B-pillar Reinforcement Research Articles

MBN Measurement for the Transition Characteristics of Hard-to-soft Part of Automobile B-pillar Reinforcement Plate

MBN Measurement for the Transition Characteristics of Hard-to-soft Part of Automobile B-pillar Reinforcement Plate

Integrated design for the forming process and structural performance of variable-thickness laminates

The manufacturing process of composite laminated parts has a significant influence on the final performance, especially since the draping process can change the predefined fiber orientation at local sites. With the maturing of draping-process simulation technology, an integrated structure–process–performance design has become possible. This article reports a computational framework for the integrated design of the draping process and structural performance of variable-thickness (VT) laminates. The framework is a two-loop optimization workflow. Specifically, a genetic draping optimization method features the inner optimization loop to find the optimal draping strategy and obtain the resulting fiber orientations and manufacturing layout. Structural performance optimization outlines the outer optimization loop, where a parametric method for the physical configuration of VT laminates is proposed to evaluate the structural performance considering the draping strategy. The entire framework is demonstrated by an automotive B-pillar reinforcement. The benefits of incorporating the draping design versus no draping design are illustrated by comparing the corresponding design results. The comparison results show that the integrated design not only contributes to pretreating manufacturing defects but also allows the use of reoriented fiber directions caused by draping to improve the mechanical properties and engage the load bearing. It thus achieves a further weight reduction of 18.63%. This framework facilitates resource-friendly process design, comprehensive performance evaluation, and structurally efficient laminate design.

Variable-thickness design of CFRP B-pillar reinforcement considering draping

An integrated optimization method that comprehensively considers draping factors such as fiber reorientations and cutting of layers is proposed for designing CFRP B-pillar reinforcement with a variable thickness. A laminate parameterization scheme, the local shared layer parameterization scheme (LSL-PS), is developed to parameterize the physical composition of laminates with variable-thickness. Kinematic draping simulations and preform designs are introduced to evaluate fiber reorientations and eliminate manufacturing defects. The optimization design of the B-pillar reinforcement is integrated with a LSL-PS, draping-simulation and preform-design, a RBF surrogate model and GA. At the same time, a comparative optimization without the consideration of draping factors is performed in parallel. The comparison results show that considering draping not only helps designers eliminate manufacturing defects but also helps to obtain a further weight reduction of 13.33% because fiber reorientations are fully utilized to improve the structural performance.

Design of Prepreg Compression Molding for Manufacturing of CFRTP B-pillar Reinforcement with Equivalent Mechanical Properties to Existing Steel Part

Prepreg compression molding (PCM) is a well-known process for manufacturing of carbon fiber reinforced thermo-plastics (CFRTP) products with high quality and production rate. However, the design method used for the development of automotive parts has not been clearly presented. In this paper, we propose a process chain that can satisfy the stiffness of existing steel products. First, the CFRTP product of a B-pillar reinforcement to satisfy the bending deformation of an existing product is designed using a structural analysis and genetic algorithms. Next, forming conditions of the product are determined by a forming analysis. To investigate the feasibility regarding the mass production of the PCM process, a rapid heating and cooling system was applied to PCM molds. The heating and cooling times of the molds were calculated using a computational fluid dynamics analysis. Finally, a CFRTP product was fabricated and its bending deformation, dimensional accuracy, and weight were evaluated.

Design of Lightweight CFRP Automotive Part as an Alternative for Steel Part by Thickness and Lay-Up Optimization.

Mechanical properties, such as strength and stiffness, of laminated carbon fiber reinforced plastic (CFRP) are generally affected by the lay-up method. However, no precise design rules to replace steel products with CFRP have been established that satisfy these properties. Therefore, this study proposes a set of rules to design automotive parts with equivalent bending stiffness through structural analysis and genetic algorithms (GAs). First, the thickness of the CFRP product was determined by comparing the bending deformation of steel products by structural analysis. To minimize the orthotropic characteristics of CFRP, the quasi-isotropic lay-up method was implemented to determine the thickness. Next, the lay-up angle was determined using GAs. The optimized lay-up angle of the CFRP product with minimum bending deformation was determined by population generation, cross-over, mutation, and fitness evaluation. CFRP B-pillar reinforcement was fabricated using the determined conditions and the bending deformation of the single component was evaluated. Finally, the B-pillar assembled with CFRP reinforcement was investigated by the drop tower test.

Multi-material forming using DP780 and CFRTP

Recently, carbon fiber reinforced thermo-plastic (CFRTP) has been used widely in a number of composite applications owing to the growing concerns about reducing energy consumption and protecting the environment. Various attempts have also been made to apply CFRTP to automotive parts in place of metal alloys because of the superior mechanical properties and being lightweight. Generally, CFRTP is applied to automotive parts with metal alloys because of the high material price. Therefore, research has been conducted on the multi-material forming process to reduce the process price. However, it is difficult to predict the formability of multi-materials and to design the shape of a CFRTP part because there is little research on the design and formability prediction of multi-materials. The aim of this study is to develop the B-pillar on automobile reinforced with CFRTP. Since the B-pillar is deformed simultaneously with CFRTP and DP780, the following study is required. First, a shape optimization analysis was performed to design the B-pillar reinforcement using CFRTP. The determined shape of the B-pillar reinforcement was used to determine the thickness of the product that satisfied the bending stiffness of the conventional product. Next, the friction coefficient at the interface between DP780 and CFRTP was measured for a multi-material forming analysis. The problems that occurred during forming process were analyzed through a multi-material forming analysis. Finally, the developed product was manufactured through the same method as in the analysis, and any problems were evaluated and analyzed.

A study on the process design of prepreg compression forming using rapid heating and cooling system

Abstract Prepreg compression forming(PCF) is well known for the manufacturing process with high mechanical properties, low equipment cost and high surface quality. Generally, the temperature difference and rapid heat transfer between the tool and laminate can lead to some problems such as heat distortion, low formability and bad surface quality. Therefore, this paper attempts to solve these problems by using the rapid heating and cooling device, similarly to injection molding. It is possible to heat the tool above T g and cool it down under T g within few minutes. Also, the defect of distortion is prevented by rapid cooling system. In this study, the manufacturing process of CFRTP B-pillar reinforcement was designed based on structural analysis and thermal forming analysis. First, the thickness of laminate satisfying the energy absorption of conventional steel product was determined through structural analysis. Second, the thermal properties of the prepreg was evaluated for the thermal forming analysis. The thermal forming analysis of CFRTP laminate was carried out to determine the holding force. Finally, B-pillar reinforcements of CFRTP were fabricated and evaluated their dimensional accuracies and shear angle.

Influence of Material and Tribological Modelling on the Prediction of Big Size Automotive Components Springback

The finite element simulation has become an essential tool for the proper design of big size automotive components stamping tooling and their process optimization. Although big improvements have been made in the last years in terms of material and tribological modelling, the accuracy of the current models should be further improved to estimate the final post-forming springback of these components, in both AHSS and mild steels.In the present paper the forming of a B-Pillar reinforcement is numerically analyzed using a DX54D mild steel and a TRIP800 high strength steel. In the first part, the influence of the elastic behavior including variable young modulus, the yield criteria and the hardening law on the final springback is studied for both materials. Secondly, the friction coefficient is defined constant and pressure dependent and springback variation is analyzed in function of this variable.In order to stablish the material and friction variables and their typical deviation, results obtained from material characterization and strip drawing tests are used.

Finite Element Modelling Full Vehicle Side Impact with Ultrahigh Strength Hot Stamped Steels

“Hot stamped boron steel” 22MnB5 has been imperative in meeting the automotive industry’s demand for materials exhibiting higher tensile strength in the final component. In this paper, the crash performance of three experimental grades developed for automotive hot stamping technologies, exhibiting wider tensile property ranges than 22MnB5, was validated by finite element modelling full vehicle side impact with the experimental material data applied to the B-pillar reinforcement. The superior anti-intrusive crash performance of grade 38MnB5 was demonstrated, with 11 mm less intrusion of the B-pillar reinforcement compared to 22MnB5. Moreover, the superior “impact-energy absorptive” crash performance of grade 15MnCr5 was demonstrated, with 0.15 kJ greater impact-energy absorption by the B-pillar reinforcement compared to 22MnB5.

Deformation Properties of Tailor Welded Blank Made of Dual Phase Steels

Abstract The paper is dedicated to forming and properties of passenger car’s B-pillar reinforcement drawn from simple blank and alternatively tailor-welded blank (TWB). Drawn part is characterised by a place with a large strain, while forming process simulation did not confirm the creation of crack using the TWB consisting of dual phase HCT980X instead of previous HCT600 steel. It is because HCT980X steel has higher strength and lower ductile properties. The analysis of properties of drawn parts is focused on the simulated crash test in Dynaform software. Obtained sizes of drawn forces in simulated frame of the drawn parts and their comparison proved the possibility of the replacement the 1.2 mm thick simple blank from HCT600 steel with the 1 mm thick TWB consisting of HCT600 and HCT980X steel. The changed thickness of the simple blank caused 20% weight saving while containing the same properties of the drawn part.

Mechanical Properties of a High Si and Mn Steel Heat Treated by One-Step Quenching and Partitioning

Purpose: In this research, Q&P heat treatments in which the partitioning step is performed at a temperature equal to the quenching temperature were applied to a high Si and Mn steel and the mechanical properties of treated specimens were evaluated and discussed in continue. Design/methodology/approach: Chemical composition of base material is a significant subject that should be taken into account in Q&P process. The base material used in this research was a low alloy C-Mn-Si steel with a chemical composition similar to conventional TRIP-assisted steels. Findings: The products of tensile strength to total elongation of Q&P processed base material in this research were considerable comparing with similar heat treatments such as austempering and conventional quenching and tempering for industrial applications. Practical implications: According to the final results, considerable balances of strength and ductility were obtainable in Q&P treated specimens for application in automotive industrial such as B-pillar reinforcement, B-pillar inner, side member front floor, door panel inner, etc. Originality/value: of this paper is applying the Quenching &Partitioning (Q&P) as a novel heat treatment for excellent combinations of mechanical strength and ductility in steels components.

Optimized Design and Numerical Simulation of B-Pillar Reinforcement Panel by Hot Stamping Steel

In a certain vehicle of Dongfeng Passenger Vehicle Company (DFPV), a new design of integrated hot stamping B-pillar reinforcement panel is introduced to replace the original design of two cold stamping parts connecting by spot-weld. A further light-weight design by thickness thinning is also attempted. All the schemes are validated by hot stamping process simulation and vehicle side impact simulation. The results show that by using hot-stamping steel of the same thickness as the original design, the performance of anti-vehicle side impact is improved; and an equivalent anti-side impact performance can be achieved by appropriate thickness reduction, while the weight of the part is lightened.

Optimized AHSS Structures for Vehicle Side Impact

This article reports on a study of advanced high strength steels (AHSS) that are used in the automotive industry to achieve both overall vehicle weight and stringent vehicle crash test performance targets. The authors focus on cross-sections of automobile components, including rocker reinforcement, B-pillar reinforcement, front seat cross-member, roof rail, and door-beams. The authors used vehicle CAE side impact models to evaluate three side impact crash test conditions (Insurance Institute for Highway Safety [IIHS] side impact, National Highway Traffic Safety Administration [NHTSA] LINCAP and FMVSS 214 side pole) and the IIHS roof strength test condition. They identified several key components affecting the side impact test performance. The authors used HyperStudy® optimization software and LS-DYNA® nonlinear finite element software to determine shape and gauge optimization. Simplified bending crush simulation models were developed and a cross-section optimization was performed for bending crush performance. Finally, a material and gauge optimization was conducted on side structures using dual phase (DP) steels with 590 to 980 MPa minimum tensile strength. The authors determined that the front seat cross-member is a key component that affects the side pole impact; the use of an octagonal cross-section increased the buckling resistance when compared to the rectangular cross-section.

Very and Ultra High Strength Steels based Tailored Blanks: a step further towards vehicle crash performance improvement

Ultra and Very High Strength Steels (UHSS, VHSS) solutions are proposed by ArcelorMittal to meet front, side, rear and rollover crash requirements. UHSS and VHSS steel monolithic solutions have strongly progressed crash safety and lightening. Another step towards higher performance is afforded by UHSS and VHSS Tailored Welded Blank (TWB) configurations. Three parts are analysed that participate actively in vehicle crashworthiness: sidemember, B-pillar reinforcement and front-end bumper. A comparison between monolithic solutions and TWB solutions is presented, in order to determinate the extra gains (i.e. mass saving, energy absorption) that a TWB solution can offer.