Papers by Keyword: Crashworthiness

Abstract: This study examines electric vehicle (EV) crashworthiness with a focus on side impact scenarios affecting high-voltage (around 400V) battery packs. Using a 2001 Ford Taurus model, the research compares the performance of side door beams constructed from HSLA steel, boron steel, and Dual-Phase (DP-590) steel in crash simulations. The results indicate that boron steel significantly enhances impact resistance, minimizing battery pack damage and improving occupant safety over HSLA and DP-590 steel. The findings recommend boron steel for critical areas in EV design, with DP-590 steel emerging as an alternative option that still maintains safety standards. Future research is suggested to confirm these results through empirical testing and to investigate advanced materials for further safety improvements in EVs.

Abstract: In automotive applications, replacing heavy and expensive materials with light and cheap natural fiber leads to noise reduction, strength enhancement and fuel management. Enhancing the absorption of energy, controlling the failure style of composite thin shell tube and utilizing it instead of thin-walled steel columns in vehicle structural parts can provide more protection for occupants during collisions. This research investigates the possibility of gradually replacing metallic materials with natural and hybrid fibers in industries. The hand layup technique is utilized to study the performance of fiber reinforced epoxy composite tubes under static crushing to examine the jute fiber effect with different fibers types on the failure mechanism. The research studies the effect of using different fibers types on stress and strain after determining the tubes load-displacement curves. Total of 48 specimens are fabricated at room temperature and tested with a constant speed 1.5 mm/sec using one resin (epoxy) type and three fibers types (Glass, Kevlar, Jute). Two circular and square geometries with three heights (200 mm,250 mm,300 mm) including two circular diameters and two square side lengths are used to investigate the crashworthiness parameters. The Kevlar and glass fiber tubes showed low and unstable behavior. Replacing two layers of Kevlar or Glass fiber by two layers of natural jute fiber enhanced the crash worthiness parameters particularly, failure type. The hybrid jute with Kevlar accomplished desirable and best results followed by hybrid jute with glass.

Abstract: Hot stamping, also known as press hardening in the context of sheet steel, has steadily gained relevance in the automotive industry, starting off as a specialist application and turning into a staple technique in the production of safety cage products in little more than a decade. However, despite the weight reduction offered by martensitic steels, further improvement could be obtained by substituting these components by high-performance aluminium. In this regard, the very same process of hot stamping could be employed to attain the required combination of shape complexity and mechanical properties at a reasonable cost for mass-market application, if the limitations imposed by cycle time and process window could be overcome. In this work, the feasibility of hot stamping of 6000-series aluminium alloy sheet is studied, first in dilatometry experiments and later in semi-industrial conditions in a pilot facility. A cycle time shortening strategy is employed, and compared to the conventional thermal cycle in terms of implementation and obtained results. In addition to basic characterization, aluminium thus processed is studied in terms of fracture toughness, in order to obtain data relevant to crashworthiness that can be readily compared with alternative materials.

Abstract: In the context of automotive crash simulation, rate-dependent properties are sought for all materials undergoing deformation. Measuring rate-dependent properties of adhesively bonded joints is a challenging and associated with additional cost. This article assesses the need for having rate-dependent properties of adhesively bonded joints for the example of a typical automotive structure, an adhesively bonded metallic T-joint. Using Finite Element simulation it could be shown that good agreement between experiment and simulation was only achieved if rate-dependent properties were considered for the adhesive.

Abstract: The motivation for this research is the desire to design a cross-section of frontal crash absorbing member that deforms in a regular controlled manner, but also the desire for cost-to-weight effectiveness. Nowadays, Friction Stir Welding (FSW) is a popular process for welding of difficult to weld aluminium alloys due to its advantages of solidification related defect free microstructure, low residual stress and comparable mechanical properties with the base metal. In order to better understand the crashworthiness of aluminium alloy joints produced by FSW, this investigation was carried out to fabricate a frontal member top hat section with base member welded by three different friction stir welding process variants. The crashworthiness was investigated by subjecting the fabricated joints to quasi static loading and the results are reported. The experimental results are compared with the results of numerical simulation.

Abstract: Filling the thin-walled tubes with a foam core is a typical method to enhance the energy absorption performance and stabilize their crushing responses under impact loading. Recently, auxetic foam material with negative Poisson’s ratio has gained remarkable popularity as an effective candidate to enhance the energy absorption capability of structures. In this paper, polyurethane auxetic foam is suggested as a foam core with the negative Poisson’s ratio of-0.31. Numerical simulation was performed to quantify the crush characteristics of auxetic foam-filled square aluminum tubes for variations in initial width of tube under quasi-static axial loading using the nonlinear finite element (FE) code LS-Dyna. Based on the numerical results, the influence of tube width was quantified in terms of energy absorption (EA), specific energy absorption (SEA), initial peak force (P_max) and crush force efficiency (CFE). It is found that the progressive collapse and deformation modes of auxetic foam-filled tube (AFFT) is pronouncedly affected by varying the tube width. Furthermore, the SEA of AFFT is remarkably sensitive to the tube width variations, yet show low sensitivity to the EA of AFFT. The present study provides new design information on the crush response and energy absorption performance of auxetic foam-filled square tube with varying tube width.

Abstract: In the case of catastrophic events, such as an emergency landing, the fuselage structure is demanded to absorb most of the impact energy preserving, at the same time, a survivable space for the passengers. Moreover, the increasing trend of using composites in the aerospace field is pushing the investigation on the passive safety capabilities of such structures in order to get compliance with regulations and crashworthiness requirements. This paper deals with the development of a numerical model, based on the explicit finite element (FE) method, aimed to investigate the energy absorption capability of a full-scale 95% composite made fuselage section of a civil aircraft. A vertical drop test, performed at the Italian Aerospace Research Centre (CIRA), carried out from a height of 14 feet so to achieve a ground contact velocity of 30 feet/s in according to the FAR/CS 25, has been used to assess the prediction capabilities of the developed FE method, allowing verifying the response under dynamic load condition and the energy absorption capabilities of the designed structure. An established finite element model could be used to define the reliable crashworthiness design strategy to improve the survival chance of the passengers in events such as the investigated one.

Abstract: The design process of fiber-reinforced plastics (FRP) is a challenging task, especially concerning passenger vehicles in crashworthiness applications where manufacturing limitations and requirements regarding passive safety have to be considered. Numerical optimization can be a helpful tool during the design process, but most available methods are not applicable because analytical sensitivities are not available in crash simulations. The Graph and Heuristic based Topology Optimization (GHT) can be utilized to optimize the topology of cross-sections of crashworthiness structures while fulfilling a wide range of manufacturing constraints, but it has to be extended for composites. Since the topology changes during optimization runs, the stress state changes as well. This demands high predictive capabilities on the material model. This paper presents the necessary adjustments to describe composite profile structures within the GHT method. A commercial material model for LS-Dyna is parameterized and used for the calculation process.

Abstract: In the aircraft industry, crashworthiness design and certification phases have been and are going to be the most attractive topics for designers, mostly because of the increasing use of composites for primary structural components. It is well known that the cargo subfloor elements of the fuselage structure play a crucial role in absorbing the kinetic energy during a crash. In particular, the stanchions, or struts, are important parts for the structural response; as a matter of fact, they connect the fuselage frames to the cabin’s floor and, ideally, are expected to crush under a compressive force in order to dissipate the impact energy in a controlled way and, consequently, to minimize the energy transferred to the passengers. The aim of this work is to demonstrate, experimentally and numerically, the energy absorption capability of the stanchions, made of both composite material and aluminium alloy, of a full-scale 95% composites made fuselage section under a critical load condition, such as an emergency landing. A Finite Element model allowing estimating the passive safety capabilities of the designed struts has been developed and herein proposed.

Abstract: Fibre-reinforced composite materials and structures have been extensively used as energy dissipating components in industries. The crashworthiness of square and circular CFRP (Carbon Fiber Reinforced Plastics) tubes have been widely studied. This paper investigates the deformation and energy absorption of square CFRP frusta under axial quasi-static crushing. The effects of various geometry parameters such as height-to-mean width (H/B) and thickness-to-mean width (t/B) ratios on the crushing resistance for square CFRP frusta with an apical angle of 10 ° have been examined experimentally. Finally the crashworthiness metrics of square CFRP frusta and square tube are compared and evaluated. The results show that the experimentally observed deformation mode of CFRP square frusta can be classified into three types, namely progressive folding collapse; splaying crushing mode characterized by a combination of progressive splaying and transverse shearing failure; and transition mode respectively. The initial peak force, mean crushing force and energy absorption of square CFRP frusta deformed in splaying mode increase with the increasing of wall thickness and width. For the desirable progressive splaying mode, three energy dissipated mechanisms have been identified as crack propagation, transverse shearing and friction energy.