Influence of Crash Box on Automotive Crashworthiness MIHAIL DANIEL IOZSA, DAN ALEXANDRU MICU, GHEORGHE FRĂȚILĂ, FLORIN- CRISTIAN ANTONACHE University POLITEHNICA of Bucharest 313 Splaiul Independentei st., 6th Sector, ROMANIA daniel_iozsa@yahoo.com; dan.micu@upb.ro; ghe_fratila@yahoo.com; antonache_florin@yahoo.com Abstract: In this paper, frontal impact behaviours of three car frontal parts with a rigid obstacle at rest is presented. The purpose is to analyze the best crashworthiness. The models have different crash boxes and are analyzed using Explicit Dynamics module of Ansys software. Shape and dimensions of the model were obtained from repeated simulations and constant improvements. Finite element mesh size for each part of the model varies, depending on its role. Velocity of the car model was computed by equalizing the kinetic energy of the modelled geometry with the kinetic energy of a considered automobile. The results present a comparison of deformations and stress, resulting an analyze of absorbed energies values during the impact. Key-Words: crash box, frontal impact, crashworthiness, Ansys, deformation, car structure 1 Introduction Crashworthiness is the ability of a structure to protect its occupants in the event of a crash. Frontal impact cars is one of the most often crash types. Automotive manufactures increasingly employ computer simulation, because physical vehicle crash-testing is highly expensive [1]. Currently, dynamic explicit integration is commonly used for the simulations like impact and collision.[2] A 2D concept model of a detailed automotive bumper model was introduced and it was discretized by using lumped mass spring elements in [3]. The time efficiency and the good approximation of results proved its utility in crash analysis, confirming that early stages of product design can make use of the simplifications and rapid decisions can be taken for early improvements. It is useful to utilize mathematical optimization by altering the geometry and the material and structural properties of the bumper- beam and crash- box to improve the low speed performance[4]. When a vehicle impacts in less than 15 km/h velocity, the insurance companies require that the damage of the vehicle should be as small as possible. Section 2 presents the steps necessary to simulate frontal impact. The first step consists in establishing a mathematical model to use in crash analyze of a car frontal part. Three models of crash boxes that belong to geometry of the impact energy management system are described in the second part presented in subsection 2.2. Initial conditions of frontal impact simulations and meshing settings are presented in the last two subsections of section 2. Variations and comparisons of stress and plastic deformations of the all three models are analyzed in section 3. 2 Simulating frontal impact 2.1 Study of mathematical models used on impact analyze of a car frontal part Simple or complex mathematic models can be used to study structure dynamics, depending on complexity of simulated phenomena, precision and/or computation rate. Figure 1 shows four of most usual mathematic models used to test bumper beams in impact computations. a. b. c. d. Fig. 1 Usual mathematical models used to test bumper beam in impact computations [5] The mathematic model with one damping element (c 1 ) and one elastic element (k 1 ) in serial communication is the most used (Fig 1.a). One damping element (c 2 ) and one elastic element (k 2 ) in Recent Advances in Civil Engineering and Mechanics ISBN: 978-960-474-403-9 49