In the recent years different types of dampers for structural control in civil engineering have ... more In the recent years different types of dampers for structural control in civil engineering have been developed, where one of the most promising solutions are viscoelastic dampers. In this paper we demonstrate that by utilizing knowledge on the effect of inherent hydrostatic pressure on the time- and frequency-dependent behavior of polymers it is possible to design and build the ultimate insulation systems for civil engineering applications. An optimal solution is achieved by using highly pressurized multimodal granular polymeric materials. The results on case material, Thermoplastic Polyurethane, showed that by increasing inherent pressure of the material from 1 bar to 2000 bar the frequency at which material exhibits its maximal damping properties was shifted from 37 kHz, at P=1 bar to 235 Hz at P=2000 bar. At the same time, the increase of inherent hydrostatic pressure from 1 bar to 2000 bar changes material stiffness up to 2.5 times, while the damping properties increase up to 5...
The closed-form shifting (CFS) algorithm is a simple mathematical methodology which determines th... more The closed-form shifting (CFS) algorithm is a simple mathematical methodology which determines the unique solution in the process of constructing master curves at selected reference temperature and pressure conditions. In a previous paper, the CFS algorithm has been fully described for monotonically increasing or monotonically decreasing functions only. This paper presents detailed steps of the generalized CFS methodology for non-monotonic functions, like the loss tangent. Performing shifting on the loss tangent, which does not require vertical shifting, is particularly important for materials which require vertical adjustment of dynamic viscoelastic functions, i.e., loss and storage moduli. Thus, based on horizontal shifting of the loss tangent, the CFS-based procedure of consecutive Marina Gergesova
Conference Proceedings of the Society for Experimental Mechanics Series, 2014
Reduction of noise and vibration coming from the rail transport activities is an important object... more Reduction of noise and vibration coming from the rail transport activities is an important objective of the environmental policy of the European Union, due to its impact on human and animal health. It has been identified that one of the major sources of noise and vibration in rail transport is from the interaction between the wheel and the rail, the so called rolling noise. One way to mitigate this noise is to attach polymeric damping elements to the rail. By modifying bulk properties of polymeric material we can modify its damping characteristics. In this chapter we demonstrated on the example of thermoplastic polyurethane (TPU) the effect of inherent hydrostatic pressure on the time- and frequency-dependent behavior of polymers. For the selected TPU material we found that increasing hydrostatic pressure from 1 to 2000 bar shifts frequency at which material exhibits its maximal damping properties (G″max) from 37 kHz to 235 Hz. It was also found that change of pressure changes values of storage modulus G′ up to 3.5 times (depending on the frequency), while the values of loss modulus G″ are changed up to 5.5 times. Using this property of polymeric materials we developed new generation damping elements composed of glass fiber textile tubes filled with pressurized granulated polymeric materials. Granular material with properly selected multimodal particle size distribution acts as pressurizing agent. At the same time the generated hydrostatic pressure changes frequency dependence of the granular material bulk properties. By modifying material bulk properties we can modify damping characteristics of the new generation damping elements. Applying these damping elements to the rail can substantially reduce vibration amplitudes as well as sound pressure levels, thus reducing exposure of human and animal to noise and vibration.
ABSTRACT To predict durability of polymeric structures an information on polymer’s long-term prop... more ABSTRACT To predict durability of polymeric structures an information on polymer’s long-term properties in the form of relaxation modulus and/or creep compliance is required. It is well known that determination of relaxation or creep properties from experimental data is an inverse problem, which, due to presence of experimental errors in input data, becomes ill-posed. To find a stable solution using standard integration schemes is practically impossible. In this paper we propose a “hands-on” methodology which bypasses the solution of ill-posed integral equation and allows finding long-term relaxation or creep properties from simple constant strain rate or constant stress-rate experiments performed at different temperatures. The proposed approach can be applied not only for characterization of viscoelastic materials in solid state but can also be used for prediction of time-dependent properties of polymer melts. The paper presents the detailed steps of the proposed method as well as its validation on several simulated and real experimental data. It has been shown that the proposed approach can accurately reconstruct the desired long-term time-dependent properties obtained in traditional way (i.e., from step loading).
Time-dependent material functions of engineering plastics within the exploitation range of temper... more Time-dependent material functions of engineering plastics within the exploitation range of temperatures extend over several decades of time. For this reason material characterization is carried out at different temperatures and/or pressures within a certain experimental window. Using the time-temperature and/or time-pressure superposition principle, these response function segments can be shifted along the logarithmic time-scale to obtain a master curve at selected reference conditions. This shifting is commonly performed manually ͑"by hand"͒ and requires some experience. Unfortunately, manual shifting is not based on a commonly agreed mathematical procedure which would, for a given set of experimental data, yield always exactly the same master curve, independent of person who executes the shifting process. Thus, starting from the same set of experimental data two different researchers could, and very likely will, construct two different master curves. In this paper, we propose a closed form mathematical methodology ͑CFS͒ which completely removes ambiguity related to the manual shifting procedures. This paper presents the derivation of the shifting algorithm and its validation using several simulated-and realexperimental data. It has been shown that error caused by shifting performed with CFS is at least 10-50 times smaller then the underlying experimental error.
This paper is aimed to introduce the reader with the specifics of viscoelastic materials, and phy... more This paper is aimed to introduce the reader with the specifics of viscoelastic materials, and physical background of their time-dependent behaviour during exploitation period. It points out, how the selection of viscoelastic material in combination with thermomechanical conditions during the processing might affect the functionality and long-term behaviour of a product in use. Both can be considered and analysed by characterizing material properties through which material and technology effects are manifested in different mechanical responses to the certain loading conditions. In relation to this, fundamental viscoelastic material functions are presented in the article, as the main characteristics to evaluate functionality and long-term behaviour of time-dependent (viscoelastic) materials.
Time-dependent material functions of engineering plastics within the exploitation range of temper... more Time-dependent material functions of engineering plastics within the exploitation range of temperatures extend over several decades of time. For this reason material characterization is carried out at different temperatures and/or pressures within a certain experimental window. Using the time-temperature and/or time-pressure superposition principle, these response function segments can be shifted along the logarithmic time-scale to obtain a master curve at selected reference conditions. This shifting is commonly performed manually ͑"by hand"͒ and requires some experience. Unfortunately, manual shifting is not based on a commonly agreed mathematical procedure which would, for a given set of experimental data, yield always exactly the same master curve, independent of person who executes the shifting process. Thus, starting from the same set of experimental data two different researchers could, and very likely will, construct two different master curves. In this paper, we propose a closed form mathematical methodology ͑CFS͒ which completely removes ambiguity related to the manual shifting procedures. This paper presents the derivation of the shifting algorithm and its validation using several simulated-and realexperimental data. It has been shown that error caused by shifting performed with CFS is at least 10-50 times smaller then the underlying experimental error.
To predict durability of polymeric structures an information on polymer's longterm properties in ... more To predict durability of polymeric structures an information on polymer's longterm properties in the form of relaxation modulus and/or creep compliance is required. It is well known that determination of relaxation or creep properties from experimental data is an inverse problem, which, due to presence of experimental errors in input data, becomes ill-posed. To find a stable solution using standard integration schemes is practically impossible. In this paper we propose a "hands-on" methodology which bypasses the solution of ill-posed integral equation and allows finding long-term relaxation or creep properties from simple constant strain rate or constant stress-rate experiments performed at different temperatures. The proposed approach can be applied not only for characterization of viscoelastic materials in solid state but can also be used for prediction of time-dependent properties of polymer melts. The paper presents the detailed steps of the proposed method as well as its validation on several simulated and real experimental data. It has been shown that the proposed approach can accurately reconstruct the desired long-term time-dependent properties obtained in traditional way (i.e., from step loading).
In the recent years different types of dampers for structural control in civil engineering have ... more In the recent years different types of dampers for structural control in civil engineering have been developed, where one of the most promising solutions are viscoelastic dampers. In this paper we demonstrate that by utilizing knowledge on the effect of inherent hydrostatic pressure on the time- and frequency-dependent behavior of polymers it is possible to design and build the ultimate insulation systems for civil engineering applications. An optimal solution is achieved by using highly pressurized multimodal granular polymeric materials. The results on case material, Thermoplastic Polyurethane, showed that by increasing inherent pressure of the material from 1 bar to 2000 bar the frequency at which material exhibits its maximal damping properties was shifted from 37 kHz, at P=1 bar to 235 Hz at P=2000 bar. At the same time, the increase of inherent hydrostatic pressure from 1 bar to 2000 bar changes material stiffness up to 2.5 times, while the damping properties increase up to 5...
The closed-form shifting (CFS) algorithm is a simple mathematical methodology which determines th... more The closed-form shifting (CFS) algorithm is a simple mathematical methodology which determines the unique solution in the process of constructing master curves at selected reference temperature and pressure conditions. In a previous paper, the CFS algorithm has been fully described for monotonically increasing or monotonically decreasing functions only. This paper presents detailed steps of the generalized CFS methodology for non-monotonic functions, like the loss tangent. Performing shifting on the loss tangent, which does not require vertical shifting, is particularly important for materials which require vertical adjustment of dynamic viscoelastic functions, i.e., loss and storage moduli. Thus, based on horizontal shifting of the loss tangent, the CFS-based procedure of consecutive Marina Gergesova
Conference Proceedings of the Society for Experimental Mechanics Series, 2014
Reduction of noise and vibration coming from the rail transport activities is an important object... more Reduction of noise and vibration coming from the rail transport activities is an important objective of the environmental policy of the European Union, due to its impact on human and animal health. It has been identified that one of the major sources of noise and vibration in rail transport is from the interaction between the wheel and the rail, the so called rolling noise. One way to mitigate this noise is to attach polymeric damping elements to the rail. By modifying bulk properties of polymeric material we can modify its damping characteristics. In this chapter we demonstrated on the example of thermoplastic polyurethane (TPU) the effect of inherent hydrostatic pressure on the time- and frequency-dependent behavior of polymers. For the selected TPU material we found that increasing hydrostatic pressure from 1 to 2000 bar shifts frequency at which material exhibits its maximal damping properties (G″max) from 37 kHz to 235 Hz. It was also found that change of pressure changes values of storage modulus G′ up to 3.5 times (depending on the frequency), while the values of loss modulus G″ are changed up to 5.5 times. Using this property of polymeric materials we developed new generation damping elements composed of glass fiber textile tubes filled with pressurized granulated polymeric materials. Granular material with properly selected multimodal particle size distribution acts as pressurizing agent. At the same time the generated hydrostatic pressure changes frequency dependence of the granular material bulk properties. By modifying material bulk properties we can modify damping characteristics of the new generation damping elements. Applying these damping elements to the rail can substantially reduce vibration amplitudes as well as sound pressure levels, thus reducing exposure of human and animal to noise and vibration.
ABSTRACT To predict durability of polymeric structures an information on polymer’s long-term prop... more ABSTRACT To predict durability of polymeric structures an information on polymer’s long-term properties in the form of relaxation modulus and/or creep compliance is required. It is well known that determination of relaxation or creep properties from experimental data is an inverse problem, which, due to presence of experimental errors in input data, becomes ill-posed. To find a stable solution using standard integration schemes is practically impossible. In this paper we propose a “hands-on” methodology which bypasses the solution of ill-posed integral equation and allows finding long-term relaxation or creep properties from simple constant strain rate or constant stress-rate experiments performed at different temperatures. The proposed approach can be applied not only for characterization of viscoelastic materials in solid state but can also be used for prediction of time-dependent properties of polymer melts. The paper presents the detailed steps of the proposed method as well as its validation on several simulated and real experimental data. It has been shown that the proposed approach can accurately reconstruct the desired long-term time-dependent properties obtained in traditional way (i.e., from step loading).
Time-dependent material functions of engineering plastics within the exploitation range of temper... more Time-dependent material functions of engineering plastics within the exploitation range of temperatures extend over several decades of time. For this reason material characterization is carried out at different temperatures and/or pressures within a certain experimental window. Using the time-temperature and/or time-pressure superposition principle, these response function segments can be shifted along the logarithmic time-scale to obtain a master curve at selected reference conditions. This shifting is commonly performed manually ͑"by hand"͒ and requires some experience. Unfortunately, manual shifting is not based on a commonly agreed mathematical procedure which would, for a given set of experimental data, yield always exactly the same master curve, independent of person who executes the shifting process. Thus, starting from the same set of experimental data two different researchers could, and very likely will, construct two different master curves. In this paper, we propose a closed form mathematical methodology ͑CFS͒ which completely removes ambiguity related to the manual shifting procedures. This paper presents the derivation of the shifting algorithm and its validation using several simulated-and realexperimental data. It has been shown that error caused by shifting performed with CFS is at least 10-50 times smaller then the underlying experimental error.
This paper is aimed to introduce the reader with the specifics of viscoelastic materials, and phy... more This paper is aimed to introduce the reader with the specifics of viscoelastic materials, and physical background of their time-dependent behaviour during exploitation period. It points out, how the selection of viscoelastic material in combination with thermomechanical conditions during the processing might affect the functionality and long-term behaviour of a product in use. Both can be considered and analysed by characterizing material properties through which material and technology effects are manifested in different mechanical responses to the certain loading conditions. In relation to this, fundamental viscoelastic material functions are presented in the article, as the main characteristics to evaluate functionality and long-term behaviour of time-dependent (viscoelastic) materials.
Time-dependent material functions of engineering plastics within the exploitation range of temper... more Time-dependent material functions of engineering plastics within the exploitation range of temperatures extend over several decades of time. For this reason material characterization is carried out at different temperatures and/or pressures within a certain experimental window. Using the time-temperature and/or time-pressure superposition principle, these response function segments can be shifted along the logarithmic time-scale to obtain a master curve at selected reference conditions. This shifting is commonly performed manually ͑"by hand"͒ and requires some experience. Unfortunately, manual shifting is not based on a commonly agreed mathematical procedure which would, for a given set of experimental data, yield always exactly the same master curve, independent of person who executes the shifting process. Thus, starting from the same set of experimental data two different researchers could, and very likely will, construct two different master curves. In this paper, we propose a closed form mathematical methodology ͑CFS͒ which completely removes ambiguity related to the manual shifting procedures. This paper presents the derivation of the shifting algorithm and its validation using several simulated-and realexperimental data. It has been shown that error caused by shifting performed with CFS is at least 10-50 times smaller then the underlying experimental error.
To predict durability of polymeric structures an information on polymer's longterm properties in ... more To predict durability of polymeric structures an information on polymer's longterm properties in the form of relaxation modulus and/or creep compliance is required. It is well known that determination of relaxation or creep properties from experimental data is an inverse problem, which, due to presence of experimental errors in input data, becomes ill-posed. To find a stable solution using standard integration schemes is practically impossible. In this paper we propose a "hands-on" methodology which bypasses the solution of ill-posed integral equation and allows finding long-term relaxation or creep properties from simple constant strain rate or constant stress-rate experiments performed at different temperatures. The proposed approach can be applied not only for characterization of viscoelastic materials in solid state but can also be used for prediction of time-dependent properties of polymer melts. The paper presents the detailed steps of the proposed method as well as its validation on several simulated and real experimental data. It has been shown that the proposed approach can accurately reconstruct the desired long-term time-dependent properties obtained in traditional way (i.e., from step loading).
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Papers by Ivan Saprunov