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Due to magnesium alloy's poor weldability, other joining techniques such as laser assisted self-piercing rivet (LSPR) are used for joining magnesium alloys. This research investigates the fatigue performance of LSPR for magnesium alloys including AZ31 and AM60. Tensile-shear and coach peel specimens for AZ31 and AM60 were fabricated and tested for understanding joint fatigue performance. A structural stress - life (S-N) method was used to develop the fatigue parameters from load-life test results. In order to validate this approach, test results from multijoint specimens were compared with the predicted fatigue results of these specimens using the structural stress method. The fatigue results predicted using the structural stress method correlate well with the test results.

Generally linear finite element analysis (FEA) is used to predict fatigue life of spot welded joints in a vehicle body structure. Therefore, the effect of plastic deformation at the vicinity of the spot welded joints is not included on fatigue prediction. This study introduces a simple technique to include the plastic deformation effect without performing elastic-plastic finite element analysis. The S-N curve obtained from fatigue test results is modified to consider this effect. Tensile strength test results of spot welded joint specimens were utilized to find the load range for FEA equivalent to the applied load range for fatigue tests. To demonstrate the proposed approach, fatigue test results of advanced high strength steels (AHSS) for lap-shear and coach peel specimens were used. Both the specimen types were tested at various constant amplitudes with the load ratios of R=0.1 and 0.3.

In the North American automotive industry, various advanced high strength steels (AHSS) are used to lighten vehicle structures, improve safety performance and fuel economy, and reduce harmful emissions. Relatively thick gages of AHSS are commonly joined to conventional high strength steels and/or mild steels using Gas Metal Arc Welding (GMAW) in the current generation body-in-white structures. Additionally, fatigue failures are most likely to occur at joints subjected to a variety of different loadings. It is therefore critical that automotive engineers need to understand the fatigue characteristics of welded joints. The Sheet Steel Fatigue Committee of the Auto/Steel Partnership (A/S-P) completed a comprehensive fatigue study on GMAW joints of both AHSS and conventional sheet steels including: DP590 GA, SAE 1008, HSLA HR 420, DP 600 HR, Boron, DQSK, TRIP 780 GI, and DP780 GI steels.

Corrosion-fatigue (CF) and stress corrosion cracking (SCC) have long been recognized as the major degradation and failure mechanisms of engineering materials under combined mechanical loading and corrosive environments. How to model and characterize these failure phenomena and how to screen, rank, and select materials in corrosion-fatigue and stress corrosion cracking resistance is a significant challenge in the automotive industry and many engineering applications. In this paper, the mathematical structure of a superposition-theory based corrosion-fatigue model is investigated and possible closed-form and approximate solutions are sought. Based on the model and the associated solutions and test results, screening and ranking of the materials in fatigue, corrosion-fatigue are discussed.

Swing-out doors can easily cause damage to adjacent parked vehicles in tight parking spaces. Also, they are not traffic-friendly when the vehicles are parallel parked on busy road sides. This paper makes an attempt to come up with an innovative to design and develop a mechanism for dual sliding doors for a small sized car. The doors are supported only on two points of contact as compared to the usual sliding minivan doors which have three contact supports for sliding. These two points are called the “Upper control link and Lower support arm”. To open the door, first the door, has to push out by 90 degrees and then it has to slide in the fore-aft direction to open or close. For the doors, a track was placed just below the window at the beltline location and a triangular sub-roller assembly was designed for sliding motion.

Sliding doors are usually employed on the rear side of minivans and some large vehicles for easy egress and ingress. Furthermore, dual sliding doors are frequently observed in various concept models. This paper describes design of a dual sliding door for a small-size car. A new sliding mechanism with two sliding contact points is proposed with the B-pillar incorporated in the door structure made of high strength steel. Two sliding tracks are located in the door and the rocker panel. The door linkages first swivel and then slide with the help of the rollers in the tracks to open the door. The sliding mechanism and the door structure were validated using CAE tools such as HyperMesh, MSC/NASTRAN [2] and LS-DYNA[3].

This paper presents a design and development approach for automotive bucket seat frame using a parametric modeling and a finite element analysis methodology. This approach is expected to help build a lightweight seat structure quickly and efficiently. This approach is general, and it can be applied in designing and developing any mechanical structural component. The design process involves, first parametric modeling of the front bucket seat frame using Pro E. This CAD model was then optimized using optimization software called Optistruct, for two cases of load case and boundary condition. The optimized design was then tested for FMVSS seat requirements using LS-DYNA. The dynamic nature of the design approach helps in changing design parameters during different stages of the design process, until the seat structure satisfies the design criteria and the strength requirements. The construction and testing of this design and the design model are still under progress.

Vehicle design is an iterative process with limited information available during the early design stages. However, vehicle design and performance tests such as crashworthiness, noise, vibration & harshness (NVH) and durability can now be conducted using CAE methods, providing useful insight into the vehicle design process prior to prototype development. A concept Low-mass vehicle (LMV) was initiated by the University of Michigan-Dearborn (UMD) and is in its early design stage. It is targeted to 30% weight reduction compared to class-B vehicle with similar performance characteristics. A full vehicle MBD (Multibody Dynamic) model was developed and simulated using ADAMS to generate road load history, on various road surfaces with the application of FTire and MF-Tire tire models. The significance of the tire model and its modeling technique was identified by observations on quantitative values such as component fatigue life rather than road-load history itself.

Gas Metal Arc Welding (GMAW) is widely employed for joining relatively thick sheet steels in automotive body-in-white structures and frames. The GMAW process is very flexible for various joint geometries and has relatively high welding speed. However, fatigue failures can occur at welded joints subjected to various types of loads. Thus, vehicle design engineers need to understand the fatigue characteristics of welded joints produced by GMAW. Currently, automotive structures employ various advanced high strength steels (AHSS) such as dual-phase (DP) and transformation-induced plasticity (TRIP) steels to produce lighter vehicle structures with improved safety performance and fuel economy, and reduced harmful emissions. Relatively thick gages of AHSS are commonly joined to conventional high strength steels and/or mild steels using GMAW in current body-in-white structures and frames.

The concept vehicle under study was equipped with a rear twist beam suspension. Apart from designing and analyzing the twist beam for structural integrity, the effects of its directional stiffness values on vehicle dynamic behavior had to be taken into account. The twist beam suspension was initially modeled using beam elements to offer more parametric freedom, followed by DOE and optimization for the target suspension kinematic and compliance (K & C) performances within MBD environment. The data obtained from DOE within the MBD environment, such as the mounting locations, geometrical requirements, etc. were the critical inputs to structural definitions used for constructing the FE model. The resulting FE suspension subsystem was then evaluated for full vehicle performances using typical cornering maneuvers within MBD.