Front Side Member Research Articles

152 半割り型自動車サイドメンバーの衝突圧潰特性に関する研究(実用版・シェル構造の衝撃と応力,OS-13 板・シェル構造の振動・座屈と設計,総合テーマ「伝統を,未来へ!」)

Dealing with car frontal crash, previous research has indicated that front side member plays major role in energy absorption. For protecting the passengers, the front side member is expected to absorb crash energy as much as possible. In this study, the front side member with half cut type is studied by parameter study and optimum design method. An optimal design system of the half cut type side member is developed, in which the objective function is to maximize the absorbed energy of side member structure; the design variables are structural parameters, number of edges of polygonal cross section; spot welding pitch length; and thickness of thin-walled side member structure; the constrained condition is that the mass of optimal side member must be less than the allowed value. The parameter study and optimum design results are then discussed. The effect of absorbed energy with each design variable is studied. And the optimal side member structure is capable of absorbing energy 17.01% more than that of original half cut type of box-shaped cross sectional side member structure which is generally used.

折紙工学援用による半割り型自動車サイドメンバーの衝突圧潰エネルギー吸収性能に関する研究

As regard to car frontal crash, previous researches have indicated that the front side member plays a major role in energy absorption. For protecting the passengers, the front side member is expected to absorb crash energy as much as possible. In this study, we investigated the crash characteristics of half cut type side member structure by optimal design method to improve energy absorption ability. We developed an automatic optimal design system, in which the analysis meshes are generated with a group of design parameters and shape optimization is carried out automatically, The design variables are side member cross section shape, spot welding pitch length, divisional section numbers and radius difference along the axial direction, and the number of subdivision levels. As the result, the optimal side member structure with half cut type is capable of absorbing 1.44 times (1.29 times per unit mass) more energy than the original rectangular cross sectional side member structure with half cut type which is generally used.

Dynamic Crushing Characteristics of Front Side Member and Construction of Simplified Spring Model

Dynamic Crushing Characteristics of Front Side Member and Construction of Simplified Spring Model

980MPa급 초고장력 강판의 자동차 프런트 사이드 멤버 부품 성형에 관한 연구

This paper is concerned with forming technology of an automotive front side member part with ultra high strength steel sheet of DP980. The forming technology considered in this paper is the draw & form type, which installs the upper pad and lower pad to produce the complicated shape of ultra high strength steel sheet. In order to produce sound product, comparison between form type and draw & form type and between draw type and draw & form type are investigated by FE-analysis. FE-analysis is carried out with commercial sheet metal forming analysis S/W, DYNAFORM. It was shown from FE-analysis that the draw & form type satisfied the required specifications such as the dimensional accuracy and soundness of automotive front side member part. The effectiveness of the analytical result was verified by the experiment. From this investigation, the draw & form type is proved to be able to supply useful forming technology in forming ultra high strength steel.

DESIGN OF THE CROSS SECTION SHAPE OF AN ALUMINUM CRASH BOX FOR CRASHWORTHINESS ENHANCEMENT OF A CAR

This paper deals with the crashworthiness of an aluminum crash box for an auto-body with the various shapes of cross section such as a rectangle, a hexagon and an octagon. First, crash boxes with various cross sections were tested with numerical simulation to obtain the energy absorption capacity and the mean load. In case of the simple axial crush, the octagon shape shows higher mean load and energy absorption than the other two shapes. Secondly, the crash boxes were assembled to a simplified auto-body model for the overall crashworthiness. The model consists of a bumper, crash boxes, front side members and a sub-frame representing the behavior of a full car at the low speed impact. The analysis result shows that the rectangular cross section shows the best performance as a crash box which deforms prior to the front side member. The hexagonal and octagonal cross sections undergo torsion and local buckling as the width of cross section decreases while the rectangular cross section does not. The simulation result of the rectangular crash box was verified with the experimental result. The simulation result shows close tendency in the deformed shape and the load–displacement curve to the experimental result.

Robot Based Laser Welding Technology

In order to obtain a good result in the laser welding process, the laser welding technology for manufacturing an automobile body is studied in this research. The monitoring of the welding quality and the seam tracking are studied to improve the productivity. The robot, the seam tracking system and CW Nd:YAG laser are used for the robot laser welding system. The laser system is 4kW Nd:YAG laser_(HL4006D) of Trumpf and the robot system is IRB6400R of ABB. The robot laser welding system is equipped with the seam tracker and plasma sensor. The seam tracking system is composed of SMART-20LS and RAPAL of Servo-Robot and MVS-5 sensor of MVS. The precise positioning of the laser beam on the joint to be assembled is obtained by seam tracker. The welding joints of steel plate are butt and lap joint. The three dimensional welding for non-linear tailored blank is performed after the fundamental experiments of bead-on-plate. Finally, the welding process for non-linear tailored blank and front side member is studied. The monitoring method of welding quality and seam tracking along the butt-joint are studied. The artificial defects in joint are well observed by the plasma intensity signal from the plasma sensor of UV and IR. The robot based laser welding system is developed for the precision seam tracking and the real-time monitoring of welding quality.

고충돌에너지 흡수용 알루미늄 크래쉬박스 개발

Crash box is one of the most important automotive parts for crash energy absorption and is equipped at the front end of the front side member. The specific characteristics of aluminum alloys offer the possibility to design cost-effective lightweight structures with high stiffness and excellent crash energy absorption potential. This study deals with crashworthiness of aluminum crash box for an auto-body with the various types of cross section. For aluminum alloys, A17003-T7 and A17003-T5, the dynamic tensile test was carried out to apply for crash analysis at the range of strain from 0.003/sec to 200/sec. The crash analysis and the crash test were carried out for three cross sections of rectangle, hexagon and octagon. The analysis results show that the octagon cross section shape with A17003-T5 has higher crashworthiness than other cross section shapes. The effect of rib shapes in the cross section is important factor in crash analysis. Finally, new configuration of crash box with high crash energy absorption was suggested.

PS26 各種断面形状を持つ車両用フロントサイドメンバのエネルギー吸収特性(ポスターセッション)

PS26 各種断面形状を持つ車両用フロントサイドメンバのエネルギー吸収特性(ポスターセッション)

경량화용 사이드부재의 적층구성 및 단면형상 변화에 따른 에너지흡수 특성

Front-side members of automobile, such as the hat shaped section members, are structures with the greatest energy absorbing capability in a front-end collision of vehicle. This paper was performed to analyze energy absorption characteristics of the hat shaped section members, which are basic shape of side member. The hat shaped section members consisted of the spot welded side member which was utilized to an actual vehicle and CFRP side member for lightweight of vehicle structural member. The members were tested under static axial loading by universal testing machine. Currently, stacking condition related to the collapse characteristics of composite materials is being considered as an issue fer the structural efficiency and safety of automobiles, aerospace vehicles, trains, ships even elevators during collision. So, energy absorption characteristics were analyzed according to stacking condition and shape of section and compared the results of spot welded side member with those of CFRP side member.

Stress-Based Springback Reduction of a Channel Shaped Auto-Body Part With High-Strength Steel Using Response Surface Methodology

In this paper, an optimum design is carried out with finite element analysis to determine process parameters which reduce the amount of springback and improve shape accuracy of a deep drawn product with the channel shape. Without springback simulation usually performed with an implicit solving scheme, the study uses the amount of stress deviation through the sheet thickness direction in the deep drawn product as an indicator of springback. The simulation incorporates the explicit elasto-plastic finite element method for calculation of the final shape and the stress deviation of the final product. The optimization method adopts the response surface methodology in order to seek the optimum condition of process parameters such as the blank holding force and the draw-bead force. The present optimization scheme is applied to the design of the variable blank holding force in the U-draw bending process and the application is further extended to the design of draw-bead force in a front side member formed with advanced high-strength steel (AHSS) sheets made of DP600. Results demonstrate that the optimum design of process parameters decreases the stress deviation throughout the thickness of the sheet and reduces the amount of springback of the channel shaped part. The present analysis provides a guideline in the tool design stage for controlling the evolution of springback based on the finite element simulation of complicated parts.

705 フロントサイドメンバの崩壊荷重の予測(GS.S 構造解析)

705 フロントサイドメンバの崩壊荷重の予測(GS.S 構造解析)

고강도강 프런트 사이드멤버의 응력분포 최적화를 통한 스프링백 저감

Optimization is carried out to determine process parameters which reduce the amount of springback and improve shape accuracy of a deep drawn product in sheet metal forming process. The study uses the amount of stress deviation along the thickness direction in the deep drawn product as an indicator of springback instead of springback simulation. The scheme incorporates with an explicit elasto-plastic finite element method for calculation of the final shape and the stress deviation The optimization method adopts the response surface method in order to seek for the optimum condition of process parameters such as the blank holding force and the draw-bead force. The present scheme is applied to design of the variable blank holding force in an U-draw bending process and the application is further extend ε d to the design of draw-bead force in a front side member formed with advanced high strength steel (AHSS) sheets of DP60. Results show that design of process parameter is well performed to decrease the stress deviation through the thickness and to reduce the amount of springback. The present analysis provides a guideline in a design stage for controlling the springback based on the finite element simulation of the complicated parts.

Numerical and experimental evaluation of springback in a front side member

In this study, a part of an automotive side front section (front side member inner) was studied and a comparison both regarding material behaviour and of accuracy of the FE simulations was made. Mild steel, Rephos steel and TRIP700 were compared both experimentally and numerically. The results showed that TRIP steel has a significantly larger springback than the other materials. Furthermore, the FE simulations overestimate the twisting in this part for all materials, with the TRIP material showing the largest deviation between the experiments and the simulations. The prediction of punch forces was, however, accurate for all materials.

Crashworthiness assessment of front side members in an auto-body considering the fabrication histories

This paper is concerned with crash analysis of a front side member in an auto-body considering the effect of fabrication. The front side member is fabricated with sheet metal forming processes that induce forming histories such as plastic work hardening and non-uniform thickness distribution. Numerical simulation is carried out with LS-DYNA3D in order to identify the forming effect on the crashworthiness. The result shows that the crash analysis of the front side member with considering the forming history leads to a different result from that without considering the forming effect. The analysis calculated crash mode, the reaction force and the energy absorption for crashworthiness assessment with the forming effect. The analysis results demonstrate that the design of auto-body members should be carried out considering the forming history for accurate assessment of crashworthiness.

등가 드로오비드를 적용한 Front Side Member의 성형해석 및 충돌평가

This paper is concerned with forming analysis of Front Side Members and effects of the forming analysis on crash analysis of an auto-body. For efficient forming analysis, equivalent draw-bead restraining forces are calculated with ABAQUS/Standard and then used as the boundary condition in forming simulation. In order to demonstrate the validity of the forming analysis, the thickness variation in the numerical simulation result is compared quantitatively with the one in the real product. Forming histories obtained kom the forming analysis are utilized as the initial condition of the crash analysis for accurate assessment of the crashworthiness. Crashworthiness such as the load-carrying capacity, crash mode and the energy absorption is evaluated and investigated for the identification of forming effects.

Crashworthiness optimisation of S-shape square tubes

During a car frontal crash, the front side member is expected to be folded progressively, so as to absorb more energy and to ensure enough passenger space. As the front member of a vehicle body, the crushing characteristics of an S-shape thin-walled box beam under an axial load has received crucial attention both experimentally and numerically. In this paper, the axial impact crushing behaviour of the S-shape square tube is studied by the finite element method, and effectiveness of stiffening at the curved parts and shape perturbation at two straight parts of tubes are discussed. Based on the numerical analyses, maximisation problem of the dynamic crushing energy absorption of S-shape square tubes is solved by using the crashworthiness maximisation technique for tubular structure which combines the techniques of the response surface approximation design-of-experiment as well as the usual mathematical programming.

927 自動車フロントサイドメンバの動的圧潰挙動

927 自動車フロントサイドメンバの動的圧潰挙動

Formability of tailored blanks

Toyota has applied laser-welded tailored blanks for stamping side panel, door inner, front side member and many other auto body panels. Judgment on the formability in actual panel stamping is difficult, because the behavior in press forming of the portion near the weld lines differs from the base material. We have obtained by experiments the forming limits of the welded area for each of the basic forming patterns: Stretch forming, flanging and deep drawing. The results have been used effectively in judging formability of actual parts stamping.

Weight reduction technology by laser irradiation for body panels

In order to reduce the weight of automobile body panels, we developed a new technology using laser. Reinforcements are attached to structural parts to ensure safety in collisions. We tried to take off the reinforcement from the front side member, and examined the laser quench method. Using the partial strength from structural hardening with laser quench, energy absorption of laser quench assembly (this assembly has no reinforcement) was almost the same as of a standard assembly with reinforcement. Thus it became possible to combine weight reduction with safety in collision.

Predicting the crashworthiness of vehicle structures made by lightweight design materials and innovative joining methods

Abstract New materials (high strength steel, aluminium) and new joining methods (spot weld-bonding, clinching, toxing, riveting) are increasingly important in body engineering due to the demands of weight and cost reduction in the automotive industry. At the same time manufacturers and customers demands on passive safety are growing. Thin-walled columns are basic components in the concept and design of automotive body structures. Their crashworthiness behaviour is of fundamental importance in the safety design of the whole vehicle because their plastic collapse is the mechanism that is used to dissipate the kinetic energy of the vehicle in an accident. The mechanism of plastic collapse should be reliable and its evolution during the crash regular so that the desired quantity of absorbed energy, a low load uniformity and the required level of deformation load can be achieved without increasing danger for the vehicle passengers. To predict the characteristic values of automotive front structures energy absorption, e.g. weight specific energy absorption, load uniformity and structural effectiveness, the buckling of thin-walled columns, representing body front side members, were investigated in an experimental study. Geometries used for front side members like closed-hat, double-U and octagonal columns made by conventional steel, high-strength steel and light alloys were joined with different joining methods e.g. spot-welding, press-joining and structural adhesive. The design parameters of the specimen (t/a-ratio, flange width, joining width, material thickness, etc.) were varied in a wide range. Axial and non-axial quasi-static tests and even dynamic tests with different collision speeds were carried out. The results of this experimental based study are useful in the advanced crashworthiness design phase of automotive body structures. A software tool for body engineers, named ‘PRE-CRASH’, will be available soon to predict crashworthiness of the design. Due to that, design time and experimental work during prototype testing can be reduced in near future.