京都大学 / 新制・課程博士 / 博士(薬科学) / 甲第23141号 / 薬科博第140号 / 新制||薬科||15(附属図書館) / 京都大学大学院薬学研究科薬科学専攻 / (主査)教授 金子 周司, 教授 髙倉 喜信, 准教授 中川 貴之 / 学位規則第4条第1項該当 / Doctor of Pharmaceutical Sciences / Kyoto University / DFAM

Content: Soluble soybean polysaccharide (SSPS) is good in emulsification, and stable emulsion may be formed with the addition of SSPS in fatliquoring agents. In this paper, with wet blues as raw materials, after being retanned and neutralized, fatliquoring and filling up with SSPS were carried out at the same time, with different amounts of SSPS, i.e., 1%, 3%, 5%,7% in weight. The leather samples were dried at room temperature. The effects of SSPS amounts on the thickness, air permeability and water vapor permeability of the crust leather were studied. The tensile properties of the leathers filled by SSPS were analyzed. The results indicated that with increasing the amounts of SSPS, the thickness and the water vapor permeability of the leathers increase, while the air permeability decreases slightly. The maximum stress-strain capacity of leathers decreases with increasing the SSPS amount. At the SSPS amount of 3%, the leather is good in softness, as well as in physical and mechanical properties. Take-Away: 1.SSPS from soybean dregs is an acidic polysaccharide, which is rich in raw materials and low in cost. 2.Leathers filled with SSPS have good performance.

Recent tailings dam failures around the world have highlighted the real risk posed by undrained slope failures. Undrained failures are fundamentally different to drained failures in the sense that different mechanisms are involved (i.e. a slope may be stable against drained failure but unstable against undrained failure). Popular methods to assess the stability of slopes against undrained failure involve the use of limit equilibrium analyses with both drained and undrained strengths assigned in the same analysis. A potential shortcoming of these methods is that no consideration is given to strain compatibility. In this study, a limit equilibrium based method where strain compatibility is maintained on the failure surface was developed. The method, referred to as the strain mobilisation method, considers a Mohr circle of stress at failure to determine the shear strength mobilised on the failure plane for use in the stability analysis as a function of the deviator stress imposed on the triaxial test result. The mobilisation of stress on a failure plane with strain was determined based on the stress-strain relationships observed during triaxial tests. A Factor of Safety (FoS) was used to express the stability of the slope as a function of the mobilised strain and the calculated FoS results obtained using the proposed method were compared to calculated FoS results using traditional methods. This was done for three tailings materials (gold, iron and platinum) for three specific hypothetical slopes. As an additional check, the proposed method was tested on Nerlerk sand, a well-known sand showing strain-softening behaviour during undrained shearing. It was found that, in general, as mobilised strain is increased, the FoS calculated using the proposed method converges to that of traditional methods so that there was no significant difference in calculated FoS between the current methods and the proposed method that does consider strain compatibility. This indicates that the proposed method provides FoS values comparable to those calculated using currently accepted methods where the failure surface passes predominantly through a single material type. For such a case, there does not appear to be a need to consider limit equilibrium methods where strain compatibility is maintained. The proposed method provides an indication of the amount of strain that may be expected to mobilise to provide the FoS. Given that this amount of strain is not excessive, the current methods which do not consider strain compatibility perform satisfactorily and can continue to be used / Dissertation (MEng (Civil Engineering))--University of Pretoria, 2021. / Civil Engineering / MEng (Civil Engineering) / Unrestricted

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<div>The proliferation of single-use plastics in the foodware and packaging sector has stimulated interest in sustainable material substitutes that can be processed efficiently and which possess sufficient structural integrity. Herein, we study the structure, mechanical response and diffusion properties of leaf-sheath from a representative palm species—<i>Areca catechu</i>—widely cultivated in the Indian sub-continent and Southeast Asia. The study of this material system, and the specific attributes, are motivated by the use of this material in foodware applications. Foodware such as plates and bowls can be produced from the areca sheath, directly, in a single step, by stretch forming analogous to sheet metals. The material is eco-friendly, biodegrading in ~100 days. Formability and water diffusion are two key attributes of relevance for foodware, since the former attribute determines the shape change capability of the material and range of producible shapes; and the latter, foodware product (structural) integrity and life.<br></div><div><br></div><div>We characterize the morphology (external structure) and anatomy (internal structure) of the sheath using imaging techniques and composition analysis. The sheath is shown to resemble a composite material, with structural characteristics intermediate between those of the palm leaf and stem. By measuring the mechanical response of the sheath to various types of 1D and 2D loading (e.g., uniaxial tension and compression, biaxial stretching, rolling), and hydration conditions, we show that the sheath material has high stretch-formability, especially when hydrated. This formability is similar to that of the most ductile sheet metals. The formability is shown to be further enhanced by addition of small quantities of NaOH (~5%) during hydration. Local deformation measurements in biaxial stretching, based on analysis of distortion of grid-markers inscribed onto sheath samples, have enabled characterization of strain-field anisotropy and mode of failure in the sheath. By consolidating the mechanical test results, we present a forming limit diagram for the leaf-sheath.<br></div><div><br></div><div>The structural integrity and life of foodware products produced from the leaf-sheath are directly determined by diffusion of liquids (e.g., water, oils) through the sheath wall thickness. Water and oils are important constituents of semi-solid and solid foods. Diffusion of water is also important for designing the hydration cycle to enhance formability. The diffusion of water through the sheath material process is studied using mass gain measurements and<i> in situ</i> imaging of water transport.<br></div><div><br></div><div>We determine the diffusion coefficient for water, which is critical for estimating product life. The diffusion coefficient for the matrix is shown to be one order of magnitude greater than for the fiber. We vary salt concentration in the water by controlled additions of NaCl and note a non-monotonic dependence of the diffusion on concentration. By subjecting the leaf-sheath to a short-time (~ 3 minutes) thermal treatment (~ 80⁰C), a hydrophobic wax layer can be made to secrete onto the leaf surface. This wax coating is found to significantly reduce the water diffusion, enabling the sheath foodware life to be increased. <br></div><div><br></div><div>Lastly, we argue, that since the leaf-sheath is a “waste product” of the palm, it has negligible embodied energy (4 to 5 orders of magnitude smaller) compared to paper and plastics based foodware.<br></div><div><br></div><div>We discuss the implications of the results for single-step forming of high-aspect ratio products and structures from the palm sheath, methods to reduce diffusion of liquids and improve foodware product life, and some directions for future research into mechanical behavior of plant leaf materials from a forming perspective.<br></div>

This master thesis is divided into three main parts. In first part is more closely described the method of tube flaring. Tube flaring was chosen for analysis of biaxial stress, in this thesis particularly in the presence of high strain rate. In the second part is more closely described influence of high strain rate on the forming process. There is described influence of high strain rate on behavior of the material, hardening, change of quasi-static yield strength to the dynamic yield strength, influence of high strain rate on the microstructure and more. During the description of these processes there is effort to describe the cause of these changes as well. For this task was used domestic and foreign literature, as well as peer review papers whose authors study intensively this problematic. Besides all of the above there is also derived the velocity of elastic and plastic wave. In the end is evaluated experiment, in which was done tube flaring, which is part of this master thesis. Results from the 3D optical system ARAMIS are interpreted with the help of Microsoft Excel, where the chosen results were used as the input to the equations modified for the dynamic loading.

The presented thesis was created in cooperation with Siemens, s.r.o. and deals with the analysis of the bending of aluminium sheets. These products are used as conductors of electrical energy. The problem happened when the bending angle was 90 ° when there was a violation outside of the bend. The aim of the thesis is to verify whether the bend is correctly designed using analytical and empirical relations and the finite element method. Because of the requirement for running numerical simulation on one of the freely available software the Salome Meca program environment was used. The results of numerical simulation did not confirm that the violation should occur. In deeper analysis appeared doubts whether it is possible to correctly evaluated result only by data from tensile test. In the final part, there are recommended some experiments which would be necessary for the correct calibration of the ductil fracture criteria.

This Master’s thesis deals with strain-stress analysis of a spine segment with an introduced fixator and a spine in natural physiological state. The work starts with a research study of literature sources that focus on similar issues. Furthermore, basic anatomy terminology and basic procedures for human spine stabilization were described. The formulated issue was resolved by computational modelling with the use of the finite element method. This solution requires a suitable computational model to be produced. This model consists of partial geometry, material, bond, and loading models. The geometric model was produced on the basis of CT scan images of a 60-year-old man which were used for producing five spine vertebrae T11–L3. Moreover, the geometric model consists of four intervertebral discs and eight articular cartilages. The material model includes homogeneous, heterogeneous and degraded properties of bone tissue. The strain-stress analysis was performed for seven loading states, which concern basic movements of human spine – standing, bending forward, bending backwards, bending left, bending right, left rotation and right rotation, with the use of ANSYS software. The assessed and analysed quantities include spine segment displacement, contact pressure of articular cartilages and stress on the fixator.

The diploma thesis deals with computational modelling of stress-strain states in elastomeric components of a flexible coupling. The first part of the thesis is dedicated to research about usage and designs of flexible coupling and about fatigue of elastomers. The second part of the thesis concerns creation of the computational model. The model of material is determined based on uniaxial tension test of a specimen produced from a real elastomer component. The results are presented in the form of comparison of two designs of elastomer component with respect to fatigue behaviour based on a maximum principal strain range. The results of computational modelling in the viewpoint of crack initiation site are in good agreement with the results from the component used in operation and dif-ferences between the two designs are negligible. The quantitative difference of the two designs is 15 %.

Applying the anisotropy of magnetic susceptibility to analogue models provides detailed insights into the strain distribution and quantification of deformation within contractional tectonic settings like fold-and-thrust belts (FTBs). Shortening in FTBs is accommodated by layer-parallel shortening, folding, and thrusting. The models in this research reflect the different deformation processes and the resulting magnetic fabric can be attributed to thrusting, folding and layer-parallel shortening. Thrusting develops a magnetic foliation parallel to the thrust surface, whereas folding and penetrative strain develop a magnetic lineation perpendicular to the shorting direction but parallel to the bedding. These fabric types can be observed in the first model of this study, which simulated a FTB shortened above two adjacent décollements with different frictional properties. The different friction coefficients along the décollements have not only an effect on the geometric and kinematic evolution of a FTB, but also on the strain distribution and magnitude of strain within the belt.  The second series of models performed in this study show the development of a thrust imbricate and the strain distribution across a single imbricate in more detail. Three models, with similar setup but different magnitudes of bulk shortening, show strain gradients by gradual changes in principal axes orientations and decrease in degree of anisotropy with decreasing distance to thrusts and kinkzones. These models show that at the beginning of shortening, strain is accommodated mainly by penetrative strain. With further shortening, formation of thrusts and kinkzones overprint the magnetic fabric locally and the degree of anisotropy is decreasing within the deformation zones. At thrusts, an overprint of the magnetic fabric prior deformation towards a magnetic foliation parallel to the thrust surfaces can be observed. A rather complex interplay between thrusting and folding can be analysed in the kinkzones. In general, this thesis outlines the characteristics of magnetic fabric observed in FTBs, relates different types of magnetic fabric to different processes of deformation and provides insights into the strain distribution of FTBs.