Enhanced SAE 3 link Leaf Spring Model to Generate Durability Virtual Loads 2022-01-0289

Heavy-duty truck vehicles are generally equipped with leaf spring suspensions. Conventionally, beam elements are used in multibody software to build the leaf spring model to calculate virtual loads. Beam elements require a high computation time due to their numerous degrees of freedoms and force components introduced by beam connections, interleaf contacts, friction, etc. Again, in these simulations, solvers frequently fail in durability loads analysis due to sudden spike in accelerations and high suspension articulation coming from severe road profiles. These drawbacks lead to the use of simplified three-link mechanism models to simulate the leaf spring’s behavior, which is computationally faster. However, the current approach is less accurate as compared to the beam element model because this model has only a torsional spring which accounts for vehicle bounce condition. In reality, the leaf spring suspension system is also subjected to cornering and braking while running on road profiles like pave, potholes, bumps etc. This paper presents a novel simplified leaf spring model based on a three-link mechanism that captures leaf spring suspension’s bounce, braking, and cornering behaviors. Leaf spring parameters are identified from the beam element model using virtual Kinematics & Compliances tests; using a detailed FEA model or physical Kinematics & Compliances test data is also viable. Proposed simplified leaf spring suspension behavior is further validated through load cases such as vertical push, axle windup, cornering, suspension roll, etc. The suspension analysis using spindle loads from different road profiles are carried out and results validated, by comparing with the beam element model for results like Pseudo damage, max-min at different locations. The results of the simplified leaf spring model were closely matched with the beam model. With this simplified leaf spring model, loads can be quickly generated maintaining desired quality standards.