Original title in Czech: Inženýrská mechanikaFSIAbbreviation: D-IMEAcad. year: 2019/2020
Programme: Applied Sciences in Engineering
Length of Study: 4 years
Accredited from: 1.1.1999Accredited until: 31.12.2020
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.
Issued topics of Doctoral Study Program
- Computational prediction of damage and fracture in continuous casting
The project is a continuation of the development of a coupled thermal-mechanical model for computational simulations of a continuous steel casting, which consists of the solution of solidification, mechanical stress and heat and mass transfer phenomena in a solidifying strand. The aim of this work is the formulation, implementation and validation of thermal-mechanical criteria, applicable to the prediction of crack, based on the evolution of thermal stress history in the strand. The possibility to apply the numerical model with experimental data in a real time analysis of continuous casting will be assessed.
- 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.
- Computational analysis and optimization of nonlinear multilayer functional resonators
The multilayer functional resonators are used on the macro, micro and nano scale for various actuating and sensing purposes. The Ph.D. thesis will be focused on the (mathematical) description and understanding of the physical behaviour of such structures considering presence of global and local nonlinearities, it will study influence of the nonlinearities on the resonance frequencies and analyse application limits of the resonators in various sensing mechanical devices. Further, an optimal design and composition of the resonator, utilizing some of the non-linearity, will be sought and modelling approaches of various complexity (1D, 2D and 3D) will be compared and their limitations defined. Outputs of the theoretical part will be confronted with available experimental observations.
- Description and optimization of dynamic temperature fields produced during laser welding
Laser welding technology allows set of many parameters that significantly affect the mechanical properties of the welds. The topic 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.
- 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.
- Development of composite structure with integrated piezoelectric skin
Smart materials and applications are currently developed for self-monitoring and self-healing airplanes wings and producers aims to use the smart material for wings and fuselage of airplanes. As well smart clothes have a huge potential when it comes to sports and health. Main goal of this PhD study is targeted to a development of as well smart mechanical parts with integrated piezoelectric layers or skins. Piezoelectric layers could be used for sensing and harvesting of both energy and data from a dynamic operation of used components. Developed parts could monitor themselves and provide information for Industry 4.0 applications.
- Development of design methodologies for servo drives in hard dynamic applications
The aim of the dissertation thesis is to develop a methodology for the design of drives used for dynamically demanding applications - for example, drives in machine tools. Dynamically demanding applications include, for example, rapid changes in load, rapid changes in the direction of rotation, etc. These changes have the effect, for example, of limiting the machine's operational properties and of increased mechanical stress, reduced lifetime, etc. In the thesis will be elaborated the methodology of creation of complex finite element models selected types of drives that will allow you to detect engine restrictions, or to modify design procedures.
- 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
- 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.
- 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.
- 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.
- Impact of properties of tissues of arterial wall with atheroma on computational modelling of their stress states
This is an actual biomechanical topic, included in the solved project of Czech Science Foundation. Assessment of vulnerability (rupture risk) of an atherosklerotic plaque in carotid artery as one of common causes of brain stroke is an issue with a significant scientific and clinical potential. Computational models of stress strain states in the artery exploit experimentally evaluated mechanical properties of individual tissues of artery wall. Impact of these properties on calculated stress values will be evaluated on the basis of own experiments, values from literature, or also structural information from histological analyses.
- 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.
- New methods of heat treatment of steels using pulse cooling
The theme combinated the cooling of hot surfaces with water jets and research of the heat treatment of steel with a very low proportion of alloying elements. The theme is experimentally focused on the emphasis on obtaining new material properties of steels.
- 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.
- 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.
- 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).
- Theory development of work roll degradation during hot rolling process and influence on final product
Steel is processed in high volumes at high temperatures. These include hot thick and thin sheets metal rolling, as well as production of various profiles such as rails, rods, pipes, H, L, U and I profiles. Processing usually takes place at temperatures above 900 ° C, where steel is rapidly oxidized and an unwanted scale layer is formed on the surface. The partially oxidized and hot steel surface comes into contact with the work roll and the work roll is rapidly cooled or different emulsions are used to prolong the work roll lifetime. During the rolling process, the mechanical and thermal stresses of the work roll are complicated and the surface of the cylinders rapidly degrades. The doctoral work will focus on the detailed study of the basic principles that occur during hot rolling and propose procedures that would allow to prolong lifetime of the work roll and improve the resulting quality of the rolled material.
- 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.
Course structure diagram with ECTS credits
Study plan wasn't generated yet for this year.