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This work deals with the effect of different blasting conditions under stress on the intensity and distribution of compressive residual stresses. The tests were performed on bars measuring 17 mm x 70 mm x 1700 mm in AISI 51CrV4 carbon steel. The samples are considered parabolic leaf spring, as there is a variation in thickness from the tip to the center, the thickness ay the center is higher than tip thickness. The samples were laminated to their thickness in double roller laminators, in order to obtain the desired thicknesses. The samples were quenched and tempered in industrial scale furnaces. The pre-tensions were calculated by the ANSYS® software and validated by characterization with strain gauges, in a test condition of 1400 MPa of pre-tension. Tensile tests and microstructure analysis were applied to ensure the specification in terms of strength and microstructure.

Vehicle suspension systems that adopt Hotchkiss layout are commonly based on leaf springs. For better comfort for passengers, some features such as rubber pads are used on the springs to reduce noise from metallic contact between leaves, but those pads can compromise the durability of the spring if not well designed or located in the spring assembly, as we will demonstrate on this paper. To do so, it will be presented comparisons using CAE methodology and physical parts test results from vehicle and bench testing which were loaded in different conditions to demonstrate how the rubber pad position can influence the durability of the spring, especially near the eyelet region for some specific load conditions. The case studies presented here are focused on the impact of the rubber pads on durability life of springs, but not defined as root cause of failures.

”U” bolts are fixing elements and they are used to clamp an elastic joint. From the past, they still looking as an old design and unfortunately, suspension engineers are not specialists in fasteners and elastic joints. That is why we will show important assumptions and concepts to design and specifications this clamp element “U” bolt and its influence over leaf-springs. Currently, “U” bolt is used to clamp an elastic or elastic-plastic joint of heavy duty suspension, formed by leaf-spring, axle, spring pad, “U” bolt plate. This kind of suspension is typically used to trucks, buses and trailers. We are wondering, which one important assumption that an engineer must be careful when designs a new suspension changing from old designs to an updated technology. We provide a theoretical analysis and a FEA analysis to compare torque efficacy x leaf-spring reactions and what are effects this relationship can cause in a suspension.