The dynamic effect of the moving trains on the railroad rails and propagation of excited vibrations

The report deals with the opportunities for the implementation of the EU “Rail Baltica” study project, evaluating the fulfillment of acoustical requirements for the railway route. The paper considers the causes of excited vibrations and noise. The railway has always been one of the most important transport means, which ensures the quality of the rail freight. Propagation of vibrations, excited by the moving train, to the environment and their evaluation is significant problem. Conducted research work will be used in laying out the new railroad line from the West to Central Europe. It will provide the possibility to improve the quality of the railroad route as well as reduce vibrations and noise generated by the trains. It was established that the transport moving along the railways caused many serious problems from the ecological point of view, noise and vibration being among the most important issues. Heavy train moves along the metal railway on its metal wheels i.e. rolling-stocks. This is one of key sources of noise and vibration: it produces audible low-frequency noise as well as non-audible noise - infrasound. The influence of the infrasound on the environment and human health has not been thoroughly investigated, yet there are plenty of means for reducing it. The research performed in this area indicates many cases when infrasound is far more harmful in comparison to the audible sounds. It is a costly and complicated process to eliminate infrasound from the aforementioned sources therefore the companies and private owners, as well as state institutions do not adopt relevant measures to solve this problem. Moreover, the audible sound would also decrease in such a case. In the paper the author treats the problem on the basis of practical tests and research conducted by different scientists as well as proposes approaches for solution of the considered proble

Damping of small electronic equipment vibrations

The present paper is aimed at developing methods of damping (decreasing) the amplitudes of random mechanical vibrations of moving equipment by using the approach suggested by the authors. In the description of random vibrations, the theory of random processes is applied, the energy dissipation of mechanisms is determined. Internal and constructional losses are analyzed. The role of viscosity at the propagation of wave energy in certain systems is specified. A level of random vibrations is evaluated. A concrete sample illustrating the role of constructive absorption of energy is analyzed. The paper presents calculation methods, which may be easily applied for the creation of a computer programm

Excitation of low-frequency vibrations and their propagation

In putting into production various new technologies, often for the forced excitation of vibrations special vibration machines, which are used in the product formation technology, are applied. The paper deals with the vibration excitation source, which is used in the production technology of construction blocks, their mass compaction. The measured parameters of vibrations show that local insulation of vibrations caused by the vibration machine is not sufficient. Theoretical and experimental investigations showed that despite of the application of standard methods, for reducing vibrations, propagated by them, the transversal and longitudinal waves, excited by vibrations are propagating through the constructions of the buildings and the ground with low extinction losses. Those harmful vibrations propagating into the environment reach the living zones and cause considerable problems for human work and recreation. Having studied the ways of vibration propagation, some were proposed and some implemented in the specific object. The data of the works performed provided in the paper show that in order to protect objects and people from the harmful impact of vibrations, while designing such plants it is necessary to implement the new methods for vibration reductio

Noise in european railway under modernization and its reduction

This research work presents various noise reduction measures, which, taking into account the relief of the country and the location of urban areas, should be designed during modernization of railway lines. European project “Silence” is dedicated to the reduction of railway noise in urban areas. Attention in this paper is devoted to the impact of infrasound on the people living near the railway. Here we present the study of propagation of vibrations through the ground to the residential buildings. With this aim in view, experimental tests were performed for clarification of vibration propagation process from the railway lines (railings) to the residential building. Evaluation of possible impact of noise caused by the trains on the environment is presented. The report provides sound pressure levels from the moving trains, which will run until the reconstruction of the main line. Moreover, noise levels are predicted when modernizing road and railway transport means (locomotives, vans, etc.). This research work studies spectrum composition of noise produced by the train in terms of quantity and quality of the radiated energy with respect to the human body, i.e. not only by the sound level dBA, but also by the spectrum composition of sound pressure level. Attention is focused on the impact of very low sound frequencies and infrasound. On the basis of the measured and calculated noise levels propagated by various future railway trains, the impact of noise produced by the trains on the environment is specified. Based on the results of noise analysis, measures are foreseen for the reduction of harmful noise propagated by the trains. The article presents the research on reduction of noise and vibrations by means of barriers theory and their implementation in practice. Acoustic barriers are divided according to their usage and structures. The article deals with the presentation of implementation of screens in practice together with their theoretical evaluation as well as dependences on structure and materials of the screens. Evaluation of their positive and negative acoustic properties is provided as well. The obtained results will be used in the recommendations when designing noise reduction measures and expanding a railway network in the Baltic countrie

Sound-insulation of ellipsoidal shells

In the introduction of this paper, the importance of the work in the period of the development of new equipment and technology is formulated when optimum constructions are sought not only in terms of resistance or firmness but also imparting additional properties to them. One of the more important properties of the constructions under development is acoustical ones, i.e. constructions that may to reduce to a maximum the sound (noise) entering the environment. The work deals with an analysis of sound insulation properties of ellipsoidal shells, comparing them with the same properties of other forms. Examples for the use of the shells of such forms and their efficiency in the environmental noise reduction are provide

Excitation of low-frequency vibrations and their propagation

In putting into production various new technologies, often for the forced excitation of vibrations special vibration machines, which are used in the product formation technology, are applied. The paper deals with the vibration excitation source, which is used in the production technology of construction blocks, their mass compaction. The measured parameters of vibrations show that local insulation of vibrations caused by the vibration machine is not sufficient. Theoretical and experimental investigations showed that despite of the application of standard methods, for reducing vibrations, propagated by them, the transversal and longitudinal waves, excited by vibrations are propagating through the constructions of the buildings and the ground with low extinction losses. Those harmful vibrations propagating into the environment reach the living zones and cause considerable problems for human work and recreation. Having studied the ways of vibration propagation, some were proposed and some implemented in the specific object. The data of the works performed provided in the paper show that in order to protect objects and people from the harmful impact of vibrations, while designing such plants it is necessary to implement the new methods for vibration reductio

The dynamic effect of the moving trains on the railroad rails and propagation of excited vibrations

The report deals with the opportunities for the implementation of the EU “Rail Baltica” study project, evaluating the fulfillment of acoustical requirements for the railway route. The paper considers the causes of excited vibrations and noise. The railway has always been one of the most important transport means, which ensures the quality of the rail freight. Propagation of vibrations, excited by the moving train, to the environment and their evaluation is significant problem. Conducted research work will be used in laying out the new railroad line from the West to Central Europe. It will provide the possibility to improve the quality of the railroad route as well as reduce vibrations and noise generated by the trains. It was established that the transport moving along the railways caused many serious problems from the ecological point of view, noise and vibration being among the most important issues. Heavy train moves along the metal railway on its metal wheels i.e. rolling-stocks. This is one of key sources of noise and vibration: it produces audible low-frequency noise as well as non-audible noise - infrasound. The influence of the infrasound on the environment and human health has not been thoroughly investigated, yet there are plenty of means for reducing it. The research performed in this area indicates many cases when infrasound is far more harmful in comparison to the audible sounds. It is a costly and complicated process to eliminate infrasound from the aforementioned sources therefore the companies and private owners, as well as state institutions do not adopt relevant measures to solve this problem. Moreover, the audible sound would also decrease in such a case. In the paper the author treats the problem on the basis of practical tests and research conducted by different scientists as well as proposes approaches for solution of the considered proble

Damping of small electronic equipment vibrations

The present paper is aimed at developing methods of damping (decreasing) the amplitudes of random mechanical vibrations of moving equipment by using the approach suggested by the authors. In the description of random vibrations, the theory of random processes is applied, the energy dissipation of mechanisms is determined. Internal and constructional losses are analyzed. The role of viscosity at the propagation of wave energy in certain systems is specified. A level of random vibrations is evaluated. A concrete sample illustrating the role of constructive absorption of energy is analyzed. The paper presents calculation methods, which may be easily applied for the creation of a computer programm

Sound-insulation of ellipsoidal shells

In the introduction of this paper, the importance of the work in the period of the development of new equipment and technology is formulated when optimum constructions are sought not only in terms of resistance or firmness but also imparting additional properties to them. One of the more important properties of the constructions under development is acoustical ones, i.e. constructions that may to reduce to a maximum the sound (noise) entering the environment. The work deals with an analysis of sound insulation properties of ellipsoidal shells, comparing them with the same properties of other forms. Examples for the use of the shells of such forms and their efficiency in the environmental noise reduction are provide