescence and x-ray photoelectron spectroscopy (XPS) for their altered surface chemistry. The final section presents eight particleboard types made from recovered painted wood, as reclaimed from window frames. The effect of painted particles on the physical and mechanical properties were evaluated. With respect to possible applications the most important finding is that all particleboards from plants stalks fulfilled minimal requirements of class P1 in EN 312, which is for general purposes in dry conditions. Furthermore, a three-layer particleboard with spruce surface layers, and a core-layer made from cup-plant would provide a regular appearance of the panel surfaces. Particleboards having 10 % BSG also fulfilled the P1 requirements of EN 312. The particle-particle bonding was found to be a weak point in a entire internal bonding systém. To improve internal bonding experiments with plasma-treated beech wood particles bonded by PVAc was performed. Results have shown a significant improvment of internal bonding due to the plasma treatment. Consequently, the identical plasma treatment was applied to PET particles, which were mixed with wood in the particleboards. Bonding was here improved as well, with the IB higher compared to the untreated control. It was shown that plasma treatment has potential to compensate for declined IB of particleboards using alternative sources. In final part of this thesis, particleboards from reclaimed wood from painted window frames were produced. Results have shown that particleboards using painted-reclaimed wood as well as cleaned reclaimed wood deliver a performance comparable with regular wooden particleboards, as well as reduced thickness swelling.
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Thermowood properties depending on the protective substances
Kroupa, Michal ; Gaff, Milan (advisor) ; Sarvašová Kvietková, Monika (referee)
Bachelor thesis Thermowood properties depending on the protective substances is divided into several chapters. The first chapter explains the concept ThermoWood, the second chapter focuses on wood modification, the third chapter deals with the properties of wood ThermoWood. The fourth chapter shows the impact on the environment ThermoWood. The fifth chapter focuses on the analysis of literary knowledge, chapter sixth chapter is devoted to the analysis of the use of paints in practice. The penultimate seventh chapter is dedicated to new trends in this area and the last eighth chapter shows the graphs of the Finnish ThermoWood companies that are focused on production statistics.
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