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Дисертації з теми "Speed deformation"
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1
Welsh, B. S. "High speed deformation and break-up of shaped charge jets." Thesis, University of Nottingham, 1993. http://eprints.nottingham.ac.uk/42489/.
Повний текст джерелаАнотація:
Jets resulting from shaped charges which contain metal liners are able to penetrate hard or armoured targets. Their penetration performance is related to the density of the jet and target material and also the length to which the jet can elongate. Models that describe the processes involved have generally assumed hydrodynamic fluid flow and as such have been very successful in most cases. However, the break-up of jets has proved to be inconsistent with the fluid flow models and cannot be accurately described. Break-up is important since it is the final phenomenon in tensile deformation and therefore represents the limiting extent of jet elongation. Additionally, following break-up the jet fragments are particularly susceptible to lateral velocities and tumbling which dissipate the jets energy and further reduce its penetration performance. Research by Hunting Engineering Limited has indicated that mechanical properties are related to the jet break-up phenomena. However, the deformation and break-up of shaped charge jets is not well understood from a metallurgical point of view. It is essential that the jet is in the solid state for jet break-up phenomena to be related to the mechanical properties of the liner material. This has been demonstrated here by theoretical analysis and more directly by observation of in-flight and captured jet fragments. A series of experiments have been carried out in order to measure and analyse the deformation and attempt to put forward models for the break-up mechanisms in shaped charge jets. These were based upon a series of selected aluminium and aluminium alloys which were processed and heat treated to produce a range of mechanical properties. The properties under consideration are those which describe the materials strength, elongation and work hardening characteristics at intermediate strain rates under laboratory conditions. These have been used to relate metallurgical details to the nature of jet break-up. The better materials for shaped charge jets would appear to be high purity metals which exhibit large ductility through to fracture.
2
Nordén, Kristina. "Surface and Inner Deformation during Shape Rolling of High Speed Steels." Licentiate thesis, KTH, Materials Science and Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4460.
Повний текст джерелаАнотація:
Shape rolling is a common manufacturing process used to produce long products i.e. bars and wire. One of the problems that might occur during rolling is defect formation leading to rejection of the finished product. This work is a step towards a better understanding of the evolution of some of these defects.
The evolution and reduction of cracks during shape rolling is studied in this thesis. To accomplish this, artificial longitudinal cracks are machined along bars of high speed steel. The cracks are positioned at different sites evenly distributed along the periphery in intervals of 45°. Some of the cracks are left open and some are filled with carbon or stainless steel welds. FE simulations are performed using the commercial code MSC.Marc and the results from the simulations are compared with experimental ones. Generally, simulations predict less reduction than observed experimentally. For most positions, the cracks tend to reduce most effectively followed by carbon steel welds and stainless steel welds.
To evaluate the inner deformation of a cross section during shape rolling in an oval-round-oval-round series, sample bars of M2 high speed steel are prepared with grids made up by stainless steel wires. After collecting samples after each pass, they are X-rayed to create an image of the grid. The deformation of the wires can favorably be described by FE simulations of a bar originally rotated 10° when entering the first pass. The results suggest that the simulations describe the deformation during shape rolling well.
3
Nordén, Kristina. "Surface and inner deformation during shape rolling of high speed steels /." Stockholm : Materialvetenskap Materials Science and Engineering, Kungliga Tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4460.
Повний текст джерела
4
Philipp, Katrin, Angelos Filippatos, Nektarios Koukourakis, Robert Kuschmierz, Christoph Leithold, Albert Langkamp, Andreas Fischer, and Jürgen Czarske. "In-process deformation measurements of translucent high speed fibre-reinforced disc rotors." SPIE, 2015. https://tud.qucosa.de/id/qucosa%3A35189.
Повний текст джерелаАнотація:
The high stiffness to weight ratio of glass fibre-reinforced polymers (GFRP) makes them an attractive material for rotors e.g. in the aerospace industry. We report on recent developments towards non-contact, in-situ deformation measurements with temporal resolution up to 200 µs and micron measurement uncertainty. We determine the starting point of damage evolution inside the rotor material through radial expansion measurements. This leads to a better understanding of dynamic material behaviour regarding damage evolution and the prediction of damage initiation and propagation. The measurements are conducted using a novel multi-sensor system consisting of four laser Doppler distance (LDD) sensors. The LDD sensor, a two-wavelength Mach-Zehnder interferometer was already successfully applied for dynamic deformation measurements at metallic rotors. While translucency of the GFRP rotor material limits the applicability of most optical measurement techniques due to speckles from both surface and volume of the rotor, the LDD profits from speckles and is not disturbed by backscattered laser light from the rotor volume. The LDD sensor evaluates only signals from the rotor surface. The anisotropic glass fibre-reinforcement results in a rotationally asymmetric dynamic deformation. A novel signal processing algorithm is applied for the combination of the single sensor signals to obtain the shape of the investigated rotors. In conclusion, the applied multi-sensor system allows high temporal resolution dynamic deformation measurements. First investigations regarding damage evolution inside GFRP are presented as an
important step towards a fundamental understanding of the material behaviour and the prediction of damage initiation and propagation.
5
Biswas, Souvik. "Simulation of thermo-mechanical deformation in high speed rolling of long steel products." Link to electronic thesis, 2003. http://www.wpi.edu/Pubs/ETD/Available/etd-1027103-203032/.
Повний текст джерелаАнотація:
Thesis (M.S.)--Worcester Polytechnic Institute.Keywords: product geometry; hot rolling; high speed rolling; rolling simulation; bar and rod rolling; free surface; finite element analysis. Includes bibliographical references (p. 69-75).
6
Jackson, Perry Francis. "An investigation into the deformation behaviour of geosynthetic reinforced soil walls under seismic loading." Thesis, University of Canterbury. Department of Civil and Natural Resources Engineering, 2010. http://hdl.handle.net/10092/5522.
Повний текст джерелаАнотація:
Reinforcement of soil enables a soil slope or wall to be retained at angles steeper than the soil material’s angle of repose. Geosynthetic Reinforced Soil (GRS) systems enable shortened construction time, lower cost, increased seismic performance and potentially improve aesthetic benefits over their conventional retaining wall counterparts such as gravity and cantilever type retaining walls. Experience in previous earthquakes such as Northridge (1994), Kobe (1995), and Ji-Ji (1999) indicate good performance of reinforced soil retaining walls under high seismic loads. However, this good performance is not necessarily due to advanced understanding of their behaviour, rather this highlights the inherent stability of reinforced soil against high seismic loads and conservatism in static design practices.
This is an experimental study on a series of seven reduced-scale GRS model walls with FHR facing under seismic excitation conducted using a shake-table. The models were 900 mm high, reinforced by five layers of stiff Microgrid reinforcement, and were founded on a rigid foundation. The soil deposit backfill was constructed of dry dense Albany sand, compacted by vibration (average Dr = 90%). The influence of the L/H ratio and wall inclination on seismic performance was investigated by varying these important design parameters throughout the testing programme. The L/H ratio ranged from 0.6 – 0.9, and the walls were primarily vertical except for one test inclined at 70o to the horizontal.
During testing, facing displacements and accelerations within the backfill were recorded at varying levels of shaking intensity. Mechanisms of deformation, in particular, were of interest in this study. Global and local deformations within the backfill were investigated using two methods. The first utilised coloured horizontal and vertical sand markers placed within the backfill. The second utilised high-speed camera imaging for subsequent analysis using Geotechnical Particle Image Velocimetry (GeoPIV) software. GeoPIV enabled shear strains to be identified within the soil at far smaller strain levels than that rendered visible by eye using the coloured sand markers. The complementary methods allowed the complete spatial and temporal development of deformation within the backfill to be visualised.
Failure was predominantly by overturning, with some small sliding component. All models displayed a characteristic bi-linear displacement-acceleration curve, with the existence of a critical acceleration, below which deformations were minor, and above which ultimate failure occurs. During failure, the rate of sliding increased significantly.
An increase in the L/H ratio from 0.6 to 0.9 caused the displacement-acceleration curve to be shallower, and hence the wall to deform less at low levels of acceleration. Accelerations at failure also increased, from 0.5g to 0.7g, respectively. A similar trend of increased seismic performance was observed for the wall inclined at 70o to the horizontal, when compared to the other vertical walls.
Overturning was accompanied by the progressive development of multiple inclined shear surfaces from the wall crest to the back of the reinforced soil block. Failure of the models occurred when an inclined failure surface developed from the lowest layer of reinforcement to the wall crest. Deformations largely confirmed the two-wedge failure mechanism proposed by Horii et al. (2004).
For all tests, the reinforced soil block was observed to demonstrate non-rigid behaviour, with simple shearing along horizontal planes as well as strain localisations at the reinforcement or within the back of the reinforced soil block. This observation is contrary to design, which assumes the reinforced soil block to behave rigidly.
7
Yuan, Fuping. "PLATE IMPACT EXPERIMENTS TO INVESTIGATE DYNAMIC SLIP, DEFORMATION AND FAILURE OF MATERIALS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1193161550.
Повний текст джерела
8
Smith, Travis Lee. "The Effect of Tool Rotation Speed and Clamping on Deformation in Friction Stir Welded 6061-T6511 Aluminum Extrusions." ScholarWorks@UNO, 2011. http://scholarworks.uno.edu/td/350.
Повний текст джерелаАнотація:
Friction Stir Welding (FSW) was used to perform Bead on Plate (BOP) welds on 6061-T6511 aluminum extrusions. Using a DOE approach, tool rotation speed, clamp spacing, and clamping force were altered to ascertain their effects on distortion in the welded panels. Mechanical forces were monitored during the weld process. Both linear and out of plane distortion were measured on the welded extrusions. The Vickers hardness of the weld nugget was measured. The effect of each parameter on weld distortion was discovered and the mechanism of this link was suggested.
9
Fraser, Steven. "Multi-variable optimal numerical control using adaptive model for identification of thermally induced deformation in high-speed machine tools." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0002/NQ39792.pdf.
Повний текст джерела
10
Tillhonová, Veronika. "Analýza naměřených dat z nárazových zkoušek - kolmé střety." Master's thesis, Vysoké učení technické v Brně. Ústav soudního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-318573.
Повний текст джерелаАнотація:
The diploma thesis deals with crash tests. Many international organizations specialize directly in conducting crash tests. Impact test simulates vehicle collision. The three most common test are front, side, and backstreets. The diploma thesis focuses on side conflicts. Side clashes are characterized by the fact that the first vehicle is damaged at the front and the second in the side. The measured data from these tests was evaluated to obtain the deformation energy consumed for permanent damage to vehicles. Deformation energy was calculated as equivalent to the individual speed of individual vehicles. EES values have been evaluated by various methods used in expert practice and compared. The impact tests were simulated to clarify assistance to experts in the analysis of traffic accidents.
11
Овчарова, Наталія Юріївна. "Скінченно-елементний аналіз швидкісного деформування захисних елементів машинобудівних конструкцій". Thesis, Інститут проблем машинобудування ім. А. М. Підгорного НАН України, 2017. http://repository.kpi.kharkov.ua/handle/KhPI-Press/32352.
Повний текст джерелаАнотація:
Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.02.09 – динаміка та міцність машин. – Національний технічний університет "Харківський політехнічний інститут" Міністерства освіти і науки України, Харків, 2017
В дисертації вирішена актуальна науково-технічна задача визначення динамічного напружено-деформованого стану захисних елементів машинобудівних конструкцій при імпульсному та ударному навантаженнях для забезпечення їх міцності та ефективного використання при експлуатації. На основі тривимірної моделі швидкісного деформування елементів конструкцій, з урахуванням пружно-пластичних скінченних деформацій і динамічних властивостей матеріалів отримані залежності розподілу напружень від швидкості удару за просторовими та часовими координатами в елементах конструкцій. Виявлені нові особливості процесу швидкісного деформування елементів при локальних навантаженнях, що відрізняються визначенням розмірів обмеженої зони напружень з великими градієнтами, утворенням кратерів тощо. Отримані залежності між напруженнями та швидкостями удару в тришаровому елементі для окремих шарів та деформаціями в шарах в залежності від швидкості ударника.The thesis for a candidate of technical science degree in speciality 05.02.09 – Dynamics and Strength of Machines (engineering sciences) – Kharkov National University "Kharkov Polytechnic Institute", Kharkiv, 2017. In the thesis, the actual scientific and technical problem of determining the dynamic stress-strain state of the protective elements of machine-building structures under impulse and shock loads solved to ensure their strength and effective use during operation. The thesis proposes an improved three-dimensional model of high-rate deformation of structural elements, which is different by taking into account elastic-plastic finite deformations and dynamic properties of materials. Based on the proposed model, the dependences of the distribution of stresses on the speed of impact on spatial and temporal coordinates in structural elements made of various materials obtained. New features of the process of high-rate deformation of elements under local loads detected, differing in the definition of the size of a restricted stress zone with large gradients, the formation of craters and the process of unloading with the appearance of residual stresses and damages. Dependencies between stresses and impact speeds in a three-layer element for individual layers and deformations in layers depending on the speed of the impactor obtained. The dynamic stress-strain state changes significantly both in space coordinates and in time. Therefore, even for thin-walled constructions, the use of the theory of plates and shells is undesirable, since in this case the law of stress distribution over the thickness is preliminarily assumed, and part of the stresses perpendicular to the middle surface are not taken into account at all. The processes of high-speed deformation occur both in the elastic and in the plastic stage and partially accompanied by rather large deformations. Therefore, the work uses three-dimensional models, even for thin-walled structures. From a mathematical point of view, such problems are essentially non-linear and require analysis of a three-dimensional dynamic stress-strain state. The problems of high-rate elastic-plastic deformation of elements of cylindrical structures are considered. It is shown, that the largest displacements and stresses develop in local zones and in the case when the speed is increase up to V ≥ 150 m/s, the area of intense displacements and stresses is R ≤ (10-12) r, where r is the radius of the zone load. These features of the dynamic stress-strain state make it possible to isolate the corresponding region of the element and to make refined calculations for it using a denser grid. A number of practical problems of analyzing the stress-strain state of the elements of the gas turbine engine corps under shock loading considered which differ in the purpose, geometric characteristics and properties of the materials. It is shown, that the largest displacements and stresses develop in bounded zones and rapidly decrease in spatial coordinates both in time and in unloading. It is shown, that when the blade fragment is detached, as well as the foreign particles fall into the flow at the working speeds of the gas turbine engine rotation, the stress intensities do not exceed the prescribed boundaries. In some cases, preference is given to two-layer structures, since they resist shock loads better, than single-layer ones with a larger thickness of the same material.
12
Forysewicz, Monika. "Analysis of the deformation and stress condition in the visco-elastic-plastic materials processing area during a high-speed single-blade cutting : PhD thesis summary : [synopsis]." Rozprawa doktorska, [s.n.], 2015. http://dlibra.tu.koszalin.pl/Content/1058.
Повний текст джерела
13
Овчарова, Наталія Юріївна. "Скінченно-елементний аналіз швидкісного деформування захисних елементів машинобудівних конструкцій". Thesis, НТУ "ХПІ", 2017. http://repository.kpi.kharkov.ua/handle/KhPI-Press/32351.
Повний текст джерелаАнотація:
Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.02.09 – динаміка та міцність машин. – Національний технічний університет "Харківський політехнічний інститут" Міністерства освіти і науки України, Харків, 2017
В дисертації вирішена актуальна науково-технічна задача визначення динамічного напружено-деформованого стану захисних елементів машинобудівних конструкцій при імпульсному та ударному навантаженнях для забезпечення їх міцності та ефективного використання при експлуатації. На основі тривимірної моделі швидкісного деформування елементів конструкцій, з урахуванням пружно-пластичних скінченних деформацій і динамічних властивостей матеріалів отримані залежності розподілу напружень від швидкості удару за просторовими та часовими координатами в елементах конструкцій. Виявлені нові особливості процесу швидкісного деформування елементів при локальних навантаженнях, що відрізняються визначенням розмірів обмеженої зони напружень з великими градієнтами, утворенням кратерів тощо. Отримані залежності між напруженнями та швидкостями удару в тришаровому елементі для окремих шарів та деформаціями в шарах в залежності від швидкості ударника.The thesis for a candidate of technical science degree in speciality 05.02.09 – Dynamics and Strength of Machines (engineering sciences) – Kharkov National University "Kharkov Polytechnic Institute", Kharkiv, 2017. In the thesis, the actual scientific and technical problem of determining the dynamic stress-strain state of the protective elements of machine-building structures under impulse and shock loads solved to ensure their strength and effective use during operation. The thesis proposes an improved three-dimensional model of high-rate deformation of structural elements, which is different by taking into account elastic-plastic finite deformations and dynamic properties of materials. Based on the proposed model, the dependences of the distribution of stresses on the speed of impact on spatial and temporal coordinates in structural elements made of various materials obtained. New features of the process of high-rate deformation of elements under local loads detected, differing in the definition of the size of a restricted stress zone with large gradients, the formation of craters and the process of unloading with the appearance of residual stresses and damages. Dependencies between stresses and impact speeds in a three-layer element for individual layers and deformations in layers depending on the speed of the impactor obtained. The dynamic stress-strain state changes significantly both in space coordinates and in time. Therefore, even for thin-walled constructions, the use of the theory of plates and shells is undesirable, since in this case the law of stress distribution over the thickness is preliminarily assumed, and part of the stresses perpendicular to the middle surface are not taken into account at all. The processes of high-speed deformation occur both in the elastic and in the plastic stage and partially accompanied by rather large deformations. Therefore, the work uses three-dimensional models, even for thin-walled structures. From a mathematical point of view, such problems are essentially non-linear and require analysis of a three-dimensional dynamic stress-strain state. The problems of high-rate elastic-plastic deformation of elements of cylindrical structures are considered. It is shown, that the largest displacements and stresses develop in local zones and in the case when the speed is increase up to V ≥ 150 m/s, the area of intense displacements and stresses is R ≤ (10-12) r, where r is the radius of the zone load. These features of the dynamic stress-strain state make it possible to isolate the corresponding region of the element and to make refined calculations for it using a denser grid. A number of practical problems of analyzing the stress-strain state of the elements of the gas turbine engine corps under shock loading considered which differ in the purpose, geometric characteristics and properties of the materials. It is shown, that the largest displacements and stresses develop in bounded zones and rapidly decrease in spatial coordinates both in time and in unloading. It is shown, that when the blade fragment is detached, as well as the foreign particles fall into the flow at the working speeds of the gas turbine engine rotation, the stress intensities do not exceed the prescribed boundaries. In some cases, preference is given to two-layer structures, since they resist shock loads better, than single-layer ones with a larger thickness of the same material.
14
Muracciole, Jean-Michel. "Influence de la vitesse de deformation sur le comportement du polymethacrylate de methyle a la temperature ambiante." Poitiers, 1987. http://www.theses.fr/1987POIT2202.
Повний текст джерелаАнотація:
Realisation d'un dispositif informatique pour mesurer et enregistrer les deformations du pmma selon trois directions perpendiculaires lors d'essais de traction a grande vitesse. Etude des cartes de deformations
15
Rybková, Tereza. "Srovnání vybraných silničních nehod se stávajícími nárazovými zkouškami." Master's thesis, Vysoké učení technické v Brně. Ústav soudního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-232796.
Повний текст джерелаАнотація:
This master’s thesis presents an overview of the basic forces acting on the vehicle, the basic methods of analysis of accident, collection of data used in the analysis of accidents, an overview of the basic performance criteria and thresholds used in the homologation test of occupant protection in a frontal impact, used crash tests, homologation tests and specifications for these tests. Attention is paid to Euro NCAP crash tests and to homologation tests of vehicles Skoda Octavia with aim to try to compare them with selected accidents in terms of depth and character deformation and evaluate findings comparision.
16
Klein, Martin. "Analýza a zpracování naměřených dat z nárazových zkoušek." Master's thesis, Vysoké učení technické v Brně. Ústav soudního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-241369.
Повний текст джерелаАнотація:
This thesis presents four crash test of two cars, in which always a moving vehicle strikes with fully overlaid front part into the side part (cabin for passengers) of another stationary vehicle. Crash test were carried out to detect the impact parameters for use in the road accidents analysis. Experimentally measured data and the acquisition of documentation during crash tests were therefore analyzed in an appropriate manner in order to obtain relevant impact parameters. One of the main evaluated parameters was the deformation energy that has been used for the permanent damage to vehicles. In the forensic engineering practice for analyzing vehicle impacts is as a control parameter used EES (Energy Equivalent Speed), this parameter was counted according to measured values during crash tests.
17
Mikulášková, Lucie. "Analýza naměřených dat z nárazových zkoušek - čelní střety." Master's thesis, Vysoké učení technické v Brně. Ústav soudního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-318563.
Повний текст джерелаАнотація:
In this thesis are solved the problematics of crash tests. It is focused primarily on front impacts with full or part overlap. In the introduction are described the best known methods used in forensic - engineering practice for determination of energy equivalent speed (EES). Exactly specified impact tests, which are part of passive safety, are being addressed by several organizations around the world. In the practical part of this diploma thesis are solved four frontal impact tests, which were documented with the participation of the Institute of Forensic Ingeneering BUT in Brno.. These impact tests were performed to capture and analyze the data, resulting in the deformation energy used for permanent damage to the vehicle. Subsequently, the EES parameters were set for each vehicle.
18
Solignac, Marie-Paul. "Etude du comportement a la fissuration en fluage et en fatigue d'aciers inoxydables austenitiques z2 cnd 17-12 (316 l) a 550 c." Paris 6, 1986. http://www.theses.fr/1986PA066540.
Повний текст джерелаАнотація:
Description du comportement du materiau en fluage par une loi puissance. Etude des relations entre la vitesse de propagation et les parametres mecaniques. Prevision de la duree de vie. En fatigue, etude de l'influence des parametres experimentaux et de certains traitements (vieillissement, ecrouissage) sur la fissuration. Etude par microscopie electronique des modes de rupture, ainsi que de la microstructure necessaire a la comprehension du comportement de l'acier
19
LIU, ZENG-GANG. "Comportement et modelisation des materiaux composites carbone/epoxyde en cisaillement a grande vitesse." Nantes, 1987. http://www.theses.fr/1987NANT2011.
Повний текст джерела
20
Bravenec, Ladislav. "Porovnání různých metod nelineárního výpočtu konstrukcí s hlediska rychlosti, přesnosti a robustnosti." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226458.
Повний текст джерелаАнотація:
The aim of the thesis is to compare the iterative methods which program RFEM 5 uses the non-linear calculations of structures, namely the analysis of large deformations and post critical analysis. Comparison should serve as a basis for which calculation method is the most accurate, fastest and most reliable in terms of getting results. Time-consuming will be judged according to the calculation of the solution and the time needed to compute one iterativ. Robustness we will compare the reliability of methods in in normal use. Accuracy of the calculation will be determined by comparing the maximum deformation structures. Comparison will be made with examples from practice.
21
Zimmermann, Karsten. "Prognose und bergschadenkundliche Analyse dynamischer Bodenbewegungen durch oberflächennahen Steinkohlenbergbau in den USA." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2011. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-65009.
Повний текст джерелаАнотація:
Der untertägige Abbau von Steinkohle führt zu Bewegungen des überlagernden Gebirges und der Tagesoberfläche. Eine Bewegungsprognose ist im Hinblick auf entstehende Bergschäden weltweit von großer Bedeutung. In dieser Arbeit wird untersucht, ob eine Prognose von Bodenbewegungen im amerikanischen Steinkohlenbergbau mit einem in Europa bewährten Verfahren, einem dynamischen stochastischen Senkungsmodell, möglich ist. Dazu wurde eine Literaturstudie über den bisherigen Kenntnisstand in den USA durchgeführt, abbaubegleitende Bodenbewegungsmessungen aus dem Steinkohlengebiet der Appalachen ausgewertet und durch Modellrechnungen nachgebildet. Es wurde darüber hinaus untersucht, welchen Einfluss die spezifischen Abbaubedingungen und die räumliche und zeitliche Abbauführung auf die Größe und Dynamik von Bodenbewegungen haben. Die theoretischen und praktischen Untersuchungen zeigen einen deutlichen Know-how Vorsprung des europäischen Bergbaus in den Bereichen der Senkungsmodellierung und Bewertung abbauinduzierter Bodenbewegungen und belegen die Anwendbarkeit des Senkungsmodells. Es wurden wichtige Erkenntnisse gewonnen, die Möglichkeiten und Grenzen einer Optimierung des Abbauzuschnitts und der zeitlichen Abbauführung im Sinne einer bergschadensmindernden Abbauplanung aufzeigen. Die Arbeit trägt zur Verbesserung der bergmännischen und markscheiderischen Abbauplanung im Steinkohlenbergbau bei.
22
Vašíček, Jiří. "Kompatibilita vozidel při čelním střetu." Master's thesis, Vysoké učení technické v Brně. Ústav soudního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-232731.
Повний текст джерелаАнотація:
Thesis deals with the compatibility of vehicles in a frontal collision. The first section discusses about compatibility from different views. There are the physical processes used in the mechanics of impact. The second part is focused on solving the compatibility of vehicles in a frontal collision by crash analysis using the finite element method. Firstly there are described collisions of vehicles from different vehicle classes (small cars, lower middle class, Pick up / SUV) into the fixed barrier by the US NCAP. Furthermore there are simulated head-on collisions of vehicles from different vehicle classes. In the end there is shown the possibility of using data from crash tests to determine the EES.
23
Sousa, Pedro José da Silva Carvalho Pereira de. "Deformation monitoring of high-speed rotating targets." Tese, 2020. https://hdl.handle.net/10216/131190.
Повний текст джерела
24
Sousa, Pedro José da Silva Carvalho Pereira de. "Deformation monitoring of high-speed rotating targets." Doctoral thesis, 2020. https://hdl.handle.net/10216/131190.
Повний текст джерела
25
SHIH, CHENG-HUA, and 施承華. "The Research on High-speed Rail Track Deformation Survey." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/2645bj.
Повний текст джерелаАнотація:
碩士建國科技大學
土木與防災研究所
107
This research is primarily dealing with the influence on the high-speed rails from the increasing service time, artificial activities, and other environmental elements. Also, it will deal with the influence on its running safety and riding comfort from the problems of deterioration and distortion of the rails. All the data obtained in this research came from the collection made by the orbital examination vehicle, and the sections which need adjusting are determined by the High-speed Railroad Company. With the help of the high-precision electronic level and the total station to obtain more precise data, as well as the calculation of track deviation quantity, and the analysis of the data, we can figure out the sections of the track lines which need to be adjusted. The data will then be offered to corresponding department to do the necessary adjustments. After the adjustments, a further surveying will be done to make sure if the rails adjusted meet the required standards. In this study, the data required for orbital adjustment, using the automatic station theodolite and electronic level measurement, can not only meet the requirements of adjusting the accuracy of the track measurement data, but also save manpower requirements and costs, so that the contractor has more construction. The contractor has more space for construction. Keyword：High Speed Rail, Electronic level, Total station
26
Shieh, Luan-Chyuan, and 謝瑞權. "The Effects of Centrifugal Deformation on the High-Speed Spindle." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/23354007320678927551.
Повний текст джерелаАнотація:
碩士國立高雄第一科技大學
機械與自動化工程所
90
In a high-speed spindle, the Belleville spring is seted to apply put-in force on the toolholder through a drawbar. The toolholder can tightly hold the tool on the rotor of the spindle. Therefore, the spindle provides adequate torque and bending stiffness during machining. This study is aim at the bending stiffness, drivable torque and put-in force of the spindle on the PCB drilling machine, when its rotational speed about 120,000 rpm. First, the accuracy of ANSYS is examined by comparing its result with experiment test result, analytical results and experience formula of centrifugal deformation or stress of spindle parts. Then, the bending stiffness and drivable torque of high-speed spindle on the PCB drilling machine are calculated and the put-in force of that spindle is decided. After that, the axial deformation of toolholder, drawbar, Belleville spring, rotor and taper between toolholder and rotor are computed. Finally, the pre-load of Belleville spring is adjusted to keep the bending stiffness, drivable torque and put-in force of spindle adequate at 120,000 rpm.
27
Lin, Chia-Chun, and 林家駿. "Conjugate Heat Transfer and Thermal deformation Analysis of High Speed Spindle." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/53285549285621026713.
Повний текст джерелаАнотація:
碩士國立中正大學
機械工程學系暨研究所
102
The study develops a research method applied for the thermal inhibition on high speed spindle to achieve the goal of diminishing the thermal deformation and improving the precision during the manufacturing process. Firstly, we establish the heat transfer model of high speed spindle, such as the heat source formula and fluid theory model. Next, we apply finite element method to conduct a conjugate heat transfer analysis based on Spalart-Allmaras turbulence model. The content of analysis includes the two types of water channel, axial and helical water channel. Moreover, the numerical result of temperature of helical water channel was compared with the experimental data. Subsequently, we use the previous temperature result as the initial condition so that distribution of thermal deformation could be calculated. The result of numerical simulation near the outlet of water channel and solid indicates a good agreement with the experimental data, including the temperature at steady state. The method is reliable and could predict the temperature distribution of high speed spindle in the future. Key Words: High speed spindle, Thermal inhibition, Finite element method, Conjugate heat transfer, Thermal deformation.
28
Chen, Chih-Ming, and 陳志明. "Structure Thermal Deformation Analysis of High Speed One Axes Linear Drive Machine." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/92660130653905812172.
Повний текст джерелаАнотація:
碩士國立雲林科技大學
機械工程系碩士班
90
Recently, the linear motor used in machine tool to improve CNC machine achieving high speed and high precision performance is popular in the world. However, the heat generating from linear motor is the main factor to affect the accuracy in machine. To confirm the accuracy in machine, the study of thermal characteristics including heat source、heat dispersion and thermal deformation is necessary. The purpose of the research is to set up heat measuring system within the linear drive machine designed by factories. In connection with setting parameter and cool system would be searched for structure temperature influence and develop heat and thermal deformation model using finite element method to analyze the error and accuracy influenced by heat dispersion from linear motor in machine. Finally, searching for improvement of thermal deformation or displacing material would be applied to linear drive machine.
29
Lin, Meng-Ju, and 林孟儒. "Fracture behavior of die-attach solder joints for power modulus under high speed deformation." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/92grkk.
Повний текст джерелаАнотація:
碩士國立東華大學
材料科學與工程學系
100
High temperature solders are widely used as die-attach solders in power semiconductor packaging. Considering the application of power devices in the automotive, solder joints may suffer dynamic loading or even impact. In this study, we present ball impact test (BIT) responses and fracture modes obtained at an impact velocity of 0.6 m/s of the joints with Pb-free Zn-Sn and commercial Pb-Sn solders, which are bonded with substrates of Cu, Ag and Ni surface finishes respectively. All in all, Zn-Sn joints exhibit greater impact strength but inferior impact toughness than Pb-Sn joints. This can be ascribed to the high hardness of Zn-Sn solder resulting in partial or overall interfacial fracturing. Among those cases, Zn-Sn/Ag show a multi-layer interfacial structure which gives rise to fast cracking and thus poor impact energy. Zn-Sn/Ni samples possess a better performance because only one intermetallic phase, Ni5Zn21 forms at the interface and it exhibits fair plastic ability which can be demonstrated by nanoindentation data. In contrast, all the Pb-Sn solder joints show ductile fracture feature and the impact performance is related to the alloying effect by dissolved substrate elements. Ag has a great solubility in liquid Pb and forms large amounts of Ag3Sn embedded in the solidified microstructure, which gives rise to significant degradation in the BIT properties.
30
Kamalzadeh, Amin. "Precision Control of High Speed Ball Screw Drives." Thesis, 2008. http://hdl.handle.net/10012/4189.
Повний текст джерелаАнотація:
Industrial demands for higher productivity rates and more stringent part tolerances require faster production machines that can produce, assemble, or manipulate parts at higher speeds and with better accuracy than ever before. In a majority of production machines, such as machine tools, ball screw drives are used as the primary motion delivery mechanism due to their reasonably high accuracy, high mechanical stiffness, and low cost. This brings the motivation for the research in this thesis, which has been to develop new control techniques that can achieve high bandwidths near the structural frequencies of ball screw drives, and also compensate for various imperfections in their motion delivery, so that better tool positioning accuracy can be achieved at high speeds.
A precision ball screw drive has been designed and built for this study. Detailed dynamic modeling and identification has been performed, considering rigid body dynamics, nonlinear friction, torque ripples, axial and torsional vibrations, lead errors, and elastic deformations. Adaptive Sliding Mode Controller (ASMC) is designed based on the rigid body dynamics and notch filters are used to attenuate the effect of structural resonances. Feedforward friction compensation is also added to improve the tracking accuracy at velocity reversals. A bandwidth of 223 Hz was achieved while controlling the rotational motion of the ball screw, leading to a servo error equivalent to 1.6 um of translational motion.
The motor and mechanical torque ripples were also modeled and compensated in the control law. This improved the motion smoothness and accuracy, especially at low speeds and low control bandwidths. The performance improvement was also noticeable when higher speeds and control bandwidths were used. By adding on the torque ripple compensation, the rotational tracking accuracy was improved to 0.95 um while executing feed motions with 1 m/sec velocity and 1 g acceleration.
As one of the main contributions in this thesis, the dynamics of the 1st axial mode (at 132 Hz) were actively compensated using ASMC, which resulted in a command tracking bandwidth of 208 Hz. The mode compensating ASMC (MC-ASMC) was also shown to improve the dynamic stiffness of the drive system, around the axial resonance, by injecting additional damping at this mode. After compensating for the lead errors as well, a translational tracking accuracy of 2.6 um was realized while executing 1 m/sec feed motions with 0.5 g acceleration transients. In terms of bandwidth, speed, and accuracy, these results surpass the performance of most ball screw driven machine tools by 4-5 times.
As the second main contribution in this thesis, the elastic deformations (ED) of the ball screw drive were modeled and compensated using a robust strategy. The robustness originates from using the real-time feedback control signal to monitor the effect of any potential perturbations on the load side, such as mass variations or cutting forces, which can lead to additional elastic deformations. In experimental results, it is shown that this compensation scheme can accurately estimate and correct for the elastic deformation, even when there is 130% variation in the translating table mass. The ED compensation strategy has resulted in 4.1 um of translational accuracy while executing at 1 m/sec feed motion with 0.5 g acceleration transients, without using a linear encoder. This result is especially significant for low-cost CNC (Computer Numerically Controlled) machine tools that have only rotary encoders on their motors. Such machines can benefit from the significant accuracy improvement provided by this compensation scheme, without the need for an additional linear encoder.
31
CHANG, YUNG-YEH, and 張永燁. "On the Deformation and Reverse Snapping Speed of a Spinning Disk with Unsymmetrical Initial Shape." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/51240826090842991225.
Повний текст джерелаАнотація:
碩士國立臺灣大學
機械工程學研究所
93
In this paper we study the steady state deflection and reverse snapping phenomenon of a spinning non-flat disk. Both the initial and the deformed shapes of the disk are allowed to have axisymmetrical and unsymmetrical components. For the analysis of a rotating axisymmetrical disk, we conclude that there is no need to include the unsymmetrical assumed modes in the expansion because all the unsymmetrical deformations are unstable and the stability of the axisymmetrical positions will not be changed. We then consider the case when the initial shape of the disk contains a dominant axisymmetrical component and a smaller unsymmetrical component. Attention is focused on the effect of this unsymmetrical component on the overall deformation and stability of the spinning disk. It is found that the unsymmetrical component with one nodal diameter tends to slightly defer the occurrence of the reverse snapping phenomenon. On the other hand, all other unsymmetrical components with more than one nodal diameter tend to reduce dramatically the reverse snapping speed. Experiment is conducted on a non-flat copper disk containing an axisymmetrical component and an unsymmetrical component with two nodal-diameters. The experimental measurement confirms the theoretical prediction.
32
Dwivedi, Sarvajna Kumar. "Analysis of particle deformation mechanisms and compact expansion during compaction on a high speed rotary tablet press." Thesis, 1992. http://hdl.handle.net/2429/2963.
Повний текст джерелаАнотація:
Pharmaceutical tablets are the most widely used dosage form and are
prepared by the high speed compaction of powders or granules in a die on a
rotary tablet press. The tablets produced must be coherent and capable of
withstanding the stresses of handling and transportation. Successful
compact formation depends on the ability of the particles to deform and
form interparticulate bonds during compression in the die and the ability
of these bonds to withstand elastic expansion during decompression and
ejection from the die.
Compaction on the high speed rotary presses used in the
pharmaceutical industry normally occurs in less than 50 ms. The mechanisms
of particle deformation during compaction are often analysed using presses
operating at slow speeds or by using specialised equipment which perform
tests on either preformed compacts or on single crystals.
In the present work a sixteen-station rotary tablet press - a Manesty
Betapress - was used to analyse high speed compaction. The analysis
involved a study of the relationship between punch force and machine
deformation, and its use in understanding the deformation of powder
particles during compression and the elastic expansion of compacts during
decompression. Rotary presses have been used to analyse compaction
previously but either the materials were compressed under static
conditions, or the results were obtained by complex viscoelastic modeling.
These results were in error because the machine deformation was ignored
when the punch displacement was calculated from the machine and punch-head
geometry.
In contrast, the relationship between machine deformation and punch
force was used in this work to calculate punch displacements on the
Betapress from the measurements of upper punch force. A previously
reported method of calculating the punch displacement (Oates and Mitchell,
1989, 1990) was refined and simplified. This requires only the force
versus time data where the force was measured by a strain-gauged upper roll
support pin. Since it is relatively easier to measure punch force on a
rotary press than make direct measurements of punch displacement, this
method offers accurate punch displacement analysis without using complex
instrumentation and/or geometric calculations.
Over forty solids were studied on the Betapress. The solids were
characterized for various physicochemical properties including true and
bulk densities, and melting and/or decomposition temperatures. Powder X
ray diffraction, melting points and a two-component melting pointcomposition
phase diagram of R and S-ibuprofen showed that racemic
ibuprofen is a one phase ‘racemic compound’ as opposed to a two phase
‘racemic mixture’. Thus, the USP description of ibuprofen as a ‘± mixture’
is misleading. All solids, including the commercially available S
ibuprofen and racemic ibuprofen, were compressed on the Betapress under
speed.
The force signals from the upper roll support pin were collected as a
function of time on a desk-top computer via an analog to digital converter.
The compaction cycle was divided into compression and decompression phases
by the dead centre position at which the punches are vertically aligned
with the centres of the compression roll support pins. The force-time data
were analysed using specially written software to obtain several parameters
from the compaction cycle. Parameters obtained from the compression phase
included peak offset time, decrease in punch pressure during peak offset
time, porosity changes, work of compression and yield values of the solids.
These parameters related particle deformation to pressure. The
relationship between force and machine deformation was used to subtract the
machine recovery from the total recovery during decompression. This gave a
novel method of estimating tablet expansion during decompression. The
tablet expansion data was used to calculate the work of tablet
decompression and to estimate the Young’s modulus of several pharmaceutical
solids.
Since particle deformation during compression is dependent on strain
rate, the strain rate during compaction was approximated by using the
decrease in volume of the powder bed in the die during compaction, and
this, along with the above parameters, was used to ascertain the
deformation mechanism of each solid.
The solids were categorised into groups ranging from low yield strength
ductile solids such as acetylsalicylic acid, ibuprofen and their
formulations to high yield-strength brittle solids such as the various
calcium phosphates. The tableting parameters of formulated drugs and
processed excipients were different from the parent samples. Racemic
ibuprofen and S-ibuprofen showed little difference in their tableting
parameters, hence a decision to use S-ibuprofen instead of racemic
ibuprofen in tableting should be based on differences in other properties
such as solubilities and pharmacokinetic differences.
A simple and inexpensive method of analysing the behaviour of powder
particles during compaction on a high speed rotary press using only
force-time measurements is presented. This method is potentially
applicable to any tablet press, and can be used for the in-process
validation of compaction, for the quality control of raw materials, and for
the development of new tablet formulations.
33
Lin, Wen-Han, and 林文瀚. "Development of a Real-time Measurement System for Axial Thermal Deformation Error of High-Speed Motorized Spindles." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/fjh62y.
Повний текст джерелаАнотація:
碩士國立虎尾科技大學
光電與材料科技研究所
100
This study aims to develop a detection system for axial thermal deformation error occurring in spindle to realize real-time monitor on axial thermal deformation error of imbedded high-speed spindle. Its overall structure is composed of optical detection module and cat''s eye reflector: its optical detection module is established based on the principle of autocollimators; its system components, such as laser diode, optical elements, and quadrant photo-detector integrate to form a non-contact optical measure module; as for the reflective component, micro cat''s eye reflector serves the function. The cat''s eye reflector is made up of a spherical lens which has high level of roundness and is evaporated by highly reflective aluminum film. It is implanted as a spindle''s component in the imbedded high-speed spindle to serve as a medium as to transmit messages of the spindle''s rotation and error of axial thermal deformation. This optical detection system works in way of direct measurement. It is micronized in design and installed on external of the shell of the spindle in order to real-time monitor physical magnitude of axial thermal deformation caused by long time cutting processing exerted by the imbedded spindle. However, the detection system is calibrated by a Renishaw ML-10 Laser Interferometer. In application of this system in axial thermal deformation error detection for imbedded high-speed spindle, axial thermal deformation error is detected under the condition the spindle runs at rotational speed 12000rpm without load for a span of 3 hours. Through validation by AR200-6 triangulating laser displacement sensor system, the error range of thermal deformation detection is around ±2μm. This thesis provides a novel orientation for application of spindle’s axial thermal deformation error detection to realize measurement, compensation, and monitor of thermal deformation error generated by machine tools in cutting process with the detection system directly, and it saves manpower and time for building thermal error compensation model for the spindle.
34
Gong, Ruei-Cing, and 龔瑞清. "Development of Fiber Bragg Grating Sensors for the Multi-point and Real-time System to Measure the Temperature, Deformation and Speed of Built-in High-speed Spindle and Milled Workpiece." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/22fuqp.
Повний текст джерелаАнотація:
碩士國立臺灣大學
機械工程學研究所
105
Fiber Bragg grating (FBG) has been developed rapidly as a research field of sensors. The advantage is that the FBG can simultaneously measure the temperature, deformation, vibration and other physical quantities, and all information is included in the signal measured by a slender FBG with excellent accuracy, precision and stability. Because FBG central wavelength signal is transmitted as an optical signal, the signal will not be affected by the environmental electrical signal. Due to the ability to resist corrosion and high temperature, the measuring capacity is still very good in the harsh environment. Besides, because the thin geometries characteristics of FBG, it is quite suitable for internal measurement and it also can measure multiple points in the same time with wavelength division multiplexer. FBG sensors measuring systems were developed in our laboratory and this thesis will use these techniques to measure the temperature, deformation, vibration, rotating speed, cutting frequency and flutter frequency of built-in high-speed spindle and milling workpiece. Before measuring the high-speed spindle and milling workpiece, the resonant wavelength drift to strain and rising-temperature coefficient are discussed firstly, and use real-time system to measure aluminum cylinder temperature, thermal strain, and the coefficient of linear thermal expansion. Then measure the temperature, deformation, rotating speed and vibration of the high-speed built-in spindle. Firstly use two FBG to measure the rising temperature and strain of spindle to get the accurate fiber temperature rise coefficient, and then use just one single fiber for measurement. Then, the thermal expansion and vibration of the spindle are measured by the multi-grating fiber and the optical fiber real-time measurement system, and data is verified by the digital image correlation（DIC）developed by the laboratory. Finally, FBG is attached to the milling machine spindle and the milling workpiece for rising temperature, thermal deformation, force deformation, cutting and chatter frequency measurement and analysis, in order to achieve the monitoring and quantitative measurement for machine tool spindle and milling workpiece. All these problems measurement will be able to significantly improve the manufacturing process for the accuracy processing requirements, and will analyze and discuss the flutter phenomenon caused by milling machine.
35
Schuldt, Stefan. "Analysis of rate-dependent deformation and fracture phenomena during cutting of viscoelastic materials." Doctoral thesis, 2017. https://tud.qucosa.de/id/qucosa%3A30989.
Повний текст джерелаАнотація:
The cutting of foods is characterized by deformation, fracture and friction processes, and the viscoelastic properties of the cutting materials determine their rate-dependent cutting behavior. This is responsible for uncontrolled fracture and deformation events with increasing cutting velocity. There is a significant information deficit regarding the assignment of material properties and cutting parameters, as well as regarding a process description for industrial high-speed cutting.
The aim of the work is the analysis of the velocity-dependent cutting behavior of foods up to the high-speed range. The focus is on the deformation and fracture phenomena, analysed by methods of classical material analysis but also associated cutting experiments performed in the range from low to high cutting velocities. For high-speed analyses, a test station enabling cutting velocities of up to 10 m/s was designed. To identify relevant material and cutting parameters and to establish a systematic experimental program, elastomer-based model systems with controllable viscoelastic profiles were developed. The results of the respective investigations were further verified for foods. The velocity-dependent deformation behavior during cutting could be described by dynamic-mechanical material analyses in the frequency range. Cutting force slopes at the beginning of the cutting process correlated with the complex moduli and were furthermore dependent on the cutting velocity; this dependency corresponded to the frequency behavior from material analysis. The fracture properties could be attributed to ductile (polymeric systems) or brittle behavior (cellular plant systems). Confectionary products had a strong temperature- and time-dependent behavior with ductile-brittle transition within the experimental conditions.
The results obtained demonstrate that there is a significant relationship between viscoelasticity and velocity-dependent cutting behavior. They allow a phenomenological process description of high-speed cutting and can be used as a basis for the balancing of cutting forces and as input parameters for numerical analyses of the cutting process.Das Schneiden von Lebensmitteln ist geprägt durch Deformations-, Bruch- und Reibvorgänge. Dabei bestimmen die viskoelastischen Eigenschaften der Schneidgüter deren geschwindigkeitsabhängiges Schneidverhalten. Dies führt mit zunehmender Schneidgeschwindigkeit zu unkontrollierten Bruch- und Deformationsereignissen. Dabei besteht ein Informationsdefizit bei der konkreten Zuweisung von Materialeigenschaften und Schneidparametern sowie einer Verfahrensbeschreibung für das industrielle Hochgeschwindigkeitsschneiden. Ziel der Arbeit ist die Analyse des geschwindigkeitsabhängigen Schneidverhaltens von Lebensmitteln bis in den Hochgeschwindigkeitsbereich. Der Fokus richtet sich auf die Untersuchung der Teilphänomene Deformation und Bruch durch Methoden der klassischen Materialanalyse sowie zugeordnete Schneidexperimente im Bereich von niedrigen bis hohen Schneidgeschwindigkeiten. Für entsprechende Hochgeschwindigkeitsanalysen wurde ein Versuchsstand mit Schneidgeschwindigkeiten von bis zu 10 m/s konzipiert. Zur Identifikation relevanter Material- und Schneidparameter und zur Aufstellung des systematischen Versuchsprogramms wurden Modellsysteme auf Elastomerbasis mit steuerbarem viskoelastischen Profil entwickelt. Die Ergebnisse wurden für Lebensmittel verifiziert. Das geschwindigkeitsabhängige Deformationsverhalten beim Schneiden konnte durch dynamisch-mechanische Materialanalysen im Frequenzbereich beschrieben werden. Dabei korrelierten Kraftanstiege zu Beginn des Schneidvorganges mit den Komplexmoduln. Die Anstiege zeigten eine Abhängigkeit von der Geschwindigkeit; diese entsprach dem Frequenzverhalten aus der Materialanalyse. Die Brucheigenschaften konnten produktspezifisch duktilem (polymere Systeme) oder sprödem Verhalten (zelluläre, pflanzliche Systeme) zugeordnet werden. Zuckerwaren zeigten ein stark temperatur - und zeitabhängiges Verhalten mit duktil-sprödem Übergang innerhalb der Versuchsbedingungen. Die gewonnenen Erkenntnisse demonstrieren den Zusammenhang von Viskoelastizität und geschwindigkeitsabhängigem Schneidverhalten. Sie erlauben eine phänomen ologische Verfahrensbeschreibung des Hochgeschwindigkeitsschneidens und können als Basis für die Bilanzierung von Schneidkräften und als Eingangsparameter für numerische Analysen des Schneidvorganges dienen.
36
Bonal, Nedra Danielle 1975. "Field experiments for fracture characterization: studies of seismic anisotropy and tracer imaging with GPR." Thesis, 2007. http://hdl.handle.net/2152/3593.
Повний текст джерелаАнотація:
Knowledge of fracture orientation and density is significant for reservoir and aquifer characterization. In this study, field experiments are designed to estimate fracture parameters in situ from seismic and GPR (radar) data. The seismic experiment estimates parameters of orientation, density, and filling material. The GPR experiment estimates channel flow geometry and aperture. In the seismic study, lines of 2D data are acquired in a vertically fractured limestone at three different azimuths to look for differences in seismic velocities. A sledgehammer, vertical source and a multicomponent, Vibroseis source are used with multicomponent receivers. Acquisition parameters of frequency, receiver spacing and source-to-receiver offset are varied. The entire suite of seismic body waves and Rayleigh waves is analyzed to characterize the subsurface. Alford rotations are used to determine fracture orientation and demonstrate good results when geophone orientation is taken into account. Results indicate that seismic anisotropy is caused by regional faulting. Average fracture density of less than 5% and water table depth estimates are consistent with field observations. Groundwater flow direction has been observed by others to cross the fault trend and is subparallel to a secondary fracture set. In this study, seismic anisotropy appears unrelated to this secondary fracture set. Vp/Vs and Poisson's ratio values indicate a dolomite lithology. Sledgehammer and Vibroseis data provide consistent results. In the GPR experiment, reflection profiles are acquired through common-offset profiling perpendicular to the dominant flow direction. High frequency waves are used to delineate fluid flow paths through a subhorizontal fracture and observe tracer channeling. Channeling of flow is expected to control solute transport. Changes in radar signal are quantitatively associated with changes in fracture filling material from an innovative method using correlation coefficients. Mapping these changes throughout the survey area reveals the geometry of the flow path of each injected liquid. The tracer is found to be concentrated in the center of the survey area where fracture apertures are large. This demonstrates that spatial variations in concentration are controlled by fluid channel geometry.
37
Zimmermann, Karsten. "Prognose und bergschadenkundliche Analyse dynamischer Bodenbewegungen durch oberflächennahen Steinkohlenbergbau in den USA." Doctoral thesis, 2010. https://tubaf.qucosa.de/id/qucosa%3A22748.
Повний текст джерелаАнотація:
Der untertägige Abbau von Steinkohle führt zu Bewegungen des überlagernden Gebirges und der Tagesoberfläche. Eine Bewegungsprognose ist im Hinblick auf entstehende Bergschäden weltweit von großer Bedeutung. In dieser Arbeit wird untersucht, ob eine Prognose von Bodenbewegungen im amerikanischen Steinkohlenbergbau mit einem in Europa bewährten Verfahren, einem dynamischen stochastischen Senkungsmodell, möglich ist. Dazu wurde eine Literaturstudie über den bisherigen Kenntnisstand in den USA durchgeführt, abbaubegleitende Bodenbewegungsmessungen aus dem Steinkohlengebiet der Appalachen ausgewertet und durch Modellrechnungen nachgebildet. Es wurde darüber hinaus untersucht, welchen Einfluss die spezifischen Abbaubedingungen und die räumliche und zeitliche Abbauführung auf die Größe und Dynamik von Bodenbewegungen haben. Die theoretischen und praktischen Untersuchungen zeigen einen deutlichen Know-how Vorsprung des europäischen Bergbaus in den Bereichen der Senkungsmodellierung und Bewertung abbauinduzierter Bodenbewegungen und belegen die Anwendbarkeit des Senkungsmodells. Es wurden wichtige Erkenntnisse gewonnen, die Möglichkeiten und Grenzen einer Optimierung des Abbauzuschnitts und der zeitlichen Abbauführung im Sinne einer bergschadensmindernden Abbauplanung aufzeigen. Die Arbeit trägt zur Verbesserung der bergmännischen und markscheiderischen Abbauplanung im Steinkohlenbergbau bei.