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Recently, novel material concepts for high-performance carbon fiber–reinforced composites with active stiffness control were presented in the literature. Although this new class of intelligent, smart, and responsive materials has wide application potential, actual design concepts using active stiffness control are still rare. The integration of smart materials into conventional products often requires radically new design concepts. This communication presents an innovative automotive hood design concept, which integrates active stiffness control composites in order to achieve improved design performance trade-offs in terms of structural weight reduction and vulnerable road user safety. The integration of active stiffness control composites in the hood structure aims to enable active stiffness reduction of the hood or bonnet structure in order to reduce head impact injuries in case of a collision, while satisfying the structural stiffness requirements and lightweight objectives under normal operating conditions. The design concept is investigated using simulation-based evaluation of static, dynamic, and lightweight design criteria. The results are promising, and the presented concept design is a step toward the realization of lightweight smart hood structures for head impact mitigation. Several design features could also be of interest for the integration of active stiffness control composites, in other applications. [ABSTRACT FROM AUTHOR]

With the intent to improve the efficiency of car operation, we offer to manage the value of the cross-section of the grille. It allows achieving the reduction of the pollutant emissions of exhaust gases during the preparation period to operate the engine when warming it up at idle and also decreasing the engine warm-up time and increasing the time of cooling. [ABSTRACT FROM AUTHOR]

Recently, there has been a growing interest in the use of naturally sourced fibers for use in composites design and manufacture. In this work, a structural design on automobile hood using natural flax fiber composite was performed. The structural design results of flax/vinyl ester composite hood were compared with the design results of metal hood structure. Through the structural analyses using commercial FEM software, it is confirmed that the designed automobile hood using natural composite is reasonable for structural safety, stability and weight. Through the structural test, it is confirmed that the designed hood structure is acceptable for structural safety and stability. [ABSTRACT FROM AUTHOR]

One factor that determines the quality of an automobile's appearance is its appearance integrity, which means that the degree to which an automobile's physical appearance coincides with its mechanical quality. The painting process of an automobile can cause the permanent deformation of its hood, which lowers its appearace integrity. The painting process is comprised of the dipping process and the oven process. In the dipping process, pressure caused by the flow of fluid can cause the deformation of the automobile hood; in the oven process, the thermal deformation of sealers can cause the deformation of the hood. In an effort to increase automobiles᾿appearance integrity, this study identifies the major causes of deformation and predicts the types of deformation occurring in each process. The numerical model of a hood is established using the stiffness scanning method and analysis, and deformation in the dipping process is confirmed using Finite Elements Method (FEM). Sealers are hypothesized as the main reason for deformation in the oven process, so a study of the sealers is conducted to predict the deformation occurring after the oven process. Further, through a thermal property experiment and viscosity test, we are able to deduce the properties of sealers that cause deformation. This study also examines the effects of hood deformation in the oven process using numerical analysis and compares the degree of deformation caused by pressure and heat. The results show that the absolute value of deformation in the dipping process is greater than that in the oven process. Moreover, it is shown that deformation can occur bi-directionally in the oven process, and the quantity of mastic sealer does affect the degree of deformation. [ABSTRACT FROM AUTHOR]

During automobile dipping process, surface defects such as very small or micro deformation occurs intermittently on the assembled hood. The main cause of the surface defect is the location of hood supporting stay, structure of hood and pressure distribution resulted from fluid behavior in a paint pool. In order to minimize the defect, it is necessary to understand and predict the stiffness of the assembled hood as well as the fluid flow behavior in the paint pool, and the effects of locations of stays which are used in dipping process. This study has analyzed and simulated the micro deformation which occurs during dipping process. The difference between the measured and the computed stiffness of an assembled hood could be minimized by applying an equivalent material in the numerical model of assembled hood. It was found that the sequential application of fluid pressure to the hood structure in a painting pool was indispensable to obtain accuracy in the computation. By comparing the amounts of deformation which are measured in the actual process line with those of computation, the validity of the technique of computational fluid dynamics and technique of structural analysis have been confirmed. The optimal location of supporting stays to reduce the surface defects was given quantitatively with the coordinates. [ABSTRACT FROM AUTHOR]

This paper presents a novel method for modifying the shapes of existing uniform bi-cubic B-spline surfaces by interactively editing the curvatures along isoparametric curves. The method allows us to edit the curvatures of the two intersecting isoparametric curves at each knot with specified positions, unit tangents, and unit normals. The user adjusts the radii of circles, representing the radii of curvature in the u and v isoparametric directions directly via a GUI without having to work with control points and knots. Such shape specifications are converted into iterative repositionings of the control points on the basis of geometrical rules. Using these point-based curvature-editing techniques, we successfully embedded log-aesthetic curves into existing surfaces along their isoparametric curves. Moreover, we were able to distribute the cross curvature with log-aesthetic variation along the isoparametric curves. We applied our technique to the design of automobile hood surfaces to demonstrate the effectiveness of our algorithms. [ABSTRACT FROM AUTHOR]

An automobile's engine hood is important. It performs several functions, for example, during maintenance of engine area, the hood mechanisms should enable manipulation, and during everyday operation or in case of crashes, the engine hood must be rigid to enable safety; hence it is important to perform engine hood global and local stiffness analysis. This paper applies finite element analysis techniques to evaluate global and local stiffness for the first Saudi Arabian designed SUV; thus checking hinges, lateral firmness, closed and open spring latches, among other engine hood components. Target global and local stiffness values were determined based on the analysis of a similar SUV (i.e., Mercedes G class 500). The results of the finite element analysis indicated that the bump stopper bracket thickness should be increased from 1.2 to 1.5 mm and some parts' geometries should be redesigned in order to improve stiffness. Overall, this paper provides a unified framework to evaluate stiffness of important automobile parts (such as engine hoods) via finite element analysis, and establishes a mechanism for parts' redesign to ensure that pre-established design targets are met. [ABSTRACT FROM AUTHOR]

Technicians have been going through trial-and-error processes to solve very small or micro deformation on automobile hood during the painting process. In order to establish a systematic improvement procedure which can replace the time-consuming trial-and-error method to reduce defects, an accurate analysis of how micro deformation occurs during the painting process is needed. We have utilized a stiffness scanning method in automobile hood and reverse engineering to build up a reliable and accurate structural analysis and measurement procedures. We measured the load-stroke data at critical locations on automobile hood through stiffness scanning to determine material constants closest to the measurement by assuming several critical hood parts, such as sealer inside the hood, hemming part, spot weld part, and other uncertain joints, as virtual elastic materials. After setting the difference between analytical and measured load-stroke data as an objective function, we computed and minimized it by using the response surface method and partial differentiation of the object function. As a result, by obtaining the reliability was over 91%, which showed a strong correlation between analysis and measured results. By comparing the actual strain measured in real painting lines with calculated strain, we confirmed the validity of our structural analysis method. It was concluded that the proper analysis tool could be utilized in determination of optimal locations of supports during the painting process. [ABSTRACT FROM AUTHOR]

The objective of the present study was to present a method to assess the protective performance of a passenger car hood to decrease pedestrian head injuries in car-to-pedestrian collisions by using a validated human head finite element (FE) model. Three types of hoods, sandwich structure hood, multi-cone and wavilness inner-panel hoods, made of aluminium were proposed to protect the pedestrian's head. The head FE model was used to evaluate the protection performance of the proposed hood designs by modelling of head impact to the hood. The head intracranial pressure and the linear and rotational acceleration were measured using the head FE model to predict the risk of brain injury. The results indicated that the proposed hood designs showed a significant improvement in injury mitigation from simulations of the head FE model impact to the hood in the investigated passenger car. [ABSTRACT FROM PUBLISHER]

Reliability-based topology optimization (RBTO) is used to obtain an optimal topology satisfying given constraints, as well as to consider uncertainties in design variables. In this study, RBTO was applied to obtain an optimal topology for the inner reinforcement of a vehicle's hood based on bidirectional evolutionary structural optimization (BESO). A multi-objective topology optimization technique was implemented to obtain the optimal topology for two models with different curvatures while simultaneously considering the static stiffness of bending, torsion, and natural frequency. A performance measure approach (PMA) with probabilistic constraints formulated in terms of the reliability index was employed to evaluate the probabilistic constraints. The optimal topology obtained by RBTO was evaluated and compared to that obtained by deterministic topology optimization (DTO). A more suitable topology was obtained through RBTO than DTO even though the final volume obtained by RBTO was generally slightly greater than that obtained by DTO. The multiobjective optimization technique based on BESO can be applied very effectively with topology optimization for a vehicle's hood reinforcement. [ABSTRACT FROM AUTHOR]

The majority of pedestrian fatalities and injuries are caused by traffic accidents. Injuries of occupants in a vehicle have been considerably decreased due to many efforts by the industry. However, efforts for the protection of pedestrians still seem to be insufficient. Many industries are striving for better protection of pedestrians by using an active hood lift system, rather than reforming the existing structure. The active hood lift system lifts the hood when the vehicle hits a pedestrian, thus mitigating head injury to the pedestrian. In this research, the active hood lift system is designed to enhance the performance for protection. The active hood lift system is analysed by using the non-linear finite element method. Computer simulation is conducted for the impact between the headform and the hood. An optimization problem is formulated to incorporate the analysis results. An iterative optimization algorithm using orthogonal arrays is utilized for the design in a discrete space. The injury level to the head is significantly reduced in the newly designed product. [ABSTRACT FROM AUTHOR]