Projects / Programmes
January 1, 2015
- December 31, 2018
| Code |
Science |
Field |
Subfield |
| 2.05.00 |
Engineering sciences and technologies |
Mechanics |
|
| Code |
Science |
Field |
| T000 |
Technological sciences |
|
| Code |
Science |
Field |
| 2.03 |
Engineering and Technology |
Mechanical engineering |
Shape memory alloys, models, generalized plasticity, constrained recovery, geometry optimization level-set method, flutter, structural dynamics, vibrational fatigue, distributed damping, constitutive modelling, digital images, computer vision
Researchers (38)
Organisations (1)
Abstract
Mathematical models which describe thermomechanical behavior of SMA can be classified into three major categories: microscopic thermodynamic models, macroscopic phenomenological models and micromechanics- based macroscopic models. Our goal is develoving macroscopic phenomenological models to describe multiaxial stress-strain state in multiaxial SMA elements and nonconstant stress-strain state in uniaxial SMA elements.
Geometry optimization of die-cast brackets of the car engine with the purpose of material saving at prescribed load-carrying capacity, geometrical and technological constraints. Geometry optimization is based on variational formulation of the optimization problem in combination with level-set method to describe the geometry of the element.
Theoretically and practically we will analyze the impact of wind gusts (bora) on a vehicle and develop a wind barrier specifically for protection against northern wind.
The pressure of hot gases in the exhaust system will be measured with a high dynamic pressure gauge with aim to determine the velocity of hot gases. For this we have to develop a passive Doppler method for the detection of progressive and reverse shock wave formed at the opening of the exhaust valve.
Specific interest will go into vibrational fatigue research. Different mechanisms of damping in materials will be addressed focused at spatial damping distribution of composite structures. Another goal includes the characterisation of smart structures with included primary or secondary sensing function. In the field of dynamics of systems of rigid and flexible bodies the continuation of moving 1D and 2D continuum will be researched applying the absolute nodal coordinate approach.
A key topic of the research will be constitutive modelling and numerical aspects related to efficient implementation into FEM programs. The topic has arisen from an industrial problem, where we tried to predict springback behaviour of a sheet metal formed part using FEM. In order to create a computationally efficient method for material modelling, the majority of efforts will be focused into the development of numerical methods in the field of constitutive modelling.
Another important issue in the practical use of constitutive models is material characterization. Complex models have a larger number of parameters, hence their identification becomes more difficult. When there is a lack of experimental data, an identification problem becomes ill-posed. Our plan is to develop our own algorithm for inverse identification of model parameters.
Algorithms for measuring the parameters of digital images enable measurement and represent a basis for steering vehicles in automotive industry. In addition to existing algorithms new algorithms are under development based on Bezier curves and their use will be introduced into computer vision recognition in automotive industry and automation of production lines.
Significance for science
Modeling of large deformations of multi-axial structural elements is usually quite challenging. Due to the complex mechanical response it is necessary to find solutions of the mathematical model numerically, since analytical solutions are rarely available. To confirm the theoretical predictions it is necessary to perform also carefully designed and conducted laboratory experiments, which together with the theory contribute to a better understanding of the problem.
Modeling of constrained recovery is very important because the process can be innovatively applied in many practical applications. Since the process is still not well described, especially in multiaxial SMA elements with complex stress-strain state, its consequences cannot be predicted adequately. Efficient mathematical models of constrained recovery would lead to better understanding of the process.
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 with respect to stability boundary, based on the analytical flutter model.
The method for determining 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, measurements of shock waves in moving fluid cannot be performed, which is nevertheless essential for proper assessment of physical events in the exhaust system.
The analysis of the flying projectile disturbance at the outlet of the pipe has not been studied in detail. We believe that for successful solutions we have to prevent oscillations at the exit of the tube, which would contribute to smaller scatter of projectiles.
Understanding the structural dynamics behaviour is essential in order to increase fatigue life or decrease the noise levels of products. With the proposed research we plan to increase scientific knowledge of distributed damping in real structures. Specifically our aim is to contribute to damping modeling and identification. This is very fundamental in structural dynamics. Some improvements in joint modeling are also expected.
Nowadays researchers are dealing with a field of constitutive modelling worldwide. Especially, for industrial purposes it is very important to handle complex boundary value problems with complex geometries, hence in this regard the most promising way for the researchers is to upgrade FEM programs with new constitutive models.
Non-contact measurements and control require the development of new algorithms that enable fast and accurate image processing and preparation of results for further processing. The developed new algorithms will be publishable in the field of mathematical and engineering science.
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 quality end products.
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. 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.
The goal of geometry optimization is material saving or better exploitation of material, which results in better competitiveness of the product. The proposed research can be applied especially in automotive and aerospace industry.
All the research results will be transferred to Pipistrel company which will manufacture the propeller. The active control boundary layer propeller will be used on Pipistrel electric airplanes.
Further development of high-temperature dynamic pressure sensor will enable even higher temperatures and vibration of exhaust gases. Based on the research results the company Akrapovic will construct and manufacture high performance exhaust systems for the internal combustion engine to increase torque, power and efficiency.
The development of high performance propellers for aircraft with electric drive will increase efficiency and reduce airplane noise especially at the stage of acceleration, which will contribute to environment protection measures in Slovenia.
Direct impact is forseen with the collaboration to our industrial partner, which is a big Slovene export Tier 1 supplier and develops the pressure sensing glow plugs. With the help of the proposed programme it is aimed to strenghten the position of global markets. Indirect impact is expected at competences development, used in a broader sense in many Slovene automotive companies. Additional impact is also expected from supervising several PhD students and increasing their knowledge in noise and vibration.
In Slovenia, one of the better-standing industries is automotive industry. Progress and development in this sector also presents computer vision including the recognition and identification of objects. For this purpose, algorithms for determining the contours of digital curves and their transformation to parametric curves are essential.
Most important scientific results
Annual report
2015,
2016,
2017,
final report
Most important socioeconomically and culturally relevant results
Annual report
2015,
2016,
2017,
final report
