crashworthiness design for functionally graded foam-filled bumper beam.docx
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1、Advances in Engineering Software 85 (2015) 8195 Contents lists available at ScienceDirect Advances in Engineering Software journal h omepage: cate/advengs oft Crashworthiness design for functionally graded foam-lled bumper beam Zhi Xiao a, Jianguang Fang b,c, Guangyong Sun a,c, Qing Li c a State Ke
2、y Laboratory of Advanced Design and Manufacture for Vehicle Body, Hunan University, Changsha 410082, China b School of Automotive Studies, Tongji University, Shanghai 201804, China c School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, NSW 2006, Australia a
3、r t i c l e i n f o Article history: Received 17 November 2014 Received in revised form 5 February 2015 Accepted 1 March 2015 Available online 27 March 2015 Keywords: Bumper beam Functionally graded foam (FGF) Crashworthiness Energy absorption Multiobjective optimization Kriging model a b s t r a c
4、t Automotive bumper beam is an important component to protect passenger and vehicle from injury and damage induced by severe collapse. Recent studies showed that foam-lled structures have signicant advantages in light weight and high energy absorption. In this paper, a novel bumper beam lled with fu
5、nctionally graded foam (FGF) is considered here to explore its crashworthiness. To validate the FGF bumper beam model, the experiments at both component and full vehicle levels are conducted. Parametric study shows that gradient exponential parameter m that controls the variation of foam den- sity h
6、as signicant effect on bumper beams crashworthiness; and the crashworthiness of FGF-lled bum- per beam is found much better than that of uniform foam (UF) lled and hollow bumper beam. The multiobjective optimization of FGF-lled bumper beam is also performed by considering specic energy absorption (S
7、EA) and peak impact force as the design objectives, and the wall thickness t, foam densities qf1 and qf2 (foam densities at the end and at mid cross section, respectively) and gradient exponential parameter m as design variables. The Kriging surrogate modeling technique and multiobjective particle s
8、warm optimization (MOPSO) algorithm were implemented to optimize the FGF-lled bumper beam. The optimized FGF-lled bumper beam is of great advantages and it can avoid the harmful local bending behavior and absorb more energy than UF lled and hollow bumper beam. Finally, the optimized FGF- lled bumper
9、 beam is installed to a passenger car model, and the results demonstrate that the FGF-lled bumper beam ensures the crashworthiness performance of the passenger car while reduces weight about 14.4% compared with baseline bumper beam. 2015 Elsevier Ltd. All rights reserved. 1. Introduction Vehicle cra
10、shworthiness and lightweight design have attracted more and more attention by automobile manufactures and researchers 1,2. Automotive bumper beam is the rst component to undergo crashing deformation and a key part to ensure the crashworthiness performance of passenger cars. One of the main functions
11、 of the bumper beam is to transfer the impact load and energy to left and right side crash boxes and longitudinal rails as uniformly as possible, thereby decreasing the deformation on side during vehicle frontal impact especially frontal offset impact. Therefore, its design signies a critical issue
12、for entire vehicle. Traditionally, bumper beam is a hollow thin-wall structure made of steel sheet or aluminum extrusion. During the impact, Corresponding author at: State Key Laboratory of Advanced Design and Manufacture for Vehicle Body, Hunan University, Changsha 410082, China. Tel.: +86 731 8881
13、 1445; fax: +86 731 8882 2051. E-mail address: (G. Sun). the hollow bumper beam undergoes a bending collapse mode, which is typically localized in a small area and the other parts of the bumper beam experiences almost a rigid body rotation. In this regard, some studies on the bending behavior of th
14、in walled beams were reported. A comprehensive investigation into the bending performance of square and rectangular prismatic beams was conducted by Kecman 3. Wierzbicki et al. 4 derived the mathematical equations to predict the bending resis- tances of thin-walled box sectional beams. Liu and Day 5
15、 also investigated the bending characteristics of thin-walled channel section beams. Due to the localized bending deformation, the resistance force drops drastically after bending collapse and the energy absorbing ability is fairly low 6. The presence of foam material in thin- walled structures seem
16、s to be a proper solution to enhance struc- tural rigidity and reduce localized bending deformation for better energy absorption 7,8. In this respect, ultra-light cellular metals such as aluminum foams have been considered an ideal ller mate- rial in the thin-walled structures on account of their lo
17、w density, http:/dx.doi.org/10.1016/j.advengsoft.2015.03.005 0965-9978/ 2015 Elsevier Ltd. All rights reserved. 82 Z. Xiao et al. / Advances in Engineering Software 85 (2015) 8195 p high stiffness, good impact resistance, high energy absorption capacity, and easy to manufacture 9,10. Wierzbicki and
18、his coworkers 11,12 explored the effect of ultralight metal foam on the bending collapse behavior of thin-walled columns and drew a conclusion that lling aluminum honeycomb or foam core is preferable to enhance the energy-absorbing efciency. Zarei and Krger 13 performed bending crash tests and simul
19、ation for empty and foam-lled square beams, and they investigated the strengthening effect of foam and implemented the optimization technique to search for an optimum foam-lled beam. Guo and Yu 6 studied the dynamic bending responses of foam-lled bitu- 2. Finite element model and experimental valida
20、tion 2.1. Crashworthiness criteria 2.1.1. Crashworthiness criteria for bumper beam To evaluate the crashworthiness of bumper beam structure, such quantitative criteria as energy absorption (EA), specic energy absorption (SEA), peak crashing force (Fmax) and crash force efciency (CFE) are commonly us
21、ed. The energy absorption can be formulated as: Z d bal structures experimentally and numerically and they found that foam-lled bitubal structure has a more stable load bearing EAd 0 Fxdx 1 capacity and much higher energy absorption efciency in compar- ison with the traditional foam-lled single tube
22、. Duarte et al. 14 studied dynamic and quasi-static 3-point bending responses of foam-lled tubal structures experimentally and concluded that foam ller changes the transverse crashing mode and allows generating a higher load carrying capacity and much higher energy absorption efciency comparing with
23、 the empty counterpart. However, the practical application of foam-ller to bumper beam structure for a passenger car has not been reported yet in literature to date. These abovementioned foam materials contain approximately where d is the crash displacement and F(x) is the impact force. The specic e
24、nergy absorbed SEA is dened as energy absorbed per unit mass of structure material and is a key criterion to evaluate energy absorption capabilities of different materials and structures 21. SEA d EAd 2 mass The average force curve (Favg) for a given deformation can be calculated as: EAd uniform mic
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