PSI - Issue 27

Laksmana Widi Prasetya et al. / Procedia Structural Integrity 27 (2020) 125–131 Prasetya et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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2.2. Impact scenario In this study, the finite element model of impact attenuators with waste food cans is performed using ANSYS LS DYNA (ANSYS, 2019). This impact attenuator is modeled with a type of shell element consisting of waste food cans and a rigid wall, as shown in Fig. 2. For conditions in the analysis, the rigid wall was fully constrained at all degrees of freedom, except the translation in the Z direction defined as -200 mm. The anti-intrusion plate component was considered as fully fixed in all rotation and translation. For waste food cans, all are modeled with the type of quadrilateral element with a size of 5 mm. the total analysis time is 40 seconds, which is defined as quasi-static analysis. Defining material type for waste food cans is used piecewise linear plasticity and for all of the rigid parts using rigid material type. This material selection is functioned so that when the impact process occurs, the can will be deformed, and the rigid wall will push the can underneath with a compressive force that is passed on from the can at the top level. In the numerical modeling of this impact attenuator, there are two contacts used, automatic node to surface and automatic single surface. Automatic nodes to surface contact type is used for contacts between the rigid wall with cans, and between cans with rigid plates and anti-intrusion plates as support. Based on ANSYS LS-DYNA information and previous work in the crash analysis (Bae et al., 2016b), this contact is suitable for contacts involving rigid objects. Automatic single surface contact type used on cans walls. This type of contact is ideal for applications in crashworthiness. According to body interaction, the contact between the plate and the impact attenuator was defined as a frictional phenomenon in which the values of static and dynamic friction coefficients 0.4 and 0.3 are applied. In an experimental research note, there are three methods that can be done to test the impact attenuator. The first is the impact test by directly impacting the impact. The second is a drop test where the load is dropped vertically towards the impact attenuator with the height and the load set, and the last is a quasi-static test where the impact attenuator is tested by the compressive test method using UTM. As already said at the beginning that the numerical method simulation testing this time is adjusted to the quasi-static test.

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Fig. 2. Finite model of impact attenuator (a) Isometric view; and (b) Left side view.

3. Results and discussion 3.1. Global results

In this research, after conducting a process that runs with the ANSYS LS-DYNA software, the results are obtained that describe the crushing force, internal energy, kinetic energy, and total energy curve as a whole. For the first is the crushing force curve taken in Fig. 3a below. The crushing force curve is derived from the total amount received by the can. From this curve, 609 kN was obtained in 21.8 seconds. As for the average load received per can is 43.7 kN. Next to the internal energy curve, which is shown in Fig. 3b. This internal energy curve is an energy absorbed curve or curve that shows the amount of energy that can be absorbed by the can as a whole. It can be seen from the curve