Front Longitudinal Beam Research Articles

Material Selection Decision-Making Method for Multi-material Lightweight Automotive Body Driven by Performance

This work proposes a material selection decision-making method for multi-material lightweight body driven by performance to achieve that the right materials are used for the correct positions of the automotive body. The internal relationship between performance and mass, cross-sectional shape, wall thickness parameters, and material properties of a thin-walled structure is studied. The lightweight material indices driven by performance are then established. The lightweight material indices and material price are taken as the decision-making criteria for the material selection of automotive body components. A hybrid weighting method integrated with the analytic hierarchy process, fuzzy analytic hierarchy process, and quality function deployment is proposed. The difficulty of quantitatively evaluating the performance requirements of different components of the body is solved using the proposed weighting method combined with the numerical analytical results of the component performance under multiple operating conditions of the automotive body. Then, the weight of the decision-making criteria for material selection is calculated. Grey relational analysis is used to make multicriteria decision-making on a variety of candidate materials to select the best material for body components. After the lightweight material selection of the front longitudinal beam of the automotive body, the frontal collision safety performance of the body is effectively improved, and the mass of the front longitudinal beam is reduced by 45%. Material selection result of the front longitudinal beam indicates that the proposed material selection decision-making method can effectively achieve the fast material selection of components in different positions of the body.

Multi-objective optimization of crashworthiness of vehicle front longitudinal beam

Front longitudinal beam (FLB) is an important structure for the analysis of force transmission and energy absorption path in different crashing scenarios. In the present paper, the finite element (FE) model of a full-scale vehicle yun-100 Zotye is employed to explore the energy absorption of FLB, and aiming at its poor energy absorption problem, circular beam was used as the original topology optimization space of FLB. The advantages of both static and dynamic topology optimization methods are fully considered, and a variable density method is combined with a hybrid cellular automaton (HCA) method. The substructure dissipated energy and force for frontal crash in a full-scale vehicle are obtained at a speed of 13.8 m/s. The maximum stiffness in axial is obtained through the static topology optimization method and the maximum energy-absorbing structure of FLB which is satisfied with axial strength obtained through the dynamic topology optimization method. According to the results of topology optimization, a multi-cell thin-walled structure is interpreted as the novel FLB. A parametric study on geometric parameters is also performed to explore their effects on crashing characteristics of novel FLB, and it is found that they significantly influenced the crashworthiness of multi-cell thin-walled structure (especially the absorption of energy). Furthermore, in order to maximize the characteristics of novel FLB, a multi-objective optimization process is carried out using non-dominated sorting genetic algorithm (NSGA-II). The optimized FLB after multi-objective optimization is applied to Zotye of 100% vehicle frontal crash. The results showed that the peak value of acceleration decreased by 10.3% and the mass of the optimized FLB reduced to 0.59 kg. It indicated that the optimized FLB manifested excellent crashworthiness and better protective characteristics.

Parameter Optimization of Hot Stamping for an Extension Part Based on DYNAFORM under the Background of New Engineering

Based on the finite element analysis software eta/DYNAFORM, the hotstamping mo del of the front longitudinal beam on an extension part was established. The finite element numerical simulation of the beam was carried out by the method of thermal coupling. The effects of different stamping speed, holding time, and temperature field and friction factor on forming quality were analyzed. The results show when the stamping speed of 200 mm/s, the holding time of 6s and the friction factor of 0.4, the martensite content is relatively higher and the springback is smaller. It provides an important basis for reasonable technological parameters of ultra-high strength parts, and also provides technical support for the new engineering construction.

Forming study on a tailor rolled blank (TRB) structure- formability evaluation and model verification

Tailor rolled blank (TRB) technique, as a relatively novel configuration, is of potential to fulfill the lightweight design. The examination of TRB defects in stamping process using traditional forming limit curve (FLC) is challenging. In this paper, the forming limit surface (FLS), which considers thickness changes, was used to evaluate the formability of front longitudinal beam (FLB) with TRB structure. A numerical model was developed to study the strain distributions and thickness transition zone (TTZ) movements during the TRB forming process. The effects of tool parameters (die clearance and draw-bead) on formability and TTZ movement were investigated. Results showed that the adaptive die gaps and segmented draw-beads were required in tool design to reach a better forming quality in the formed part. Besides, TTZ movement appears to be more structural dependent because the movements near the area with transition corner were larger and suffered smaller impact from parameter changes. The measured thicknesses of typical sections from formed part agree well with those predicted by simulation. This result confirms that the simulation strain used in formability evaluation was relatively reliable.

Energy Absorption and Lightweight Potential Analysis of the Front Longitudinal Beam

Different high-strength structural steel materials such as DP590, TR590, DP780, QP980, DP980, and MS1180 are tested for frontal impact in this research. The deformation modes and energy absorption characteristics of various materials and thicknesses are studied based on the trolley bump test. Then the average acceleration and the light weight potential under each structure are analyzed and compared. The research providedan optimized direction for the choice of stringer material and thickness.

Parameter Analysis and Cross-Section Shape Optimization of Front Longitudinal Beam with Variable Cross-Sectional Shape

Parameter Analysis and Cross-Section Shape Optimization of Front Longitudinal Beam with Variable Cross-Sectional Shape

Parametric modeling and multiobjective crashworthiness design optimization of a new front longitudinal beam

The front longitudinal beam (FLB) is the most important energy-absorbing and crashing force–transmitting structure of a vehicle under front-impact collision. For better weight reduction and crashworthiness of the FLB, a new structure, variable rolled blank–variable cross-sectional shape FLB (VRB-VCS FLB), is proposed. It has both the continuous variation of thickness and variable cross-sectional shape in space. As the thickness distribution and cross-sectional shape change continuously, the proposed structure evolves into three distinct forms, i.e., the uniform-thickness FLB, variable rolled blank FLB, and variable cross-sectional shape FLB. However, literature on parametric modeling and crashworthiness design optimization of the VRB-VCS FLB is very limited. This paper proposes a parametric modeling method of VRB-VCS FLB with manufacturing constraints. Multiobjective crashworthiness design optimization is performed to explore the lightweightness and crashworthiness performance of the VRB-VCS FLB. Firstly, thickness distribution and cross-sectional shape parameters are defined. Secondly, local parametric subsystem front-impact model is established to balance accuracy and efficiency. Thirdly, a multiobjective optimization model of VRB-VCS FLB is constructed. Finally, a fully automated design of experiment platform is established to improve the data collection efficiency, and epsilon-support vector regression technique and non-dominated sorting genetic algorithm II are utilized to search the Pareto optimal frontier. The numerical results show that the lightweightness and crashworthiness of the VRB-VCS FLB are significantly improved when compared with the uniform-thickness FLB.

Multi-objective reliability-based design optimization for the VRB-VCS FLB under front-impact collision

The front longitudinal beam (FLB) is the most important energy-absorbing and crashing-force-transmitting structure of a vehicle in a front crash. Its structure directly determines the safety performance of a car in front collisions and the effectiveness of passenger protection. In this study, a new structure, variable-rolled-blank and variable-cross-sectional-shape FLB (VRB-VCS FLB), is developed. It possesses both the continuous variation of thickness and variable cross-section shape in space. To make the VRB-VCS FLB structure more lightweight and crashworthy under reliability constraints, multi-objective reliability-based design optimization (RBDO) is performed in this paper. The multimodal radial-based importance sampling (MRBIS) method is integrated into the multi-objective RBDO to solve the system reliability for multiply-constrained problems, while the non-dominated sorting genetic algorithm II (NSGA-II) is used for solving deterministic optimization. The numerical results show that the crashworthiness performance and reliability of the VRB-VCS FLB is significantly improved when compared with uniform-thickness FLB.

Multi-objective optimisation on crashworthiness of front longitudinal beam (FLB) coupled with sheet metal stamping process

Nowadays, improving the accuracy of vehicle collision simulation is of great significance to the design and manufacture safety automobiles. Many parts in automobile manufacture are obtained by stamping process. The thickness, plastic deformation and residual stress will change after stamping process which will affect the simulation precision of vehicle collision. However, traditional collision simulation does not consider the influence of these factors. In this paper, a collision simulation method of the front longitudinal beam was studied which maps the stamping results to a collision structure model. The effects of stamping on the crashworthiness of front longitudinal beam (FLB) were analyzed to improve the accuracy and effectiveness of the automobile crash finite element simulation. To further study the effects of the manufacturing parameters (e.g. the thickness of the sheet metal, friction coefficient and two draw-bead coefficients on the energy absorption and peak crushing force), a multi-objective optimisation was carried out with non-dominated sorting genetic algorithm (NSGA-Ⅱ) through combining the stamping and collision process. The optimal results of the FLB show that the proposed method significantly improved the formability and crashworthiness.

Analysis of the Energy Absorption Capacity of Vehicle Front Components in Crash

Front crash has high probability in tranfic accident, and the front energy absorption part plays a very important role during the crash and is the key point to protect the safety of the occupant. The whole vehicle front crash is simulated in software LS-DYNA. This paper fix out the key steps and parameters in FEMB, and make good advise for finite anlysis. Finite anlysis is used in this paper to study motionstate of the vehicle and the energy absorption. Due to the anlysis, we find out that the front longitudinal beam is the most important component in the crash.

Vehicle Front Structure Energy Absorbing Optimization in Frontal Impact

Energy absorption performance is one of the most important indexes in the vehicle safety during impact. Research on the car frontal structure energy performance and structure optimization was conducted in this paper. Whole vehicle model was established by HyperMesh and simulated in LS-DYNA. Simulation results indicated that modification was needed for the original structure to meet the industry requirements. Based on simplified whole vehicle model, orthogonal design optimization was implemented, including bumper cross beam material (A), bumper cross beam thickness (B), energy absorber groove distance (C), and front longitudinal beam groove number (D), with 3 levels for each factor. The best option was B3D1A3C3 which was gained by using range analysis and integrated balance method. Simulation results showed that both front and total energy absorptions were improved. The optimized structure increased front energy absorption to 51.1%, which can meet the industry requirement.

Analysis and Application of the Impact Absorption Behavior of the Composite Tube

Composite tube is one new kind of multi-material shell structures. It has both of metal and composite energy absorption advantage. In order to find the energy absorption characteristic of composite tube and put it into use, the Drop-Weight Tear Test (DWTT) was carried out. The LD2Y aluminum was chosen as the inner metal material which was wrapped fiberglass epoxy composite outside. During the test, the displacement signal and velocity signal, acceleration signal were got by piezoelectric acceleration transducer. Furthermore, the DWTT test of the composite tube was simulated in LS-DYNA, and proved the validity of the model by comparing the simulation results with the experiment results. We established the vehicle front longitudinal beam model with the material type of the composite tube, and carried out the simulations of whole car collisions in LS-DYNA according to FMVSS 208. Through the analysis of occupant head injury got from the simulations, we got the result that using the composite tube material could not only elevate the cars safety but also reduce front longitudinal beam weight effectively.

Improvement of energy-absorbing structures of a commercial vehicle for crashworthiness using finite element method

This paper describes the results of the frontal crash simulation of a commercial vehicle using the nonlinear finite element method. The dynamic responses of the vehicle during the frontal crash at 48.3 km/h and 8 km/h are presented. In the developing stage of the design the structure of the front longitudinal beam is optimized, hence the amount of energy absorbed increases greatly. In the test stage of the whole vehicle, the data of the simulation predict that the hinge of the engine hood would fracture during the crash. This fact has also been validated by the test. The failure of the engine hood hinge would be a danger to both the driver and the passengers. So, according to the simulation, the structure and material of the engine hood and hinge are modified. As a result the deformation mode of the engine hood is improved accordingly.