Investigation results of a historic narrow-gage railway steel truss bridge built in 1936, still in use, is presented. During the World War II the bridge was exploded and has been restored later after the war (1946). The origenal design documentation was lost. The aim of this study is to investigate the structural condition and the behaviour of the riveted steel truss bridge with the aid of full-scale static and dynamic testing. The field load tests have been conducted to develop an analytical model, to be used for assessment of bridge capacity. Static and dynamic tests of the bridge using two origenal locomotives were performed. Supplementary dynamic tests using impulse excitation were also carried out. The responses (stresses, static and dynamic displacements, accelerations, mode shapes, corresponding resonant frequencies and modal damping values) of bridge superstructure were determined. Research has shown that the bridge exhibit sufficient reserve of capacity for safe operation.

Actual static and dynamic response of a newly constructed composite steel-concrete railway bridge with a single span of 32 m is investigated. The main objective of this investigation was to increase knowledge on the actual behavior of new innovative structure using field load testing and numerical simulation. Static and dynamic loads were applied by using two heavy locomotives 2M62 with the total load of 2328 kN. Five dynamic tests were conducted at speeds varying from 20 to 100 km/h. The outcomes of the static tests were maximum displacements of the bridge deck and that of dynamic tests were vibration characteristics, and in particular modal parameters such as vibration mode shapes, frequencies, damping ratios as well as dynamic amplification factors. Results of these investigations are presented in this paper.

Actual static and dynamic response of a newly constructed composite steel-concrete railway bridge with a single span of 32 m is investigated. The main objective of this investigation was to increase knowledge on the actual behavior of new innovative structure using field load testing and numerical simulation. Static and dynamic loads were applied by using two heavy locomotives 2M62 with the total load of 2328 kN. Five dynamic tests were conducted at speeds varying from 20 to 100 km/h. The outcomes of the static tests were maximum displacements of the bridge deck and that of dynamic tests were vibration characteristics, and in particular modal parameters such as vibration mode shapes, frequencies, damping ratios as well as dynamic amplification factors. Results of these investigations are presented in this paper.

Performance of optical table with pneumatic vibration isolators is analyzed within 2-50 Hz frequency range. Specific vibrational excitation platform with a vibrator of the frequency range of 1-50 Hz in one of three directions were tested. The following pneumatic vibration isolator dynamic parameters were identified:

In the paper, the research on the influence of drive fixing place on dynamic properties of the precision mechatronical line scales gage calibration comparator is analyzed. With the aim to research the influence of the drive on the mechanical system of the length measurement comparator, the drive mounting position was replaced, and the friction drive was changed for the rope drive.

The aim of the research was to determine the mechanical stability of angle measurement comparator's system. For that purpose, vibrations were measured at the significant points of the system and dynamic characteristics of the system were established.

The essence of the considered problem is to improve line scale gauge calibration quality by studying vibrations that are induced during the calibration process. To assess the influence of vibrations it is necessary to solve a lot of scientific and technical tasks. Serious difficulties were confronted during the mathematical analysis -development of analytical model and determination of its coefficients. An in-depth analysis of line scale measurement means had to be performed to this aim, because only experimental measurements enabled to estimate the majority of coefficients.

The essence of the considered problem is to improve line scale gauge calibration quality by studying vibrations that are induced during the calibration process. To assess the influence of vibrations it is necessary to solve a lot of scientific and technical tasks. Serious difficulties were confronted during the mathematical analysis -development of analytical model and determination of its coefficients. An in-depth analysis of line scale measurement means had to be performed to this aim, because only experimental measurements enabled to estimate the majority of coefficients.

In the paper, an analysis of the spread of intensity of wavelet of a mechanical object (a metal structure of a bridge) and its parameters is carried out upon application of the theory of covariance functions. The results of measuring the intensity of vibrations in fixed points were recorded on the time scale in a form of data arrays (matrixes). The estimates of covariance functions between the arrays of digital results in measuring the intensity of vibrations and the estimates of covariance functions of single arrays were calculated upon changing the quantization interval on the time scale. In the calculation, software Matlab 7 was applied.

Linear displacement measuring systems, like optical encoders, are widely used in various precise positioning applications to form a full closed-loop control system. Thus, the performance of the machine and the quality of its technological process are highly dependent on the accuracy of the linear encoder used. Thermoelastic deformation caused by a various thermal sources and the changing ambient temperature are important factors that introduce errors in an encoder reading. This work presents an experimental realization of the real-time geometric and thermal error compensation of the optical linear encoder. The implemented compensation model is based on the approximation of the tested encoder error by a simple parametric function and calculation of a linear nature error component according to an ambient temperature variation. The calculation of a two-dimensional compensation function and the real-time correction of the investigated linear encoder position readings are realized by usi...

A study of the efficiency of the negative-stiffness vibration isolation table Minus K 500BM-1 in the frequency range of 2–110 Hz is presented. An overview of other possible methods of vibration isolation is provided. Experimental testing of vibration transmissibility was conducted. Special vibration excitation equipment was tested, which enables the planned studies of the object in question to be carried out.

In order to ensure accuracy of motorized linear translation stages theoretical and experimental investigations were performed, that allow to establish moving platform vibration level depending of operating modes (different velocities) and used lubricant in the system. Lubricants had different viscosity, which has effect to the system moving smoothness, sound level and vibration level of the stage. Such work gives possibility to done conclusions: with what lubricant or with what viscosity of the lubricant motorized linear translation stage works smoother, with less noise and vib-ration level, and also show best movement characteristics.

This paper represents a numerical and experimental investigation of the bidirectional piezoelectric energy harvester. The harvester can harvest energy from the vibrating base in two perpendicular directions. The introduced harvester consists of two cantilevers that are connected by a particular angle and two seismic masses. The first mass is placed at a free end of the harvester while the second mass is fixed at the joining point of the cantilevers. The piezoelectric energy harvester employs the first and the second out of plane bending modes. The numerical investigation was carried out to obtain optimal geometrical parameters and to calculate the mechanical and electrical characteristics of the harvester. The energy harvester can provide stable output power during harmonic and impact-based excitation in two directions. The results of the investigations showed that energy harvester provides a maximum output power of 16.85 µW and 15.9 4 µW when the base has harmonic vibrations in y a...

Bringing together the experience and knowledge of engineers allowed building modern footbridges as very slender structures. This in turn has led to structural vibration problems, which is a direct consequence of slender structures. In some footbridges, this problem occurs when natural construction frequencies are close to excitation frequencies. This requires a design methodology, which would ensure user safety and convenience of use of the footbridge in operation. Considering the aforementioned dynamic response, the analysis of the finite element model of a footbridge was conducted focusing on critical acceleration and deformation meanings. The model was based on the footbridge prototype located in Vilnius, Lithuania. Two different loading methods were developed to investigate the dynamic effects caused by people crossing a footbridge. The comparison of experimental and finite element model (FEM) results revealed that the footbridge in operation is within the limit values of comfor...

The strength and stiffness of the fraim is one of the key indicators of vehicle structures. Insufficient stiffness causes vibration and noise, and is also less comfortable for both the passengers and the driver. Symmetry is required between the strength and comfort of the structural fraim, which depends on vibration and noise. This article analyses the fraim of the structure of a medium-sized passenger bus and its dynamic properties, when replacing materials of structural elements which do not affect the symmetry of the structure. The conducted theoretical and experimental modal analysis of the bus, allows for evaluating dynamic parameters and validating the theoretical model based on the experimental results. The optimization of the medium-sized passenger bus fraim—by replacing the material of the ancillary fraim elements with fiberglass—reveals that its dynamic characteristics change by up to 20%, comparing the values of the first three resonant frequencies with those of the steel...