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Modeling and Analysis of a Heavy Vehicle with Self-Steering Axle
Abstract:
Commercial vehicles often incorporate self-steering axles to meet the axle load requirements while providing improved maneuverability, reduced off-tracking, and reduced tire and pavement wear. Market forces promote the design of more efficient self-steering axle products with reduced weight and more features. Manufacturers also work to differentiate their products through unique designs and new concepts. Traditional design methods for self-steering axles include empirical and trial-and-error methods to set the steering mechanism design parameters based on known design baselines and prior experience. For innovative new concepts that are too far from the traditional designs, it is desirable to have alternative ways for evaluating the expected performance.
This article introduces a reduced-order model that allows the rapid analysis of the steering dynamic behavior of self-steering axles. The model combines a pendulum-like lateral stiffness model with the axle steering dynamics which are then coupled to suitable reduced-order models for tractor-trailer combinations on which the self-steering axle can be mounted. The proposed model is shown to capture the shimmy behavior of the self-steering axle using phase portraits of the coupled nonlinear system. The model provides a way to identify the important stiffness and damping parameters of steering axle design concepts that are not yet sufficiently developed, and therefore the details required for full multi-body dynamic analysis are not available.