CC BY
31
Figure 3. Changing the energy efficiency of vehicles Nexia SOHC ва Nexia DOHC depending on driving cycles
Difficulty levels of a few driving cycles (ECE, IM240, EUDC_ LOW, EUDC, ARTERIAL) for two models of the vehicle NEXIA, were defined with the help of the method mentioned above (Fig. 3).
Hence, we can see that Nexia DOHC has high energy efficiency than Nexia SOHC in ECE driving cycle [4, 93-94]. In fact the fuel consumption of the Nexia DOHC more than Nexia SOHC but energy usage efficiency of the first is high. The energy efficiency of both vehicles is the same in EUDC LOW and ARTERIAL driving cycles. Driving cycle IM240 is most difficult and driving cycle
EUDC_LOW is easier for mentioned vehicles by energy efficiency than others.
This method allows choosing optimal type of a vehicle for urban conditions or choosing optimal driving cycle for certain vehicle by energy usage efficiency.
The conclusion is that nowadays with the help of applied complex and continuously monitoring system of transport it is possible to define and evaluate the energy efficiency of vehicles all time.
References:
1. Антипов С. И., Дементьев Ю. В. "Современные испытательные ездовые циклы и их актуальность при создании алгоритма работы системы управления автомобиля с КЭУ", Известия Волгоградского государственного технического университета, - 2013. - № 10 (113)/том 6. C. 8-11.
2. Гудцов В. Н., Современный легковой автомобиль. Экология. Экономичность. Электроника. Эргономика. - Кнорус, - 2015. -449 с.
3. Кушвид Р. П., Испытания автомобиля, - М.: Москва, - 2011. - 380 с.
4. Правила ЕЭК ООН N 83 «Единообразные предписания, касающиеся официального утверждения транспортных средств в отношении выбросов загрязняющих веществ в зависимости от топлива, необходимого для двигателей».
5. URL: http://www.oica.net/category/production-statistics/2014-statistics
6. URL: http://www.nationmaster.com
DOI: http://dx.doi.org/10.20534/ESR-16-9.10-234-236
Shermukhamedov Abdulaziz Adilkhakovich, Tashkent Automobile and Road Institute, professor, Head of Department of Reliability of Land Transport Systems
E-mail: [email protected]
Baboev Alijon Madaminovich, Tashkent Automobile and Road Institute, senior staff scientist-applicant of Department of Reliability of Land Transport Systems
Design procedure of the mode of movement of the articulated lorry transporting liquid cargo in mountain conditions
Abstract: The mathematical model and design procedure of a motion mode (regime) of the semi-trailer truck transporting liquid cargo is proposed. The model allows to define average speed of the semi-trailer truck taking into account change of motion parameters (turn radius, speed, acceleration, up- or down-hilling, influence of dynamics of a liquid cargo on tank walls).
The comparative analysis of results of calculations with experimental data shows adequacy of the offered mathematical model and the design procedure to real processes, the average deviation is in limits of 4,8%.
Keywords: semi-trailer truck lorry; a motion mode; liquid cargo; mountain conditions; external factors; operational properties.
Road transport plays an important role in the transportation of goods in different regions of the country. It is known that the main important issues in transportation of goods are the safety and efficiency of transportation. However, road routs of semi-trailer trucks are constituted of rapidly changing road and weather conditions.
In this paper, the method of selecting a safe and effective motion mode of semi-trailer truck, carrying liquid cargo in the mountainous conditions is proposed.
It is known that liquid cargo sloshing during transportation seriously alter train instant center of gravity and thus affects the critical speed of motion. For these reasons, the definition of the critical speed of semi-trailer trucks on dangerous sections of the mountain road can be considered relevant problem.
The theoretical, practical and organizational issues of road transport of goods in severe mountain conditions studied by many researchers [1,2,3,4]. However, it is not enough investigated the complex influence on the functioning of semi-trailer truck carrying liquid cargo, such factors as the turning radius, speed, acceleration and the dynamic effects ofliquid on the tank wall and the road conditions.
Quite often the process of interaction of machine with the environment, particularly in curvilinear motion, is associated with and dependent upon the speed, it would be appropriate to define also stability as a function of speed [1,5].
The motion mode is affected by the operation and usage conditions of these trucks.
Operating conditions in general are determined by road, transport and climatic conditions, each of which is characterized by certain factors: road conditions — the elements of the road profile and outline, terrain, type ofpavement and its irregularities, traffic, traffic
disturbances, road condition continuity and motion modes [4].
Change of road conditions at different altitude on the mountain roads leads to a corresponding change in motion modes and safety of the vehicle.
Each specific route is largely different and may consist of areas characterized by different road conditions on which motion modes can vary drastically [5].
The parameters that affect average speed vavg mainly include traffic volume, road speed limits, the presence on the settlements along the road, the number of intersections with other roads and the number of lanes [3; 5].
Thus, the analysis of key factors influencing the mode of motion has shown that there are the finite numbers of factors that must be considered when developing a method of selecting a mode of motion.
Let's consider the mode of motion of semi-trailer truck under the «Kamchik» passage in Uzbekistan.
It is known that the road Tashkent-Osh highway (A-373) is the only transport route connecting the Fergana valley with the main regions of Uzbekistan. Along 78 kilometers (in interval 117-195 km) the road it crosses the Kurama mountain system through Kamchik and Rezak passages. The interval of the road between 144-192 km (48 km length) is the most severe, characterized by large road meander, a significant number of turns and protracted deviations of the longitudinal profile. In this section of road a turning radius of 50-70m and protracted deviations of the longitudinal profile of 7-10% can be observed. The highest elevation of the Kamchik passage is 2196 meters above sea level.
General methodology of the study with a comprehensive structural scheme consisting of theoretical and experimental studies is shown in Figure 1.
Figure 1. General research methodology
Limit values for the velocity of the semi-trailer trucks transporting petroleum products during motion on road A-373 in the «Ka-mchik» passage in group (train) and in individual modes, depend on the average speed of traffic on this part of the road.
The average speed of the motion of the vehicles is one of the most important indicators used to determine the motor expenses and investment in road transport during the feasibility study of design decisions. Traffic speed varies along the length of the road and a time depending on the traffic and the composition of the traffic flow, traffic conditions and characteristics of the means of traffic regulation and influence of climatic factors.
The average speed of the flow ofvehicles on homogeneous part of the road, within which there is no change of any characteristics of road conditions determined by the formula [5]:
marginal strips 0.75 m, the roadside of 3.5 meters wide (accepted v0 = 80 km/h); t — coefficient depending on the proportion of passenger cars as part of the transport flow [5]; Kt — correction factor to the valueT; Nh — traffic intensity, number ofvehicles in one hour, which is determined by the formula:
Nh = 0.076 • N N - annual average daily traffic, vehicles/day.
G = td • gd + tw ■ gw + t, ■ g, + t, • g
365
(2)
(3)
v = G-e-v.-t-K ■ N.
(1)
where G - coefficient taking into account the effect of the road pavement condition to average speed; Q — coefficient taking into account the impact of the road conditions and the composition of the traffic flow at the speed of motion; v0 — the average speed of the free motion of a uniform flow consisting of passenger cars in a straight horizontal areas with carriageway width of7.5 m, a width of
where td, t^ t, t — the number of days in the year, respectively, dry, wet, snow-covered and covered with icing; gd, g^ gs, gi — speed reduction coefficients: for dry coating gd = 1.0, wet gw = 0.85, snowy gs = 0.8, icy gi = 0.45;
e = n ^; (4)
i=i
Tj, t..., t9 — coefficients depending on the proportion of passenger cars as part of the transport flow, road slope, type of marking, roadside width, horizontal curve radius, the visibility distance, number oflanes, the characteristics of the village, the road conditions before the rise with a slope of more than 30%.
Figure 2. Forces acting on semi-trailer truck ISUZU EXZ 51 K with semi-trailer "ISTANBUL-FRUEHAUF"
When defining the parameter Q using Equation (4), it must be noted that in areas with a significant road slope the influence of latter on speed is predominant over other characteristics of road conditions. Therefore, slopes greater than 45% and the uphill length of more than 200 m, with slopes greater than 55% and the uphill length of more than 200 m, and slopes greater than 64% and the uphill length of more than 100 m the values of t, tt3 t4, t5 are taken as the lowest calculated, and all other coefficients are considered equal to 1.0.
Thus, from the Equations (1)-(4) the average speed of the traffic flow can be calculated depending from external factors, such as traffic flow and traffic flow composition, especially road conditions, employed traffic control means and climatic conditions.
To describe the impact of operational properties of semi-trailer trucks on the mode of motion it is necessary to write down equilibrium equations of forces and moments [1; 6; 7; 8].
Tractor and semi-trailer is a complex dynamic system consisting of two subsystems, a tractor and a semi-trailer (Figure 2).
Using the components of forces on the coordinate axes and torques about the axes, we obtain a system of equations for a semitrailer and the tractor. As a result, the decision determined by the three forces of reaction wheels on the assumption that the reaction force of left and right wheel axles are not the same, the reaction force and the inertia force of the coupling device.
For semitrailer balance of acting forces can be written as:
£Z = 0; RK + Rr + Rn - mg cosa = 0;
Zdv
X = 0; P - mg sma-m— = 0; " dt
dv
P.k -m—— mgsina-PE = 0; ^C(-) = 0; Rl -Rl, -P (h -h )-Fh = 0;
3 2 k 1 ]k\ g c) x g '
dv
r = m
' L
cosa -| — + g sma |(hg - hc ) | ;
+ ) = f
^cosa+f 'dt + g sina ](hg - hc ) ] ;
mg cos a(l2 - hgfan )-l m— + mg sina 1 (hg - hc )
R =-
R + Rn ) = -
dt
m
L - h à,
¿r, 1
Nk +( + Rn ) • fat2 + mg sin p -R„ + Rn - mg cos p = 0;
L - h à,
( dv | dt
m&2
g cosa-1, +[ — + g sin a ](( - hc )) ;
(5)
-P* = 0;
R ■ ^ - R ■ -+(R + Rn B 2 h + N ( - h )-P • h = 0
R = [ mg cos P ■ (B - 2№c ) + 2 ^ mg sin p - - h ));
Rn = ^ ^ mg cos P-(B + 2 fa. 2hc ) - 2 ^ mg sin p- j (hg - hc ))j ; R = R . + R ,, + R R . = R ^ = R . ;
n ni n2 n3 ' ni n2 n3 '
R = R. + R ,, + R R . = R ^ = R . ;
n ni n2 ni ' ni n2 n3 '
Balance of acting forces for tractor: dv
R + R - P., - mg sma = m — ;
1 2 ,k dt
R1 + R2 + R3 - Rk - mg cosa = 0; R2 = R3; -Ra + 2R2 - Pjk (h - h) - Rkl0 - (F + F2 )h = 0;
(6)
dv.
R2 =
mg cosa • a + mg sina • h + m—h + Pjkhc + Rk (a +10 )
a + b
dv.
R =
mg cosa • b - mg sina • h - m—h - Pjkhc + Rk (b -10 )
2 (a + b )
B m &2 B
mTg — cos p + mTg sin p- hg--^—hg + Nkhc - Rk — = 0
m q2
—+ NK - mT gsin^-X R • = 0
r * i
Rr = RR1+RR 2+RR 2; RR 2 = RR 3; R = R . + R ,, + R R ^ = R
n n1 n 2 n 3 ' n 2 n 3 '
where R, Rn - the forces of reaction wheels; R - reaction force coupling, N- lateral reaction force coupling, P - longitudinal inertia force acting on the coupling; mn- gross weight of the semitrailer and u mm - gross weight of the tractor, h - height of the center of gravity, v - speed articulated lorry, r - radius turn, ft - angle cross slope of the road, ai -the distance from the center of mass of the towing vehicle to the front axle, a2 - the distance from the center of the tractor weight to the rear axle, l0 - the distance from the center of the tractor weight to coupling, h - height of the tractor's center of gravity, Bt -track tractor, g - acceleration due to gravity, g=9.8 m/s2, L - the distance from the rear wheel of the semitrailer up hitch, hg- height of the center of gravity of semitrailer, h- height hitch, l2- the distance from the rear wheel ofthe semitrailer to a semitrailer of center of gravity, - the distance from the center of gravity of semitrailer to the hitch, a - road ramp angle, B -track semitrailer, fa u - longitudinal friction coefficient, fa - cross-coupling coefficient, dv/dt - linear acceleration articulated lorry, PB -cross dynamic effects ofliquid cargo in the tank wall, Pn - longitudinal dynamic influence of liquid cargo on the tank wall.
PB and Pn values are determined by the dependencies shown in Figure 4.
Thus, using the projection of forces on the coordinate axes and torques about the axes, we obtain a system of 28 differential equations. These equations together with initial and boundary conditions are a mathematical model of the motion of the semi-trailer truck.
This mathematical model allows the calculation of the following basic parameters of vehicles:
— Reaction forces of the wheels and coupling, lateral reaction force on the coupling, longitudinal force of inertia acting on the coupling;
— The critical speed for roll over and skidding of the semitrailer as well as the tractor;
In addition to equations (5) and (6) for the calculation of the critical speed as a function of given forces, i. e., the total forces that contribute or prevent rollover, and the total force contributing or preventing the skidding, with and without dynamic effects ofliquid cargo in the tank wall, the following equations are used:
for semi-trailer
Fonp =1 mng ~C0S P + mng sin P-hg
F > 0
onp
■mf K-Nthc-RtB-Ph I/B,
(7)
F =
m S2
+ Pn-N - mngsin,8-£R • $2> F3 > 0
(8)
for tractor unit:
F„e=I mTg^cos p+mrgsin P- h- h+Nkhc- RkB I/ B'
F p > 0
onp
F =
m&2
+ N - mTgsin^-^ R • fa, F > 0
(9) (10)
The foregoing parameters are determined depending on the lead angle and the turning radius. In the calculations the following parameters are accepted: mT=8950 kg; a = 1.71 m; a2 = 1.89 m; l0 = 0.26 m; h = 0.975 m; Bt = 2.032 m; m = 30500 kg; g = 9.8 m/s2;
L = 6.30 m; hg = 1.97 m; hc = 1.4 m; l2 = 2.65 m; l1 = 3.65 m; fi = 0.03 rad; B = 22.095 m; f. = 0.35; f2= 0.^; dv/dt = 1 m/s2.
The above mentioned mathematical model is implemented in a numerical simulator using MatLab/Simulink environment developed by the authors.
The calculated numerical values of reaction forces at each wheel of the truck will determine the parameters of steady motion of a truck in mountain conditions.
Dynamic effects of liquid cargo on the tank wall are defined by means of the Navies — Stokes equations using a software package Solid Works + Cosmos.
Figure 3 shows a simulation result of the speed for liquid flowing in the tank.
Figure 3. Solid Works + Cosmos simulation result for the flow of the liquid in the tank
Figure 4 and 5 shows the dependence of change of fluid pressure on the tank wall of the acceleration and the speed of the semi-
trailer truck in rectilinear and curvilinear motion path.
Figure 4. Fluid pressure force on the tank wall as a function of the truck acceleration and speed: 1 — Numerically calculated value; 2 — Polynomial approximation
Having examined the complex influence of parameters such as the slop angle of uphill, turning radius, acceleration (deceleration) of the cargo on the proposed model, we can determine the truck critical speed under all road conditions.
Figure 5 shows the variation of the total force, contributing or preventing roll over and skidding. Based on these values we can determine the critical speed of the semi-trailer truck at which the motion starts to be unstable (point of intersection of the curves skidding and roll over the abscissa passing through the «0» of the ordinate axis).
x ID
-2
E *
o *
Hh
-10
-12
—*— drift a] • tilting '
i
i
x 10
-2
o -3 Ph
..........i.......... .......... ..........T.........1..........r........ —*— drift .. ________ • tilting .
*
10
15 20
Velocity, [m/s]
25
30
35
10
15 20
Velocity, [m/s]
30
35
Figure 5. Dependence of the forces contributing and preventing skidding and roll-over of the speed of the tractor train in the 145th km part of the road A-373 (turning radius R = 80 m, longitudinal slope of 7%) a) - taking into account the effects of liquid cargo, b) - excluding the effects of liquid cargo
Analysis of the graphs shows that the critical speed of truck carrying petroleum products, when the dynamic effects of the fluid in the tank wall is taken into account is smaller than the one when this impact is excluded (for the rectilinear motion by 8-10%, for curvilinear motion 10-14%).
Figure 6 shows the curves reflecting the following relationship:
— Average speed of truck in steady motion in terms of condi-
tions as skidding, roll over and dynamic effects of the fluid obtained from equations (5) — (10) (curve 1).
— The average speed of vehicles at maximum traffic intensity (14,000 units, curve 2);
— The average speed of vehicles at minimum traffic intensity (8000 units, curve 3).
at
75
7D
ffi
a>
E ffi
a)
Tf
£ «
a. «
Lft
u 35
en 3D
s a
< 3D
15
1D
5
D
st
— -n / y ? 1
in-" T-
JLi-- I F -ft—h ^rfW ■■ ■ ,U A
%
PA Np^rfv-
IW |-1-
—r ■ i i]
1D
3D
30
91
S) 7D 9)
Route, km
so
1ID tID 131 13D 1« 19)
Figure 6. The dependence of the average speed
Analysis of dependencies shows that the average speed values, at a steady motion of the truck and at maximum traffic intensity, are close one to other and the smaller of them can be chosen. With a decrease of traffic intensity an average speed of steady motion becomes the main criterion for determining the motion of trucks. This confirms the importance of taking into account the conditions of stability in skidding and roll over, as well as the dynamic effects of the fluid that is determined using the mathematical model.
Within the research program method of experiments was developed. The adopted object of investigation is the tractor-trailer ISU-
of trains on the route Angren — Pap (wet coating)
ZU EXZ5IK ISTANBUL -FRUEHAUF, transporting petroleum products in the mountains. Tests were carried out on the road A -373 on site of Kamchik passage under various road conditions (the road is covered with asphalt).
To determine the speed of the semi-trailer truck the satellite navigator «Navibe GPS receiver» with 20 channels is used. It receives the signal from 10 satellites of the Earth every 0.2 seconds and records the change of parameters. The results of the acquisition is shown in Figure 7.
60 55 50 45 40 35 30 25 20 15 10 5 0
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 The average speed on different road sections, km
Figure 7. The average speed on different road sections (from the Angren to Pap terminals on the dry road surface)
m
k
d,
e
e p
s
e g
a r e
£
Comparative analysis of the results obtained from mathematical models and experimental data showed that the average deviation is within 4.8%.
Thus, according to the results of the research the following conclusion can be drawn: the proposed method allows determining trucks average speed, adjusting the parameters of motion (turn radius, speed, acceleration, up- and down-hilling, the dynamic effect of the fluid on the wall of the tank).
References:
1. Litvinov A. S. The theory of operational properties: The Textbook for High Schools on a speciality «Cars and an automobile economy». - Moskow: Mechanical Engineering, - 1989. - 240 p. (in Russian).
2. Babkov V. F. Road conditions and modes of movement of cars. - Moscow: Transport, - 1971. - 185 p. (in Russian).
3. Babkov V. F., Andreev O. V. Designing ofhighways. In 2 part. - Moskow: Transport, - 1987. - 368 p. (in Russian).
4. Siljanov V. V. The theory of transport streams in designing of roads and the movement organisation. - Moscow: Transport, - 1977. -303 p. (in Russian).
5. Mohammad Biglarbegian and Jean W. Zu, - 2006, Tractor-semitrailer model for vehicles carrying liquids. Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, Ontario, Canada M5S 3G8.
6. Magomedov M. M. Mountain roads. Features of designing, building and operation on an example of Dagestan. - M: The Technopolygraph center, - 2006. - 247 p. (in Russian).
7. Antonov D. A. Calculation of stability of movement is a lot of axle cars. - Moskow: Mechanical Engineering, - 1984. - 240 p. (in Russian)
8. Farobin J. E. The theory of movement of a specialised rolling stock/Farobin J. E., Ovcharov V. A., Kravtsova V. A. - Voronezh: VSU, -1981. - 160 p. (in Russian).
