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Design of leg for crash test dummy
Maršálek, Petr ; Semela, Marek (referee) ; Bilík, Martin (advisor)
This thesis is devoted to the design model of the lower limbs crash test dummies. It describes how the dummy developed historically, what are currently available for crash tests, what they are made and what their future will be. The main motive of the work is to design a model of lower limb for crash tests, with emphasis on the human anatomy. The work is characterized by how the figurine is produced using the form from material Thermolyne Clear, wood as a substitute human bones and the agar substitutes such as human muscle.
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Vliv teploty lepidla a povrchu adherendu na hloubku penetrace lepidla do masivního dřeva
Voldřichová, Anna
The final thesis deals with the influence of different gluing conditions on the depth of penetration of the adhesive into the surface of solid wood, specifically of the influence of increased pressure during pressing. Furthermore, the thesis investigates the effect of penetration on the strength of the glued joint under tensile loading. Specimens of spruce and oak wood were glued with UF glue and PVAC glue, pressed under different compression pressures and then subjected to tensile test. SEM analysis on an electron microscope was used to evaluate the depth of penetration. The results of the investigation of the effect of ink on the strength of the bonded joint and the penetration depth of the adhesive into the material are also included. The ink was used in the adhesive mixtures for the purpose of colouring the bonded joint.
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Vplyv extrémneho umyvacieho procesu na pevnosť v ohybe lepeného spoja v listnatom dreve
Tuhý, Dušan
The diploma thesis is focused on the issue of the effect of the washing process on the bending strength of the glued joint in a special solid wood panel made of hardwood. The goal was to analyze currently available adhesives and types of joints in solid wood panels and to deal with the issue of the washing process and its influence. The selected glue was PVAc glue Rakoll ® GXL 4 and a butt joint, and then the changes in bending strength were compared on wood samples from beech, oak, ash and maple after thirty cycles of an intensive washing process using cleaning tablets and subsequent acclimatization of the samples. These were compared with samples that did not undergo the cleaning process.
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Ztráta účinku výchovných zásahů ve smíšeném dubo-bukovém porostu (36A8) na ŠLP Křtiny
Černíková, Karla
The aim of the work was to evaluate the loss of the effect of individual thinnings in the oak-beech forest in Training Forest Enterprise. A research area of 0.84 ha was established in 1989 in a stand that was 49 years old. Thinnings were carried out on this research area (crown, low and Voropanov-Borgrewe thinning). Part of the area was left to natural development (reference area), which took as a comparison. The height, height of the base of the crowns, thickness was measured and the form of the trunk and crown according to Polansky's classification were estimated on individual tree. Measurements were carried out in 1989, 1999, 2005, 2010, 2015 and 2020. There was no response for the thickness when the variants of the thinning method were compared with the reference plots. In the first 10 years, the height increase was recorded in the case of Voropanov-Borgrewe thinning for the oak, and also, in the reference area, where the weakest and lowest oaks died. After 15 years, the height curves of Voropanov-Borgrewe thinning and reference plots were similar as the other methods, and the thinning effect was lost. In the beech, there was no effect of the thinning methods on the height. The effect of self-thinning was very successfully in beech, which is most noticeable in recent years. In the oak, there was no effect of the thinning methods for the parameter the height of the base of the crown compared to natural development. In the beech, there was the effective thinning method in the case of Voropanov-Borgrewe thinning. The factors that were evaluated based on the Polansky classification (the form of the trunk and crown) did not show improvement in oak and beech in any case of thinning methods. In conclusion, we can say that the final evaluation of the effectiveness of thinning methods, which were carried out only once, is not considered significant compared to the natural development of the stand.
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Zhodnocení škod mrazem na zakládaných lesních kulturách v podmínkách ŠLP ML Křtiny
Patáková, Aneta
On the forest property managed by ŠLP ML Křtiny, an assessment of the damage caused by late frosts on the plantations of forest trees was carried out. Data collection took place at the beginning of the growing season (from May to June), when woody plants begin to sprout and are exposed to the greatest risk of damage from late frosts. Frost events were measured using TMS data loggers, which record the ground air temperature using temperature sensors. The assessment was carried out on young cultures of beech, oak, spruce and fir with a maximum age of 3 years. A total of 28 leguminous areas of different sizes (categories up to 0.1; 0.11 – 0.5 and over 0.51 ha) were evaluated, on which the average damage of the assimilation apparatus was determined on a representative sample of 100 seedlings. The results showed that the most sensitive tree species to late frosts are beech (damaged 56.9 ±30.7% of seedlings) and fir (52.4 ±46.6%).
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Souběžná obnova dubu zimního (Quercus petraeaMatt./ Liebl.) a dřevin přípravných
Žákovský, Jan
This work focuses on alternative solutions for forest regeneration in areas affected by calamity, namely the simultaneous regeneration of target and preparatory trees. The aim of the work is to evaluate experiments of simultaneous regeneration of winter oak (Quercus petraea Matt. / Libel.) and pioneer trees - grey poplar (Populus x canescens (Aiton) Sm.), aspen (Populus tremola L.), sticky alder (Alnus glutinosa L.), white birch (Betula Pendula Roth). established in the areas - Valšovice (SLT 3 B ) and Olšovec (SLT 4 S, 4 O) in 2015 and 2016 respectively. The results showed that aspen grows the fastest in height among the pioneer tree species. Rapid thickness and height growth was recorded for alder and birch. In the Olšovec alder there was a significant deterioration in vigour in the last year of the survey. Grey poplar did not progress on the Olšovec forest. Positive effect on oak regeneration was found only in alder on TVP Valšovice. The effect of pioneer tree species on oak quality was not unanimous.
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Sestavení historické části regionální dubové standardní chronologie pro oblast jihozápadní Ukrajiny
Formánek, Šimon
Due to the high number of preserved wooden churches and bell towers in the southwest of Ukraine, it is possible to study their architecture and history. By the use of dendrochronological dating, we can determine with annual accuracy their construction or reconstruction year, which can be compared with the information available in historical literary sources. The aim of this thesis was to use dendrochronological analysis to determine the age of individual sacral buildings and to create a local standard oak chronology. Dendrochronological dating took place on a total of 11 churches and bell towers in the region of southwestern Ukraine. 167 samples were collected for analysis using Pressler borer. 41 oak and 5 fir samples were successfully dated. Oak wood had the highest representation among individual samples – 144. The wood of fir, spruce, poplar, ash and birch was present to a lesser extent. The oldest wooden element that has been reliably dated is from the Church of St. Nicholas in Serednia Vodiane, dating from 1591–1599. On the other hand, the youngest dated structural elements dating back to 1973/1974 are from the Church of St. Michael the Archangel in Uzhgorod. Other wooden churches and bell towers date back to the period between the 16th and the turn of the 17th and 18th centuries. Based on the successfully dated tree-ring series it was possible to create a local oak standard chronology covering the years 1366–1805 and 1890–1972. Dendrochronological dating helped to clarify the structural and historical development of wooden sacral buildings in the southwest of Ukraine and to provide information that is often missing in literary historical sources. The newly developed standard oak chronology will be able to serve as one of the cornerstones of a new oak standard chronology for the region of southwestern Ukraine.
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Creep behavior of oak pegs under tension in dry and wet conditions
Kunecký, Jiří ; Kloiber, Michal ; Hasníková, Hana ; Hrivnák, Jaroslav ; Sebera, V. ; Tippner, J. ; Milch, J.
Carpentry joints equipped with oak pegs are well suited for applications where increased moisture is not a significant factor. However, for the use in outside conditions, e.g. in the repairs of historical timber bridges, the pegs connecting the two halves of the joint may deform and change their original shape. This happens especially during long-term loading and can be augmented significantly by environmental changes. Creep behavior can play a crucial role for some types of carpentry joints, especially when precise contacts of faces in the joint are required. The paper deals with experimental testing of creep behavior of 16 mm oak pegs under dry and wet conditions loaded by the combination of shear and bending between two planks made of spruce in the direction parallel to grain. The results show that the decrease of theoretical stiffness values over time plays a significant role in the force redistribution in the joint especially due to moisture effects (drop 50-70% of the original stiffness).
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Mechanical analysis of scarf joint fastened using cylindrical wooden dowel
Tippner, J. ; Milch, J. ; Kunecký, Jiří ; Kloiber, Michal ; Brabec, M. ; Sebera, V.
Traditional all-wooden woodworking joints play an important role in the behaviour of timber structures. These joints are also widely used when historically valuable constructions are being reconstructed and the connections are usually the masterpieces that testify to the high carpentry skills and knowledges of the overall mechanical behaviour. Within historical timber structures traditional carpentry joints were used while wooden dowel fixed mutual position of elements. Main aim of this study was to contribute to knowledge base about prediction and analysis of the mechanical performance of frequently used scarf joints made from spruce wood fastened using oak dowels. The objectives were to determine the joints' slip moduli and load-carrying capacity by means of theoretical and experimental approaches, in next to assess the mechanical behaviour of dowels through experimental investigation, and finally to perform a strain analysis of dowels. For these purposes, the optical technique employing three-dimensional full-field digital image correlation was used. The experiments were done on the full-scale specimens meeting the requirements of European standards (EN 383 and EN 26891), which were made from Norway spruce (Picea abies L. Karst.) and English oak (Quercus robur L.). The mechanical load consisted in tensile parallel and perpendicular to grain direction within the main components. The results of this study showed good correlation between theoretical approach based on based on Beam on Elastic Foundation theory and European yield model theory and experimental observations.
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THE EFFECT OF AN INCREASING COVERAGE OF INVASIVE BLACK LOCUST ON BIRD COMMUNITIES IN FOREST STANDS
Kroftová, Magdalena ; Reif, Jiří (advisor) ; Ferenc, Michal (referee)
Biological invasions are one of the most important threats to global biodiversity and they were also found to negatively affect some bird species. Despite relatively large number of scientific studies dealing with the impacts of invasive plants on bird communities, their results are inconsistent, especially it is not clear how birds respond to increasing levels of expansion of invasive species in native species stands. Moreover, bird responses to plant invasions seem to depend on the ecological characteristics of individual bird species. This study contributes to elucidation of this problem; I investigated the impacts of black locust (Robinia pseudoacacia) invasion on bird communities in three types of forest stands with different levels of invasion: in stands containing solely the native oak (Quercus spp.), in partially invaded stands with different proportions of black locust and oak (mixed stands) and in pure black locust stands. Previous studies that examined birds in pure oak and pure black locust stands have found that they differ markedly in vegetation structure, but not in the total number of bird species. However, habitat specialists were associated with the oak stands, while generalists with the black locust stands. Therefore, I predicted that (1) the total species richness will be...
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