2020 – present – PRELUDIUM BIS 1
The project is focused on topological elastic metamaterials. Topological metamaterial is a periodic material in which some properties are described by integer numbers called topological invariants. To find topological invariants one have to first get spectral phase characteristics – dispersion curves – which connect waves frequencies with wavenumbers. Each one of dispersion curves have its’ topological invariant.

 

The title of the project is “Analysis and design of protected states in topological metamaterials”. So first of all we focuse on how topological invaraints impact waves propagation phenomena in elastic metamaterials – in particular protected states. Protected states allow for special propagating modes at the boundary of two metamaterials with different topological invariants. Such mode is propagating only on the boundary as it is highly attenuated in the bulk of both bounded structures. It is also protected from wave backscattering what results in low energy losses of such boundary modes. We also aim to develop some design techiques for topological metamaterials in structers which are built of layers of different materials and/or contains attached point impedances.

2019 – present
The main goal of the project is design and implementation of structures which are composed of “metamaterials” to use with elastic waves. This unique type of medium allows for unusual behaviour, resulting is such phenomena as cloaking, invisibility or smart filtering and built-in logic solution implementation. Using advanced methods for analytical and numerical simulation, 1-D (bars and rods) and 2-D structures (plates) will be designed and fabricated, using 3D printers for both composite and metallic materials.

 

The project title, „Analysis and development of acoustical logical devices based on nonlinear elastic metamaterials”, and its objectives, refer to facilitating analysis of elastic wave propagation and numerical simulations of ultrasonic waves in complex structures. The acronym, CA-WAVE – similarly toCAx systems, emphasizes computer aided analysis and simulation of mechanical waves-related phenomena.

 

The proposed project addresses the idea of mechanical energy flow management through the design of acoustical logical devices (ALDs) with tunable (controllable) spectral characteristics. It is expected that application of such devices may significantly reduce vibrations and noise by performing logical operations on wavefields propagating in the structure. These would include logical N/AND, X/OR operations, frequency filtering, multiplexing, directing energy flow, switching, phase-shifting and amplifying.

 
Among the main objectives of the Project is development of devices for nonlinear media, along with a set of tools for numerical models analysis.

2016 – 2016
The main goal of the project was the development and implementation of an integrated simulation framework for linear and nonlinear elastic waves. Classical nonlinearities related to geometric and constitutive relationships were considered. Structural damage models for cracks and delaminations were analysed and modelled based on approaches for non- classical nonlinear phenomena. Numerical tools were implemented using graphical processing units leading to significant reduction in calculation times. The software was integrated with measurement devices in order to aid results analysis and solve inverse problems. Additional tools for numerical errors estimation and analysis were integrated into the software.

 

The project title, „Computer aided integrated simulation framework for analysis and simulation of nonlinear elastic guided waves propagation”, and its objectives, refered to facilitating analysis of elastic wave propagation and numerical simulations of ultrasonic waves. The acronym, CA-WAVE – similarly toCAx systems, emphasizes computer aided analysis and simulation of mechanical waves-related phenomena.
 

• GUI for cuLISA3D package – allows for fully visual design and analysis of wave propagation in 3D structures. The original Matlab implementation remains active with all functions.
• DISPERSION curves calculation module – allows for calculation of dispersion characteristics for arbitrarily complex plate-like structures. Its functionalities include layered systems and periodic metamaterials in 2D and 3D.
• EXCITABILITY curves calculation module – allows for calculation of excitability characteristics, i.e. amplitudes of waves under assumed excitation conditions. Together with the DISPERSION module, this part of the program enables calculation of full spectral properties of waves in guiding media.
• NONLINEAR DISPERSION SHIFTING – occurs due to the acoustoelastic effect, i.e. the influence of stress on wave propagation velocity. This effect, also observed for waves in plate-like structures, displays complex mode-dependent influence on dispersive waves. This module allows for computing amplitude-dependent dispersion curves for 2D nonlinear systems.
• SPECTRAL CHARACTERISTICS ANALYSIS module is devoted to analysing spectral properties for future inverse problem solution or model parameters adjustment. This is a practical tool that allows for design and development of a numerical model with possibly small errors and allows for quantifying errors due to spatial discretisation.
• OPTIMIZATION module is equipped with built-in libraries for importing experimental data and comparing them to model-based results. Subsequently, numerical models can be used for solving physics-based inverse problems.

 

Host Institution: AGH – University of Science and Technology in Krakow, Poland
Funded by: the National Science Centre
Project Leader: dr Pawel Packo
Project Team: mr Mateusz Gawroński, mr Beniamin Sawicki
Supporting Team Members: mr Bartlomiej Piwowarczyk
Key words: elastic waves, nonlinear acoustics, numerical modeling, metamaterials