Faculty of Mechanical Engineering, Technical University of Liberec Ph.D. Thesis Topics for academic year 2018/2019. Study programme: Applied Mechanics

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1 Thesis Topics for academic year 2018/2019 Study programme: Applied Mechanics Téma disertační práce Školitel Katedra 1. Research on mechanical properties of vibration isolation materials, modelling and simulation Abstract: Modelling and stress-strain analysis of flexible structural materials. The aim of the work is to create simulation model of flexible materials with internal structure and carry out its experimental verification. Such kind of material for instance is a polyurethane foam which is commonly used for production of cushioning of car seats. Its properties efficiently reduce vibration load of sitting person and increase travel comfort. During deformation of these porous materials there occur buckling of foam-like structure and energy dissipation caused by damping. One of targets of this work is to analyse principles of energy dissipation. The frequency response of material and other characteristics of force response will be investigated in case of vibration load. The results of this research will be taken in to account for modification of current simulation model and verified experimentally. Other vibration isolation or structured material may be investigated as well. 2. Elastic and viscoelastic behaviour of magneto-sensitive elastomers - experimental and theoretical research and numerical simulation of their response to mechanical loading in an applied magnetic field Abstract: Properties of magneto-sensitive composites with elastomeric matrix, which contains a certain volume of iron micro-particles, can be rapidly changed by the application of magnetic field. The subject of research is the elastic and viscoelastic response of the magneto-sensitive elastomers subjected to a mechanical loading. The response depends on the composition of material and on the applied magnetic field. The subject of the dissertation is experimental and theoretical research on the influence of the matrix material and micro particles on the final properties of the composite and numerical modelling of the response using FEM based on an appropriate material model. The examination of the damping properties with respect to prospective use for vibration control is also expected. 1 doc. Ing. David Cirkl, prof. Ing. Bohdana Marvalová, CSc.

2 Thesis Topics for academic year 2018/ Experimental and theoretical research of the mechanical properties of composites reinforced with selected types of hybrid textiles and numerical modelling of their response to mechanical loads using FEM based on a suitable material model Abstract: Such composites are used in innovative lightweight structures in aerospace and automotive industries. The subject of the work will be the design and verification of the type hybrid textile reinforcement and a method of composition of the different materials with respect to the required rigidity strength and durability of the composites in accordance with the technical requirements of function, particularly with respect to dynamic load and impact. The research of the response of composites to loading speeds and the research of the failure of the composite. 4. Research of the behaviour of rubber composites reinforced with textile cords and fabrics and numerical modelling of their response on mechanical loading using FEM Abstract: The composites are used in tires, conveyor belts, air springs, etc. The stiffness of rubber composites and its directional characteristics can be controlled by appropriately selection of the materials and the direction of the reinforcing fabric. The dissertation will deal with the research and the description of the response of rubber composites on thermo-mechanical loading. The deformation of these composites is nonlinear, anisotropic and it is much greater in comparison with conventional composites. The response of rubber composites on mechanical loading depends on the speed of loading. 5. Experimental and theoretical research of the mechanical properties of composites with the matrix of acrylic resin reinforced by natural fibres and textiles of natural fibres. Numerical modelling of their response using FEM based on a suitable material model Abstract: Experimental and theoretical research on mechanical properties of composites with the matrix of acrylic resin reinforced by natural fibres and textiles made of natural fibres. Numerical modelling of their response using FEM. Water-based acrylic resins are suitable for composites with natural fibres reinforcement for good wettability. Such composites are 100% green as even during their cure do not release any harmful organic substances. The composites are lightweight and are used in the automotive and 2 prof. Ing. Bohdana Marvalová, CSc.

3 Thesis Topics for academic year 2018/2019 aerospace industries. 6. Experimental and theoretical research of elastomers filled by the particles of Magnetic Shape Memory Alloys (MSMA). Abstract: The stiffness, dynamic modulus and damping of elastomeric composites filled by the particles of MSMA (such as Ni-Mn-Ga) are controlled by an external magnetic field. MSMA exhibit high magnetostriction and the large change of dimensions, of dynamic properties and of damping as a response to the external magnetic field of relatively low intensity. The subject of the dissertation is experimental and theoretical research on the influence of the matrix material and MSMA particles on the final properties of the composite, proposal of constitutive relations and numerical modelling of the response using FEM based on an appropriate material model. The examination of the damping properties with respect to prospective use for vibration control is also expected. 7. Experimental and theoretical research of magnetorheological foams, comprised of micro-sized magnetically permeable particles dispersed in the foam matrix. Abstract: Magnetorheological foams are a new class of lightweight smart materials based on a polymeric matrix with embedded magnetic micro-particles. The application of a magnetic field during the foaming of samples induces the alignment of magnetic particles. The micro-particles are improving the mechanical stiffness and dynamical modulus. The magnetorheological behaviour is obtained at the relatively low intensity of magnetic field. The subject of research is the preparation of MR foams and the determination of their elastic and viscoelastic response to a compressive qualities and dynamic loading. 8. Experimental and theoretical research of behaviour of shape memory polymers (SMP) Abstract: The properties and response of SMP are controlled by external fields electric, magnetic, thermal and other. The subject of the dissertation is experimental and theoretical research on the influence of the external stimuli on the final properties of the SMPs, proposal of constitutive relations and numerical modelling of the response using FEM based on an appropriate material model. The examination of the mechanical properties with respect to prospective applications. 9. Smart materials in the application of the energy processes The smart materials are able to capture, store and again release mass and heat. There 3 Prof. Ing. Karel Fraňa, KEZ

4 Thesis Topics for academic year 2018/2019 are several applications of the smart materials starting from the gas capturing up to the energy storage. The objective of the research will be description of the process and its improvement in respect to the effectiveness and periodicity. The research takes into account the fact, that during the long-term service, materials can lose the availability of these properties. The main attention will be focused on the TiO2 and similar materials used for the materials production and heat storage. The part of the work will be a design of the experiments, a selection of the measurement techniques, a composition of the appropriate mathematical model and its verification. 10. Analytical and numerical modelling of twisted non-linear cantilever rotating blade using reduced order finite element models for dynamic analysis Rotating cantilever blades, Fig 1, are very common structure in the turbomachinery application, e.g. Helicopter rotor, power turbine rotor, propeller, etc. Therefore, accurate structural modelling of such structure according to different size, shape and surrounding condition is very challenging. However, there are well developed full 3D finite element numerical models are available to accurate model the rotating beam, but sometime it is expensive calculation. Therefore, the proposed research topic will be focused on mathematical and numerical modelling of nonlinear twisted rotating cantilever beam using reduced order beam models for dynamic analysis for aeroelastic application. The model includes most of the physics involved e.g., geometrical stiffness due to rotation, thermal effects on damping, material layer and the beam profile etc. There are some studies carried out on rotating beam, however, very few are addressed to model the lifting body profile shape of the beam. This research work will be mainly focused on airfoil profile of the beam cross section. 11. Experimental investigation of thermal and momentum boundary layer Dissertation thesis deals with the investigation of a thermal and momentum boundary layers with respect to the properties of the surface in case of low Reynolds numbers. The influence of the surface parameters as roughness and hydrophobic treatment and shape as micro-ripples and micro-ribs on stability and character of the flow will be studied. The influence of temperature gradient on the stability of the flow will be also studied. The preliminary testing experiments will be performed using visualization and main experiments using 2D and 3D PIV (particle image velocimetry) and CTA (constant temperature anemometry). Dr. Luděk Pešek Ing. Václav Vinš, (ÚT AV ČR, v. v. i.) Ing. Petra Dančová, 4

5 Thesis Topics for academic year 2018/2019 Results will be continuously analysed and compared both with the theory and the works of other researchers. An important part of the research will be a thorough literature review of the investigated problem. The experimental part of the work will be carried out primarily at the Technical University of Liberec. The data analysis and theoretical part of the study will be conducted in a close collaboration with the Institute of Thermomechanics of the CAS, v. v. i. in Prague. 12. Experimental and numerical investigation of heat transfer coefficient Dissertation thesis deals with the heat transfer coefficient (HTC) determination on a plate caused by the impacted nozzle flow. The temperature and velocity flow field will be also investigated. Experiments will be performed using CTA (constant temperature anemometry), DHI (digital holographic interferometry), and D PIV (particle image velocimetry). CTA will be used for HTC and velocity flow field measurement, DHI for temperature field, and 3D PIV for velocity and pressure field investigation. Based on the experiments, CDF simulations using FVM will be carried out. Results will be continuously analysed and compared both with the theory and the works of other researchers. An important part of the research will be a thorough literature review of the investigated problem. Doc. Ing. Tomáš Vít, Ing. Petra Dančová, 5