Ahmed Elmarakbi

Crash analysis and modeling of two vehicles in frontal collisions using two types of smart front-end structures: an analytical approach using IHBM

Abstract The aim of this paper is to investigate and to enhance crashworthiness of vehicle-to-vehicle full and offset frontal collisions using two smart front-end structures. Two different types of smart front-end structures, fixed and extendable, have been proposed to support the function of the existing vehicle. The work carried out in this paper includes developing and analyzing mathematical models of vehicle-to-vehicle in full and offset frontal collision events for the two types of smart front-end structures. In this paper, the dynamic responses of the crash events are obtained with the aid of an analytical approach using Incremental Harmonic Balance Method (IHBM). Moreover, the intrusion injury and occupant deceleration are used for interpreting the results. It is demonstrated from simulation results that significant improvements to both intrusion and deceleration injuries are obtained using the smart front-end structures. Furthermore, it is shown that the mathematical models are convenient and can be used in an effective way to give a quick insight of crash accidents.

Advanced composite materials for automotive applications : structural integrity and crashworthiness

The automotive industry faces many challenges, including increased global competition, the need for higher-performance vehicles, a reduction in costs and tighter environmental and safety requirements. The materials used in automotive engineering play key roles in overcoming these issues: ultimately lighter materials mean lighter vehicles and lower emissions. Composites are being used increasingly in the automotive industry due to their strength, quality and light weight. Advanced Composite Materials for Automotive Applications: Structural Integrity and Crashworthiness provides a comprehensive explanation of how advanced composite materials, including FRPs, reinforced thermoplastics, carbon-based composites and many others, are designed, processed and utilized in vehicles. It includes technical explanations of composite materials in vehicle design and analysis and covers all phases of composite design, modelling, testing and failure analysis. It also sheds light on the performance of existing materials including carbon composites and future developments in automotive material technology which work towards reducing the weight of the vehicle structure. Key features: Chapters written by world-renowned authors and experts in their own fields. Includes detailed case studies and examples covering all aspects of composite materials and their application in the automotive industries. Unique topic integration between the impact, crash, failure, damage, analysis and modelling of composites. Presents the state of the art in composite materials and their application in the automotive industry. Integrates theory and practice in the fields of composite materials and automotive engineering. Considers energy efficiency and environmental implications. Advanced Composite Materials for Automotive Applications: Structural Integrity and Crashworthiness is a comprehensive reference for those working with composite materials in both academia and industry, and is also a useful source of information for those considering using composites in automotive applications in the future.

Longitudinal Hierarchy Co3O4 Mesocrystals with High-dense Exposure Facets and Anisotropic Interfaces for Direct-Ethanol Fuel Cells

Novel electrodes are needed for direct ethanol fuel cells with improved quality. Hierarchical engineering can produce catalysts composed of mesocrystals with many exposed active planes and multi-diffused voids. Here we report a simple, one-pot, hydrothermal method for fabricating Co3O4/carbon/substrate electrodes that provides control over the catalyst mesocrystal morphology (i.e., corn tubercle pellets or banana clusters oriented along nanotube domains, or layered lamina or multiple cantilevered sheets). These morphologies afforded catalysts with a high density of exposed active facets, a diverse range of mesopores in the cage interior, a window architecture, and vertical alignment to the substrate, which improved efficiency in an ethanol electrooxidation reaction compared with a conventional platinum/carbon electrode. On the atomic scale, the longitudinally aligned architecture of the Co3O4 mesocrystals resulted in exposed low- and high-index single and interface surfaces that had improved electron transport and diffusion compared with currently used electrodes.

Sunflower oil-based hyperbranched alkyd/spherical ZnO nanocomposite modeling for mechanical and anticorrosive applications

Approaches for designing advanced nanomaterials with hyperbranched architectures and lack of volatile organic content (VOC) have attracted considerable attention. In this study, eco-friendly hyperbranched alkyd resins for mechanical and anticorrosive coatings with high solid content were successfully synthesized based on sunflower oil (SFO) via a polyesterification approach. These resins are characterized by energy-efficient polymer synthesis, lack of gelation properties, high functionality, and low viscosity. A chemical precipitation process was used to fabricate zinc oxide (ZnO) spherical nanostructures with controlled diameters and morphologies. A series of conformal, novel, low-cost SFO-based hyperbranched alkyd/spherical ZnO nanocomposites were fabricated through an ex situ method. Various nanofiller concentrations were distributed to establish synergetic effects on the micro–nano binary scale performance of the materials. The features of the nanocomposites, including the molecular weight, acid and hydroxyl values of the prepared alkyd resins, were concomitantly assessed through various standard tests. The nanocomposites were also subjected to various tests to determine their surface adhesion and mechanical properties, such as impact, T-bending, crosscut, and abrasion resistance tests. Furthermore, the physico-mechanical properties, anticorrosive behavior, thermal stabilities and cellular cytotoxicities of the fabricated materials were assessed. The anticorrosive features of the nanocomposites were investigated through salt spray tests in 5 wt% NaCl. The results indicate that well-dispersed ZnO nanospheres (0.5%) in the interior of the hyperbranched alkyd matrix improve the durability and anticorrosive attributes of the composites; thus, they exhibit potential applications in eco-friendly surface coatings.

Incremental Harmonic Balance Method for Analysis of Standard/Smart Vehicles-to-Rigid Barrier Frontal Collision

The aim of this paper is to investigate and to enhance crashworthiness of frontal barrier impact using a new idea of crash improvement. Two different types of smart front-end structure are proposed to support the function of the existing vehicle. The work described includes developing and analysing mathematical models of vehicle-to-rigid barrier full and offset frontal collision events for the two types of smart front-end structure. In these models, vehicle components are modelled by lumped masses and nonlinear springs. Moreover, the hydraulic cylinders are represented by non-linear damper elements. In this paper, the dynamic responses of the crash events are obtained with the aid of analytical approach using the Incremental Harmonic Balance Method (IHBM). In addition, the intrusion injury and occupant deceleration are used for interpreting the results. It is demonstrated from simulation results that significant improvements to both intrusion and deceleration injuries are obtained using the smart front-end structures.

Mathematical Modelling of a Vehicle Crash with Emphasis on the Dynamic Response Analysis of Extendable Cubic Nonlinear Dampers Using the Incremental Harmonic Balance Method

Abstract A new direction of crashworthiness improvement using a smart extendable front-end structure is introduced in this paper to support the function of the existing vehicle structure. The smart front-end structure consists of two extendable, independently controlled hydraulic cylinders (dampers) integrated with the front-end longitudinal members. The main objectives of the smart front-end structure are to find solutions of the trade-off problem faced by the designer for offset collision events and to mitigate full frontal collisions. The work carried out in this paper includes developing and analysing mathematical models of different vehicle crash scenarios, including vehicle-to-vehicle frontal collision in both full and offset events. In these models, vehicle components are modelled by lumped masses and cubic non-linear springs. The hydraulic cylinders are represented by cubic non-linear damper elements. In this paper, the dynamic responses of the crash events are obtained with the aid of an analytical approach using the incremental harmonic balance method. The intrusion injury as the maximum deformation of the front-end structure and the occupant deceleration injury are used for interpreting the results. It is demonstrated from simulation results that significant improvements to both intrusion and deceleration injuries are obtained using the smart front-end structures.

Parametric effects on the performance of traffic light poles in vehicle crashes

Abstract Collisions between vehicles leaving the road and unforgiving roadside objects (trees, poles, road signs, and other street furniture) are a major road-safety problem. The severity of these collisions depends in part on the incompatibility of vehicle-to-roadside hardware. The literature review shows that a few finite element computer simulation attempts have been conducted using existing traffic roadside hardware, without further research to enhance their safety performance against vehicle impacts. The aim of this research is to contribute to the efficient design of traffic light poles involved in vehicle frontal collisions by developing an experimentally calibrated, computer-based, finite element model capable of capturing all impact characteristics. This is achieved by using the available nonlinear dynamic analysis software ȁLS-DYNAȁ, which can accurately predict the dynamic response of both the vehicle and the traffic light pole. A parametric study was conducted to evaluate the effects of key parameters on the response of the pole embedded in soil when impacted by vehicles. These parameters included soil type (clay and sand), pole material type (steel and aluminum), embedment length of the pole, and vehicle impacting speed. It is demonstrated from the results of the numerical analysis that the aluminum pole–soil system has favorable advantages over steel poles, where the aluminum pole absorbed vehicle impact energy in a smoother manner, which leads to smoother acceleration pulse and less deformation of the vehicle than those encountered with steel poles. Also, it was observed that clayey soil brings slightly more resistance than sandy soil, which helps in reducing pole movement at ground level. Moreover, results show that the longer the embedment length, the better the intrusion and acceleration of the vehicle.

Simulation of Incremental Forming Processes Using a Thermo-Mechanical Partitioned Algorithm

The aim of this paper is to study the simulation of cogging process using a thermo-mechanical partitioned algorithm. The thermal and mechanical problems are solved separately. The mechanical problem is based on the balance equation whereas the thermal problem is based on the heat equation. The two physics are coupled trough the mechanical parameters that depends on the thermal problem and vice versa. The results obtained using the software Forge3 show that the mechanical deformation is high inside the zone of deformation and negligible outside whereas the temperature is high overall the mesh with a gradient at the zone of contact between the dies and the work piece.

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.

Modelling and analysis of vehicle crash system integrated with different VDCS under high speed impacts

The behaviour of a vehicle at high-speed crashes is enhanced by using active vehicle dynamics control systems. A 6-Degree-of-Freedom (6-DOF) mathematical model is developed to carry out this study. In this model, vehicle dynamics is studied together with vehicle crash structural dynamics. Validation of the vehicle crash structure of the proposed model is achieved to ensure that the modelling of the crumble zone and the dynamic responses are reliable. Five different speeds are selected to investigate the robustness of control system and its effect on the vehicle crash characteristics at low and high speeds with full and offset collision scenarios. A great improvement of vehicle pitch and yaw angels and accelerations at high speed collision are obtained from this analysis.