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Section 4. Machinery construction
DOI: http://dx.doi.org/10.20534/ESR-17-3.4-13-17
Rahimov Rustam Vyacheslavovich, Tashkent Institute of Railways Engineering, PhD in technics, associate professor, Dean of the Electromechanical Faculty
E-mail: [email protected] Khatamov Sardor Abdullayevich Tashkent Institute of Railways Engineering, Junior researcher Rakhmatov Zafar Xasanovich, Tashkent Institute of Railways Engineering, Junior researcher
Scientific substantiation of technical solutions for the improvement of the construction of the body of a hopper car for transportation of cement produced in the Republic of Uzbekistan
Abstract: The article describes the need to replenish the park of the Republic of Uzbekistan with modern freight cars. The questions of designing and putting into operation a new construction of a four-axial covered hopper car for cement transportation are considered. The main technical characteristics and results of strength studies of load-bearing elements of the body of a hopper car are given.
Keywords: hopper car, body, cement, transportation, method of final elements, coefficient of vertical dynamics, strength, load, model.
Introduction
Confident steps of Uzbekistan on the path of market reformations, constructing a modern democratic society, improving the living standards of the population necessitate the need to reform the basic sectors of the economy of the country. Under these conditions, residential building and its accompanying infrastructure — communal and social sector, transport and communication networks, production of modern building materials and structures — becomes the focus, which can and should serve as one of the most effective areas of capital expenditures and investment.
During the recent period, a special role in the development was assigned to the industry of construction materials, an area determining the potential of the construction industry as a whole. Based on decisions of the President of the Republic of Uzbekistan there have been accepted and implemented state sectorial modernization programs on technical and technological upgrading of production in the industrial structure [1; 2].
The growth of requirements of the domestic market, rich natural resources and prospects for expanding the export potential create conditions for further development of the cement production. Currently, Uzbekistan disposes of a powerful cement industry, which produces about half of the cement in the Central Asian region.
Taking into account the significant advantages of the country, such as a favorable geographical location and advanced transport infrastructure expedient availability of transport units for the export of cement produced.
Among other means, railway transport is most adapted to mass transportation, operating around the clock, regardless of the time of year and weather. Railways are a universal means of transport for
the transportation of all kinds of goods at relatively low prime cost and high speed of delivery to the consumer.
Therefore, the availability of a fleet of modern freight cars, in particular the presence ofhopper cars for transportation of cement will allow to carry out the timely delivery ofthe produced goods to the consumer.
The technical specifications and design of the new hopper car for the transportation of cement
Keeping in mind above mentioned, as well as to implement the resolutions of the President of the Republic [3; 4] designers of Subsidiary "Foundry-Mechanical Plant", whose production base has been updated in accordance with [5], developed the design of the new hopper car for cement transportation.
The new four-axle covered hopper car model 19-9596 with the volume 61.6 m 3 and load capacity of 72.5 tons is designed for transportation of cement in bulk from the place of production to places of consumption or storage, having special receiving equipment in inter-rail space [6; 7].
The design of car body enables loading the cargo in mechanized way through four round loading hatch with a diameter of 620 mm. Charging hole covers securely protect the cargo from atmospheric precipitations, have simple and reliable locking mechanisms to operate.
The body has block and vertical sidewalls inclined at an angle of 50° with a thickness of sheathing 3 and 4 mm, respectively. Sheathing block walls - is made of flat sheet metal, the side - is from the curved profile with periodic corrugations.
In the lower part of the body in the inter-truck area there installed unloading hoppers. Each hopper has a discharge hatch of 500x400 mm, locking lid with labyrinth seal.
Technical specifications of the new hopper cars for transporta- Table 1. tion of cement model 19-9596 with volume of 61.6 m 3 are shown in
Table 1. - Technical specifications of the hopper car for transportation of cement
Parameter Indication Quantity
The weight (tare), t m 21,0
Cargo weight, t m 72,5
Car weight (gross), t m 93,5
The base carriage, mm 2l 7800
Car length over the end of the frame beams, mm 2L 10800
Car Length over coupler pulling faces, mm 2L 12020
Body volume (max) m3 V 61.6
Constructional speed, km/h v 120
Weight truck, t mt 5
Static deflection of the truck, mm L 48
Dimension according to GOST 9238-83 1-VM
The research of a strength of supporting elements of a hopper car for the transportation of cement
Later, the young scientists of the department "Cars and car economy" of Tashkent Institute of Railways Engineering conducted theoretical studies to assess the strength of the proposed design of hopper car for transportation of cement model 19-9596 with volume of 61.6 m 3 at axial load up to 23.5 tons [8; 9].
The strength of the body of a hopper car for transportation of cement in accordance with the requirements [10; 11] was estimated at two analysis modes:
a) the first rated conditions considered a relatively rare combination of extreme loads. The main requirement for the strength
based on this regime — is to prevent the appearance of residual deformation (damage) in the site or parts;
b) the third rated condition regime dealt with a relatively frequent possible combination of largest load characteristic of the normal operation of the car on a moving train. The main requirement for the calculation according to the regime — to prevent fatigue failure of parts or unit.
9596.00.00.000 steels elements of the body of a hopper car adopted in accordance with the design documentation project and allowed data voltage grades are presented in Table 2 [7].
Table 2. - Material and allowable stress elements of the body of a hopper car
Name of the element construction Brand of steel Allowable stress, MPa
I mode (stroke, jerk) I mode (Compression, tension) III mode
Centersill 375-10G2BD GOST 5267.0-90 375 337,5 230
The other elements of the frame 345-09G2S GOST 19281-89 345 310,5 210
The other elements of the car body 345-09G2S GOST 19281-89 345 327,75 220
In accordance with the requirements used for the steel modulus of elasticity was assumed to be 2.1-10 5 MPa, the Poisson's ratio was assumed to be 0.3.
The calculation was performed using finite element method using the technology of digital prototyping in the environment of modern engineering programs [12-13]. The volume finite-element model of the body of a hopper car was used to calculate. Body ele-
Figure 1. General view of the calculation model of the car body
ments were simulated by linear finite volume elements with three degrees of freedom at each node: three displacement. Car trucks were simulated by elements such as concentrated mass. Elements such as the mass of the car were connected with the frame by means of an absolutely rigid links. Estimated assembly model includes elements of 61121 and 234959 units. General view and the view of the finite element model ofthe body ofa hopper car are shown in Figures 1 and 2.
Figure. 2. General view of the finite element model of the car body
The restriction of the vertical and transverse movements in the frame pivot assemblies; limited longitudinal movements in the plane of the rear and front coupler horn were adopted as the kinematic
boundary conditions. Kinematic and force boundary conditions for different calculation modes are shown in Figures 3-4.
Figure 3. Kinematic and force boundary conditions for
dynamic compression forces on the car according to I and III design mode (stroke)
In accordance with the requirements [11] of the body of a hopper car for the transportation of cement was estimated on the strength ofthe first (stroke, jerk, compression and tension) and third (stroke, jerk, compression and tension) calculated regimes.
The combination of loads acting of the body of a hopper car for transportation of cement in the first and third modes of settlement was determined in accordance with the requirements.
Longitudinal force of inertia of the body and trucks of hopper car was determined by multiplying the weight ofthe body and trucks by the normalized value of the longitudinal acceleration. Acceleration was applied during the calculation of the model of the body of a hopper car.
Longitudinal force of load inertia Nu was determined by the formula
N = nm., (1)
where m , m - respectively the mass ofthe cargo and the car weight
w car r / o o
(gross), t;
N - outer longitudinal impact force, MN.
Inserting data into the formula (1) we obtained that the force of inertia of the cargo was for the first mode under the stroke N. = 2.71 MN, under the jerk N. = 1.94 MN (N. = 0.77 MN for the third mode).
Vertical force at the non-central interaction of automatic couplers P was determined by the formula
(2)
P = N-> b
where e - the difference between the levels of the axes of automatic couplers;
b - the length of the rigid rod, formed of dual-clutch automatic couplers.
Inserting data into the formula (2), we have found that the power at the non-central interaction of automatic couplers was for the first mode with the stroke of P = 175 kN, with a jerk of P = 138 kN (compressive P = 125 kN, tensile P = 110 kN), for third mode was of P = 25 kN with the impact and compression, P = 27.6 kN with the jerk and stretching).
Active (static) maximum pressure of the load thrust for per unit of the body wall area made up 3438 N/m 2 on the first rated regime, while it was 15435 N/m 2 on the third rated regime.
The pressure load on the block wall was 124059 Pa.
Transverse forces of interaction between the cars in the curves Pt were determined by the formula:
- under compression
Figure 4. Kinematic and force boundary conditions of tensile dynamic forces on the car according to I and III calculated regimes (jerk)
Pt = N - under tension
8-L l2
i+L
a
(3)
1} = , (4)
} R
where 2l, 2L, 2Lc - respectively the car database, the distance between the thrust plates of couplings and car length on the axes of automatic couplers clutch;
a - the estimated length of the coupler body;
R - curve radius, according to the requirements [11] R = 250 m;
S - the possible lateral movement of the pivot section of the car body due to gaps in rail wheelset track, in the axle guides, rods and elastic deformations of springs.
Substituting these into the formula (3) and (4), we have found out that the transverse forces between the cars in curves for the first mode when compression is equal to Pt = 200 kN, and tensions Pt = 160 kN.
The coefficient of vertical dynamics of the Cvd in accordance with the requirements [11] is determined by the formula
f^ave
c, =
vd ß
4 .in-J_
n l-P(Cvd)
(5)
where Cvd - the average probable value of the vertical dynamics of the coefficient is determined by the formula (6);
P - allocation option, according to the requirements [11]
P = 1,13;
P (CJ - confidence level, which determines the ratio ofthe vertical dynamics, according to the requirements [11] P (Cvd) = 0.97. The average probability of a value determined by the formula
" (6)
Cave = a+3,6-10-
vd
v-15
fst
where a - coefficient for the body elements, as required by [11] was assumed to be 0.05;
v - constructional speed, km/h;
6 - coefficient taking into account the effect of n axes in the truck at one end of the crew;
f - static deflection of spring suspension, m. Inserting data into the formula (5), we received Cvd = 0.35. As a result of the calculation, the equivalent stresses were obtained, resulting in the elements of the body of a hopper car on the first and third rated regimes.
Assessment of strength in accordance with the requirements [11] was performed on equivalent stresses calculated by the Mises theory. Distribution fields of maximum equivalent stress elements of the body of a hopper car considered for calculation modes are shown in Figures 5-6.
а) general view b) view from below
Figure 5. Fields of equivalent stress distribution in the hopper car elements (under dynamic compressive forces on the car according to I design mode (stroke)), MPa
a) general view b) view from below
Figure 6. Fields of equivalent stress distribution in the hopper car elements (under the compressive forces on the car dynamic according to III design mode (stroke)), MPa
Conclusion
As a result of evaluation of the strength of the car body — hopper for transportation of cement model 19-9596 established that the strength of the structural elements of the body satisfies the requirements [6-7; 11]. In this case the following values are taken:
1) When I design mode the maximum equivalent stress in the body elements are as follows:
- in the end and side walls and frame elements (impact) 308 MPa (89.3% of the allowable stress).
2) In design mode III, the maximum equivalent stress in the body elements are as follows:
- in the end and the side wall elements (impact) 195 MPa (88.6% of the allowable stress).
The new hopper car design for the transportation of cement with improved technical and economic performance will significantly reduce transport costs for the carriage of cement by rail. Operation of modern hopper cars in the future will provide economic benefits both for carrier and cement manufacturer.
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