Thin-Walled Structures 180 (2022) 109937 Contents lists available at ScienceDirect Thin-Walled Structures journal homepage: www.elsevier.com/locate/tws Full length article Crashworthiness design and impact tests of aluminum foam-filled crash boxes Gaofei Wang, Yongliang Zhang ∗ , Zhijun Zheng ∗ , Haibo Chen, Jilin Yu CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, University of Science and Technology of China, Hefei, Anhui 230026, P.R. China ARTICLE INFO Keywords: Foam-filled crash box Crashworthiness Finite element analysis Impact test Trigger design ABSTRACT The optimization of foam-filled crash boxes is desired to enhance the energy-absorbing capacity of frontal crash management systems and improve vehicle crash safety. A novel foam-filled crash box with partial filling and combined trigger design is proposed based on a double tubular structure. Compression and impact simulations were performed to analyze the energy absorption capacity, initial peak force, deformation modes, and protection capability of the original and improved crash boxes. It is shown that the partial filling design can reduce 67% of the foam used and increase the specific energy absorption compared with the full-filling design. The triggers and the crash-box length together determine the stability of the subsequent deformation after initial buckling. An improved optimization design strategy for the foam-filled crash box is proposed by considering the material utilization and the deformation stability of the frontal system. The design strategy is validated by compression and trolley impact tests. Therefore, the optimization design method of the crash box, considering the joint action of key indicators, is appropriate and convenient for the crashworthiness design of crash boxes. 1. Introduction Improving the crashworthiness of vehicles is of great significance to prevent fatal injuries to occupants in the event of collision [1]. An automotive frontal crash energy management system of the popular design consists of a bumper and two crash boxes connected at the two ends of the front bumper [2]. The crash box is classified as the main crash energy-absorbing member in the frontal system [3] and is expected to be capable of absorbing kinetic energy during frontal impact, maintaining vehicle deceleration within a safe limit [4]. Therefore, the design of crash boxes deserves much attention to min- imize the possibility of serious damage to the vehicle in a frontal collision. Thin-walled tubes are often used as energy-absorbing elements in crash boxes, as they can absorb significant impact energy through plastic deformation [5] and maintain a relatively stable load through progressive folding [6] under axial compression. Many studies have focused on the optimization of the material properties [7], cross- section configuration (e.g., square, circular [8], or polygonal [9,10]), and wall thickness [11] of thin-walled column. Moreover, several en- hancement strategies have been applied to the thin-walled tubes to increase their crashworthiness by foam-filling [12], multi-cell [13,14], or nesting [15]. Aluminum foam is a cellular material with excellent compressive energy-absorption characteristics and light weight [16], and has extensively been used as fillers in thin-walled structures for crashworthiness and protection applications [17]. Foam-filled tubes can ∗ Corresponding authors. E-mail addresses: [email protected] (Y.L. Zhang), [email protected] (Z.J. Zheng). significantly increase energy absorption due to the interaction between the foam filler and wall column [18]. Moreover, a foam-filled double tubular design could improve the specific energy absorption [19]. However, the high costs of the aluminum foam-filling design keep it away from manufacturers. Thus, a design strategy based on partial filling is necessary to reduce material costs. The control of the initial peak force is of great significance to improve the crashworthiness of a crash box. A high initial peak force of a crash box may threaten vehicle safety. Introducing imperfections, also called triggers or inductions, to thin-walled columns is the major approach to reducing the initial peak force of axial compression [20]. Some types of trigger designs, including pre-buckle [21], dents [22, 23], cutouts [24–26], and grooves [27,28], have been developed and examined. The effectiveness of reducing the initial peak force of a foam- filled tube by triggers has also been studied and validated [29,30]. Thus, introducing an inductive strategy to a crash box is of great importance. Axial compression and impact tests of crash boxes are the main methods used in many previous design studies. Compression tests with different loading conditions have been carried out, such as quasi- static tests [31,32], constant-velocity loading [33], and drop weight tests [34]. Trolley impact tests were applied in some work [35]. How- ever, most studies are only concerned with the compression behavior of a crash box rather than its effect on the response of the frontal system. There is less consideration of joint action with other components within the frontal system in the previous crash box design. https://doi.org/10.1016/j.tws.2022.109937 Received 19 April 2022; Received in revised form 28 July 2022; Accepted 28 July 2022 Available online xxxx 0263-8231/© 2022 Elsevier Ltd. All rights reserved.
Crashworthiness design and impact tests of aluminum foam-filled crash boxes
Jun 16, 2023
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