Branch Details

Applied Mechanics

Original title in Czech: Inženýrská mechanikaFSIAbbreviation: D-IMEAcad. year: 2020/2021

Programme: Applied Sciences in Engineering

Length of Study: 4 years

Accredited from: 1.1.1999Accredited until: 31.12.2024

Profile

The Ph.D. study focuses on the following fields of mechanics:
· Mechanics of solids. Theory of modelling mechanical systems, constitutive material relations with emphasis on non-linear behaviour, limit state conditions of materials and structures, mechanics of composites, biomechanics, analysis of stress, deformation and dynamic behaviour of selected groups of bodies (including composite bodies), inverse problems of mechanics of rigid bodies, modelling of stress and deformation in selected technological processes (forming), theory of experiments in interactive driving and mechatronic systems, dynamic of vehicles and of machinery, solution of selected problems in vibroacoustics.
· Mechanics of liquides and gases. Flow theory of compressible and incompressible fluids. Flow of gases and vapours. Nonstacionary flow and impact. Orientation on the flow in hydralic machines and heat engines.
· Thermomechanics. Theory of heat and substance transfer. Application of interferometry and other modern experimental methods. Thermodynamic problems of metallurgy and foundry technologies and heat treatment. Applications in the field of design of thermal power-generating machines. Inverse problems of heat transfer.

Supervisor

Issued topics of Doctoral Study Program

  1. Adaptive control and state estimation of dynamic systems using local linear models

    The thesis will deal with research in the field of control and identification of nonlinear dynamic systems using methods based on the idea of local linear models (Lazy Learning, LWR, RFWR). The identificated inverse dynamic model will be used as a feedforward compensator in the structure of a composite regulator. The results of the research will be verified experimentally with real systems available in the Mechatronics laboratory (education models, automotive actuators, etc.) using the Matlab/Simulink computational environment and available hardware resources. Implementation in the form of an electronic control unit with a microcontroller is expected.

    Tutor: Grepl Robert, doc. Ing., Ph.D.

  2. Analysis of collagen fibre structure in soft tissues and its impact on constitutive models

    This actual topic aims at analysis of direction arrangement of collagen fibres in soft tissues, especially in arterial walls. Constitutive models applied nowadays enable us consideration of not only main directions of collagen fibres in the tissue but also of their directional distribution and waviness. However, there is a lack of experimental histological results for identification of these models and, moreover, transformation of the existing results into the form of parameters applicable in computational models suffers from low level of their mathematical treatment. The objective of this topic is to create a methodology of transformation of histograms representing the directional distribution of collagen fibres in the tissues (obtained from experiments done in our group or published in literature) into parameters of constitutive models.

    Tutor: Burša Jiří, prof. Ing., Ph.D.

  3. Biomechanical study of dental replacements

    The PhD research topic is focused upon the realm of dental biomechanics. In dentist’s offices, missing teeth are commonly replaced by dental implants, bridges or hybrid prosthesis. Although the efficiency of those replacements is usually very high, damage of the replacements in mandibular or maxillary region occurs in many cases due to mechanical overloading or accidental tooth bites. The damages can be accompanied by overloading of bone tissue resulting in bone resorption, inflammatory disease or a severe injury. Therefore, the selection of the suitable replacement and its proper application are still of utmost importance in stomatology and dental implantology. There is a plethora of tooth replacement types on the market and the selection of the suitable replacement is dependent on the patient and the specifics of his or her problem. Nowadays, the suitability is increasingly being assessed also by using methods and procedures of dental biomechanics, especially by analyses based on computational modeling. Such an assessment, however, is not routine and needs further improvements. The aim of this PhD thesis is to explore and improve the possibilities of such assessment on the dental implant inserted in human jaws. A special attention will be paid to the implementation of material properties obtained from imaging devices such as the computer tomography to get computational models of high resolution level.

    Tutor: Marcián Petr, Ing., Ph.D.

  4. Biomechanical study of spinal fixation

    The work will be focused as follows: 1. A research of spinal fixation related to the treatment of degenerative diseases of the spine. 2. Based on the research study, an assessment of the trends in spine fixation techniques will be done and an impact of various techniques on spinal biomechanics will be analyzed. 3. For selected fixation techniques, a comparative stress-strain analyses will be carried out. Point 3 will be further specified later based on results of points 1 and 2.

    Tutor: Florian Zdeněk, doc. Ing., CSc.

  5. Comparison and computational simulation of ductile fracture of material produced by the additive and conventional technology

    Topic of the thesis corresponds to the long-term research at the institute of mechanics, which deals with the large plastic deformation and resulting ductile fracture. With the advent of a new production technology, new demand of knowledge of additive material behavior has emerged. Both macro and micro level of description is needed together with its influence on response to various types of loading. In a similar way like conventional materials, where the rolling direction can influence the material behavior, we shall be now interested in the influence of addition technology, powder quality and other parameters. The aim of the thesis will not only be to describe the differences of behavior, but also their influence on computational modelling of ductile fracture. The work will be concentrated to the most frequent materials prepared by additive technology like the austenitic stainless steel AISI 316L or nickel superalloy Inconel 718. The topic is related to two prepared grant projects of GACR: „Non-associate model of plasticity and robust ductile fracture criteria in the prediction of limit states of metal parts“ and „Behavior at large plastic deformation and ductile fracture of materials produced by the additive technology in comparison with the conventional production“.

    Tutor: Petruška Jindřich, prof. Ing., CSc.

  6. Computational analysis of shape memory alloy-based hybrid structures with changeable mechanical and physical properties

    Shape memory alloys (SMAs) pose unique functional properties like shape memory effect and superelasticity. These two effects are linked to the reversible diffusionless martensitic transformation of SMA. The high energy density makes SMA highly attractive for nanotechnology applications. Since majority of SMA actuators is set into a periodic motion by a heat induced phase transformation, they can achieve a relatively low actuating speed of a few kHz caused by the necessity of cooling the SMA components. Recently, the hybrid SMA-based nanomechanical resonators made of an elastic substrate and SMA in a form of the thin film were proposed. These hybrid resonators were proven to operate at high resonant frequency ranges (i.e., up to tens of MHz) that can be significantly tuned up / downward. The frequency tuning has been realized by intentionally changing of the Young`s modulus and interlayer stress of SMA during its martensitic transformation, while the elastic substrate guarantees high frequency actuation. The SMA resonators are capable being used in applications that cannot be achieved by conventional nanotechnology materials. For large values of generated interlayer stress, the SMA resonator can easily exhibit either a non-linear response or buckling. For instance, buckling of mechanical structure yields two different bi-stable states that may be of great value in many sensing applications. The network of weakly nonlinear resonators enables to achieve a complex response and to study interaction between individual resonators. It can be expected that similar responses can be achieved by resonator consisting of several independently controlled SMA elements. The combination of non-linear and linear responses of individual SMA elements in a complex system can open a way for further studies of actuators, dynamical systems, including chaos dynamics as well as for design of engineering materials not feasible in nature (i.e., metamaterials). The main objective of this thesis is to develop models capable to predict behavior of the hybrid structures utilizing several SMA elements. We suppose that each element can easily exhibit weak / strong nonlinearities. Models would be primarily developed using numerical simulations and, afterwards, the experimental verification at the Institute of Physics, Czech Academy of Sciences would be realized. This thesis may be a part of the GACR-MOST bilateral project realized with collaboration of the Department of Functional Materials (OFM), Institute of Physics of the Czech Academy of Sciences. To a student might be offered a part-time contract of OFM (participation on the bilateral project) as well as oversea research stay in Taiwan.

    Tutor: Kotoul Michal, prof. RNDr., DrSc.

  7. Computational modelling of blood flow interactions with the artery with atheroma

    Sclerotic plaque rupture in the carotid artery is one of the common causes of stroke. Analysis of stress-strain states of artery with atheroma thus has great potential for clinical practice. The aim of this work is to create a computational model of the interaction of flowing blood as a non-Newtonian fluid with a deromable arterial tube containing an atherosclerotic plaque or a pair of stenosis caused by atherosclerotic plaques using the finite element method.

    Tutor: Burša Jiří, prof. Ing., Ph.D.

  8. Computational modelling of self-oscillations of the human vocal folds

    Human voice production is based on interaction between by air flow excited oscillations of the vocal folds and acoustic processes in the vocal tract. A detailed study of this mechanism is important for understanding of voice production in healthy individuals and particularly patients with voice disorders. The aim is to create finite element model of interaction between self-excited oscillation of the vocal folds and acoustic spaces of the vocal tract. After verification of the model results by comparison with experimental data, on this model further analyze the influence of some pathological changes in the tissue of the vocal folds (Rinke's edema, Sulcus vocalis etc.) on the vocal folds oscillations and produced voice.

    Tutor: Švancara Pavel, Ing., Ph.D.

  9. Critical length of a crack emanating from notches.

    Study of stress intensity factors for cracks head of crack tips emanating from circumferential notches of cylindrical specimens and notches of three-point-band specimens. Assessment of an influence of specimen geometry on the minimal crack length at which K-factor is already not affected by the notch stress field, e.i., the so-called critical crack length. Numerical elastic and elasto-plastic solution of stress and strain field ahead of cracks loaded in modes I, II and III for specimens of various geometry. Elastic-plastic analysis aiming to determine changes of the plastic zone size in the region near the critical crack length.

    Tutor: Horníková Jana, doc. Ing., Ph.D.

  10. Description and optimization of dynamic temperature fields produced during laser welding

    The process parameters of advanced variants of laser welding technology allow to change the distribution of the heat field in the weld area and consequently influence the structure and mechanical properties of the welds. The topic will be focused on measuring of the temperature fields mathematical simulation of these fields and the optimization of the welding parameters in relation to the mechanical properties of the welds will be solved.

    Tutor: Kotrbáček Petr, doc. Ing., Ph.D.

  11. Design of new spraying bars for hydraulic descaling

    Hydraulic descaling is a technological process used to remove oxides layers from the surface of the steel. This process is energy-intensive and optimization can achieve maximum effect with minimal energy consumption. The properties of the hydraulic headers are affected by a variety of parameters. The role of the PhD student will be based on numerical modeling and experimental research to clarify the mechanism of removing the surface layer from the surface and to optimize spray parameters with regard to surface quality and energy intensity of the process.

    Tutor: Kotrbáček Petr, doc. Ing., Ph.D.

  12. Development and experimental verification of deformation model of steel strip during continuous heat treatment

    Nowadays it is trend to produce high-grade steels without the need for a large percentage of expensive admixtures such as nickel, chromium, titanium, copper, aluminum, etc. This is achieved by appropriate heat treatment in continuous steel production. During the heat treatment, there is a significant but undesirable deformation of the steel, in which the phase changes (changes in the metallographic grid) occur during this process. The steel deforms during the heat treatment and the resulting product often does not reach the required geometry - most often flatness. Poor flatness causes, among other things, major problems in post-processing such as surface treatment, or causes problems in passing through the conveyor system. The aim of this work is to create a complex model that will describe in detail the processes that occur during continuous heat treatment of steel sheets. This model will allow to better understand the processes that occur here and will help optimize cooling to achieve better flatness of the final sheets. During the work, the measurement and simulation of the heat transfer coefficient during cooling of hot plates, measurement of the impact forces from the cooling nozzles, the study of the coolant flow on the curved surface and its effect on the cooling change are expected.

    Tutor: Pohanka Michal, doc. Ing., Ph.D.

  13. Development of active postsurgical orthoses

    Active postsurgical orthoses can essentially shorten rehabilitation period. The subject of the thesis is the development in this field, mainly in the area of patient activity sensing, sensors calibration, drives and its control and the way the apparatus is attached to the patient. Due to complexity of the orthoses it is expected that the student will specialize in one of partial problems.

    Tutor: Krejsa Jiří, doc. Ing., Ph.D.

  14. Development of auxetic structure with integrated piezoelectric elements

    Metamaterials are currently being developed mainly for the aerospace industry as autonomous monitoring structures with wide potential for future applications. An interesting solution of such metamaterial is the patented auxetic structure with piezoelectric elements. The main goal of this PhD study is to develop this structure as a smart engineering component that has the potential to monitor itself and provide information for industry 4.0 applications.

    Tutor: Hadaš Zdeněk, doc. Ing., Ph.D.

  15. Development of Czech sign language recognition methods

    The problem of sign language recognition is not yet successfully solved. The subject of the thesis is the development of methods for recognition of unitary elements (e.g. letters of sign alphabet) both static and dynamic (diacritics), and subsequently recognition of more complex elements. Machine learning approach is assumed, together with the development of special HW sensing elements. The thesis will be focused on Czech sign language, however, the usage of obtained results will be more general not only with respect to sign languages recognition, but gestures recognition in general.

    Tutor: Krejsa Jiří, doc. Ing., Ph.D.

  16. Development of Czech Sign Language Recognition Methods using Machine Learning Approach

    The subject of the thesis is the development of methods for recognition of unitary elements of Czech Sign Language (e.g. letters of sign alphabet) both static and dynamic (diacritics), and subsequently recognition of more complex elements. Machine learning methods are assumed to be the essential approach, with focus on convolution neural networks. The thesis will be focused on Czech sign language, however, the usage of obtained results will be more general not only with respect to sign languages recognition, but gestures recognition in general.

    Tutor: Krejsa Jiří, doc. Ing., Ph.D.

  17. Development of mathematical model for compensation of distortions of planachromatic optics for scanning of nanometric distortions in 3D

    1. Analysis of possibilities of integration of camera technology into a stereomicroscope 2. Investigation of distortion correction due to the construction of the microscope and the used planachromatic optics 3. Precision / inaccuracy analysis and sensitivity measurement of deformation measurements 4. Design of the solution with respect to the variable depth of field due to the setting of the optical system 5. Experiment

    Tutor: Návrat Tomáš, doc. Ing., Ph.D.

  18. Development of new mathematical models for preheating furnaces

    Heating of semi-finished product in preheating furnaces is a very energy-intensive process. This process can be optimized using mathematical models based on operational measurements. The PhD student will participate in the operational measurements and of a mathematical model used to optimize the heating of semi-finished products.

    Tutor: Kotrbáček Petr, doc. Ing., Ph.D.

  19. Failure prediction of sandwich panel structures

    Standard sandwich panel for space application composes of two face skins (CFRP or high strength aluminium alloy) and honeycomb core (aluminium alloy). Sandwich panel structures have superior performance in terms of stiffness to mass and strength to mass ratio. The sandwich panel structure of a spacecraft needs to withstand mechanical loadings caused mainly by launcher quasi-static, vibrational, acoustic and shock load environment but also thermal-elastic loads during in-orbit operation due to uneven temperature distribution and coefficient of thermal expansion mismatch. There are several failure modes of the sandwich panel structure given by the composite nature of the panel and the standard way how the structural joints are made. The methods used for failure prediction of these structures are based on combination of numerical, analytical and empirical approaches. The main focus of the research will be to develop and incorporate innovative methods in sandwich panel structures failure prediction.

    Tutor: Klusák Jan, doc. Ing., Ph.D.

  20. Fault detection and isolation for nonlinear systems

    Application of poweful microcontrollers allows implementation of advanced supplementary functions. One of an important areas of recent development are algorithms for detection, isolation and management of faults in mechatronic systems. This work will deal with the development of new algorithms based on local linear models and soft computing methods. Theoretical and simulation results will be verified on real systems available at Mechatronics laboratory (edu models, automotive actuators etc.). The modelling in Matlab+ is expected as well as the experimental use of Real-Time Rapid Prototyping dSPACE.

    Tutor: Grepl Robert, doc. Ing., Ph.D.

  21. Finite element modelling of mechanical behaviour of living cells

    This actual topic aims at computational modelling of stress strain states induced in the smooth muscle cells during their mechanical testing, on the basis of published experimental results. The computational model used represents the inner structure of the cell (nucleus, cytoplasm, membrane, cytoskeleton) and should be used in identification of constitutive parameters of the individual components on the basis of results of mechanical tests with cells. The model will then be used for estimation of stress-strain states in the vascular wall. The changes of stress-strain states of the vascular smooth muscle cells influence pathophysiological or biochemical processes in the wall; therefore knowledge on these states can constribute to understanding of the principles of atherosclerotic and remodelation processes in the vascular wall.

    Tutor: Burša Jiří, prof. Ing., Ph.D.

  22. Heat transfer during interaction of fluid flows on a moving surface

    Heat treatment of metal (mainly steel and aluminum) products is a modern trend to improve mechanical properties without using of expensive alloying elements (nickel, chromium, copper, titanium, aluminum, etc.). In heat treatment, it is very important to control the flow of a coolant on a product moving surface to avoid, due to wrong flow direction, overcooling or undercooling of a heat-treated product. For this purpose, other fluids are used to control cooling fluid flow in desired direction and in many cases they flows just against the cooling fluid and thereby cut it from the surface. The interaction of these flows affects the heat transfer between the hot surface and the coolant. Goal of the thesis is experimental and computational study of fluid flows interaction and its influence on a cooling intensity and homogeneity.

    Tutor: Hnízdil Milan, Ing., Ph.D.

  23. In-line heat treatment of steel semi-finished products

    The aim is to develop new methods of in-line heat treatment of rolled materials to achieve a new structure and new mechanical properties of steels. The theme combines experimental research of cooling of hot moving surfaces with the research of material properties of steels. Research will be focused on explaining the influence of heat treatment dynamics on the structure of materials.

    Tutor: Kotrbáček Petr, doc. Ing., Ph.D.

  24. Mechanical properties of nanocrystalline metals, influence of grain size, orientation, and grain boundaries

    The mechanical properties of polycrystalline materials change significantly when their grain size is in the nanometric range. Then the volume fraction of the grain boundaries to the crystalline material inside grains cannot be neglected. Usually, the mechanical properties of the crystalline material and the polycrystalline material with large grains are well known, but the properties of grain boundaries and their thickness are challenging as they depend on the grain boundary type, its orientation, and possible precipitation. The influence of grain size and orientation will be studied on polycrystalline tungsten with randomly oriented grains. The simulation samples of polycrystals are prepared in Atomsk and the molecular dynamics simulations are carried out in LAMMPS. The results of the simulations are visualized in OVITO. All the necessary software is open-source. Simulations are used to develop a simple model to predict the mechanical properties of such nanocrystalline materials. The influence of grain boundaries will be studied on aluminum-based thin films. The boundaries can be strengthened by precipitates of magnesium or other additives. The experimental work will be conducted in collaboration with MFF UK. The films with a thickness of 20 – 100 nm will undergo heat treatments to optimize the grain size and stabilize the grain boundaries. The toughness of the samples will be tested by deformation at temperatures up to 400°C and their micro-structure will be studied using transmission electron microscopy.

    Tutor: Fikar Jan, Mgr., Ph.D.

  25. Multiscale modeling of fluid-structure interaction problems in cardiovascular system

    There have been great progress in computational sources which allow raising the level of computational models of the human vascular tree toward more realistic one. Specifically, 3D fluid structure interaction (FSI) simulations of a part of the vascular tree are feasible. However, at the truncated ends of the model, spurious reflection resulting in unphysiological waveform of pressure and flow. Problem can be solved via coupling of the 3D FSI model with reduced 1D FSI model, which acts as an „absorbing“ device for the waves exiting the computational domain.

    Tutor: Burša Jiří, prof. Ing., Ph.D.

  26. Multi-scale modelling of functional MEMS/NEMS exhibiting non-linear behavior

    The current trend in nanotechnology is to design hybrid multilayered MEMS / NEMS (Micro-/Nano Electro-Mechanical System) devices that in order to either enhance the sensor performance or obtain multifunctional measuring properties combine multiple solid and polymer material layers with piezoelectric, electrostatic or functional properties. The multilayered MEMS / NEMS devices are mainly connected with a very complex physics that have not yet been systematically investigated, particularly, in sensor levels. It can be easily expected that the multilayered structures can exhibit not only a global but also local (weak and strong) nonlinearities as well as the various forms of damping mechanisms that are originating from different material layers, interfaces, micro-cracks, etc. Correspondingly, it is of emergence importance for i) further design of MEMS / NEMS devices, and ii) understanding of complex physics in nanoscale to develop methodology(ies) for nonlinear qualification, i.e. the identification of the linear and nonlinear regimes and estimation of the degree of nonlinearity for multilayered micro-/nanomechanical structures with global and local nonlinearities. The main objective of this thesis is to develop methodologies for nonlinear qualification of the multilayered structures with global and local nonlinearities using analytical and numerical computational approaches. The work will be done also in a close cooperation with Institute of Physics ASR Prague and it is planned to employ the Ph.D. student on the grant project which will be related to the similar topic (in case when the project will be accepted by the end of 2020). There is also possibility of the internship on the Taiwanese university during Ph.D. studies.

    Tutor: Ševeček Oldřich, Ing., Ph.D.

  27. Predictive maintenance for custom production machines

    Predictive maintenance combines the processing of large quantities of measured data with machine and plant process models to obtain accurate wear data for machine parts and potentially achieve significant economic savings. Currently, it is an intensively used, applied and researched topic of science and research. The topic of the thesis is related to a specific MPO project.

    Tutor: Grepl Robert, doc. Ing., Ph.D.

  28. Residual lifetime of parts with residual stresses

    The aim of the PhD thesis is determination of mechanism of crack propagation in bodies with residual stresses induced during manufacturing process. The PhD student will contribute to the better understanding of damage mechanism of bodies with residual stresses, to refine the applied methods for estimation of residual lifetime and to the safer operation of studied parts. FE system Ansys and mathematical software Matlab will be used for necessary numerical calculations.

    Tutor: Náhlík Luboš, doc. Ing., Ph.D.

  29. Sensitivity analysis of factors influencing secondary cooling in continuous casting

    This theme is focused on the secondary cooling in continuous casting applications. Cooling of hot surfaces by water or air-water nozzles is often used in technical practice. Mathematical models of monitored processes need to use realistic boundary conditions, which depend on many parameters. Clarification and generalization of the influence of the most important parameters on the heat transfer intensity would be the aim of the doctoral study.

    Tutor: Kotrbáček Petr, doc. Ing., Ph.D.

  30. Separation of fatigue crack closure mechanisms

    Mechanism of fatigue crack closure is well described in the literature and confirmed experimentally. Separation of the crack closure components is useful to explain the significance of each mechanism responsible for the resistance of material against fatigue crack propagation. Therefore aim of the work will lie in the quantitative estimation of the fatigue crack closure based on numerical models as well as based on experimental data.

    Tutor: Hutař Pavel, doc. Ing., Ph.D.

  31. Stability of Bi-Piezo-Material Notch

    The intensive developmentof robotics, mechatronics as well as the diagnostic tools in medicine requires the understanding of the behavior of piezoelectric materials, which are integrated in various components of sophisticated and expensive structures. These components can be sensors, actuators, piezo transformers and other advanced devices. The characteristic property of piezoelectric materials is the production of electric field if they are deformed and conversely they undergo the deformation if they are subjected to the electric field. This is so called intrinsic electro-mechanical coupling phenomenon. The key insufficiency of piezoelectric materials is their inclination to be very brittle and prone to the initiation and developing of the cracks and fracture. It is a consequence of the fact that piezoelectric materials are ceramics with inappropriate mechanical properties gained from the ceramic processing. Brittle fracture appears near the stress and electric field concentrators. An important factor influencing the crack initiation from the stress concetrator is the way how the mechanical, electrical and thermal external loading is applied. A multimaterial notch is the typical representative of the stress and electric field concentrator and it is a rather common structure member. The aim of student is (i) the evaluation of the parameters describing the stress and electric field singularity and (ii) establish the fracture criterion of the bi-material notch composed of piezo materials under the various modes of mechanical, electrical and thermal loads.

    Tutor: Profant Tomáš, doc. Ing., Ph.D.

  32. Stochastic resonance in energy harvesting

    Vibrations as a source of electricity have been studied in the scientific world for the last 20 years. The limitation of this source is still in its low energy yield. One way to harvest more energy is to use stochastic resonance operation. The aim of this work will be an analysis of this phenomenon in energy harvesting, its practical use and design of an energy harvesting device.

    Tutor: Hadaš Zdeněk, doc. Ing., Ph.D.

  33. Study of flow and optimization of nozzle geometry for laser cutting of material

    The internal structure of the nozzles used in the laser cutting of materials significantly influences the flow in the nozzle jet. The shape of the nozzle jet determines the quality of the cutting surfaces, the performance and the consumption of the gases. The theme will deal with optimization of beam flow based on measurements and mathematical simulations.

    Tutor: Kotrbáček Petr, doc. Ing., Ph.D.

  34. The influence of flexoelectricity on fracture of piezo/ferro electric nano-components

    Flexoelectricity refers to the linear coupling of strain-gradient and electric polarization. Like other gradient effects, it gives rise to non-local and size-dependent phenomena. Flexoelectricity is a more widespread property than piezoelectricity—it is an universal property of all insulators and it is particularly strong in materials with high dielectric constants such as ferroelectrics. Following its discovery several decades ago, studies of flexoelectricity in solids have been scarce due to the seemingly small magnitude of this effect in bulk samples. The development of nanoscale technologies, however, has recently renewed the interest in flexoelectricity, as the large strain gradients often present at the nanoscale can lead to strong flexoelectric effects. Since flexoelectricity is a gradient effect, thus size-dependent, it cannot be directly incorporated into continuum mechanics, which does not possess an intrinsic length scale. Rather, flexoelectricity needs to be modelled under the framework of strain-gradient elasticity theory. The aim of the dissertation will be to develop a FEM model of flexoelectricity for solving boundary value problems using Python environment and after its testing to apply it for analysis of an orientation of electric polarization, electric field and domain switching ahead of the crack tip on its propagation in piezoelectric materials.

    Tutor: Kotoul Michal, prof. RNDr., DrSc.

  35. The use of collaborative robots for precise handling in fully automated production

    Collaborative robotics is generally defined by the standards of a safe, shared human-robot workspace. The aim of the dissertation thesis is to use the characteristics of collaborative robots defined by the standard ČSN EN ISO 10218 (Requirements for safety of industrial robots) in the areas of fully automated production. Partial content of the work will be focused on literature review in the field of use of collaborative robots in automated production, identification of the area of use of these robots for precise manipulation and application of new knowledge to specific tasks from practice. The topic of the thesis will be modified and based on the literature review.

    Tutor: Krejčí Petr, Ing., Ph.D.

  36. Theory development and experimental verification of hydraulic descaling

    During the steel production and hot processing the surface of steel is exposed to an oxidizing atmosphere and surface oxide layer (called scales) is formed. These scales are usualy removed using high-pressure flat jet nozzles. During this process surface quality (amount of remaining scales) is monitored and the amount of heat dissipated from the steel is measured. The quality of the surface depends not only on the configuration of the hydraulic spray, but also on the quality of steel (chemical composition), thermal treatment and coating. Water spray causes a sharp drop in temperature and thus significant change of material properties of scales. Moreover, they are usually not formed by homogeneous layer. It is a layer composed of several types of scales: wüstit, magnetite and hematite; whereby their ratio depends on the oxidation temperature. Oxide scales are usually porous, which allows water to penetrate into the cracks which may lead to steam explosion due to very high temperatures (above 1000°C) of scales. Hydraulic descaling is very complicated process, which consists of the mechanical effect of the water jet, thermal contraction of the surface layers, shear stresses at the interface of scales / steel, bending of scales due to temperature gradient and steam explosions in the cracks. The aim is to create theory and verification model of hydraulic descaling and describe the principles in this combined thermo-mechanical stresses. Computational model based on the theory will be used for verification of developed theory. Results from the model will be compared with results obtained from real descaling measurements in laboratory. Model should serve also for optimization of the hydraulic descaling for hard to descale materials (e.g. steel with increased content of silicon for the automotive industry).

    Tutor: Pohanka Michal, doc. Ing., Ph.D.

  37. Thermal resistance between roll and continuously cast steel

    Investigation of the contact thermal resistance of two solid metal surfaces is the aim of the thesis. The motivation of this work is to obtain real thermal resistances between the cylinder and the continuously cast material, and description of selected parameters on the thermal resistance.

    Tutor: Kotrbáček Petr, doc. Ing., Ph.D.

  38. Transferability of fatigue crack propagation data between bodies with different size and geometry

    Measurement of fatigue crack propagation data is standardized. However, different laboratories using different experimental specimens in different environmental conditions produced inconsistent experimental results. Therefore, transferability of the laboratory data to engineering objects is questionable. The main aim of the Ph.D. study is to explain the effect of specimen thickness and geometry on the fatigue crack propagation data in terms of both numerical and experimental analysis.

    Tutor: Vojtek Tomáš, Ing., Ph.D.

  39. Virtual twin high-speed electric machines

    The work will be focused on research and development of virtual twin of high-speed electric machines. The aim will be development of procedure for complex modeling of dynamic temperature states of elektric machines. Theoretical results will be practically verified on real machines.

    Tutor: Vlach Radek, doc. Ing., Ph.D.


Course structure diagram with ECTS credits

Study plan wasn't generated yet for this year.