Marcin Wikło, Ph.D., Eng.


Doctoral thesis
2009-01-22Projektowanie ustrojów adaptacyjnych poddawanych obciążeniom udarowym 
supervisor -- Prof. Jan Holnicki-Szulc, Ph.D., Dr. Habil., Eng., IPPT PAN
625
 
Recent publications
1.Szklarski J., Wikło M., Designing of Elastoplastic Adaptive Truss Structures with the Use of Particle Swarm Optimization, MATHEMATICAL PROBLEMS IN ENGINEERING, ISSN: 1024-123X, DOI: 10.1155/2015/652824, Vol.2015, pp.652824-1-14, 2015
Abstract:

In the paper we demonstrate how Particle Swarm Optimization (PSO) can be employed to solve the Adaptive Impact Absorption (AIA) problem. We consider a truss structure which is subjected to impact loads. Stiff bars can be replaced by elastoplastic fuses which control theirs dynamical response. The point of optimization is to maximize or minimize a given objective function by redesigning the structure. This is realized by redistributing the initial mass, finding proper fuse localizations and adjusting, in real-time, the elastoplastic limits. Comparing to the previous results, we show that PSO is capable of achieving results at least as good as gradient-based optimization, having at the same time much larger flexibility regarding the definition of the objective function. This gives significantly broader field of potential applications. In particular, we present how PSO can be used to solve the simultaneous optimization problem: mass redistribution and fuse positioning for a set of expected, various impacts.

Keywords:

adaptive impact absorption, particle swarm optimization, truss structures

Affiliations:
Szklarski J.-IPPT PAN
Wikło M.-other affiliation
2.Wikło M., Holnicki-Szulc J., Optimal design of adaptive structures: Part I. Remodeling for impact reception, STRUCTURAL AND MULTIDISCIPLINARY OPTIMIZATION, ISSN: 1615-147X, DOI: 10.1007/s00158-008-0233-8, Vol.37, No.3, pp.305-318, 2009
Abstract:

The paper (written in two parts) is devoted to the presentation of numerical tools, based on the so-called virtual distortion method (VDM) for fast structural reanalysis and to the application of this tools for optimal design of adaptive structures exposed to impact loads. The first paper deals with fast modifications of the material distribution (coupled stiffness and mass redistribution) in dynamically loaded structures, which allows their optimal remodeling, e.g., to minimize average deflections. The VDM-based approach allows analytical sensitivity determination, which is very helpful in efficient implementation of the optimization procedure, utilized to solve the defined remodeling problem. The presented methodology is illustrated with a numerical example of truss–beam structure exposed to random impact loads.

Keywords:

Fast structural reanalysis, Virtual distortion method, Adaptive impact absorption, Optimal design, Impact loads

Affiliations:
Wikło M.-IPPT PAN
Holnicki-Szulc J.-IPPT PAN
3.Wikło M., Holnicki-Szulc J., Optimal design of adaptive structures: Part II. Adaptation to impact loads, STRUCTURAL AND MULTIDISCIPLINARY OPTIMIZATION, ISSN: 1615-147X, DOI: 10.1007/s00158-008-0242-7, Vol.37, No.4, pp.351-366, 2009
Abstract:

This paper is a continuation of the article entitled “Remodeling for Impact Reception.” It presents a generalization of the previously discussed concept on optimal remodeling of elasto-plastic structures exposed to impact load, where remodeling process is simulated via virtual distortion method (VDM). The resultant stiffest structure determined in the first part of this paper determines the initial configuration to design the optimal adaptive structure. It is assumed that considered structure can be equipped with so-called structural fuses with plastic-like behavior and controllable yield stress levels. Such an adaptive structure can still be optimized by the proper selection of locations for structural fuses and by the proper tuning of yield stress levels to the identified impact load. Maximization of the impact energy dissipation as the objective function allows significant reduction of residual vibrations after a few milliseconds. VDM-based algorithms for fast, complex reanalysis of dynamically loaded elasto-plastic structures and their sensitivity analysis are the key tools for the above-mentioned optimization procedures.

Keywords:

Fast structural reanalysis, Virtual distortion method, Adaptive impact absorption, Optimal design, Impact loads

Affiliations:
Wikło M.-IPPT PAN
Holnicki-Szulc J.-IPPT PAN
4.Kołakowski P., Wikło M., Holnicki-Szulc J., The Virtual Distortion Method - a versatile reanalysis tool for structures and systems, STRUCTURAL AND MULTIDISCIPLINARY OPTIMIZATION, ISSN: 1615-147X, DOI: 10.1007/s00158-007-0158-7, Vol.36, No.3, pp.217-234, 2008
Abstract:

For 20 years of development, the virtual distortion method (VDM) has proved to be a versatile reanalysis tool in various applications, including structures and truss-like systems. This article presents a summary of principal achievements, demonstrating the capabilities of the VDM both in statics and dynamics, in linear and nonlinear analysis. The major advantage of VDM is its exactness and no need for matrix inversion in the reanalysis algorithm. The influence matrix—numerical core of the VDM—contains the whole mechanical knowledge about a structure, by looking at all global responses due to local disturbances. The strength of the method is demonstrated for truss structures.

Keywords:

Exact structural reanalysis, Sherman–Morrison–Woodbury formulas, Nonlinear statics and dynamics, System analysis

Affiliations:
Kołakowski P.-IPPT PAN
Wikło M.-IPPT PAN
Holnicki-Szulc J.-IPPT PAN
5.Jankowski Ł., Wikło M., Holnicki-Szulc J., Robust post-accident reconstruction of loading forces, KEY ENGINEERING MATERIALS, ISSN: 1662-9795, DOI: 10.4028/www.scientific.net/KEM.347.659, Vol.347, pp.659-664, 2007
Abstract:

The paper presents a novel methodology for robust post-accident reconstruction of spatial and temporal characteristics of the load. The methodology is based on analysis of local structural response, and identifies an observationally equivalent load, which in a given sense optimally approximates the real load. Compared to previous researches this approach allows to use a limited number of sensors to reconstruct general dynamic loads of unknown location including multiple impacts and moving loads. Additionally, the problem of optimum sensor location is studied.

Keywords:

impact identification, inverse dynamics, smart systems, structural health monitoring

Affiliations:
Jankowski Ł.-IPPT PAN
Wikło M.-IPPT PAN
Holnicki-Szulc J.-IPPT PAN

List of chapters in recent monographs
1.
197
Jankowski Ł., Sekuła K., Błachowski B.D., Wikło M., Holnicki-Szulc J., Smart technologies for safety engineering, rozdział: Dynamic load monitoring, Wiley, Holnicki-Szulc J. (Ed.), pp.105-151, 2008
2.
200
Kołakowski P., Wikło M., Holnicki-Szulc J., Smart technologies for safety engineering, rozdział: The virtual distortion method - a versatile reanalysis tool, Wiley, Holnicki-Szulc J. (Ed.), pp.11-35, 2008
3.
202
Wikło M., Jankowski Ł., Mróz M., Holnicki-Szulc J., Smart technologies for safety engineering, rozdział: VDM-Based remodeling of adaptive structures exposed to impact loads, Wiley, Holnicki-Szulc J. (Ed.), pp.215-249, 2008

Conference papers
1.Kołakowski P., Jankowski Ł., Świercz A., Wikło M., Time-domain identification of damage in skeletal structures using strain measurements and gradient-based optimization, ISMA 2008, International Conference on Noise and Vibration Engineering, 2008-09-15/09-17, Louvain (BE), pp.3257-3266, 2008
Abstract:

This paper presents an improved numerical tool for identification of damage in skeletal structures. The problem of identification has been formulated in the time domain within the framework of the Virtual Distortion Method (VDM). VDM generally belongs to fast structural reanalysis methods and can be applied to Structural Health Monitoring problems, among others. The major computational asset of VDM is the influence matrix, containing all the local-global inter-relations for a structure due to given perturbations e.g. initial strain or external force. A non-linear least squares problem with strains, entering the objective function, is the subject of consideration. Strains are used in order to have relatively smooth variations (compared to accelerations) of the analyzed signal in time. The change of stiffness is the design variable. Analytical gradients are implemented in the optimization code based on the Levenberg-Marquardt algorithm with some penalty function terms. The efficiency of the software tool is demonstrated for a numerical example of a 2D truss structure. A breakthrough in terms of computational time reduction has been observed compared to the previously used steepest-descent optimization. The presented software assumes the feasibility of reliable measurements of strains in time for real skeletal structures (e.g. truss bridges). Future research will include experimental verification of the idea with piezoelectric sensors acting as tensometers.

Affiliations:
Kołakowski P.-IPPT PAN
Jankowski Ł.-IPPT PAN
Świercz A.-IPPT PAN
Wikło M.-IPPT PAN