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This paper describes the implementation effort behind adding a pair of suspension links between the axle and frame of a light truck with a Hotchkiss-type suspension. These links, referred to as anti-windup bars (or traction bars), were introduced into an existing system to improve NVH performance; however, doing so required modifications to maintain other vehicle attributes, including vehicle safety and durability life. The authors address the management of these attributes and related design decisions for the components involved, focusing on the conflicting requirements involved. Physical vehicle testing, using design revisions recommended by Finite Element (FE) simulations, was performed to confirm component performance and related system behavior. Test results suggested improvements to the FE models that were required to more closely approximate the vehicle's behavior.

In this study the finite element method is used to simulate a light truck multi-leaf spring system and its interaction with a driven axle, u-bolts, and interface brackets. In the first part of the study, a detailed 3-D FE model is statically loaded by fastener pre-tension to determine stress, strain, and contact pressure. The FE results are then compared and correlated to both strain gage and interface pressure measurements from vehicle hardware test. Irregular contact conditions between the axle seat and leaf spring are investigated using a design of experiments (DOE) approach for both convex and discrete step geometries. In the second part of the study, the system FE model is loaded by both fastener pre-tension and external wheel end loads in order to obtain the twist motion response. Torsional deflection, slip onset, and subsequent slip motion at the critical contact plane are calculated as a function of external load over a range of Coulomb friction coefficients.