Multi-Axial Mechanical Characterization Of Rubber Bushings: Radial, Torsional, And Cardanic Stiffness Analysis

<p style="text-align: justify; ">Rubber bushings are among the most critical elastic components in modern vehicle suspensionsystems. Their primary functions are to damp shocks and impacts from the road, filter vibrations,and ensure superior ride comfort by reducing Noise, Vibration, and Harshness levels. Furthermore,&nbsp;they help maintain suspension geometry, directly impacting vehicle safety, road handling, and thelifespan of general mechanical components. Due to this critical role, the accurate characterizationof the bushings' stiffness values in the three main loading directions—radial, torsional, andcardanic —is of vital importance. This study details the hyperelastic and viscoelastic behavior ofrubber bushings under three different loading modes. For the scope of this study, a rubbercompound with a standard 59,45 Shore A hardness was used, and three different interference ratiovariations in the bushing geometry (1,95 mm, 2,05 mm, and 2,15 mm) were tested. The stiffnessvalues were determined using calibrated MTS and Zwick universal testing machines, incompliance with industrial standards. These tests comprehensively revealed the non-linear andhysteretic behavior of rubber materials under load. The test results indicated that the bushingproduced from the 59,45 Shore A hardness rubber compound with a 2,05 mm interferenceapplication exhibited the best results in terms of performance criteria. For this optimal bushing, theradial stiffness value was measured as 45,33 kN/mm, the torsional stiffness value as 10,2 Nm/°,the torsional torque value as 285,88 Nm, the conical stiffness value as 9,38 Nm/°, and the conicaltorque value as 252,06 Nm. These findings serve as an important reference for the optimized designof rubber bushings for heavy-duty vehicle suspension systems.