Front Side Member Research Articles

Effective Press Folding Line Processing as Deformation Induction for Adjusting Impact Energy Absorption

Press formed products have recently been applied widely in various structures. Press forming is a mass production method that is used to manufacture many machine components such as automobiles, industrial machinery, and various plants. However, there is a limit to the degree of shape freedom that can be applied, so measures against cracks, wrinkles, spring-back, etc., must be taken in the development process. It is well known that it is difficult to apply it economically in the case of small-lot production because of its high capital investment. The previous report shows that the folding line processing by press method / bending has a high degree of shape freedom, requires little capital investment, and can be expected to be applied for experiments and prototypes, and for commercial products from small to mass production. This paper shows that press folding line processing using V-shaped punch can be applied as deformation induction based on impact crushing experiments using square steel tubes/ aluminum thin wall cylinders and FEM results. To improve the impact energy absorption performance in the event of a collision, notches and uneven surfaces called beads have been formed in the crush boxes and front side members as automobile parts manufactured by press forming. The bead has the role of inducing deformation so as to improve the impact energy absorption performance during the axial crushing process. However, beads as deformation induction by the press forming, in addition to the difficulty of die design/manufacturing, needs to correct the bead design after impact experiments using prototypes. This paper shows press folding line processing as deformation induction is very convenient and effective to adjust impact energy absorption only by setting folding lines arrangement, not for bending along folding lines. Press folding line processing can be applied for the high performance crush box development.

変形誘発で衝撃エネルギー吸収を調節できるプレス折線加工の提案

Press forming is a mass production method that is used to manufacture many machine components such as automobiles, industrial machinery, and various plants. However, there is a limit to the degree of shape freedom that can be applied, so countermeasures against cracks, wrinkles, spring-back, etc., must be taken in the development process. It is well known that it is difficult to apply it economically in the case of small-lot production because of its high capital investment. In a previous report, the author reported that the folding line processing by press method / bending has a high degree of shape freedom, requires little capital investment, and can be expected to be applied for experiments and prototypes from small to mass production. This paper shows that press folding line processing using V-shaped punch can be applied as deformation induction based on experiments and FEM results. To improve the impact energy absorption performance in the event of a collision, notches and uneven surfaces called beads have been formed in the crush boxes and front side members as automobile parts manufactured by press forming. The bead has the function of inducing deformation so as to improve the impact energy absorption performance during the axial crushing process. However, bead setting for inducing deformation by the press forming, in addition to the difficulty of mold design/manufacturing, needs to correct the bead design after impact experiments using prototypes. This paper shows press folding line processing as deformation induction is very convenient and effective.

Simulation and Optimization of Body Structure of Electric Vehicles with Offset Collision

In recent years, as the rapid growth of the number of electric vehicles, people have more and more requirements on the safety performance of vehicles. However, compared with fuel vehicles, the structure of electric vehicles has its own particularity which makes the safety design of body structure more difficult. Thus, improving the passive safety of electric vehicles and protecting the passengers from injury in the collision to the greatest extent have become important issues for the automotive industry. This paper simulates the frontal offset impact simulation analysis of a certain type of SUV, and analyzes the safety performance of the vehicle from the perspective of member protection. The front side member structure and impact energy absorption which affect the passive safety of the whole vehicle are optimized and improved. The finite element model of the whole vehicle is rebuilt, and the frontal offset impact simulation test is carried out to verify the effectiveness of the optimization scheme.

The impact behavior of the crash boxes

This article will study the impact behavior of the crash box structures. The crash boxes are found between the front cross member and the front side members. They play an important role in case of minor frontal impact, speeds up to 15km/h. For this study, we propose three models of crash boxes of different sections. The impact analysis will be performed using the software ANSYS, Explicit Dynamics module. The shape and dimensions of the models were obtained from repeated impact tests. Thus, the obtained results were used for the continuous improvement of the crash boxes. The proposed models are made from extruded Aluminum bars with different sections. With the help of finite element analysis (FEM) one can compare the results and what impact energy absorption characteristics each proposed model of structure presents.

Energy Absorption Due to Oblique Impact Crushing of Thin-Walled Tubes

From the viewpoint of improving both the crash safety and the fuel efficiency, various shaped thin-walled tubes have been utilized as energy absorbers of automobiles such as front side members, crash boxes and so forth. In the axial crushing test of the regular polygonal tube, if the number of angles was small enough, it showed a certain inherent wrinkle mode, and the mean buckling load increased with that number, while it showed the mode of cylindrical tube if that number became larger. In the oblique crushing test, the same tendency was also shown within the range that the transition from axial collapse to bending collapse did not occur. This transition considerably decreases the mean buckling load so that it is important to know the threshold crush angle for the transition. Then, the crushing behavior of regular 4-12 angled tubes were investigated with changing the crush angle mainly by the experiment. The threshold angle is sensitively influenced by the initial imperfection and the boundary condition so that both the threshold angles obtained by the experiment and by the calculation for the square tube are 8-13° smaller than that predicted by the equation proposed by Han and Park. For the carbon steel S25C, the increase of the strain rate in the axial collapse mode raises the mean buckling load, while it shows little strain rate dependence once the transition occurs.

Design of a half cut side member structure for optimal car crash energy absorption characteristics

The front side members of a car play a vital role in energy absorption for improved occupant safety during a crash. The response of side members with a half cut structure was examined with a parameter study. The structural design variables were the number of edges of the polygonal cross section, the spot welding spacing, and the thickness of the thin-walled side member structure. An optimal design method for the half cut side member was developed to maximise the absorbed energy by applying a response surface optimisation method. An objective function was used to maximise the energy absorbed by the side member structure. The mass of the optimal side member was constrained to be less than an allowed value.

熱可塑性CFRP異形断面ビームのプレス成形と強度評価

As a demonstration of the production process of thermoplastic carbon fiber reinforced plastic (CFRTP) parts by press forming, a varying-cross-section beam has been press formed using thermoplastic carbon fiber composite sheets. The shape of a front side member in an automobile has been applied as the formed shape 800mm long, 170mm wide in front, 270mm wide in the rear and 50mm high. Deformation of the fiber during the press forming has been investigated. Inserting sheets with fiber orientations corresponding to the corner line in the varying width part had an effect on the uniformity of the mechanical strength in the formed beam. Two beams are joined to a closed beam and a drop impact test has been carried out. The results showed that the beam has the favorable characteristic that a constant destruction load is maintained from the front to the distance in which the impact energy is absorbed. The constant destruction load depended on the combined strength of the sheets in the press-forming process.

Simultaneous optimization of blank shape and variable blank holder force of front side member manufacturing by deep drawing

This paper presents a method to determine an optimal blank shape minimizing earing for a front side member. In addition, variable blank holder force, meaning that the blank holder force (BHF) varies through punch stroke, is adopted. Blank shape directly affects the material cost, and it is important to determine an optimal blank shape minimizing earing that is trimmed out. BHF also have an influence on the product quality. Large BHF leads to tearing, whereas small BHF results in wrinkling. Variable BHF (VBHF) approach is recognized as one of the advanced manufacturing technologies, but it is difficult to determine the optimal VBHF for successful sheet metal forming. To determine the optimal blank shape and VBHF simultaneously, design optimization is performed. Numerical simulation in sheet metal forming is so intensive that a response surface approach is valid. In particular, a sequential approximate optimization that the response surface is repeatedly constructed and optimized is used to determine the optimal blank shape and VBHF. Front side member provided from NUMISHEET 2011 (BM3) is used for the numerical simulation. It is found from the numerical result that the proposed approach can drastically reduce the earing. In addition, the maximum thinning is much improved, compared with other results reported in NUMISHEET 2011.

Thermo-Mechanical Forming Analysis and Mapping of Material Properties in Press Hardened Components with Tailored Material Properties

A finite element model for failure prediction has been used for axial compression simulation of a front side member beam with tailored material properties. A corresponding experiment has been performed. The numerical simulation is divided into forming, mapping and axial compression. The coupled thermo-mechanical hot stamping simulation includes an austenite decomposition model that accounts for carbon segregation. In the mapping step, the phase composition is first mapped and then translated into global stress-strain curves and failure parameters using two different models. An elastic-viscoplastic material model including mesh size dependent localization and crack initiation with a ductile and shear fracture model is used in the axial compression simulation. The simulation shows acceptable agreement with the experimental results.

Springback Prediction Compensation and Optimization for Front Side Member in Sheet Metal Forming Using FEM Simulation

Numerical simulation by finite element method has become a powerful tool in predicting and preventing the unwanted effects of sheet metals technological processing. One of the most important problems in sheet metal forming is the compensation of springback. To improve the accuracy of the formed parts, the die surfaces are required to be optimized so that after springback the geometry falls at the expected shape. This paper presents and discusses numerical simulation procedure of die compensation by using the methods of Simplified Displacement Adjustment (SDA). This analysis use Benchmark 3 models of Numisheet 2011. Sensitively analysis was done by using finite element method (FEM) show that the springback values are influenced by element size, integration points and material properties.

Springback Prediction Compensation and Optimization for Front Side Member in Sheet Metal Forming Using FEM Simulation

Numerical simulation by finite element method has become a powerful tool in predicting and preventing the unwanted effects of sheet metals technological processing. One of the most important problems in sheet metal forming is the compensation of springback. To improve the accuracy of the formed parts, the die surfaces are required to be optimized so that after springback the geometry falls at the expected shape. This paper presents and discusses numerical simulation procedure of die compensation by using the methods of Simplified Displacement Adjustment (SDA). This analysis use Benchmark 3 models of Numisheet 2011. Sensitively analysis was done by using finite element method (FEM) show that the springback values are influenced by element size, integration points and material properties.

Prehistoric Effect of the Stamping Process on the Crash Analysis of an Automobile under Frontal Impact

In this paper, a frontal crash analysis is carried out with a full vehicle model in order to investigate the influence of stamping effects of auto-body members on the crash characteristics of the vehicle. Stamping effects are considered for load carrying members such as the front side member and the rear lower. From the analysis result considering stamping effects, it is conformed that stamping history has to be considered for longitudinal members simultaneously that transfer the impact load under the frontal impact. Comparison of simulation result with experimental one also shows that the prediction accuracy of the crash analysis is remarkably improved.

비드 형상 최적화를 이용한 전방 측면 부재의 충돌 최적화 연구

본 논문은 위상최적화 기법을 이용하여 전방측면 부재를 최적화 한다. 전방측면 부재에 최적화를 진행하기 전에 사각단면 부재에 최적화를 진행한다. 목적함수는 1 차 좌굴 계수가 길이방향으로 최소화 되도록 설정한다. 설계변수는 법선방향으로 질점의 이동이다. 사각단면부재의 반응표면법을 이용한 최적화 모델과 위상최적화 모델에 대해 충돌해석을 수행한다. 위상최적화 기법을 검증하기 위해 두 결과를 비교한다. 그 결과 위상최적화 기법을 충돌해석에 적용할 수 있다는 것을 확인하고 실제차량의 전방측면부재에 적용한다. 결과적으로 전방측면 부재는 최적화되고 내충격성이 향상한다.

방사소음 및 투과소음에 대한 승용차량 대시패널의 설계인자 별 영향도 분석

While a dash panel component, close to passengers, plays a very important role to protect heat and noise from a power train, it is also a main path that transfers vibration energy and eventually radiates acoustic noise into the cavity. Therefore, it is important to provide optimal design schemes incorporating sound packages such as a dash isolation pad and a floor carpet, as well as structures. The present study is the extension of the previous investigation how design variables affect sound radiation, which was carried out using the simple plate and framed system. A novel FE-SEA hybrid simulation model is used for this study. The system taken into account is a dash panel component of a sedan vehicle, which includes front pillars, front side members, a dash panel and corresponding sound packages. Design variables such as panel thicknesses and sound packages are investigated how they are related to two main NVH indexes, sound radiation power(i.e. structure-borne) and sound transmission loss(i.e. air borne). In the viewpoint of obtaining better NVH performance, it is shown that these two indexes do not always result in same tendencies of improvement, which suggests that they should be dealt with independently and are also dependent on frequency regions.

2215 自動車サイドメンバーの衝突エネルギー吸収性能の最適設計(OS6-4 設計と最適化IV)

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 more than that of original half cut type of box-shaped cross sectional side member structure which is generally used.

Forming process design for the twist reduction of an automotive front side member

Forming process design for the twist reduction of an automotive front side member

Simulation Analysis of Crash Tests for the Front Side Member in LS-DYNA

How to improve the collision process of safety performance has become one of the most important issue in the automobile manufacturing enterprises. This paper using LS-DYNA made a security analyses about former girders, based in half vehicle model, analyzing the security of the front side member to reflect the vehicle’s performance. At the same time, through the front side member’s assembly structure’s contrast with the modified ones, the result has proved the improvement is more effective.

Shape Optimization to Improve Energy Absorption Ability of Cylindrical Thin-Walled Origami Structure

During car frontal crash, crush energy is absorbed by the parts of front bumper, front side member, front panel member and so on. 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 crush energy as much as possible. In this study, we adopt cylindrical thin-walled structure using origami engineering as front side member instead of structure with rectangular cross section which is generally used. We develop an optimization system of the cylindrical thin-walled origami structure, in which the objective function is to maximize the energy absorption of origami structure; the design variables are structural parameter, number of divisional sections along axis, number of edges of polygonal cross section and number of subdivision levels; the weight and initial peak load of optimal structure must be less than those of structure with rectangular cross section. We then discuss the optimization results that the optimal structure is capable of absorbing energy 91% more than that of original rectangular cross sectional structure which is usually bended on the way of being crushed, 37% more than that of original structure which is ideally crushed to 70% length without bending.

Study on Crash Characteristics of Half Cut Type Vehicle Side Member Structure of Energy Absorption Ability by Using Origami Engineering

As regard to 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, we investigated the crash characteristics of half cut type side member structure by optimal design method to improve the performance for energy absorption. 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 number 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.

Robust optimization of front members in a full frontal car impact

In the search for lightweight automobile designs, it is necessary to assure that robust crashworthiness performance is achieved. Structures that are optimized to handle a finite number of load cases may perform poorly when subjected to various dispersions. Thus, uncertainties must be accounted for in the optimization process. This article presents an approach to optimization where all design evaluations include an evaluation of the robustness. Metamodel approximations are applied both to the design space and the robustness evaluations, using artifical neural networks and polynomials, respectively. The features of the robust optimization approach are displayed in an analytical example, and further demonstrated in a large-scale design example of front side members of a car. Different optimization formulations are applied and it is shown that the proposed approach works well. It is also concluded that a robust optimization puts higher demands on the finite element model performance than normally.