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Given the importance of vehicle safety, OEMs are focused on ensuring the safety of passengers during car accidents. Injury is related to the passenger’s kinematics and interaction with airbag, seatbelt, and vehicle drop. However, the correlation between vehicle drop (vehicle pitch) and passengers’ injury is the main issue recently being discussed. This paper presents the definition of vehicle drop and analyzes the relationship through a dynamic sled test. This study defines the relationship between individual vehicle systems (body, chassis, tire, etc.) and vehicle drop, and how to control the amount of vehicle drop to minimize the injury of passengers.

Polylactide (PLA), which is one of the most important biocompatible polyesters that are derived from annually renewable biomass such as corn and sugar beets, has attracted much attention for automotive parts application. The manufacturing method of PLA is the ring-opening polymerization of the dimeric cyclic ester of lactic acid, lactide. For the PLA composites including stereocomplexed with L- and D-PLA, we developed the unit processes such as fermentation, separation, lactide conversion, and polymerization. We investigated D-lactic acid fermentation with a view to obtaining the strains capable of producing D-lactic acid, and through catalyst screening test for polycondensation and depolymerization reactions, we got a new method which shortens the whole reaction time of lactide synthesis step. Poly(d-lactide) is obtained from the ring-opening polymerization of d-lactide. Also we investigated several catalysts and polymerization conditions.

Squeak and rattle (S&R) problems in body structure and trim parts have become serious issues for automakers because of their influence on the initial quality perception of consumers. In this study, various CAE and experimental methods developed by Hyundai Motors for squeak and rattle analysis of door systems are reported. Friction-induced vibration and noise generation mechanisms of a door system are studied by an intelligent combination of experimental and numerical methods. It is shown that the effect of degradation of plastics used in door trims can be estimated by a numerical model using the properties obtained experimentally. Effects of changes in material properties such as Young's modulus and loss factor due to the material degradation as well as statistical variations are predicted for several door system configurations. As a new concept, the rattle and squeak index is proposed, which can be used to guide the design.

An innovative design process is proposed to be applicable in the early conceptual design phase as a means of front loading design. The objective of the study is to minimize trial and errors in the detailed design phase and to shorten the overall design period. The process includes design optimization which is based on efficient modeling techniques. An integrated CAD/CAE modeling method and a simplified quality FE model are key factors in the course of effectuation. The conceptual modeling takes into account the adaptability of computer-generated models with the use of CAD/CAE integrated design environment. To achieve maximum efficiency in the repeated computations in optimization, an FE modeling approach is introduced in terms of simplicity and quality. The proposed FE modeling employs beam and spring elements to construct vehicle body models, which is targeted to produce an instant analysis result with a robust conceptual design at the incipient phase of development.

Hyundai Motor Group launched a Continuously Variable Valve Lift (CVVL) engine in 2012. The engine is equipped with HMG's unique CVVL mechanism and is characterized by low fuel consumption, high performance and its responsiveness. The CVVL mechanism is based on a six-linkage mechanism and has advantages of compactness and durability. The engine is a 4 cylinder In-Line, 2.0L gasoline engine and is designed for a mid-sized passenger car. The engine increases fuel efficiency by 7.7% and the peak engine power by 4.2%. One of the most challenging issues in producing a CVVL engine is the valve lift deviations throughout the engine cylinders. The valve cap shim and set screw were designed to adjust the valve lift deviations. Cap shim thickness is chosen by measuring the valve top height, and shoe lift of the cam carrier assembly. The set screw is an auxiliary device to adjust the valve lift deviation.

Reducing unsprung mass of the car is a representative method to enhance the ride & handling performance and fuel efficiency. In this study, brake disc weight is reduced 15∼20% using a hybrid type material. The basis for this study is the separation of the friction surface and HAT(mounting part). Aluminum material is applied in the HAT for a light weight effect. Gray iron is applied in the friction surface section to maintain braking performance. Two types of joining between aluminum and cast iron are developed. One is the aluminum casting method utilizing a gray iron insert and the other is a bolted assembly method. Detailed structure, process and material are optimized using try-out & dynamometer experiments. The Reliability of this development is proved through durability (dynamometer and vehicle) testing.

Many high risks of failure in developing and applying new technologies exist in the recent automotive industry because of big volume of selling cars in a global market. Several recalls cost companies more than $ 100 million per problem. New technologies always have uncertainty in performing intended functions at various given conditions despite the fact that engineers do their best to develop technologies to meet all the requirements. Uncertainty of new technologies put companies into danger of failing in their business. Therefore, many companies tend to take interest in reducing risks from the uncertainty in technologies, but the increasing complexity of modern automotive technologies make it difficult to develop complete technologies. A new engineering methodology called SPEED Engineering was introduced to reduce the risks of new technology applications and to facilitate engineers to conceive innovative ideas dominating the market in the future.

This paper outlines an improved methodology to perform calculations to verify the compliance of automotive door latch systems to minimum legal requirements as well as to perform additional due diligence calculations necessary to comprehend special cases such as roll over crashes and locally high inertial loadings. This methodology builds on the calculation method recommended by SAE J839 and provides a robust and clear approach for application of this method to cable release systems, which were not prevalent at the time J839 was originally drafted. This method is useful in and of itself but its utility is further increased by the application of the method to a Computer Aided Design (CAD) template (in this case for Catia V5), that allows some automation of the calculation process for a given latch type. This will result in a savings of time, fewer errors and allows for an iterative concurrent analysis during the design process.

We developed the hard IP (Instrument Panel) that is integrally over molded with a soft layer (TPO, Thermo Plastic Olefin) for the soft feeling and cost reduction. And also we produced the cost-effective PAB(Passenger-side Airbag) door system that had an in-mold tearseam and avoided competitors' patents simultaneously. The development procedure of this technology is; ① Material for overmolding ② Design optimization ③ Solving tool challenges. The reduction of process through integrally molding with soft material helped to accomplish a soft feeling on the IP and cost reduction at the same time. The deployment, head impact and heat aging tests were conducted and 5 patents were applied such as the optimization of the mold structure and injection condition.

Invisible Passenger-side Airbag (IPAB) door system must be designed with a weakened area such that the airbag will break through the Instrument Panel (IP) in the intended manner, with no flying debris at any temperature. At the same time, there must be no cracking or sharp edges at the head impact test (ECE 21.01). Needless to say, Head impact test must keep pace with the deployment test. In this paper, we suggested soft airbag door system that is integrally molded with a hard instrument panel by using Two-shot molding. First of all, we set up the design parameters of IPAB door for the optimal deployment and head impact performance by CAE analysis. And then we optimized the open-close time at each gate of the mold so that the soft and hard material could be integrally molded with the intended boundary. We could make the boundary of two materials more constant by controlling the open-close time of each gate with resin temperature sensor.

Due to technological evolutions and social demands, motor vehicles are requested to be enhanced in terms of occupant safety and comfort. As a result, many countries are reinforcing crash regulations and new car assessment programs. Automotive seats are essential parts for providing passenger safety and comfort and have become most important. Many automotive companies concentrate on optimization of the seat structure. This paper presents an overview of the recent evolution of the seat structures and gives a development procedure covering seat frame design, optimization and validation. Through the study, a competitive frame design is drawn as a case result and a design guideline and a standard development procedure is established

An increasing number of cars which are being used to foster leisure and a convenient life for consumers are being outfitted with roof racks and/or cross bars. This trend of installing roof racks is partly for the function of carrying objects on the roof of the vehicle and partly as a way to affect the style and exterior look of the vehicle. Therefore, the application of roof racks and cross bars is becoming increasingly important in the automotive industry. Because of the expanding application of roof racks on vehicles, the challenge of reducing wind noise caused by exposed cross bars becomes the main issue in this field. For solving this problem, the cross bar shape is designed and evaluated in the development stage, and if there is a problem, it is re-designed and re-evaluated many times. This repetitive corrective action is called “trial and error”.

Hard panel types of invisible passenger-side airbag (IPAB) door system must be designed with a weakened area such that the airbag will deploy through the Instrument Panel (IP) in the intended manner, with no flying debris at any required operating temperature. At the same time, there must be no cracking or sharp edges in the head impact test (ECE 21.01). If the advanced-airbag with the big difference between high and low deployment pressure ranges are applied to hard panel types of IPAB door system, it becomes more difficult to optimize the tearseam strength for satisfying deployment and head impact performance simultaneously. We introduced the ‘Operating Window’ idea from quality engineering to design the hard panel types of IPAB door applied to the advanced-airbag for optimal deployment and head impact performance. To accurately predict impact performance, it is important to characterize the strain rate.

In order to meet FMVSS 201 (U) requirements, the upper vehicle interior structures with trim in a vehicle need to be properly designed to minimize injuries when head impacts these components. This paper presents a study of countermeasures in pillars using FEA approach by considering some design factors. Optimal designs are then selected for interior head impact protection based on CAE analysis using LS-DYNA non-linear finite element code.

Hands-free stability, one of the handling characteristics of a vehicle, is a stability criterion evaluated in case of a driver's steering wheel release after a certain steering input during driving. During the development process, a hands-free-unstable vehicle needs many steering and suspension parts to be repeatedly tested to improve the performance. In this paper, CAE methods are proposed to investigate easily the influence of the steering and suspension design parameters on the hands-free stability. And the results of CAE methods were compared with the prototype vehicle test to verify the validity of the methods.

Conventional steering system has a mechanical connection between the driver and the front tires of the vehicle, but in steer-by-wire system, there is no such a connection. Instead, actuators, positioned in the vehicle's front corners receive input from the control module and turn the front wheels accordingly. In steer-by-wire system, steering wheel is an important part that not only transfers driver's steering input to the controller but also provides a road feedback feeling to the driver's hand. Thus the reactive torque actuator, providing road feedback, plays an important role in steer-by-wire system. In conventional steer-by-wire-system, a motor was used as a reactive torque actuator. But using motor has some disadvantages such as an oscillatory feeling, and improper and potentially dangerous acceleration of the steering wheel by the motor when driver's hands are released from steering wheel abruptly.

Recently weight reduction is increasingly needed in automotive industry to improve fuel efficiency and to meet a CO2 emission requirement. In this paper, we prepared composite body panels for the lightweight vehicle based on a small passenger car. Fender, roof, door, side outer panel, and tailgate are made from hand layup using a glass/carbon hybrid reinforcement. Hood is made from low pressure sheet molding compound (SMC) to investigate feasibility of mass production. Both hand layup and low pressure SMC materials are newly developed and their physical properties are examined. CAE simulation was done for strength analysis and optimization of thickness for the body panels.

To simulate the car-to-car crash accidents in the real field, the Autonomous Driving System was developed. This system consists of communicating, sensing, accelerating, braking, steering and data recording subsystems. All these were designed to be compact, light and collapsible, so that the crash characteristics of test vehicle were not affected. The velocity performance of the system covers from 10 kph to 100 kph within ± 0.5 kph error, and the lateral deviation is constrained within ± 20 mm. With this system, several frontal offset and side car-to-car crash tests were carried out successfully. Deformations, injury levels, deceleration signals and dynamic behaviors during crash were typically investigated. And the dynamic behaviors were compared with the simulation results of EDSMAC. Car-to-car crash tests between small and large vehicles with different masses were carried out and the effects on the compatibility were investigated.

In contrast to the other types of crash simulations, integrated analysis is needed to perform the side impact simulation, and the acquired injury values are so sensitive that they are difficult to assess by the deformed vehicle structure itself. Accurate FE Euro-side impact dummy (EURO-SID) model is needed to predict the various injury values in Euro side-impact simulation. In the past, rigid body model and coarse FE model have been used. The advantage of these models is low computing power. By the way, they have lack of injury predictability in integrated simulations. The deviations are caused by inaccurate geometry and improper material characteristics expression for individual components. Therefore, new Euro side-impact dummy model is developed through mass (inertia), component and sled validation. In this paper, validation results are illustrated, and their application results in two kinds of full car simulations are introduced.

A new thermoplastic polyolefin with primerless adhesion to paint has been developed by polypropylene (PP) with α-olefin copolymers, mineral fillers and some additives. It can substantially reduce costs and environmental problems by eliminating primer treating operations, traditionally treated from trichloroethene (TCE). This new material exhibits unique solid-state texture that rubbery polymer component are typically dispersed in lamellar structure matrix. Versus conventional PP or thermoplastic olefin (TPO), it provides excellent brittle-ductile (BD) transition as well as paintability. Also it is expected to have a significant impact on interior parts as requirements for material change to an emphasis on light weight, lower cost, more efficient finishing.