Projects / Programmes
Numerical and Experimental Analysis of Nonlinear Mechanical Systems
January 1, 2009
- December 31, 2012
| Code |
Science |
Field |
Subfield |
| 2.05.00 |
Engineering sciences and technologies |
Mechanics |
|
| 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 |
Fracture mechanics, structure integrity, fatigue crack growth rate, optimal design, nonlinear periodic and aperiodic oscillations, stability of mechanical systems, bifurcations, parametric identification of vibration systems, statistical mechanics, nonequilibrium mechanics
Researchers (21)
Organisations (1)
Abstract
Applicability of fracture mechanics parameters cover transferability between experimentally determined fracture behaviour of specimens and structures. This should take in account interaction of hetrogeneous mechanical properties and effect of different loading modes to structure's loading. Main research based on numerical modelling and experimental verification of global fracture behaviour of structure. In this research the new technique for mechanical properties and fracture properties will be developed by observing deformable behvaiour of surface of materials-similar as hardness indentation testing.
Into the field of shape optimization there are two dominant in-roads. The first one is of a parametrization type and the second of an evolutionary type. In the research group we will address the development of parametrization based approach. The possibility of shape parametrization of structures by employing standard finite element meshes will remove the largest drawback of parametrization based approaches and thus enhance their usability. This will be achieved by introducing design-element-independent control points which will be related to the structural shape in a much looser manner. This research will be accompanied by the development of our own gradient-based optimization method adapted to the considered optimization problems. Among the objectives the highest priority is set to the enhanced approach to shape optimization which will be usable in practice.
In the past, the research group concentrate attention on the investigation of periodic and aperiodic oscillations of nonlinear dynamical systems by using incremental harmonic balance method with multiple time scales. As independent result of this effort, an general algorithm for parametric studies of periodic and aperiodic oscillations is working out. The incremental harmonic balance method with multiple time scales will be further developed for an automated construction of frequency spectrum of some kind of nonautonomous systems exhibiting the phenomenon of internal resonance. Also, bifurcations of nonlinear oscillations will be explored by using branch tracing. The arc length method, algorithms for solving various singular points and stability analysis will be involved in the method. Beside systems with cubic nonlinearities explored in the past, the parametrically excited systems and nonlinear systems with discontinuous characteristics will be investigated, too. Stability regions of parametrically systems will be determined by using multiple time scales concept for the problem of combination frequencies. Galerkin procedure, which is a part of the method, wiil be used for parametric identification of nonlinear periodically excited systems and autonomous relaxation systems.
By using theory of nonequilibrium processes the solid state and fluid models for computation of equlibrium as well as nonequilibrium mechanical properties will be worked out in the field of statistical mechanic. The one's own models will be expanded also on the range of polymers and ion fluids. By using the developed models, elastic and shear modules, compressibility, viscosity, etc. of arbitrary materials will be computed and mechanical properties of new materials will be predicted. The influence of translation, rotation and vibration of molecules will be considered. Special attention will be paid to intermolecular potentials. The nonequlibrium mechanics study of molecules, composed from many atoms will be studied in details. The mixtures in solids and fluids will be investigated, where mixing rules will be determined on the basys of the comparison with experimental results.
Significance for science
The results of the research programme can be applied to dynamically loaded structural components and mechanical systems as they connect the strain-stress rates in the material with external static and dynamic loads. Within the framework of the programme procedures for structural integrity assessment were applied and methods for the calculation of the number of cycles/structural longevity of structures applied to dynamic loads of the S-N curve were developed. The development of measurement systems for monitoring deformation behaviour and vibrations and transfer of measured parameters using internet allows for “on-line” analysis of the strain-stress state and estimation of the danger of collapse. The system is designed for general application, but with taking into account the specification of the structure or structural component it can be integrally implemented onto a mechanical system. Investigations, which are fundamental for the research of behaviour of heterogeneous materials, are performed, however they are not implement in the framework of industrial development research.
Significance for the country
The research group is regarded as development and application oriented, which in addition to fundamental scientific research contributes to problem-solving for the needs of both domestic and foreign industry. With the development of optimal design of structural components, with introducing and combining new materials in components the performance of the dynamically loaded systems is increased, resulting in longer life time and collapse prevention, which happened often previously. The research team is qualified for research support and the performing of project with strategic impact in energetics and transportation.
Most important scientific results
Annual report
2009,
2010,
2011,
final report,
complete report on dLib.si
Most important socioeconomically and culturally relevant results
Annual report
2009,
2010,
2011,
final report,
complete report on dLib.si
