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1、Available online at Procedia Engineering 10 (2011) 2375-2380 ICM11 Structural Behaviors of a GFRP Composite Bogie Frame for Urban Subway Trains under Critical Load Conditions Jung Seok Kima*, Hyuk Jin Yoona aRailway Structure Department, Korea Railroad Research Institute, Korea Abstract In order to
2、replace a conventional steel bogie to a composite one, in this study, a GFRP composite bogie frame has been designed and manufactured to be applied to the bogie of urban subway trains. To evaluate the structural behavior, the composite bogie frame was manufactured using the autoclave curing method a
3、nd tested under the critical load conditions; vertical loads and twisting load. Through the test, the stresses at the connection region between a cross beam and a side beam and deflection were measured and used to assess the structural safety. Moreover, the stress and strain distribution for the who
4、le bogie frame was evaluated through finite element analysis and compared with the experimental results. 2011 Published by Elsevier Ltd. Selection and peer-review under responsibility of ICM11 Keywords: Composites; bogie frame; subway; Goodman; GFRP 1. Introduction The bogie of a railway vehicle sus
5、tains the weight of the car body, controls the wheel sets on straight and curved track, and absorbs the vibrations 1. The weight of the bogie makes up approximately 37% of the total vehicle weight. Therefore, reducing the weight of the components making up the bogie system is essential for lightweig
6、ht railway vehicle design. In particular, a bogie frame, which accounts for approximately 20% of the bogie weight, is intended to support heavy static and dynamic loads, such as the vertical load by the body of the vehicle, braking and accelerating load, twisting load induced by track twisting, and
7、traction load. This is why it is common to produce bogie frames with solid steel (especially a freight bogie) or welded structures. Such bogie frames are rigid and heavy, weighing from 1 to 2 tons. They have to be equipped with suspension and damping systems to safeguard the comfort of passengers an
8、d to absorb vibrations due to the unevenness of the railway track on which the vehicles run. Usually, the bogie of urban subway trains is subjected to much more load variation than passenger trains due to passenger weight difference between the full weight condition during rush hour and the tare wei
9、ght condition. The passenger weight difference of the urban subway train is in the range of 25tones to 30tones while in case of the * Corresponding author. Tel.:+82-31-460-5663; fax:+82-31-460-5289. E-mail address: jskimkrri.re.kr. 1877-7058 ?2011 Published by Elsevier Ltd. Selection and peer-review
10、 under responsibility of ICM11 doi:10.1016/j.proeng.2011.04.391 2376Jung Seok Kim and Hyuk Jin Yoon / Procedia Engineering 10 (2011) 2375-2380passenger train, it ranges from 6tones to 10tones. Therefore, the bogie frame of the urban subway train has to sustain a severe load condition although its sp
11、eed ranging from 80 km/h to 100 km/h is lower than the passenger train. In order to evaluate the structural behavior of a composite bogie frame, in this study, it was tested under the critical load conditions; vertical loads and twisting load. From the test, the stresses at the stress concentration
12、areas such as the connection region between the side beams and the cross beams were measured. Moreover, the stress distribution for the whole bogie frame was evaluated through the finite element analysis. 1.1. Composite bogie frame The conventional bogie frame of a urban subway train is manufactured
13、 as a welded steel box format (like a hollow tube) to reduce the weight (Fig. 1(a). The SM490A steel is usually used as the base material of the bogie frame. In case of the composite bogie frame, its external shape is similar to the conventional one as in Fig. 1(b). It also has two side beams and tw
14、o cross beams. It is 2970 mm long and 2170 mm wide. In order to meet the structural requirements, the inside of the side beams of the proposed composite bogie frame was filled with the following structural parts; composite chords, ribs, and foam cores. The glass/epoxy prepregs were stacked up on the
15、 inner structural part to form the skin, as seen in Fig. 1(b). Cross beam Cross beamSide beamSide beam(a)(b)Fig. 1 The conventional steel bogie frame and the composite bogie frame for the urban subway train. 1.2. Manufacturing process In order to manufacture the composite bogie frame, first, the pla
16、tes for ribs were manufactured using the resin infusion process. For this process, eleven quad axial glass fiber perform (QGFP, Owens corning, USA) sheets with a thickness of 0.91mm were laid up. The QGFP sheet was composed of four layers of 0o, 90o, 45o and -45o unidirectional glass fiber. After th
17、e completion of the layup, the resin was infused into the stacked QGFP sheets by vacuum. After completion of the resin infusion, the plate was cured in an oven for 2 hours at 80oC, and finally, the plate for ribs was completed. The cured plate was cut using a diamond cutting machine and bonded with
18、the foam cores (Airexfoam, Alcan Composites), which were already trimmed, using FM73 adhesive film (Cytec, USA). The bonded parts were vacuum-packed and then cured in the oven for one and half hours at 80oC. In order to make the composite chords, 4-harness satin fabric glass/epoxy prepregs (GEP224,
19、SK Chem., Korea) were laid up between the ribs and the foam cores to the required thickness. The composite chord increases the bending stiffness and sustains the compressive force imposed on the width direction. After the completion of the layup, the part was vacuum-packed and then cured in the oven
20、. After the manufacturing of the inner structural part, the two cross beams and the two side beams were assembled by adhesively bonded method using fixing jig. Then, the GEP224 prepregs were laid up on the surface of the assembled structure to form the skin. The totally stacked composite frame was v
21、acuum bagged and cured in the autoclave. The final product weighed 145kg. 1.3. Material property evaluation The static and fatigue material properties of the 4-harness satin fabric glass/epoxy were evaluated according to ASTM and ISO standards 2-6. In case of the static mechanical properties, both o
22、f the in-plane and out-of plane properties were measured because the skin and the composite rib parts were composed of thick composites. Fig. 2 (a) and (b) show the pictures of the out-of plane tensile modulus and the interlaminar shear strength measuring test. Jung Seok Kim and Hyuk Jin Yoon / Proc
23、edia Engineering 10 (2011) 2375-23802377In order to evaluate the fatigue limit of the 4-harness glass/epoxy composite, the fatigue test using specimen was conducted under the sinusoidal cyclic loading, R= -1 as shown in Fig. 2 (c) and the loading frequency of 5 Hz was selected to ignore temperature
24、rise in the test specimen during the fatigue test 7. Table 1 lists the material properties of the GEP224 glass/epoxy. The properties of the quadaxial glass fiber perform and the Airex?foam were referred from the data sheets supplied by the manufacturers. (a)(b)(c)Fig. 2 Pictures of the material prop
25、erty evaluation test: (a) through thickness modulus, (b) interlaminar shear strength, (c) fatigue limit.Table 1. Material properties of the GEP224.Static propertiesValuesLongitudinal modulus, E1134.4 GPaTransverse modulus, E2213.2 GPaThrough thickness modulus, E336.73GPaShear modulus, G126.1 GPaFati
26、gue propertiesValuesFatigue limit (warp direction)141.4MPaFatigue limit (fill direction)21.4MPaFatigue limit (warp/fill laminate)89.2MPa-2. Static test and durability evaluation 2.1. Static test results In this study, four load cases (vertical, dynamic, +twisting and -twisting) were considered. The
27、vertical load is induced by the carbody weight. The dynamic load, which takes into account the dynamic effect acting on the carbody, is corresponding to 1.3 times of the vertical weight. The force induced by the track twist is corresponding to a track twist of 5 at the level of the wheels. The +twis
28、ting and -twisting means the opposite track twist situation on the real track. Table 2 presents the load cases and values applied to the bogie frame. Fig. 3 shows an experimental setup for the static test. Two hydraulic actuators were used for the test. For the vertical loads, two actuators of 50-to
29、n capacity (MTS, USA) were installed on the centers of the each side beam. For the twisting load application, two steel liners with 16mm thickness were inserted on the two dummy axles placed diagonal positions. For the placement of the bogie frame on the test facility, four dummy axle boxes were man
30、ufactured and connected with the side beams of the composite bogie frame. The dummy axle boxes are able to rotate with respect to axis paralleled with axel and allow displacement in longitudinal direction. The loads were applied through two steps. And, in each step, the applied loads were increased
31、in sequence of 0% 75% 100%. The actuators and test facilities were stabilized in the first step and thus the test data were measured in the second step. The center deflection of the side beams were measured using two LVDTs (Tokyo Sokki, Japan), which was located in the bottom of the side beam. A tot
32、al of 25 gauges (TML, Japan) were used. 13 single gauges, 2 biaxial gauges and 10 rosette gauges were used. Fig. 4 illustrates the rosette and uni-axial gauges bonded on the joint region and the side beam bottom surface. All of the rosette gauges were placed around the joint region and the uni-axial
33、 gauges were bonded on the top and bottom surfaces of the side beam. 2378Load caseVertical loadTwisting loadJung Seok Kim and Hyuk Jin Yoon / Procedia Engineering 10 (2011) 2375-2380Table 2. Load data imposed on the composite bogie frame.Stress symbolLoad value (kN)RemarkA140Static (1.0g)B182Dynamic
34、 (1.3g)+twisting condition,C132C2321, 3 position (in Fig. (b)-twisting condition, 2, 4 position (in Fig. (b) Rosette gauge(joint region)Cross beamSide beamz yxR7R8R3R4Uniaxial gauge(side beam bottom)R9 Fig. 3 Static test setup of the composite bogie frame. Fig. 4 Strain gauges bonded on joint region
35、 and the side beam bottom. Fig. 5 plots the longitudinal strains measured from the rosette gauges under the +twisting load. Under the loading condition, the R8 gauge bonded the inner joint region showed the maximum value. The value was 6 times to 16 times higher than other strain gauge values. The R
36、5 and R6 gauges with negative strain were located on the top surface of the joint region. Fig. 8(a) presents the Goodman diagram of the composite bogie frame under the four load cases. In the Fig. 8, there are three endurance limits: warp direction, fill direction and warp/fill laminate. The fatigue
37、 test for the warp/fill laminate was carried out because the skin of the composite bogie frame has the layup of warp/fill30T. The mean stress and the stress amplitude of the diagram were calculated using Eq. (1) based on the standard for performance test of the urban subway train 8. In Eq. (1), the
38、A, B, C1, and C2 are the stress values measured under the vertical, dynamic, +twisting and -twisting load cases, respectively. The stress data obtained from the strain gauges in the static test were processed based on their material directions and plotted on the Goodman diagram.( C 1A )( C2A )22( C
39、1A )( C2A )2meanA25040302010-1000-5000 050010001500Longitudinal strain (), amp( BA )R1R2R3R4R5R6R7R8R92000250030002Twisting loadUxUyUz0UR xURy0Twisting loadVertical loadUyUz0UR xUR y0Vertical loadz y Twisting loadxU xUyUz0UR xUR y0(1)Twisting loadUyUz0UR xUR y0 Fig. 5 Longitudinal strains-twisting l
40、oad.Fig. 6 Boundary and loading conditions for the FE analysis.Jung Seok Kim and Hyuk Jin Yoon / Procedia Engineering 10 (2011) 2375-23802379As known from the Fig. 8(a), all stress values except the R8 gauge were within the endurance limit for fill direction. Although the stress value of the joint r
41、egion were outside of the endurance limit for fill direction, they were still in the safe region because the stress value of the R8 gauge marked the outside of the endurance limit for fill direction is the stress corresponding to the warp direction. 2.2. Finite element analysis results For the finit
42、e element analysis of the composite bogie frame, the composite core and rib was modeled with C3D8R solid elements and the foam core was modeled using C3D8I solid elements. The skin part was modeled using layered shell elements. The layup structure definition, such as fiber orientation, ply thickness
43、, local coordinate definition, and number of integration points through the ply thickness, of the three composite parts, except the foam core, was completed using the composite layup module supplied by ABAQUS. The layered shell elements of the skin part were connected with the inner parts meshed by
44、the solid elements using tie constraints. Fig. 5 shows the finite element model of the composite bogie frame, the loading positions and the boundary conditions. Fig. 7 represents the longitudinal stress (11) contours under the vertical load of 140kN and +twisting loading condition. Under the vertica
45、l load, the maximum value of the longitudinal stress occurred the bottom region of the side beam and the joint region (blue dashed circle in Fig. 7(a). In case of the twisting load, the maximum tensile stress occurred the bottom part of the joint region (blue dashed circle in Fig. 7(b). (a)(b)Fig. 7
46、 Longitudinal stress contours: (a) vertical loading condition, (b) +twisting loading condition.1601401201008060405JDXJH200-600-400-2000 200Mean stress (MPa)(a)Endurance limit for warp directionEndurance limit for fill directionEndurance limit for warp/fill laminateInner joint region (warp direction)Joint bottom surface (warp direction)Joint top surface (warp direction)Side beam bottom (warp direction)Inner joint region (fill direction)Joint bottom surface (fill direction)Joint top surface (fill direction)400600800-600-400-200
