Tabela A z publikacjami w czasopismach wyróżnionych w Journal Citation Reports (JCR) 
Tabela B z publikacjami w czasopismach zagranicznych i krajowych, wyróżnionych na liście MNSzW
Publikacje konferencyjne indeksowane w bazie Web of Science Core Collection
Inne publikacje w pozostałych czasopismach i wydawnictwach konferencyjnych
Afiliacja IPPT PAN

1.Tauzowski P., Błachowski B., Lógó J., Topology optimization of elasto-plastic structures under reliability constraints: a first order approach, COMPUTERS AND STRUCTURES, ISSN: 0045-7949, DOI: 10.1016/j.compstruc.2020.106406, Vol.243, pp.106406-1-15, 2021
Tauzowski P., Błachowski B., Lógó J., Topology optimization of elasto-plastic structures under reliability constraints: a first order approach, COMPUTERS AND STRUCTURES, ISSN: 0045-7949, DOI: 10.1016/j.compstruc.2020.106406, Vol.243, pp.106406-1-15, 2021

Abstract:
The objective of this study is to propose a relatively simple and efficient method for reliability based topology optimization for structures made of elasto-plastic material. The process of determining the optimal topology of elasto-perfectly plastic structures is associated with the removal of material from the structure. Such a process leads to weakening of structural strength and stiffness causing at the same time increase the likelihood of structural failure. An important aspect of engineering design is to track this probability during the optimization process and not allow the structure safety to exceed a certain level specified by the designer. The purpose of this work is to combine the previously developed yield-limited topology optimization method with reliability analysis using first order approach. Effectiveness of the proposed methodology is demonstrated on benchmark problems proposed by Rozvany and Maute, and the elasto-plastic topology design of L-shape structure which is frequently used in different approaches for stress constrained topology optimization.

Keywords:
topology optimization, reliability analysis, elasto-plastic analysis

(140p.)
2.Opiela K.C., Zieliński T.G., Microstructural design, manufacturing and dual-scale modelling of an adaptable porous composite sound absorber, COMPOSITES PART B-ENGINEERING, ISSN: 1359-8368, DOI: 10.1016/j.compositesb.2020.107833, Vol.187, pp.107833-1-13, 2020
Opiela K.C., Zieliński T.G., Microstructural design, manufacturing and dual-scale modelling of an adaptable porous composite sound absorber, COMPOSITES PART B-ENGINEERING, ISSN: 1359-8368, DOI: 10.1016/j.compositesb.2020.107833, Vol.187, pp.107833-1-13, 2020

Abstract:
This work investigates a porous composite with modifiable micro-geometry so that its ability to absorb noise can be accommodated to different frequency ranges. The polymeric skeleton of the composite has a specific periodic structure with two types of pores (larger and smaller ones) and two types of channels (wide and narrow ones), and each of the large pores contains a small steel ball. Depending on the situation, the balls block different channels that connect the pores, and therefore alter the visco-inertial phenomena between the saturating air and solid skeleton which take place at the micro-scale level and are responsible for the dissipation of the energy of acoustic waves penetrating the porous composite. All this is studied numerically using advanced dual-scale modelling, and the results are verified by the corresponding experimental tests of 3D-printed samples. Particular attention is paid to the prototyping and additive manufacturing of such adaptive porous composites.

Keywords:
porous composite, adaptive sound absorber, microstructure-based modelling, additive manufacturing

(200p.)
3.Zieliński T.G., Venegas R., Perrot C., Červenka M., Chevillotte F., Attenborough K., Benchmarks for microstructure-based modelling of sound absorbing rigid-frame porous media, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2020.115441, Vol.483, pp.115441-1-38, 2020
Zieliński T.G., Venegas R., Perrot C., Červenka M., Chevillotte F., Attenborough K., Benchmarks for microstructure-based modelling of sound absorbing rigid-frame porous media, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2020.115441, Vol.483, pp.115441-1-38, 2020

Abstract:
This work presents benchmark examples related to the modelling of sound absorbing porous media with rigid frame based on the periodic geometry of their microstructures. To this end, rigorous mathematical derivations are recalled to provide all necessary equations, useful relations, and formulae for the so-called direct multi-scale computations, as well as for the hybrid multi-scale calculations based on the numerically determined transport parameters of porous materials. The results of such direct and hybrid multi-scale calculations are not only cross verified, but also confirmed by direct numerical simulations based on the linearised Navier-Stokes-Fourier equations. In addition, relevant theoretical and numerical issues are discussed, and some practical hints are given.

Keywords:
porous media, periodic microstructure, wave propagation, sound absorption

(200p.)
4.Wasilewski M., Pisarski D., Adaptive semi-active control of a beam structure subjected to a moving load traversing with time-varying velocity, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2020.115404, Vol.481, pp.115404-1-20, 2020
Wasilewski M., Pisarski D., Adaptive semi-active control of a beam structure subjected to a moving load traversing with time-varying velocity, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2020.115404, Vol.481, pp.115404-1-20, 2020

Abstract:
A novel method for adaptive semi-active vibration control of structures subjected to a movingload is studied. The velocity of the load is assumed to be time-varying. The controller consistsof an internal model of the moving load, which is being frequently updated to accommodatechanges in the load's velocity. The control method relies on a near-optimal switching con-trol law that is based on the solution to the algebraic Lyapunov equation. The infinite-horizonformulation of the control problem enables us to use efficient numerical algorithms for adap-tive recomputing of the control signal. The asymptotic stability of the closed-loop system andperformance improvement in comparison to the passive method are analysed and formallyproven. The controller is tested by means of numerical experiments involving a flexible beamequipped with a set of semi-active viscous dampers. We investigate three distinct simulationscenarios, which correspond to highly non-uniform motions of the load that consist of accel-eration, deceleration and temporary halt phases. The results of the simulations are comparedto passive and optimal open-loop strategies.

Keywords:
vibration control, adaptive control, semi-active control, moving load, stabilisation

(200p.)
5.Zieliński T.G., Opiela K.C., Pawłowski P., Dauchez N., Boutin T., Kennedy J., Trimble D., Rice H., Van Damme B., Hannema G., Wróbel R., Kim S., Ghaffari Mosanenzadeh S., Fang N.X., Yang J., Briere de La Hosseraye B., Hornikx M.C.J., Salze E., Galland M.-A., Boonen R., Carvalho de Sousa A., Deckers E., Gaborit M., Groby J.-P., Reproducibility of sound-absorbing periodic porous materials using additive manufacturing technologies: round robin study, Additive Manufacturing, ISSN: 2214-8604, DOI: 10.1016/j.addma.2020.101564, Vol.36, pp.101564-1-24, 2020
Zieliński T.G., Opiela K.C., Pawłowski P., Dauchez N., Boutin T., Kennedy J., Trimble D., Rice H., Van Damme B., Hannema G., Wróbel R., Kim S., Ghaffari Mosanenzadeh S., Fang N.X., Yang J., Briere de La Hosseraye B., Hornikx M.C.J., Salze E., Galland M.-A., Boonen R., Carvalho de Sousa A., Deckers E., Gaborit M., Groby J.-P., Reproducibility of sound-absorbing periodic porous materials using additive manufacturing technologies: round robin study, Additive Manufacturing, ISSN: 2214-8604, DOI: 10.1016/j.addma.2020.101564, Vol.36, pp.101564-1-24, 2020

Abstract:
The purpose of this work is to check if additive manufacturing technologies are suitable for reproducing porous samples designed for sound absorption. The work is an inter-laboratory test, in which the production of samples and their acoustic measurements are carried out independently by different laboratories, sharing only the same geometry codes describing agreed periodic cellular designs. Different additive manufacturing technologies and equipment are used to make samples. Although most of the results obtained from measurements performed on samples with the same cellular design are very close, it is shown that some discrepancies are due to shape and surface imperfections, or microporosity, induced by the manufacturing process. The proposed periodic cellular designs can be easily reproduced and are suitable for further benchmarking of additive manufacturing techniques for rapid prototyping of acoustic materials and metamaterials.

Keywords:
porous materials, designed periodicity, additive manufacturing, sound absorption

(200p.)
6.Zawidzki M., Szklarski J., Multi-objective optimization of the floor plan of a single story family house considering position and orientation, Advances in Engineering Software, ISSN: 0965-9978, DOI: 10.1016/j.advengsoft.2019.102766, Vol.141, pp.1-16, 2020
Zawidzki M., Szklarski J., Multi-objective optimization of the floor plan of a single story family house considering position and orientation, Advances in Engineering Software, ISSN: 0965-9978, DOI: 10.1016/j.advengsoft.2019.102766, Vol.141, pp.1-16, 2020

Abstract:
Improving the architectural layout for diverse objectives using rigorous mathematical optimization methods gradually receives more attention by the researchers. Such optimization however, is usually reduced to a much simpler and relatively well-defined problem such as: facility layout optimization, quadratic assignment problem, rectangle partitioning. Nonetheless, architects are usually skeptical about such approaches since they produce solutions which lack certain architectural qualities. This paper proposes a framework where architectural functional layout (FL) is optimized for the following objectives: functionality (defined by users), insolation (calculated according to geographical conditions), outside view attractiveness (assessed on-site) and external noise (measured on-site). Incorporating the latter two and simultaneous optimization of FLs for objectives related specifically to the site: position and orientation are the novel contributions of this paper. Firstly, a set of candidate FLs is generated, next they are evaluated for optimal location and orientation on a given site. Optimality is conceived here as maximization of real-valued objective function combining: user's satisfaction level of the outside views, shielding from external noise, and insolation
preference. The importance of these factors for each type of room is assessed by the user (as weights). A case study on an existing site is presented. The view quality was arbitrarily assessed and the noise map was assessed by A-weighted equivalent sound level measurements. A general gradient-based method for finding optimal and near-optimal solutions was applied. The output of this optimization is a set of room configurations with their locations and orientations on the site returned to the user for final selection.

Keywords:
architectural optimization, subjective evaluation, functional layout, acoustic comfort, coarse grid

(140p.)
7.Błachowski B., Świercz A., Ostrowski M., Tauzowski P., Olaszek P., Jankowski Ł., Convex relaxation for efficient sensor layout optimization in large‐scale structures subjected to moving loads, Computer-Aided Civil and Infrastructure Engineering, ISSN: 1093-9687, DOI: 10.1111/mice.12553, Vol.35, No.10, pp.1085-1100, 2020
Błachowski B., Świercz A., Ostrowski M., Tauzowski P., Olaszek P., Jankowski Ł., Convex relaxation for efficient sensor layout optimization in large‐scale structures subjected to moving loads, Computer-Aided Civil and Infrastructure Engineering, ISSN: 1093-9687, DOI: 10.1111/mice.12553, Vol.35, No.10, pp.1085-1100, 2020

Abstract:
This paper proposes a computationally effective framework for load‐dependent optimal sensor placement in large‐scale civil engineering structures subjected to moving loads. Two common problems are addressed: selection of modes to be monitored and computational effectiveness. Typical sensor placement methods assume that the set of modes to be monitored is known. In practice, determination of such modes of interest is not straightforward. A practical approach is proposed that facilitates the selection of modes in a quasi‐automatic way based on the structural response at the candidate sensor locations to typical operational loads. The criterion used to assess sensor placement is based on Kammer's Effective Independence (EFI). However, in contrast to typical implementations of EFI, which treat the problem as a computationally demanding discrete problem and use greedy optimization, an approach based on convex relaxation is proposed. A notion of sensor density is applied, which converts the original combinatorial problem into a computationally tractable continuous optimization problem. The proposed framework is tested in application to a real tied‐arch railway bridge located in central Poland.

Keywords:
optimal sensor placement, effective independence method, Fisher information matrix

(140p.)
8.Jankowski Ł., Quality over quantity: the case of a model journal, Computer-Aided Civil and Infrastructure Engineering, ISSN: 1093-9687, DOI: 10.1111/mice.12560, Vol.35, No.7, pp.649-649, 2020(140p.)
9.Pisarski D., Konowrocki R., Jankowski Ł., Scalable distributed optimal control of vibrating modular structures, STRUCTURAL CONTROL AND HEALTH MONITORING, ISSN: 1545-2255, DOI: 10.1002/stc.2502, Vol.27, No.4, pp.e2502-1-21, 2020
Pisarski D., Konowrocki R., Jankowski Ł., Scalable distributed optimal control of vibrating modular structures, STRUCTURAL CONTROL AND HEALTH MONITORING, ISSN: 1545-2255, DOI: 10.1002/stc.2502, Vol.27, No.4, pp.e2502-1-21, 2020

Abstract:
A scalable optimal control method for structural vibration mitigation is studied. The method relies on a structure's partitioning that leads to a set of dynamically interconnected subsystems. Each subsystem is operated with an individual subcontroller that collects the local state information and collaborates with the neighboring subcontrollers to estimate a short time prediction of the interconnecting forces defining the subsystem's boundary conditions. Using the extended model that represents the subsystem's dynamics together with the evolution of its boundary conditions, each subcontroller computes the control decision based on the solution to a finite‐time horizon optimal control problem. In order to cope with the changes in the boundary conditions, the optimal solution is computed repetitively according to the receding horizon scheme. The method is validated numerically for a cantilever structure equipped with actively controlled electromagnetic actuators and subjected to a variety of initial condition scenarios. The performance of the designed controller is tested by comparisons to the centralized and isolated decentralized controllers. The introduced system partitioning and distributed controller allow performing parallel computing which makes the method fully scalable and applicable to large‐scale structures. The computational complexity of the designed distributed control is studied for different settings in the modeling of the subsystem's boundary conditions.

Keywords:
active control, distributed control, modular structure, scalable optimization, stabilization

(140p.)
10.Hou J., Li Z., Jankowski Ł., Wang S., Estimation of virtual masses for structural damage identification, STRUCTURAL CONTROL AND HEALTH MONITORING, ISSN: 1545-2255, DOI: 10.1002/stc.2585, Vol.27, No.8, pp.e2528-1-21, 2020
Hou J., Li Z., Jankowski Ł., Wang S., Estimation of virtual masses for structural damage identification, STRUCTURAL CONTROL AND HEALTH MONITORING, ISSN: 1545-2255, DOI: 10.1002/stc.2585, Vol.27, No.8, pp.e2528-1-21, 2020

Abstract:
Adding a virtual mass is an effective method for damage identification. It can be used to obtain a large amount of information about structural response and dynamics, thereby improving the sensitivity to local damage. In the current research approaches, the virtual mass is determined first, and then the modal characteristics of the virtually modified structure are identified. This requires a wide frequency band excitation; otherwise the crucial modes of the modified structure might be out of the band, which would negatively influence the modal analysis and damage identification. This paper proposes a method that first determines the target frequency and then estimates the corresponding value of the additional virtual mass. The target frequency refers to the desired value of the natural frequency after the virtual mass has been added to the structure. The virtual masses are estimated by tuning the frequency response peaks to the target frequencies. First, two virtual mass estimation methods are proposed. One is to directly calculate the virtual mass, using the frequency‐domain response at the target frequency point only, whereas the second method estimates the mass using a least‐squares fit based on the frequency‐domain response around the target frequency. Both proposed methods utilize merely a small part of the frequency domain. Therefore, an impulse, a simple harmonic, or a narrow spectral excitation can be used for damage identification. Finally, a numerical simulation of a simply supported beam and experiments of a frame structure and a truss structure are used to verify the effectiveness of the proposed method.

Keywords:
damage identification, frequency response, structural health monitoring (SHM), virtual distortion method (VDM), virtual mass

(140p.)
11.Pisarski D., Szmidt T., Konowrocki R., Decentralized semi‐active structural vibration control based on optimal system modelling, STRUCTURAL CONTROL AND HEALTH MONITORING, ISSN: 1545-2255, DOI: 10.1002/stc.2624, Vol.27, No.11, pp.e2624-1-20, 2020
Pisarski D., Szmidt T., Konowrocki R., Decentralized semi‐active structural vibration control based on optimal system modelling, STRUCTURAL CONTROL AND HEALTH MONITORING, ISSN: 1545-2255, DOI: 10.1002/stc.2624, Vol.27, No.11, pp.e2624-1-20, 2020

Abstract:
The problem of decentralized semi‐active stabilization of vibration of a beam structure is studied. The decentralized controller's architecture is attained by means of optimal system modelling. In this approach, based on a specially designed and optimized set of basis functions, the solution to the continuous Euler-Bernoulli beam equation is approximated by a discrete system, where the mass and stiffness matrices ensure that the assumed stabilizing control law can be operated by using solely the local state information. The performance of the method is examined through numerical experiments for a series of free‐vibration scenarios with comparison to competitive decentralized and centralized control strategies. The performance impact of the selection of the parameters of the optimal system model is also studied. The designed method allows practical modular arrangements of the control system and is applicable to large‐scale structures.

Keywords:
bilinear system, decentralized control, polynomial basis, semi-active control, stabilization

(140p.)
12.Konowrocki R., Chojnacki A., Analysis of rail vehicles' operational reliability in the aspect of safety against derailment based on various methods of determining the assessment criterion, EKSPLOATACJA I NIEZAWODNOŚĆ - MAINTENANCE AND RELIABILITY, ISSN: 1507-2711, DOI: 10.17531/ein.2020.1.9, Vol.22, No.1, pp.73-85, 2020
Konowrocki R., Chojnacki A., Analysis of rail vehicles' operational reliability in the aspect of safety against derailment based on various methods of determining the assessment criterion, EKSPLOATACJA I NIEZAWODNOŚĆ - MAINTENANCE AND RELIABILITY, ISSN: 1507-2711, DOI: 10.17531/ein.2020.1.9, Vol.22, No.1, pp.73-85, 2020

Abstract:
The article features the results of computer and experimental research on operational issues in the aspect of safety in relation to a freight wagon derailment on a railway track. It presents the knowledge regarding the methods of assessing the operational safety of rail vehicles on railroad tracks for the purpose of comparative analysis. The theoretical analyses were performed based on several methods that assess the safety of their derailments, qualifying for operational reliability, comparing them with the results obtained from experimental research. For the purpose of the research, a computer model of rail vehicle- railway track was created. It took into consideration dynamic parameters of elements used in the real track and rail vehicle. The results obtained from theoretical analyses were validated with experimental tests carried out on real objects (freight vehicle - test track, freight wagon - test rig). As part of the research, new test track geometry for testing rail vehicles was proposed. The results obtained in this way allowed estimating the conditions threatening the operation of a freight vehicle while running on the test rail infrastructure with different assessment criteria and to compare them.

Keywords:
operational safety, rail vehicle dynamics, derailment, experimental tests, numerical investigations

(100p.)
13.Hou J., Li Z., Zhang Q., Jankowski Ł., Zhang H., Local mass addition and data fusion for structural damage identification using approximate models, International Journal of Structural Stability and Dynamics, ISSN: 1793-6764, DOI: 10.1142/S0219455420501242, pp.1-24, 2020
Hou J., Li Z., Zhang Q., Jankowski Ł., Zhang H., Local mass addition and data fusion for structural damage identification using approximate models, International Journal of Structural Stability and Dynamics, ISSN: 1793-6764, DOI: 10.1142/S0219455420501242, pp.1-24, 2020

Abstract:
In practical civil engineering, structural damage identification is difficult to implement due to the shortage of measured modal information and the influence of noise. Furthermore, typical damage identification methods generally rely on a precise Finite Element (FE) model of the monitored structure. Pointwise mass alterations of the structure can effectively improve the quantity and sensitivity of measured data, while the data fusion methods can adequately utilize various kinds of data and identification results. This paper proposes a damage identification method that requires only approximate FE models and combines the advantages of pointwise mass additions and data fusion. First, an additional mass is placed at different positions throughout the structure to collect the dynamic response and obtain the corresponding modal information. The resulting relation between natural frequencies and the position of the added mass is sensitive to local damage, and it is thus utilized to form a new objective function based on the modal assurance criterion (MAC) and l1-based sparsity promotion. The proposed objective function is mostly insensitive to global structural parameters, but remains sensitive to local damage. Several approximate FE models are then established and separately used to identify the damage of the structure, and then the Dempster-Shafer method of data fusion is applied to fuse the results from all the approximate models. Finally, fractional data fusion is proposed to combine the results according to the parametric probability distribution of the approximate FE models, which allows the natural weight of each approximate model to be determined for the fusion process. Such an approach circumvents the need for a precise FE model, which is usually not easy to obtain in real application, and thus enhances the practical applicability of the proposed method, while maintaining the damage identification accuracy. The proposed approach is verified numerically and experimentally. Numerical simulations of a simply supported beam and a long-span bridge confirm that it can be used for damage identification, including a single damage and multiple damages, with a high accuracy. Finally, an experiment of a cantilever beam is successfully performed.

Keywords:
structural health monitoring (SHM), damage identification, adding mass, data fusion, objective function, modal assurance criterion (MAC)

(100p.)
14.Pnevmatikos N., Konstandakopoulou F., Błachowski B., Papavasileiou G., Broukos P., Multifractal analysis and wavelet leaders for structural damage detection of structures subjected to earthquake excitation, Soil Dynamics and Earthquake Engineering, ISSN: 0267-7261, DOI: 10.1016/j.soildyn.2020.106328, Vol.139, pp.106328-1-4, 2020
Pnevmatikos N., Konstandakopoulou F., Błachowski B., Papavasileiou G., Broukos P., Multifractal analysis and wavelet leaders for structural damage detection of structures subjected to earthquake excitation, Soil Dynamics and Earthquake Engineering, ISSN: 0267-7261, DOI: 10.1016/j.soildyn.2020.106328, Vol.139, pp.106328-1-4, 2020

Abstract:
This work is an effort to join, for the first-time, multifractal analysis and damage detection in civil structures subjected to strong ground seismic motions. Specifically, based on the singularity spectrum quantitative and qualitative criteria are proposed. The qualitative criteria are based on the concave of singularity spectrum of damage and undamaged structure. The proposed quantitative criterion is based on calculation of damage index taken the parameters of singularity spectrum. In order to achieve the above goal, a robust signal processing method, which is known as multifractal wavelet leader (MFWL) is used. The multifractal analysis is a tool to calculate fractal properties as well as scaling behavior of the structural response excited by an earthquake. The singularity spectrum is obtained from the Legendre-transformation to Holder exponents. In this paper, a parameter which is based on the shape of singularity spectrum and can identify the damage in the structure is proposed. The proposed method is an output-only approach for damage detection. Considering that the dynamic behavior of an inelastic system subjected to strong ground motion appears to be a non-stationary process, the above procedure of multifractal wavelet leader is suitable to retrieve the simulation response data. The findings from the analysis show that the MFWL is an appropriate scheme for structural damage detection.

Keywords:
multifractal wavelet leader, damage detection, singularity spectrum, earthquake engineering, structural safety

(100p.)
15.Meissner M., Wiśniewski K., Investigation of damping effects on low-frequency steady-state acoustical behaviour of coupled spaces, Royal Society Open Science, ISSN: 2054-5703, DOI: 10.1098/rsos.200514, Vol.7, No.8, pp.200514-1-14, 2020
Meissner M., Wiśniewski K., Investigation of damping effects on low-frequency steady-state acoustical behaviour of coupled spaces, Royal Society Open Science, ISSN: 2054-5703, DOI: 10.1098/rsos.200514, Vol.7, No.8, pp.200514-1-14, 2020

Abstract:
In the low-frequency range, the acoustical behaviour of enclosed spaces is strongly influenced by excited acoustic modes resulting in a spatial irregularity of a steady-state sound field. In the paper, this problem has been examined theoretically and numerically for a system of coupled spaces with complex-valued conditions on boundary surfaces. Using a modal expansion method, an analytic formula for the Green's function was derived allowing to predict the interior sound field for a pure-tone excitation. To quantify the spatial irregularity of steady-state sound field, the parameter referred to as the mean spatial deviation was introduced. A numerical simulation was carried out for the system consisting of two coupled rectangular subspaces. Eigenfunctions and eigenfrequencies for this system were determined using the high-accuracy eigenvalue solver. As was evidenced by computational data, for small sound damping on absorptive walls the mean spatial deviation peaks at frequencies corresponding to eigenfrequencies of strongly localized modes. However, if the sound damping is much higher, the main cause of spatial irregularity of the interior sound field is the appearance of sharp valleys in a spatial distribution of a sound pressure level.

Keywords:
interior acoustics, coupled spaces, steady-state sound field, modal expansion method, sound damping, Green's function

(100p.)
16.Graczykowski C., Faraj R., Identification-based predictive control of semi-active shock-absorbers for adaptive dynamic excitation mitigation, MECCANICA, ISSN: 0025-6455, DOI: 10.1007/s11012-020-01239-6, Vol.55, No.12, pp.2571-2597, 2020
Graczykowski C., Faraj R., Identification-based predictive control of semi-active shock-absorbers for adaptive dynamic excitation mitigation, MECCANICA, ISSN: 0025-6455, DOI: 10.1007/s11012-020-01239-6, Vol.55, No.12, pp.2571-2597, 2020

Abstract:
The paper is aimed at detailed discussion of the Identification-based Predictive Control (IPC) developed for semi-active fluid-based shock-absorbers which protect structures and machines against impact excitations. The problem addressed is the optimal impact absorption providing adaptive mitigation of dynamic response of the mechanical system. The goal of applied control is dissipation of the entire impact energy and minimization of the impacting object deceleration during the process. Three proposed implementations of the IPC are based on sequentially repeated procedures, which include identification of excitation parameters and calculation of the valve opening providing minimization of tracking error of the optimal path. The presented numerical examples concerning mitigation of the dynamic excitation acting on the double-chamber pneumatic shock-absorber reveal high efficiency and prove robustness of the proposed control methods. The developed algorithms are compared against each other in terms of path-tracking efficiency and character of required control actions. The most important challenges in practical implementation of the proposed methods are indicated.

Keywords:
adaptive control, adaptive impact absorption, identification-based predictive control, model predictive control, self-adaptive shock-absorber, semi-active control

(100p.)
17.Zhang Q., Hou J., Jankowski Ł., Bridge damage identification using vehicle bump based on additional virtual masses, SENSORS, ISSN: 1424-8220, DOI: 10.3390/s20020394, Vol.20, No.2, pp.394-1-23, 2020
Zhang Q., Hou J., Jankowski Ł., Bridge damage identification using vehicle bump based on additional virtual masses, SENSORS, ISSN: 1424-8220, DOI: 10.3390/s20020394, Vol.20, No.2, pp.394-1-23, 2020

Abstract:
Structural damage identification plays an important role in providing effective evidence for the health monitoring of bridges in service. Due to the limitations of measurement points and lack of valid structural response data, the accurate identification of structural damage, especially for large-scale structures, remains difficult. Based on additional virtual mass, this paper presents a damage identification method for bridges using a vehicle bump as the excitation. First, general equations of virtual modifications, including virtual mass, stiffness, and damping, are derived. A theoretical method for damage identification, which is based on additional virtual mass, is formulated. The vehicle bump is analyzed, and the bump-induced excitation is estimated via a detailed analysis in four periods: separation, free-fall, contact, and coupled vibrations. The precise estimation of bump-induced excitation is then applied to a bridge. This allows the additional virtual mass method to be used, which requires knowledge of the excitations and acceleration responses in order to construct the frequency responses of a virtual structure with an additional virtual mass. Via this method, a virtual mass with substantially more weight than a typical vehicle is added to the bridge, which provides a sufficient amount of modal information for accurate damage identification while avoiding the bridge overloading problem. A numerical example of a two-span continuous beam is used to verify the proposed method, where the damage can be identified even with 15% Gaussian random noise pollution using a 1-degree of freedom (DOF) car model and 4-DOF model.

Keywords:
structural health monitoring, damage identification, vehicle bump, additional virtual mass, bridge

(100p.)
18.Olaszek P., Wyczałek I., Sala D., Kokot M., Świercz A., Monitoring of the static and dynamic displacements of railway bridges with the use of inertial sensors, SENSORS, ISSN: 1424-8220, DOI: 10.3390/s20102767, Vol.20, No.10, pp.2767-1-24, 2020
Olaszek P., Wyczałek I., Sala D., Kokot M., Świercz A., Monitoring of the static and dynamic displacements of railway bridges with the use of inertial sensors, SENSORS, ISSN: 1424-8220, DOI: 10.3390/s20102767, Vol.20, No.10, pp.2767-1-24, 2020

Abstract:
In the case of the monitoring of bridges, the determination of vertical displacements is one of the most important issues. A new measuring system has been developed and implemented for assessment of railway bridges based on measurements of the structural response to passing trains. The system uses inertial sensors: Inclinometers and accelerometers that do not need any referential points. The system records signals related to the passage of a train over a monitored bridge. The signals from inclinometers before the train's entry are used to determine the static movement. Integrated signals from inclinometers and accelerometers are used to determine dynamic displacements when the train goes through the bridge. Signals from inclinometers are used to determine the so-called "quasi-static" component of the displacement and signal from the accelerometer to determine the dynamic component. Field tests have been carried out on a viaduct along a high-speed railway line. Periodic comparative measurements are carried out using a Total Station to verify static measurements and using inductive sensors to verify dynamic measurements. Tests of the system carried out so far have proven its usefulness for monitoring bridges in a high-speed railway (up to 200 km/h) with high accuracy while determining dynamic displacements.

Keywords:
bridge monitoring, dynamic and static displacements, inertial sensors, total station, indirect measurement

(100p.)
19.Faraj R., Mikułowski G., Wiszowaty R., Study on the state-dependent path-tracking for smart pneumatic shock-absorber, SMART MATERIALS AND STRUCTURES, ISSN: 0964-1726, DOI: 10.1088/1361-665X/ab9adc, Vol.29, No.11, pp.115008-1-25, 2020
Faraj R., Mikułowski G., Wiszowaty R., Study on the state-dependent path-tracking for smart pneumatic shock-absorber, SMART MATERIALS AND STRUCTURES, ISSN: 0964-1726, DOI: 10.1088/1361-665X/ab9adc, Vol.29, No.11, pp.115008-1-25, 2020

Abstract:
The paper presents an analysis of the state-dependent path-tracking method devoted to mitigation of dynamic response of systems and structures under impact excitations. The objective of the study is an evaluation of the adaptive performance and robustness of the novel control method. Robust and adaptive control methods are intensively developed by researchers and control engineers. Progress in the field influences various areas including mechanical engineering, within which these methods are applied for control of industrial processes as well as mitigation of structure dynamic response. Commonly solved problems relate especially to mitigation of vibrations, e.g. for protection of seismically excited structures. Another closely related area is the field of impact absorption, which is still challenging because of short time periods of energy absorption and number of process uncertainties. Nevertheless, due to higher and higher performance of smart sensors and actuators, as well as increasing efficiency of data processing systems, novel high- performance solutions also for impact mitigation problems can be proposed. This fact is reflected in the paper and important contribution to the field of Adaptive Impact Absorption is demonstrated. The importance of presented study results from the fact that applied smart absorber controlled with the use of kinematics-based approach ensures efficient mitigation of the impact excitation and automatic adaptation to various loading conditions. In contrast to shock-absorbers developed so far, the system implemented in laboratory provides adaptation to unknown impact conditions and compensates the influence of unpredictable perturbations. Within the paper an experimental validation of the novel control method is discussed and the system robustness to contact conditions, as well as to different values of operational medium parameters, is demonstrated. Possible extension of the method is analyzed and directions of further research are indicated.

Keywords:
adaptive impact absorption, experimental study, kinematic feedback control, pneumatic absorber, self-adaptive system, smart shock-absorber

(100p.)
20.Błachowski B., Tauzowski P., Lógó J., Yield limited optimal topology design of elastoplastic structures, STRUCTURAL AND MULTIDISCIPLINARY OPTIMIZATION, ISSN: 1615-147X, DOI: 10.1007/s00158-019-02447-9, pp.1-24, 2020
Błachowski B., Tauzowski P., Lógó J., Yield limited optimal topology design of elastoplastic structures, STRUCTURAL AND MULTIDISCIPLINARY OPTIMIZATION, ISSN: 1615-147X, DOI: 10.1007/s00158-019-02447-9, pp.1-24, 2020

Abstract:
This study is devoted to a novel method for topology optimization of elastoplastic structures subjected to stress constraints. It should be noted that in spite of the classical solutions of the different type of elastoplastic topology problems are more than 70 years old, the integration of the Prandtl-Reuss constitutive equations into the topology optimization process is not very often investigated in the last three decades. In the presented methodology where the classical variational principles of plasticity and the functor-oriented programming technique are applied in topology design, the aim is to find a minimum weight structure which is able to carry a given load, fulfills the allowable stress limit, and is made of a linearly elastic, perfectly plastic material. The optimal structure is found in an iterative way using only a stress intensity distribution and a return mapping algorithm. The method determines representative stresses at every Gaussian point, averages them inside every finite element using the von Mises yield criterion, and removes material proportionally to the stress intensities in individual finite elements. The procedure is repeated until the limit load capacity is exceeded under a given loading. The effectiveness of the methodology is illustrated with three numerical examples. Additionally, different topologies are presented for a purely elastic and an elastoplastic material, respectively. It is also demonstrated that the proposed method is able to find the optimal elastoplastic topology for a problem with a computational mesh of the order of tens of thousands of finite elements.

Keywords:
topology optimization, elastoplastic structures, minimum-weight design, stress constraints

(100p.)
21.Knap L., Graczykowski C., Holnicki-Szulc J., Wołejsza Z., Strategies for reduction of energy consumption during ascending and descending process of modern telescopic HAPS aerostats, BULLETIN OF THE POLISH ACADEMY OF SCIENCES: TECHNICAL SCIENCES, ISSN: 0239-7528, DOI: 10.24425/bpasts.2020.131833, Vol.68, No.1, pp.155-168, 2020
Knap L., Graczykowski C., Holnicki-Szulc J., Wołejsza Z., Strategies for reduction of energy consumption during ascending and descending process of modern telescopic HAPS aerostats, BULLETIN OF THE POLISH ACADEMY OF SCIENCES: TECHNICAL SCIENCES, ISSN: 0239-7528, DOI: 10.24425/bpasts.2020.131833, Vol.68, No.1, pp.155-168, 2020

Abstract:
In this article, the authors propose and investigate a new concept of HAPS aerostat design in a modular form, which allows for sequential increasing or decreasing of the total volume, up to the desired size. In its initial form, the aerostat has relatively small dimensions but its central cylindrical part is multi-segmented and can be easily extended. The application of controllable construction couplings enables precise control of the aerostat expansion process and significantly improves its vertical mobility. The paper describes details of telescopic aerostat construction, presents a mathematical model of its vertical motion and investigates numerically two volume control strategies aimed at maximization of operation efficiency and minimization of operation cost. The results obtained reveal the main problems that have to be addressed and the factors that play a key role in design of such telescopic aerostats and control of their vertical mobility.

Keywords:
helium airship, control of vertical mobility, reduced energy consumption, optimum ascending and descending path

(100p.)
22.Ario I., Yamashita T., Chikahiro Y., Nakazawa M., Fedor K., Graczykowski C., Pawłowski P., Structural analysis of a scissor structure, BULLETIN OF THE POLISH ACADEMY OF SCIENCES: TECHNICAL SCIENCES, ISSN: 0239-7528, DOI: 10.24425/bpasts.2020.134623, Vol.68, No.6, pp.1-14, 2020
Ario I., Yamashita T., Chikahiro Y., Nakazawa M., Fedor K., Graczykowski C., Pawłowski P., Structural analysis of a scissor structure, BULLETIN OF THE POLISH ACADEMY OF SCIENCES: TECHNICAL SCIENCES, ISSN: 0239-7528, DOI: 10.24425/bpasts.2020.134623, Vol.68, No.6, pp.1-14, 2020

Abstract:
This paper presents equilibrium mechanics and a finite element model for analysing a scissor structure that contains pivots with zero bending stiffness representing structural instability. The pivot at the centre of each structural unit, which is a feature of scissor structures, can be used to transfer the displacement between the units. It cannot, however, transfer the rotation between these units, and the angular stiffness must be considered independently for each unit. To construct a general model of the scissor structure, a scissor unit was developed using the left and right boundary connections of adjacent units to simulate a periodically symmetric structure. The proposed method allows us to obtain an accurate distribution of the internal forces and deflections without the use of special elements to account for central pivots.

Keywords:
scissor structure, deployable structure, smart bridge, scissors finite element, equilibrium mechanics

(100p.)
23.Hou J., Wang H., Xu D., Jankowski Ł., Wang P., Damage identification based on adding mass for liquid-solid coupling structures, Applied Sciences, ISSN: 2076-3417, DOI: 10.3390/app10072312, Vol.10, No.7, pp.2312-1-20, 2020
Hou J., Wang H., Xu D., Jankowski Ł., Wang P., Damage identification based on adding mass for liquid-solid coupling structures, Applied Sciences, ISSN: 2076-3417, DOI: 10.3390/app10072312, Vol.10, No.7, pp.2312-1-20, 2020

Abstract:
Damage identification for liquid–solid coupling structures remains a challenging topic due to the influence of liquid and the limitation of experimental conditions. Therefore, the adding mass method for damage identification is employed in this study. Adding mass to structures is an effective method for damage identification, as it can increase not only the experimental data but also the sensitivity of experimental modes to local damage. First, the fundamental theory of the adding mass method for damage identification is introduced. After that, the method of equating the liquid to the attached mass is proposed by considering the liquid–solid coupling. Finally, the effectiveness and reliability of damage identification, based on adding mass for liquid–solid coupling structures, are verified through experiments of a submerged cantilever beam and liquid storage tank.

Keywords:
structural health monitoring, damage identification, liquid-solid coupling, adding mass, sensitivity

(70p.)
24.Szolc T., Falkowski K., Kurnyta-Mazurek P., Design of a combined self-stabilizing electrodynamic passive magnetic bearing support for the automotive turbocharger rotor, JOURNAL OF VIBRATION AND CONTROL, ISSN: 1077-5463, DOI: 10.1177/1077546320933486, pp.1-12, 2020
Szolc T., Falkowski K., Kurnyta-Mazurek P., Design of a combined self-stabilizing electrodynamic passive magnetic bearing support for the automotive turbocharger rotor, JOURNAL OF VIBRATION AND CONTROL, ISSN: 1077-5463, DOI: 10.1177/1077546320933486, pp.1-12, 2020

Abstract:
The purpose of this study is to create a concept for what would be a structurally simple and perationally robust support for the automotive turbocharger rotor in electrodynamic passive magnetic bearings. Because this kind of magnetic suspension-in its fundamental version-is dynamically unstable, to avoid the disadvantages contained therein, what is being proposed is the addition of external damping through the employment of the newly designed combined self-stabilizing electrodynamic passive magnetic bearing. The electromagnetic stiffness and damping characteristics of combined electrodynamic passive magnetic bearings have been determined for various shaft rotational speeds by means of the advanced 3D finite element method. In this study, a dynamic interaction between the turbocharger rotor shaft and the passive magnetic suspension is proposed as a support for both the fundamental electrodynamic passive magnetic bearings and the suggested combined self-stabilizing passive magnetic bearings. Here, the main attention is focused on the asymptotic stability of both the rotor shaft suspension variants. The additional damping magnitudes required to stabilize the most sensitive lateral eigenmodes of the object under consideration have been determined by means of the Routh-Hurwitz stability criterion.

Keywords:
rotor dynamics, combined electrodynamic passive magnetic bearings, turbocharger flexible rotor shaft, stability analysis, stabilizing damping magnitude

(70p.)
25.Orłowska A., Gałęzia A., Świercz A., Jankowski Ł., Mitigation of vibrations in sandwich-type structures by a controllable constrained layer, JOURNAL OF VIBRATION AND CONTROL, ISSN: 1077-5463, DOI: 10.1177/1077546320946130, pp.1-11, 2020
Orłowska A., Gałęzia A., Świercz A., Jankowski Ł., Mitigation of vibrations in sandwich-type structures by a controllable constrained layer, JOURNAL OF VIBRATION AND CONTROL, ISSN: 1077-5463, DOI: 10.1177/1077546320946130, pp.1-11, 2020

Abstract:
This study presents and tests a method for semi-active control of vibrations in sandwich-type beam structures. This method adapts a strategy called prestress accumulation release. The prestress accumulation release strategy is based on structural reconfiguration: it uses short time, impulsive and localised changes of actuator properties (such as stiffness or damping), which are applied to a part of the system in the moments, when its strain energy attains a local maximum. The method has been earlier applied as a global control scheme to mitigate the fundamental vibration mode of a cantilever beam (by stiffness control) and in the task of mitigating the first four modes of a frame structure (by damping control). This study proposes a prestress accumulation release strategy and tests its effectiveness for the case of a three-layered sandwich structure, with the internal layer fabricated from a material with dissipative characteristic locally controllable through the material damping coefficient. In contrast to the earlier research, the control is applied thus at the level of material characteristics instead of a discrete set of dedicated actuators. Based on the finite element method, a numerical experiment involving a passively damped, as well as prestress accumulation release-controlled, three-layered cantilever beam excited by initial displacements was performed. The effectiveness of the approach was studied for a broad range of internal layer damping parameters. The presented results revealed a high potential of the prestress accumulation release strategy in semi-active damping of vibrations of sandwich-type structures.

Keywords:
vibration control, sandwich structure, semi-active control, decentralised control, smart structures, constrained layer method

(70p.)
26.Bajkowski J.M., Dyniewicz B., Bajer C.I., Bajkowski J., An experimental study on granular dissipation for the vibration attenuation of skis, Proceedings of the Institution of Mechanical Engineers, ISSN: 1754-338X, DOI: 10.1177/1754337120964015, pp.1-8, 2020
Bajkowski J.M., Dyniewicz B., Bajer C.I., Bajkowski J., An experimental study on granular dissipation for the vibration attenuation of skis, Proceedings of the Institution of Mechanical Engineers, ISSN: 1754-338X, DOI: 10.1177/1754337120964015, pp.1-8, 2020

Abstract:
Due to the continuous deformations and irregularities of the surface of snow, alpine skis exhibit dynamic excitation, leading to drastic vibrations and decreased manoeuvrability. Therefore, attenuating these unwanted vibrations, while ensuring that the ski experience is not compromised, is an important challenge. The possibility of using granular material in a damping device is studied in this paper. A container that was partially filled with loose granules was fixed at the tip of an alpine ski to suppress vibrations by dissipating energy through collisions. The performance was verified experimentally by studying the transient response of a ski mounted in a horizontal cantilever orientation. Moreover, on-snow tests were performed. Different numbers of plastic granules were used as a dissipating material. To identify the nonlinear damping characteristics of the system, a Hilbert transform was used. In the laboratory test, the displacement amplitude decay was up to 16 percentage points higher when a granular dissipator was attached to the ski than without the damper. During field testing, acceleration amplitudes were 9% lower compared to the ski without the dissipator. This solution could possibly be adapted to other boardsports on a wide variety of terrain, including ground, water and snow.

Keywords:
vibration damping, alpine ski, granular material, Hilbert transform, bending beam

(70p.)
27.Popławski B., Mikułowski G., Orłowska A., Jankowski Ł., On/off nodal reconfiguration for global structural control of ‎smart 2D frames, Journal of Applied and Computational Mechanics, ISSN: 2383-4536, DOI: 10.22055/jacm.2020.32454.2016, pp.1-9, 2020
Popławski B., Mikułowski G., Orłowska A., Jankowski Ł., On/off nodal reconfiguration for global structural control of ‎smart 2D frames, Journal of Applied and Computational Mechanics, ISSN: 2383-4536, DOI: 10.22055/jacm.2020.32454.2016, pp.1-9, 2020

Abstract:
This paper proposes an on/off semi-active control approach for mitigation of free structural vibrations, designed for application in 2D smart frame structures. The approach is rooted in the Prestress-Accumulation Release (PAR) control strategies. The feedback signal is the global strain energy of the structure, or its approximation in the experimental setup. The actuators take the form of on/off nodes with a controllable ability to transfer moments (blockable hinges). Effectiveness of the approach is confirmed in a numerical simulation, as well as using a laboratory experimental test stand.

Keywords:
structural reconfiguration, structural control, semi-active control, frame structures, controllable nodes‎

(20p.)
28.Zawidzki M., The Overview of Optimization Methods Applied to Truss-Z Modular System, COMPUTER ASSISTED METHODS IN ENGINEERING AND SCIENCE, ISSN: 2299-3649, DOI: 10.24423/cames.291, Vol.27, No.2-3, pp.155-176, 2020
Zawidzki M., The Overview of Optimization Methods Applied to Truss-Z Modular System, COMPUTER ASSISTED METHODS IN ENGINEERING AND SCIENCE, ISSN: 2299-3649, DOI: 10.24423/cames.291, Vol.27, No.2-3, pp.155-176, 2020

Abstract:
Extremely Modular Systems (EMSs) are comprised of as few types of modules as possible and allow creating structurally sound free-form structures that are not constrained by a regular tessellation of space. Truss-Z is the first EMS introduced, and its purpose is to create free-form pedestrian ramps and ramp networks in any given environment. This paper presents an overview of various multi-objective optimization methods applied to Truss-Z structures.

Keywords:
Truss-Z, extremely modular system, discrete optimization, multi-objective

(20p.)
29.Ostrowski M., Błachowski B., Jankowski Ł., Pisarski D., Modal energy transfer by controlled structural connections, DIAGNOSTYKA, ISSN: 1641-6414, DOI: 10.29354/diag/116692, Vol.21, No.1, pp.61-70, 2020
Ostrowski M., Błachowski B., Jankowski Ł., Pisarski D., Modal energy transfer by controlled structural connections, DIAGNOSTYKA, ISSN: 1641-6414, DOI: 10.29354/diag/116692, Vol.21, No.1, pp.61-70, 2020

Abstract:
This paper describes a semi-active control strategy that allows to transfer the vibration energy from an arbitrarily induced to a selected structural mode. The intended aim of the proposed control strategy is energy harvesting from structural vibrations. Another potential application is related to structural safety. In the paper, a mathematical model is first introduced to describe the phenomenon of vibrational energy transfer, and then, based on this model, an efficient semi-active control strategy is proposed. Finally, some problems related to measurement techniques are discussed. The effectiveness of the proposed methodology is demonstrated in an example of energy transfer between vibrational modes of a three-bar planar frame structure.

Keywords:
vibration energy, modal control, lockable joint, modal coupling

(20p.)