Issued topics of Doctoral Study Program:|
- Adaptive control 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.
- Biomechanical study of the distractional intramedullary nail of the lower limb.
Majority of the population has unequal leg lengths. If the leg length discrepancy exceeds 2 cm, the discrepancy must be corrected. The nature of the correction depends on a number of factors. Indications for surgical correction are arthritic changes of the joints of the lower limb. The surgical correction causes significant changes of the force conditions of the lower limb to be the subject of the dissertation.
- Complex modeling of special electrical rotating machines
The work will be focused on research and development of computational modeling of special 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.
- Computational assessment of rupture risk of cerebral arterial aneurysms
This is an actual biomechanical topic, cerebral arterial aneurysms represent a basic cause of brain strokes also at young patients, and computational prediction of their rupture is beeing solved at many research institutions worldwide. The objective is to exploit experience of the supervisor and his team collected in the field of computational modelling of stress-strain states in abdominal aortic aneurysms. In the topic solution computational modelling will be combined with description of arterial wall geometry and properties on the basis of experiments.
- Computational modeling of nanoindentation
Principle of nanoindetation is pushing a tiny tip into the material at the level nm - the output of the experiment is the dependence of the force-displacement tip. In the first phase, the objective is to determine the material characteristics so as to ensure consistency between experimental and computational (finite element method) determine the dependence of the force-displacement tip. For a running calculation model will be in the next phase of computational modeling process nanoindetation for bodies with different material properties.
- Computational modelling of effects of metabolic inhibition on electromechanic activity of cardiac cells
The reduction of coronary blood flow reduces the supply of oxygen and nutrients to cardiac cells, which results in inhibition of cell metabolisms. This is accompanied by a decrease of intracellular ATP concentration and pH. These changes affect substantially the activity of ion transporters in cell membrane. The aim of this work is to mathematically formulate the effects of metabolic inhibition on membrane ion transport system and to explore the final impact of these effects on electromechanical activity of cardiomyocytes by means of computational modelling.
- Computational modelling of electromechanic activity of cardiomyocytes in failing heart
The aim of this work is mathematically formulate the changes in membrane ion transport and in excitation - contraction coupling in failing hearts and to explore the consequences of these changes for electromechanical activity of cardiomyocytes by means of computational modelling.
- Computational modelling of mechanical behaviour of animal 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 should improve the description of the inner structure of the cell (nucleus, cytoplasm, membrane, cytoskeleton) and should enable us to model multicelloular structures and to simulate 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.
- Computational modelling of movement and stress of vocal folds during setting to phonation position
Vocal folds posturing to phonation position is a fundamental aspect of human voice production control. A detailed study of this mechanism is important for understanding of voice production in healthy individuals and particularly patients with voice disorders. Aim of the work is to create three-dimensional finite element model of laryngeal cartilages and soft tissue of the vocal folds for analysis of the motion and stress of vocal folds during setting to phonation position. Movement of the laryngeal cartilages will be activated by the action of the muscles of the larynx. Created computational models will be used for stress-strain analyses of pathological changes of the vocal folds such as unilateral vocal fold paresis.
- 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.
- Computational simulation of ductile fracture under extremely low cycle fatigue
The topic is a continuation of a long-time research in the area of ductile fracture simulation under large plastic deformation and monotonic loading. Actual results will be applied to ductile damage under extremely low cycle fatigue, up to 100 cycles. Successful models of ductile damage will be coupled with cyclic plasticity and suitable damage cumulation model, including their calibration. All the models will be tested on real materials and their predictive capacity will be assessed. The work will be a part of the finishing project TA04020806 and other subsequent research projects of the Institute.
- Detection of natural landmarks in nonstructured outdoor environment using image processing
Navigation in nonstructured outdoor environment is currently in focus in autonomous mobile robot navigation. The goal of the thesis is to create a set of image processing algorithms that enables to detect natural landmarks in the images captured by mobile robot onboard vision system. No apriory knowledge about the landmarks is allowed.
- Development of FEM solver for fibre composites with hyperelastic matrix and bending stiffness of fibres
The topic is motivated by the need of computational modelling of mechanical behaviour of composites used in production of tyres. At fibre composites with rubber matrix and steel reinforcing fibres (wires), the standard anisotropic hyperelastic constitutive models are not sufficient because they neglect the bending stiffness of fibres. Within the framework of previous doctoral theses a method was proposed how to include the bending stiffness of fibres into the constitutive model on the basis of Cosserat theory of elasticity. The created FEM solver is capable to solve some simple models of these composites but has significant limitations in the model size and problems with convergence. The topic aims at mathematical analysis of the conditions of solvability of the respective systems of equations and at creation of an own implementation of this theory with application of convenient methods. This should enlarge the range of problems for which the theory can be applied.
- Development of methods for the measurement and evaluation of the temperature characteristics of dynamic processes
Interdisciplinary research focused on experimental work, methods of measurement, data recording and evaluation. The aim is to design, develop and optimize sensors and subsequently to develop numerical methods for processing of the data obtained from sensors.
- Development of possible applications of local loads in thin-walled composite structures
The theme of the work will be the proposal of computational and experimental models of typical structural joints. These models will lead to safe way of application of point and distributed loads on composite structures, typically for example a honeycomb sandwich panels in which the acting of such loads are generally problematic. Together with the manufacturer of such structures, problematic areas/joints will be selected for assessment.
- Effect of the structure of arterial wall on its mechanical properties
Structure of arterial wall defines its mechanical properties. Although all the relevant constituents of arterial wall are well known (elastin, collagen, smooth muscle cells) their organisation in arterial wall is still a subject of research. Gaining of knowledge regarding orientation and waviness of collagen fibers will help to describe mechanical behaviour of the arterial wall more accurately. This is vital for instance in rupture risk assessment of abdominal aortic aneurysms. Knowledge of distribution and organisation of smooth muscle cells will help us to model growth and remodelling processes more reliably. This will help us to predict atheroclerosis or development of existing arterial aneurysm.
- Fault detection and isolation for nonlinear systems using local linear models
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.
- Heat exchangers with hollow fibres for utilisation in biologically active environment
Hollow plastic fibres are used in heat exchangers in past decade. Polypropylene and PVDF capillary are used only recently. Plastic capillary ere flexible and can be easily formed into various shapes. Surface of capillary can be modified and its hydrofobity can be influenced. Heat and mass problems should be studied in this theme. Condensation and evaporation of liquids on inner and outer surfaces of the hollow fibres will be studied.Special cosideration is for bio-fouling applications.
- Influence of mechanical properties of intraluminal thrombus on the rupture risk of aortic aneurysm
This actual biomechanical topic aims at computational modelling of stresses in abdominal aortic aneurysms. The objective is to model the interaction of blood (an approximately Newtonean liquid) with the aneurysm wall, covered partially by a porous intraluminal thrombus (remodelled blood clot). For identification of its constitutive models a tailored biaxial testing rig can be exploited and also the permeability of the thrombus should be evaluated experimentally. The computational models will be exploited for stress-strain analyses of abdominal aortic aneurysms.
- Influence of patient-specific parameters of abdominal aortic aneurysm on its rupture risk
This actual biomechanical topic is solved in a broad interdisciplinary team with many international colaborations. It aims at computational modelling of stresses in abdominal aortic aneurysms. For identification of constitutive models of tissues unique equipment and know-how can be exploited for biaxial material testing and assessment of directions of reinforcing collagen fibres. In accordance with up-to-date trends the topic should improve the results ot aneurysm rupture prediction through a maximum individualization of the computational model which will be used in prediction of aneurysm rupture and decisions on necessity of its surgical treatment.
- Modeling of welding process using selected elastic-plastic and elastic-viscoplastic material models
Improvement of material input data measurement for existing nonlinear material models will be achieved by developing new measurement methods. More accurate calculation of residual stresses will be made of other possible applications of nonlinear material models, which are currently starting to develop. Verification of the suitability of material models for calculation of residual stresses will be achieved by experimental measurements using currently available methods: modified hole drilling method (VUT Brno, Brno ÚAM), X-ray diffraction (ČVUT), neutron diffraction (NRI Rez). While work is expected collaboration with the Technical University in Brno, Czech Academy of IPM, EPRI and ČVUT.
- Modelling of non-elastic effects of elastomers
The topic is motivated by properties of elastomers and composites used in production of tyres. Rubber and other elastomers show large elastic strains the computational modelling of which exploits hyperelastic constitutive models. However, under extremely large strains (up to hundreds percents) also non-elastic effects occur (Mullins’effect, plasticity, viscoelasticity) and cause significant differences between models and reality as well as secondary anisotropy of the elastomer properties. Recently constitutive models are broadly developed for description of these effects. The topic aims at anisotropic behaviour of elastomers caused by Mullins’effect, implementation and exploitation of the respective constitutive models with their eventual application at fibre composites with elastomer matrix (rubber reinforced with textile and other fibres).
- Numerical modelling of fatigue crack closure
Fatigue crack closure mechanism is well described in the literature and confirmed by experimental observation. However, detail prediction of the crack closure in the case of three-dimensional structure with complex crack shape is still open scientific topic. Therefore, general goal of the work lies in the accurate numerical modelling of plasticity induced crack closure in the case of 3D crack front. The numerically obtained results will be experimentally evaluated in our own laboratory. Important issue is also separation of single effects responsible for fatigue crack closure phenomenon.
- Parameters and state estimation of dynamic model using optimization methods
The work will be focused on research and development of state and parameter estimation of dynamic model in real-time. Application area includes e.g. traction stability systems.
The simulation modelling in Matlab+ environment is supposed to use as well as experimental work with Real-Time Rapid Prototyping hardware dSPACE, which is currently de facto standard in automotive industry.
Theoretical results will be practically verified on particular real model of four wheeled vehicle.
- Reliability of the ceramic head hip endoprosthesis for multiaxial stress state
Failure probabilty of ceramic heads of the total hip joint endoprosthesis is calculated by Weibull weakest link theory. General 3-axis stress rices in the ceramic head under ISO 7206-5 loading and this stress has significant tensile component in the circumferential direction (first principal stress). Previous research included in this calculation model only the tensile stress and the remaining components were not considered. The aim is to extend the computational modeling of head's failure probability of the other two principal stresses.
- 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.
- Sandwich polymer materials failure in quasi-brittle area
Due to increase of the long term application of the polymer materials failure in quasi-brittle area became important scientific topic. Therefore, the general goal of the work lies in the accurate description of the slow crack propagation in the case of sandwich polymeric structures taking into account residual stresses. Slow crack growth can be described by the corresponding fracture mechanics parameters and using advanced numerical modelling lifetime of the polymer structure can be predicted. The correlation between experimental data of PCCL and numerical model will be presented.
- Special methods of cooling of electrical rotating machines
The work will be focused on research and development of computational modeling of special cooling method of electric machines. The aim will be development of procedure for rotor cooling of elektric machines. Theoretical results will be practically verified on real machines.
- 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 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).
- Thermal optimization of modern light sources used in automotive lamps
The strategy of automobile manufacturers is increase of the light source output while outer dimensions stays same or reduce. This leads to higher demands on the thermal management from the light source to outside of the lamp body. Temperature distribution and other physical important quantities in the operating conditions will be experimentally found in specific cases. The numerical simulation will follow to provide the optimal improve of the lifetime and reliability of the used light source.