Crash Analysis and Energy Absorption Characteristics of S-shaped Longitudinal Members

This paper presents finite element simulations of the crash behavior and the energy absorption characteristics of thin S-shaped longitudinal members with variable cross-sections made of different materials to investigate the design of optimized energy-absorbing members. Numerical studies are carried out by simulation via the explicit finite element code LS-DYNA [1] to determine the desired variables for the design of energy-absorbing members. The specific energy absorption (SEA), the weight of the members and the peak force responses during the frontal impact are the main measurements of the S-shaped members' performance. Several types of inner stiffening members are also investigated to determine the influence of the additional stiffness on the crash behavior

The influence of Vehicle Dynamics Control System on the Occupant’s Dynamic response during a Vehicle collision

This paper aims to apply a vehicle dynamics control system to mitigate a vehicle collision and to study the effects of this systems on the kinematic behaviour of the vehicle's occupant. A unique three-degree-of-freedom vehicle dynamics-crash mathematical model and a simplified lumped-mass occupant model are developed. The first model is used to define the vehicle body's crash parameters and it integrates a vehicle dynamics model with a model of the vehicle's front-end structure. In this model, the anti-lock braking system and the active suspension control system are co-simulated, and the associated equations of motion are developed. The second model aims to predict the effect of the vehicle dynamics control system on the kinematics of the occupant. The Lagrange equations are used to solve that model owing to the complexity of the obtained equations of motion. It is shown from the numerical simulations that the vehicle dynamics-crash response and occupant behaviour can be captured and analysed quickly and accurately. Furthermore, it is shown that the vehicle dynamics control system can affect the crash characteristics positively and that the occupant's behaviour is improved

Enhancement of Vehicle Safety and Improving Vehicle Yaw Behaviour Due to Offset Collisions Using Vehicle Dynamics

This study aims to optimise Vehicle Dynamic Control Systems (VDCS) in offset impact for vehicle collision mitigation. A proposed unique 3-D full-car mathematical model is developed and solved numerically to carry out this analysis. In this model, vehicle dynamics is studied together with the vehicle crash structural dynamics. Validation of the vehicle crash structure of the proposed model is achieved to ensure that the modelling of the crumple zone and the dynamic responses are reliable. It is demonstrated from the numerical simulations that the vehicle dynamic responses are captured and analysed and the influence of VDCS is determined accurately. In addition, it is shown that the mathematical model is flexible, useful and can be used in optimisation studies

Constitutive modelling of ductile damage matrix reinforced by platelets-like particles with imperfect interfaces: Application to graphene polymer nanocomposite materials

In this paper, the mechanical response of composites consisting of ductile matrix reinforced by platelets-like particles is derived with imperfect interfaces. Due to its flexibility to study imperfect interfaces with limited number of model parameters, the linear spring model LSM is considered. Moreover, the interfacial contribution to the strain concentration tensor within each material phase and inside the average strain filed is described by a modified Mori-Tanaka scheme. The material nonlinearity is established by the J2 plasticity and Lemaitre-Chaboche damage model. A generalised mid-point rule is used to solve rate equations yielding to anisotropic consistent (algorithmic) tangent operators. To avoid spurious macroscopic stress-strain response, an isotropisation procedure is adopted during the computation of a modified Eshelby's tensor. Numerical results are performed on graphene platelets GPL-reinforced polymer PA6 composite. They confirm the possibility to achieve high stiffness with low values of GPL aspect ratio. The accumulated plastic strain and the damage variable within the matrix are influenced by the GPL volume fraction which is also involved in the softening of the overall response when imperfection is considered at the interface

Performance Analysis of Hybrid and Full Electrical Vehicles Equipped with Continuously Variable Transmissions

The main aim of this paper is to study the potential impacts in hybrid and full electrical vehicles performance by utilising continuously variable transmissions. This is achieved by two stages. First, for Electrical Vehicles (EVs), modelling and analysing the powertrain of a generic electric vehicle is developed using Matlab/Simulink-QSS Toolkit, with and without a transmission system of varying levels of complexity. Predicted results are compared for a typical electrical vehicle in three cases: without a gearbox, with a Continuously Variable Transmission (CVT), and with a conventional stepped gearbox. Second, for Hybrid Electrical Vehicles (HEVs), a twin epicyclic power split transmission model is used. Computer programmes for the analysis of epicyclic transmission based on a matrix method are developed and used. Two vehicle models are built-up; namely: traditional ICE vehicle, and HEV with a twin epicyclic gearbox. Predictions for both stages are made over the New European Driving Cycle (NEDC).The simulations show that the twin epicyclic offers substantial improvements of reduction in energy consumption in HEVs. The results also show that it is possible to improve overall performance and energy consumption levels using a continuously variable ratio gearbox in EVs

Effects of chemical structure and morphology of graphene-related materials (GRMs) on melt processing and properties of GRM/polyamide-6 nanocomposites

In this work, different graphene-related materials (GRMs) and polyamide-6 (PA6) were melt compounded by twin screw extrusion. The GRMs prepared were graphene nanoplatelets (GNPs), graphene oxide (GO), reduced graphene oxide (rGO) and silane functionalised reduced graphene oxide (f-rGO). The GRMs had comparable lateral size (20-30μm), but different thickness and surface chemistry which resulted in different behaviour in processing of melt flow, maximum loading in the PA6 matrix (15%wt for GNPs, 10%wt for GO, 2%wt for rGO and 2.5%wt for f-rGO) as well as mechanical properties. A second extrusion phase produced formulations with lower concentration of GRMs. In the case of f-rGO/PA6, the melt flow index increased by over 76% at 0.5%wt loading compared with the pure PA6 resin, facilitating processing and dispersion of the flakes within the matrix and increasing the elastic modulus and tensile strength by 39%. However, high filler content above 10% has been achieved only for GNPs improving the elastic modulus by 50% at 15%wt

Crashworthiness modelling of hierarchical short glass fibres reinforced graphene polymer composites materials

This work aims to analyse the response under crashworthiness impact of an automotive crash box composite consisting on short glass fibres that are embedded within graphene reinforced polymer composite. Analytical as well as finite element techniques are employed to derive the overall composite response and mechanical characterisation for a macroscopic structural crashworthiness application. Graphene sheets are considered as platelets GPL embedded within an elasto plastic polymer matrix phase leading to a 2-phases graphene/polymer composite. The modelling of 3-phases short glass fibres/graphene polymer composite consists on a double-scale approach combining the 2-phases graphene polymer composite as matrix phase in which are embedded the glass fibres. The full structure crash box is simulated at each Gauss integration point by implementing the constitutive 3-phases composite using a user-defined materials subroutine