Evaluation of Dynamic Load Reduction for a Tractor Semi-Trailer Using the Air Suspension System at all Axles of the Semi-Trailer

The air suspension system has become more and more popular in heavy vehicles and buses to improve ride comfort and road holding. This paper focuses on the evaluation of the dynamic load reduction at all axles of a semi-trailer with an air suspension system, in comparison with the one using a leaf spring suspension system on variable speed and road types. First, a full vertical dynamic model is proposed for a tractor semi-trailer (full model) with two types of suspension systems (leaf spring and air spring) for three axles at the semi-trailer, while the tractor’s axles use leaf spring suspension systems. The air suspension systems are built based on the GENSYS model; meanwhile, the remaining structural parameters are considered equally. The full model has been validated by experimental results, and closely follows the dynamical characteristics of the real tractor semi-trailer, with the percent error of the highest value being 6.23% and Pearson correlation coefficient being higher than 0.8, corresponding to different speeds. The survey results showed that the semi-trailer with the air suspension system can reduce the dynamic load of the entire field of speed from 20 to 100 km/h, given random road types from A to F according to the ISO 8608:2016 standard. The dynamic load coefficient (DLC) with the semi-trailer using the air spring suspension system can be reduced on average from 14.8% to 29.3%, in comparison with the semi-trailer using the leaf spring suspension system.

Experimental studies of vibration fields of a freight train in the far zone

The article analyzes the sources of radiation of seismic and acoustic signals of railway transport. To determine the wave structure of the seismic field of freight train in the experiment, a linear antenna was used, located at a distance of 1000 m from the railway track. A fine spectral analysis of the seismic signal reveals the presence of two harmonics in the frequency range 1–6 Hz. One of the dominant in amplitude discrete coincides in frequency with the harmonic of the acoustic signal, which indicates the refraction of the acoustic wave into a solid medium at the location of the seismic sensor. The source of the infrasonic signal at the specified frequency can be the resonant oscillation of the car on the spring suspension elasticity. The second discrete at a frequency of 2.7 Hz remains unchanged during the movement of various trains and is even present in microseismic noise, which indicates the imposition of a layered structure of a solid medium. The propagation velocity of this harmonic of the seismic signal is less than the velocity of sound. The totality of the marked features makes it possible to identify this wave with the surface wave formed by the layer.

IMPROVING THE DESIGN OF THE SPRING SUSPENSION OF TRAILED VEHICLES

This article presents materials related to the development of a promising design of adaptive tor-sion bar suspension for trailed special and cargo vehicles, both trailers and semi-trailers, designed for the transportation of bulk and general cargo. A number of technical solutions, created at the level of inventions, are proposed, which make it possible to simplify the existing types of spring suspensions, reduce their metal consumption, improve the smoothness of trailed vehicles (TV) and increase their operational reliability due to the operation of suspensions in automatic mode when they overcome micro and macro unevenness of the roadway. Analytical studies were carried out with the development of a design scheme and a methodology for calculating the design of an adaptive torsion spring for static and dynamic strength.

ANALISIS PENGARUH TEBAL PLAT TERHADAP KARAKTERISTIK MEKANIK PEGAS DAUN PADA PROTOTIPE MOBIL FISH CAR UNEJ (FCU) MUDSKIP

Fish Car Unej (FCU) Mudskip is a car designed with a rural terrain system, especially for fishing transportation. FCU Mudskip uses leaf spring suspension at the rear to support the weight of the vehicle, that is leaning towards the rear. The load of the vehicle is inclined to the rear due to the car carrying system in the form of fish and water. This conveying system can cause leaf spring failure. Therefore, this study aims to determine the value of stress, strain and cycle on leaf springs. Ansys 18.1 software was used to obtain stress, strain, and leaf spring cycle values with a thickness of 7 mm, 10 mm, and 13 mm. The value of stress on leaf springs with thickness 7 is 124,31 x 106 N/m2; thickness 10 mm is 74,92 x 106 N/m2; thickness 13 mm is 48,08 x 106N/m2; the value of strain on leaf springs with a thickness of 7 mm is 0,00075; a thickness of 10 mm is 0,00045; a thickness of 13 mm is 0,00029; Acceptable cycles of leaf springs are 7 mm thick is 69206 cycles, 10 mm is 77833 cycles, and 13 mm thick is 93054 cycles. Leaf springs with a thickness of 13 mm are the most optimal leaf springs because they can receive the most cycles of 93054 cycles, according to the function of leaf springs as vibration dampers.

Strength of Flexible Shell of Pneumatic Springs

The strength for a flexible shell of a vehicle pneumatic spring during movement relative to a rail track has been studied in the paper. The calculation has been carried out using the finite element method implemented in the SolidWorks software environment. For this purpose, 3D drawings of a balloon-type pneumatic spring have been reproduced. A specific feature of the design is that the distance between the upper and lower bottoms in static conditions is unchanged – thanks to the body position regulator, which maintains its constancy relative to the trolley frame. The results obtained have made it possible to conclude that there are certain reserves for the level of stresses, i.e., in addition to the vertical, it is possible to take into account also transverse mutual displacements of the air spring bottoms which will occur when the trolley moves relative to the body. At the next stage, the stresses in the material of the flexible shell are investigated for mutual transverse displacements of the bottoms, which are observed with transverse displacements of the trolleys relative to the body of the vehicle when traveling along curved sections of the track. At the same time, the maximum stresses in the material of the flexible shell of the pneumatic spring are about 11 MPa, even with twice the nominal air pressure and transverse mutual displacements of the bottoms of 40 mm, that is, they are much less than the breaking strength (30 MPa). The carried out researches allow to draw a conclusion that the design and parameters of a flexible shell of a balloon-type air springs ensure its strength under operational loading schemes. Therefore, in order to improve the dynamic qualities of vehicles, it is proposed to use a flexible shell of a pneumatic spring as a component of the spring suspension.

Dynamics of electric rolling stock

The textbook describes the physical foundations, theory, principles of selection and calculation of the main parameters of spring suspension schemes, discusses the issues of fitting crews into curves, vertical dynamics of the traction drive, the use of coupling weight and vibrations of electric rolling stock. It is intended for the training of certified specialists in the direction of "Railway rolling stock".

Design and dynamics of electric rolling stock

The physical foundations, theory, principles of selection and calculation of the main parameters of spring suspension schemes are presented, the issues of fitting crews into curves, the dynamics of traction drive, the use of coupling weight and vibrations of electric rolling stock, and the design features of modern locomotives are considered. For students and teachers, as well as anyone interested in this topic.

The Design, Simulation and Fabrication of an Omnidirectional Inertial Switch with Rectangular Suspension Spring

An omnidirectional inertial switch with rectangular spring is proposed in this paper, and the prototype has been fabricated by surface micromachining technology. To evaluate the threshold consistency and stability of omnidirectional inertia switch, the stiffness of rectangular suspension springs is analyzed. The simulation result shows that the coupling stiffness of the rectangular spring suspension system in the non-sensitive direction is a little more than that in the sensitive direction, which indicated that the omnidirectional switching system’s stability is reinforced, attributed to the design of rectangular springs. The dynamic response simulation shows that the threshold of the omnidirectional inertial switch using the rectangular suspension spring has high consistency in the horizontal direction. The prototype of an inertial switch is fabricated and tested successfully. The testing results indicate even threshold distribution in the horizontal direction. The threshold acceleration of the designed inertial switch is about 58 g in the X direction and 37 g in the Z direction; the contact time is about 18 μs.