Projects / Programmes
January 1, 2009
- December 31, 2014
| Code |
Science |
Field |
Subfield |
| 2.05.00 |
Engineering sciences and technologies |
Mechanics |
|
| 2.11.00 |
Engineering sciences and technologies |
Mechanical design |
|
| 2.04.00 |
Engineering sciences and technologies |
Materials science and technology |
|
| Code |
Science |
Field |
| T210 |
Technological sciences |
Mechanical engineering, hydraulics, vacuum technology, vibration and acoustic engineering |
| Code |
Science |
Field |
| 2.03 |
Engineering and Technology |
Mechanical engineering |
Nonlinear mechanics of structures, dynamics, optimisation of technological processes
Researchers (46)
Organisations (1)
Abstract
The main goal of the program is geometric, static, kinematic and dynamic optimisation of structure elements and structures and optimisation of some special technological processes. The optimisation includes research in the field of non-linear mechanics of material and structures considering the non-linear relationship between outer loads and displacements and non-linear stress-strain function, as follows: static and dynamic buckling problems of thin-walled elements and structures and structures whose behaviour is based on the snap-through phenomenon. The research also includes the post buckling problems and non-linear dynamic problems of real structures with non-linear behaviours in the time, frequency and phase space.
Significance for science
Modeling of large deformations of multi-axial structural elements is usually quite challenging. In connection with the non-linear properties of the material it still represents a considerable challenge also in the theoretical framework. Due to the complex mechanical response it is necessary to find solutions of the mathematical model numerically, since analytical solutions are rarely available. Depending on the needs of industry and the rapid changes that are inevitable in this environment, it is necessary to develop efficient numerical algorithms that will be able to follow the requirements and describe the given problem as accurately as possible. Modeling and understanding of constrained recovery is very important because the process can be innovatively applied in many practical applications. A lot of publications can be found in available literature in the case of tensile loadings during constrained recovery in uniaxial SMA elements. But in the case of compressive loadings during constrained recovery no publications were found in available literature. The process is important since during compressive loadings an SMA element can become unstable. In our investigations compressive constrained recovery was treated theoretically and experimentally. Variational formulation of general geometry optimization problem using the level-set method in order to simplify the description of complex geometry. Aeroelastic optimization of a flexible airfoil due to the stability boundary, based on the analytical flutter model. Due to the non-linear mechanical and geometrical properties of aerodynamic craft it is very difficult to predict the critical threshold flutter speed. A new method for measuring the dynamic response of the vessel will reduce the required number of accelerometers to determine the swing shape, and frequency fluctuations of the vessel. The method for determining the fluid velocity based on the speed of the progressive and reverse shock wave is an extension of the basic method of generating a shock wave in the solid shock tube. Due to physical limitations of a classical shock tube, the measurements of shock waves in the moving fluid cannot be performed in solid shock tube. Moving fluid is essential for proper census of physical events in the exhaust system. The four -stage Euler angle transformation allows the avoidance of passage through singularity in transformations around the axes. We do not need to use complex transformation of quaternion mathematical structures. By using inner obstacles one can control the speed of the gunpowder combustion in cartrige and limit the maximum overpressure. Flying disorder that is inserted into the projectile at the outlet of the pipe is studied in detail. We believe that for successful solutions we have to prevent oscillations at the exit of the tube. This will significantly reduce the dispersion of missile hits. Research results could be described as interesting both for science as well as for big Slovenian export industries. Understanding of physical phenomena in supersonic flow inside and outside nozzle is of major significance for the development of new high performance supersonic nozzles. Application of gained knowledge is also possible in the development of high performance subsonic and supersonic aircraft.
Significance for the country
Based on a good predictive model of large deformations, production companies engaged in material forming, e.g. automotive, aerospace, construction industry, as well as companies that develop home and kitchen appliances can quickly and economically produce end products corresponding to the highest standards. Numerical algorithms that simulate a given process often minimize costs and enable the production. They can minimize production times and sometimes diminish the need to conduct practical experiments. Shape memory alloys belong to the category of so-called »adaptive« materials. Not only are they useful as structural elements, appreciable for their mechanical properties such as toughness; they are also capable of fulfilling functions such as that of a sensor or an actuator. They can be used in applications with high financial added value. The process of constrained recovery makes SMAs ideally suited for the use as fasteners, seals, connectors and clamps in variety of industrial applications. Similarly biomedical products could also be manufactured from shape memory alloys. For instance: implants, prostheses and stents, which are “latticed” tubes that are inserted into blood veins to increase circulation of the blood. These materials could also be used in civil engineering. The property of superelasticity can be used in special damping devices, which reduces dynamical effects in buildings. The goal of geometry optimization is material saving or better exploitation of material, which results in better competitiveness of the product. The presented research activity areas show a possibility of the results application, mostly in the automotive and aerospace industry. Further development of a high-temperature dynamic pressure sensor will enable even higher temperatures and vibration of exhaust gases. Based on the measured results, the company Akrapovic constructed and manufactured high performance exhaust systems for the internal combustion engine to increase torque, power and efficiency. Supersonic nozzle research and its optimization influence the development in two fields: research and industry. The main focus in the research field is in the geometrical optimization of dual-bell nozzles and aerospike nozzles because the improvement in performance of supersonic aircraft and rockets is inherently dependent on nozzle geometry. Essential tools for the optimization process are new numerical methods and experimental verification of the results. In the industrial field, supersonic nozzles represent a challenge because of their technological complexity. Because supersonic nozzles operate at very high temperatures and because of increase in performance, a careful selection of materials is necessary to achieve desired nozzle conditions. This can be only achieved by professional engineers and high quality materials. The impact of the conducted research is in the integration of theoretical and applied research, important for big Slovenian industries. This fact is proven by doctoral students, who after completing their study easily found jobs in big export Slovenian industries.
Most important scientific results
Annual report
2009,
2010,
2011,
2012,
2013,
final report,
complete report on dLib.si
Most important socioeconomically and culturally relevant results
Annual report
2009,
2010,
2011,
2012,
2013,
final report,
complete report on dLib.si
