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Vibration shaker testing is a great tool of validating the vibration fatigue performance of automotive components & systems. However, the representative vibration schedule requires a pre-knowledge of the acceleration history for the test object, which usually is not available until the later development phase of a vehicle program when physical properties are available. Sometimes, a generic vibration schedule developed from the worst-case loading profiles are used with risk of lacking correlation with later full vehicle durability test such as Road Test Simulator (RTS) or Proving Ground (PG) road test due to the higher loading amplitude. This paper proposes a virtual accelerometer approach to collect acceleration responses of a component from a virtual vehicle model. First, a multiple body dynamic model will be produced for virtual load calculation over a series of digitalized virtual proving ground road profiles.

An accurate representation of proving ground loading is essential for nonlinear Finite Element analysis and component fatigue test. In this paper, a rainflow counting based multiple blocks loading development procedure is described. The procedure includes: (1) Rainflow counting analysis to obtain the relationship between load range and cumulative repeats and the statistical relationship between load range and mean load; (2) Formation of preliminary multiple loading blocks with specified load range, mean load, and the approximate cycle repeats, and construction of the preliminary multiple loading blocks; (3) Calibration and finalization of the repeats for preliminary multiple loading blocks according to the equivalent damage rule, meaning that the damage value due to the block loads is equivalent to that from a PG loading.

Advanced high strength steels (AHSS) offer a good balance of strength, durability, crash energy absorption and formability. Applications of AHSS for lightweight designs of automotive structures are accelerating in recent years to meet the tough new CAFE standard for vehicle fuel economy by 2025. At the same time, the new generation pickup cargo box is to be designed for a dramatic increase in payload. Upgrading the box material from conventional mild steels to AHSS is necessary to meet the conflicting requirements of vehicle light weighting and higher payload. In this paper, typical AHSS grades such as DP590 and DP780 were applied to selected components of the pickup cargo box for weight reduction while meeting the design targets for fatigue, strength and local stiffness.

Cargo box is one of the indispensable structures of a pickup truck which makes it capable of transporting heavy cargo weights. This heavy cargo weight plays an important role in durability performance of the box structure when subjected to road load inputs. Finite element representation for huge cargo weight is always challenging, especially in a linear model under dynamic proving ground road load durability analysis using a superposition approach. Any gap in virtual modeling technique can lead to absurd cargo box modes and hence durability results. With the existing computer aided engineering (CAE) approach, durability results could not correlate much with physical testing results. It was crucial to have the right and robust CAE modeling technique to represent the heavy cargo weight to provide the right torsional and cargo modes of the box structure and in turn good durability results.

This paper describes static and fatigue behavior of resistance spot welds with the stack-up of conventional mild and advanced high strength steels, with and without adhesive, based on a set of lap shear and coach peel coupon tests. The coupons were fabricated following specified spot welding and adhesive schedules. The effects of similar and dissimilar steel grade sheet combinations in the joint configuration have been taken into account. Tensile strength of the steels used for the coupons, both as-received and after baked, and cross-section microstructure photographs are included. The spot weld SN relations between this study and the study by Auto/Steel Partnership are compared and discussed.

This paper describes a new procedure for more accurate durability predictions of stress along edges of automotive body structures. The current elemental stress based CAE procedures often require iterative mesh refinement to correlate predictions to experimental cracking on the edges of components. The new proposed procedure is based on element nodal stress. It is first studied on a circular hole representing a notch in a rectangular plate with different element sizes and options. Elemental nodal stress demonstrates an improvement over elemental stress methods by correlating with theoretical notch stress result. The proposed procedure is then studied on multiple examples of experimental cracks and successfully predicts issues where the current elemental stress method does not. In addition, it avoids the iterative mesh refinement associated with the current methods.

This paper describes a comprehensive methodology for the simulation of vehicle body panel buckling in an electrophoretic coat (electro-coat or e-coat) and/or paint oven environment. The simulation couples computational heat transfer analysis and structural analysis. Heat transfer analysis is used to predict temperature distribution throughout a vehicle body in curing ovens. The vehicle body temperature profile from the heat transfer analysis is applied as an input for a structural analysis to predict buckling. This study is focused on the radiant section of the curing ovens. The radiant section of the oven has the largest temperature gradients within the body structure. This methodology couples a fully transient thermal analysis to simulate the structure through the electro-coat and paint curing environments with a structural, buckling analysis.

This paper describes a CAE fatigue life prediction technique for a tailgate on pickup truck cargo box with inertial forces and moments applied at mass center of the tailgate as input loads. The inertial forces and moments are calculated from the accelerations measured at the corners of the tailgate as the truck is being driven over a durability schedule at the test proving grounds. All the dynamic responses of the tailgate on cargo box, including any dynamic interactions at the pivot joints between the tailgate and box sides, are captured in the acquired data and also in the inertial forces and moments computed at the mass center. Correspondingly, all the dynamic responses are included in the CAE fatigue life predictions. The dynamic interactions at the pivot joints are simulated by using two identical CAE models, one with lateral translational constraint applied at the left pivot only and the other at the right pivot only.