外文翻譯-- 圓周摩擦的盤式制動器結(jié)構(gòu)優(yōu)化（英文）

1、International Journal of Automotive Technology, Vol. 10, No. 3, pp. 321?328 (2009) DOI 10.1007/s12239?009?0037?xCopyright © 2009 KSAE 1229?9138/2009/046?07321STRUCTURAL OPTIMIZATION OF A CIRCUMFERENTIAL FRICTION DI

2、SK BRAKE WITH CONSIDERATION OF THERMOELASTIC INSTABILITYB.-C. SONG1) and K.-H. LEE2)*1)Research Engineer, R Revised 15 December 2008)ABSTRACT?This research suggests a new disk brake design using circumferential friction

3、 on the disk of a front-wheel-drive passenger car. The paper compares mechanical performance between the conventional and suggested disk brakes under dynamic braking conditions. Thermoelastic instability is considered in

4、 simulation of the test condition. An optimization technique using a metamodel is introduced to minimize the weight of the suggested disk brake. To achieve this goal, the response defined in the optimization formulation

5、is expressed in a mathematically explicit form with respect to the design variables by using a kriging surrogate model, resulting in a simple optimization problem. Then, the simulated annealing algorithm is utilized to f

6、ind the global optimum. The design results obtained by the kriging method are compared with those obtained from ANSYS analysis.KEY WORDS : Circumferential friction disk brake, Ventilated disk brake, Structural optimizati

7、on, Thermoelastic instability, Kriging1. INTRODUCTIONRecently developed vehicle components aim for a light- weight design to achieve high fuel efficiency and vehicle performance. The fact that certain components are deve

8、lop- ed with target weights in units of grams during the proto- type design stage (Lee and Kang, 2007) underscores the importance of lightweight design. However, the current disk brake has a limit for possible weight red

9、uction. This study introduces a new approach using a circumferential friction disk brake for active weight reduction. In order to investigate the thermal characteristics, the circumferential disk brake is compared with t

10、he ventilated disk brake that is currently used in the mid-size front-wheel drive car made by the Z Company. When developing an automobile disk brake, vibration and noise are the most important elements considered among

11、 the design requirements for mechanical perfor- mance. However, most vibrations and forms of noise are generated by resonance with the car body or chassis (Hwang and Park, 2005), and it may therefore be meaningless to in

12、vestigate the related performance of the brake compo- nents as separate from the car body and chassis. In general, the first natural frequency of a four-door sedan is more than 30 Hz; thus, a design improvement in the br

13、ake component alone can eliminate or minimize the noise generated fromvibrations lower than 30 Hz. The judder is divided into cold judder and hot judder, where hot judder is known to be caused by the thermoelastic instab

14、ility (TEI) phenomenon (Choi and Lee, 2003; Chung et al., 2005). It has been reported that reducing the thermal deformation is an effec- tive way to reduce hot judder (Koji et al., 2004). When the brake is applied during

15、 high-speed driving, a large contact pressure is generated on parts of the frictional surface due to unequal contact pressure between the pad and disk, such that the heat generated on certain parts is relatively higher t

16、han in other locations. This unequal con- tact pressure causes the local temperature to rise such that it, in turn, generates additional increases in local contact*Corresponding author. e-mail: leekh@dau.ac.kr Figure 1.

17、Braking conditions for FMVSS 105-75.STRUCTURAL OPTIMIZATION OF A CIRCUMFERENTIAL FRICTION DISK BRAKE WITH CONSIDERATION 323disk for 15 cycles. The temperatures are calculated during the 15 cycles, showing that the temper

18、ature at the braking endpoint tends to be increased in accordance with the increase in the number of braking cycles. Then, the stresses generated on the disk are obtained by the constitution relation for the elastic prob

19、lem with thermal expansion. The TEI analysis for subsequent coupled analysis of thermo- elastic contact behavior is only performed for the first braking cycle considering those tendencies. 2.1.2. Thermoelastic contact an

20、alysis with consideration of TEI The analysis model should ideally be constructed to simu- late the TEI phenomenon. The coupled relation between thermal and contact behaviors is represented in Figure 3. Thermal load due

21、to a friction generated between the disk and pads can be expressed as:(2)where p is the contact or braking pressure and V is the sliding velocity at the specified time, respectively. The caliper force needed to push the

22、 pad is calculated as follows. First, the braking forces, Fbf and Fbr, are obtained considering the force equilibrium in Figure 4 (Jung et al., 2008). In this arbitrary vehicle, it is assumed that the weight distribution

23、 ratio with respect to the front and rear axles is 6 to 4, the friction coefficient µ for the tire is 0.9, the rolling radius rt of the tire is 322 mm, and the distance rp between the center of the wheel and the cen

24、ter of the pad is 104 mm. The dynamic weight distribution during de- celeration is: ,(3)(4)where Rf and Rr are the forces acting on the front and rear axles (Jung et al., 2008). Next, the maximum transferable braking fo

25、rce for one side of the front axle is represented as:(5)where µ is the friction coefficient between the load and tire. Additionally, the braking torque is:(6)where Fpf is the friction force between the disk rotor an

26、d pad. From Figure 5, it can be seen that the force required to push the pad against a disk rotor is: ,(7)where µp is the frictional coefficient between the disk rotor and pad. The force, pf, in the applied vehicle

27、is calculated as 2083 kgf, and with this value, the initial contact pressure can be substituted for Equation (2). 2.2. Finite Element Analysis for Thermoelastic Contact Behaviors 2.2.1. Analysis of commercial disk brake

28、 Thermal analysis and thermoelastic contact analysis are performed for the general type of disk brake currently used in passenger cars. In the case of thermal analysis, the heat load expressed in Equation (1) is applied

29、to the free surface, which is in contact with the pad. In contrast, when TEI is considered, the pad is included in the FE model, in which case the disk and pads are modeled with 2D axisymmetric elements. The analysis se

30、quence used to simulate the thermoelastic contact behaviors using ANSYS is as follows. First, force pf is applied normal to the surfaces of the pads. Then, the y-Q=µpVRf =0.6 GVW ×GVW a g - - - × h ×l

31、 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - +Rf =0.4 GVW ×GVW a g - - - × h ×l - - - - - - - - - - - - - - - - - - - - - - - - - - - - - –Fbf 1=µ Rf 2 - - - - ?rtFbf 1=rPFpfpf = Fpf 2&#