PSI - Issue 27

Laksmana Widi Prasetya et al. / Procedia Structural Integrity 27 (2020) 132–139 Prasetya et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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1. Introduction Student Formula is a student-level competition that includes the design and manufacture of high-performance vehicles. In making these vehicles, safety is the main condition that has been regulated in detail in the FSAE (Formula Society of Automotive Engineer) Rules (SAE International (2018)). The most critical aspects during the planning of a race car are to require under consideration of its behavior just in case of a bearing (Boria, 2010; Mellor, 2002). Therefore, it is necessary to supply the car with structural devices (called impact attenuators or crash-boxes), which will absorb most of the kinetic energy and protect the motive force from serious injuries during impact. The impact attenuator has got to be designed with acceptable dimensions and to fulfill specific performances like the common deceleration and deformation during impact. Specifically, the look and assembly of the impact attenuator need to meet some requirements (SAE International, 2018). It must be a minimum of 200 mm long (along the central axis), 200 mm wide and 100 mm high. It must be installed at the bulkhead front either by welding or using a minimum of four bolts (M8, Grade 8.8). It must not penetrate the bulkhead during impact. The impact attenuator may be installed on the motorcar only after having passed a selected crash-test. During this dynamic test, the impact attenuator and the front a part of chassis are attached to a trolley. The whole weight of the system must be of 300 kg. The impact velocity against a rigid barrier must be 7 m/s. During the test, the moderate deceleration of the trolley must not exceed 20 g with peaks under 40 g. the ultimate deformation must be limited to the impact attenuator only. From the past, such a large amount of years, teams around the world had proposed many successful designs of impact attenuator using different materials and geometry. Fonteyn and Witteman (2006) suggested five different materials having different mechanical properties. Polymethacrylimide (PMI) used for IA could be a form of hard foam having excellent stress-strain properties. But features of hard foam rely on the density of the froth. It is not easy to take care of the uniform thickness throughout the fabric of the IA. Giovanni Belingardi et al. (Belingardi and Obradovic, 2010) performed the finite element simulation using Hypermesh software. The model includes two different types of materials: steel S275JR UNI EN 10025 (Fe430) and 6082T6 aluminum alloy. Results obtained by these materials are nearly identical. Still, the design of the IA is shell-like structure, and holes are punched on that as they are operating as triggers, which means have both the scope to decrease the burden of the structure itself and to get a higher crush behavior by reducing the primary peak of the collapse force. The majority of FSAE vehicles in terms of the use of attenuator impact materials, usually use material consisting of aluminum, honeycomb, Nomex, carbon composites, Kevlar, aluminum foil, or a combination of these materials (Boria et al., 2016; Boria and Forasassi, 2008; Munusamy and Barton, 2010). Based on the material research of the impact attenuator that already exists where the material has a high selling price and consideration for environmentally friendly material, the used can is chosen as the material for the impact attenuator stuffing. Therefore this research aim is to design and analyze the impact attenuator using waste cans materials, which is easy to get, affordable price, and lightweight. It is necessary to know how far the components of waste cans can absorb energy and analyze what kind of deformation occurs due to impact loads through simulation. 2. Methodology 2.1. Geometry and material The impact attenuator as a whole is composed of 3 parts. The first is waste cans, the second is a rigid plate, and the third is the anti-intrusion plate. In the arrangement at the bottom, there is an anti-intrusion plate that acts as a buffer. It holds a load of 325.4 x 305.4 mm with a thickness of 1.4 mm. Furthermore, the bottom can consists of 6 cans with a height of 113 mm, diameter 72.4 mm with a thickness of 0.5 mm. Additionally, there is a rigid plate on the top, which has a size of 250 x 250 mm and a depth of 2 mm, which serves as a buffer can on the top. The top can itself consists of 5 cans with the can located at the center and 4 other cans around it. Overall, this impact attenuator has a height of 232 mm. It has a triangular-like shape of the cans which are shrinking from the bottom to the top. The material used in this waste food cans is aluminum alloy 3004. The mechanical properties of the material are shown in Table 1 below.