Automotive Science and Engineering

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Parametric design optimization of an automotive body crashworthiness improvement is presented. The thicknesses of parts are employed as design variables for optimization whose objective is to increase the maximum deceleration value of the vehicle center of gravity during an impact. Using the Taguchi method, this study analyzes the optimum conditions for design objectives and the impact factors and their optimal levels are obtained by a range analysis of the experiment results. A full frontal impact is implemented for the crashworthiness simulation in the nonlinear dynamic code, LS-DYNA. The controllable factors used in this study consist of the six inside foreheads structural parts, while design parameters are relevant thicknesses. The most interestingly the maximum deceleration of the vehicle center of gravity is reduced by 20% during a full frontal impact while several parts experience mass reduction.

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Car body lightening and crashworthiness are two important objectives of car design. Due to their excellent performance, composite materials are extensively used in the car industries. In addition, reducing the weight of vehicle is effective in decreasing the fuel consumption. Hat shape energy absorber is used in car’s doors for side impact protection. The aim of these numerical models and experimental tests is to unveil some important fact about using composite materials in hat shape energy absorber and also show the effect of orientation angles on the amount of energy absorption. The effects of different orientation angles on crushing behavior of hat shape structure are presented.

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During the design and development of truck cabins, the safety of the driver and the front seat passenger in an accident is an important task and should be considered. The cab must be designed in such a way that in an accident a sufficient survival space is guaranteed. The aim of this study is to investigate the behavior of Iran Khodro (IKCO) 2624 truck subjected to a complex crash test according to regulation ECE-R29. This regulation is a comprehensive European regulation consisting of three tests: 1-Front impact test (Test A), 2- Roof strength test (Test B), 3-Rear wall strength test (Test C). These tests do not consider the safety of the occupant directly however, a III-50th% dummy was used to assess the cab’s deformations relative to the driver survival space. A 3D finite element model of the cab and chassis was developed and subjected to tests by using LS-DYNA software. The results indicate that the cab complied with Test A and C successfully while it passed Test B marginally. Finally, two solutions are suggested and implemented to improve the cab’s response for Test B.

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In order to reduce both the weight of vehicles and the damage of occupants in a crash event simultaneously, it is necessary to perform a multi-objective optimization of the automotive energy absorbing components. In this paper, axial impact crushing behavior of the aluminum foam-filled thin-walled tubes are studied by the finite element method using commercial software ABAQUS. Comparison of the present simulation results with the results of the experiments reported in the previous works indicated the validity of the numerical analyses. A meta-model based on the feed-forward artificial neural networks are then obtained for modeling of both the absorbed energy (E) and the peak crushing force (Fmax) with respect to design variables using those data obtained from the finite element modeling. Using such obtained neural network models, a modified multi-objective GA is used for the Pareto-based optimization of the aluminum foam-filled thinwalled tubes considering three conflicting objectives such as energy absorption, weight of structure, and peak crushing force.

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This article investigates the effects of using a thin-walled structure in the chassis front rails in the automotive industry. In frontal accidents, the front rails of the vehicle chassis, increases vehicle crash-worthiness and occupants’ safety by plastic deformation, energy absorption, increasing the crash duration and reducing the load and injuries to the occupants. The objective is to optimize the thin-walled structure of the bumper and the direct beams in the front chassis rails. An explicit FEM full vehicle model with a dummy, safety belts, and air bags are used for the modeling and analysis of the applied loads on the vehicle and the occupants. The FMVSS No. 208 and ECE No. 94 standards are considered for the simulation of a vehicle accident. Finally, the proper model will be selected based on the results.
 

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In automotive industry, foam-filled structures have aroused increasing interest because of lightweight and capacity of energy absorption. Two types of foam filled thin walled structures such as the uniform foam filled (UF) and the functionally graded foam (FGF). To improve crashworthiness performance, FGF are used to fill structures, unlike existing uniform foam materials. In addition, by seeking for an optimal design systematically, some computational optimization signifies a more effective tool to find the best crashworthiness design of structures,. This paper will an exhaustive review of the previous studies of simulation-based optimization such as metamodels, objective functions, design variables, design of experiments, optimization techniques of crashworthiness of tubes.

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Due to the extensive use of cars and progresses in the vehicular industries, it has become necessary
to design vehicles with higher levels of safety standards. Development of the computer aided design and
analysis techniques has enabled employing well-developed commercial finite-element-based crash
simulation computer codes, in recent years. The present study is an attempt to optimize behavior of the
structural components of a passenger car in a full-frontal crash through including three types of energy
absorptions: (i) structural damping of the car body, (ii) viscoelastic characteristics of the constituent
materials of the bumper, and (iii) a proposed wide tapered multi-cell energy absorber. The optimization
technique relies on the design of experimental (DOE) method to enables finding the absolute extremum
solution through the response surface method (RSM) in MINITAB software. First, the car is modeled in
PATRAN and meshed in ANSA software. Then, the full-scale car model is analyzed in ABAQUS/CAE
software. The optimization has been accomplished through a multi-objective function to simultaneously,
maximize the observed energy and minimize the passenger’s deceleration. Results are verified by the
experimental results and effects of using non-equal importance coefficients for the absorbed energy and
passenger’s deceleration in the multi-objective function are also evaluated. Influence of the optimized
parameters on the frontal crash behavior of the vehicle body structure and passenger’s deceleration is
investigated, too.

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Fillers can be employed as reinforcement in the design of automobile crash boxes to improve its performance in terms of energy absorption, expected crushing fashion and initial peak force magnitude. The current research focuses on the investigation of crashworthiness of the high-strength steel (HSS) columns filled with reinforced aluminium honeycomb fillers. The crashworthiness of HSS steel crash boxes embedded with aluminium honeycomb of varying thickness and  cell sizes are investigated. Five variants of honeycomb thickness, namely; Thickness-1, Thickness-2, Thickness-3,Thickness-4, Thickness-5 and six variants of honeycomb cell size, namely; CellSize-1, CellSize-2, CellSize-3, CellSize4, CellSize-5 and CellSize-6 are considered for the crash box analysis. Numerical crash analysis is performed for the novel reinforced sandwich honeycomb separated by steel plates in HSS crash box. A further study is also performed by inducing V-Notch triggers in the honeycomb to evaluate the effect of crashworthiness parameters. A comparative numerical investigation is performed to realize the effect of geometric parameters on the crashworthiness variables of crash boxes for low-velocity impact. The force versus displacement curves were derived and analyzed for each parameter variations and detailed comprehension of deformation pattern and energy absorption are provided. The objectives of the present work is to showcase the effect of honeycomb geometric parameters like thickness and cell size on crashworthiness parameters for low-velocity impact and also to represent the effect of sandwich honeycomb and honeycomb with V-Notch triggers methodology on the crashworthiness parameters like initial peak force (IPF), energy absorption (EA), specific energy absorption (SEA) and crush force efficiency (CFE)
 

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Fillers can be employed as reinforcement in the design of automobile crash boxes to improve its performance in terms of energy absorption, expected crushing fashion and initial peak force magnitude. The current research focuses on the investigation of crashworthiness of the high-strength steel (HSS) columns filled with reinforced aluminium honeycomb fillers. The crashworthiness of HSS steel crash boxes embedded with aluminium honeycomb of varying thickness and cell sizes are investigated. Five variants of honeycomb thickness, namely; Thickness-1, Thickness-2, Thickness-3, Thickness-4, Thickness-5 and six variants of honeycomb cell size, namely; CellSize-1, CellSize-2, CellSize-3, CellSize4, CellSize-5 and CellSize-6 are considered for the crash box analysis. Numerical crash analysis is performed for the novel reinforced sandwich honeycomb separated by steel plates in HSS crash box. A further study is also performed by inducing V-Notch triggers in the honeycomb to evaluate the effect of crashworthiness parameters. A comparative numerical investigation is performed to realize the effect of geometric parameters on the crashworthiness variables of crash boxes for low-velocity impact. The force versus displacement curves were derived and analyzed for each parameter variations and detailed comprehension of deformation pattern and energy absorption are provided. The objectives of the present work is to showcase the effect of honeycomb geometric parameters like thickness and cell size on crashworthiness parameters for low-velocity impact and also to represent the effect of sandwich honeycomb and honeycomb with V-Notch triggers methodology on the crashworthiness parameters like initial peak force (IPF), energy absorption (EA), specific energy absorption (SEA) and crush force efficiency (CFE).

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A new safe optimal consensus procedure is presented to guarantee the asymptotic and string stability as well as crash avoidance of large-scale non-identical traffic flow. Since time delay is an inherent characteristic of physical actuators and sensors, measurement delay and lags are involved in the upper level control structure. A third-order linear model is employed to define the 1-D motion of each automated vehicle (AV) and the constant time headway plan is employed to regulate the inter-AV distance. It is assumed that the network structure is decentralized look ahead (DLA) and each AV has access to relative position and velocity regarding with the front AV. A linear control law is introduced for each AV and by performing the stability analysis in frequency domain, the necessary conditions guaranteeing string stability and crash avoidance for large-scale traffic flow are derived. Afterwards, to calculate the optimal control parameters guaranteeing the best performance, an objective function combining all mentioned conditions as well as maximum overshoot, settling time and stability margin is introduced. The genetic algorithm (GA) technique is employed to optimize the presented objective function and obtain the optimal control parameters. Various numerical results are proposed to demonstrate the efficiency of this method.

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In the present work, the energy absorption study of warm-rolled LZ71 sheet is done for the first time. To do so, Lithium (7% Wt), Zinc (1% Wt) and Magnesium are cast in 770⁰C. After that, the billet has been warm-rolled at 350⁰C and its thickness reduced by 80%. Then, two different heat treatment situations are studied to reach an isotropic plate. Afterward, microstructures of the specimens have been studied using an optical microscope. Tensile tests of the samples are derived to study the mechanical properties and isotropy of the sheets. Moreover, the results of tensile tests applied for crushing simulations. Energy absorption study of the alloy is also done using ABAQUS/Explicit commercial code. The results of simulations are validated using experimental tests of A6082 and completely acceptable performance of simulations is observed. Then, the mechanical properties of LZ71 are used to study the crashworthiness behavior of the mentioned alloy. Crash absorption parameters, namely peak crush force (F_Max), mean crush force (F_Mean), Total Energy Absorption (TAE), Crush Force Efficiency (CFE), Specific Energy Absorption (SEA) and Total Efficiency (TE) of LZ71 and A6082 are compared which are shown that the performance of LZ71 is considerably more efficient than A6082. Lastly, by the help of Artificial Neural Network (ANN) and Taguchi Method, the effects of dimensional parameters of tube, namely diameter, length and thickness, on F_Max, F_Mean and TAE and also the influences of dimensionless geometrical ratios, namely L/D and D/t on CFE, SEA and TE are surveyed comprehensively.

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In this study, the driver airbag geometry and internal pressure were considered as the main parameters to investigate the head injury severity in a frontal crash. The total energy absorption of an airbag was investigated in a drop test simulation and its rate was discussed by the depression distance parameter. On the other hand, the maximum deceleration of the impactor was determined to represent the airbag stiffness by a defined deceleration peak parameter. Thus, the depression distance and the deceleration peak were the objective functions for an isolated airbag under a lumped-mass impact simulation. Furthermore, an optimal matrix was generated using the design method of experiments (DOE) and yielded the airbag parameters as outputs. After the evaluation of the design parameters by the Taguchi method, the ANOVA method was used to predict the most effective parameters. Finally, a sled test with the 50% HYBRID III dummy and the defined airbag was simulated. An experimental crash was selected as the reference point to verify the simulation and to be used to compare the outcomes. Even though the objective function of depression distance showed contradictory effects to reduce the head injury severity, the results showed a %16.4 reduction in the driver head injury in a full-frontal crash.

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Thin-walled tubes can avoid the transition of injurious acceleration and excessive forces to the protected section and minimize the damage severity. They absorb energy under axial loading circumstances as crashworthiness structures. The present study deals with the investigation of the density effects of foam on the quasi-static loading response of foam filled and empty cylindrical tubes. To investigate energy absorption parameters by varying in foam density, two different densities of polyurethane foam were used to evaluate the efficacy of polyurethane foam density under axial quasi-static loading. According to the results, the use of foam as a filler also influences the tubes’ deformation behavior in addition to the effects of thickness. It was revealed that by incrementing the thickness to 20%, the peak load increased by 25.2%. Two densities of foam were considered as 40 and 85kg/m3 to assess the effect of density of polyurethane foam as filler on the energy absorption behavior of tubes under axial loading. Result showed that when foam density increased by about two times, the peak load increased by 1%. According to the results, filling tube by foam also influences the tubes deformation behavior in addition to the effects of thickness

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The utilization of adhesively bonded square sections (ABSS) serves to enhance energy absorption and specific energy absorption (SEA) when subjected to oblique loading. Finite element models utilizing LS-DYNA were constructed in order to examine the deformation mode and load-displacement characteristics of ABSS and hybrid aluminum/carbon fiber reinforced polymer models. Subsequently, an evaluation was conducted on the general parameter pertaining to crashworthiness and the capacity for absorption of energy. The results reveal that an increase in the quantity of Carbon Fiber Reinforced Polymer (CFRP) layers within the stacking sequence of [0,90] affords enhanced potential for energy absorption. Conversely, the stacking sequence of [90] exhibits an incongruity with this trend, and achieves superior energy absorption capacity with a count of 4 CFRP layers rather than 8.
The present study indicates that carbon fiber reinforced polymer (CFRP) possessing a stacking sequence of [90] exhibits superior energy absorption capacity under both axial and oblique loading conditions at an inclination angle of 10 degrees. In contrast, the use of eight layers of CFRP with a stacking sequence of [0, 90] is found to yield better performance in achieving both axial and oblique loading up to 10 degrees.