Structural MBD Tire Models: Closing the Gap to Structural Analysis - History and Future of Parameter Identification 2013-01-0630

Today's tire models used in MBD full vehicle application scenarios like Ride&Comfort or Durability are parameterized with a variety of ‘spindle load’ measurements: quasi-static (e.g. vertical, lateral and circumferential stiffness), quasi-steady-state (e.g. pure lateral and longitudinal slip) and transient (e.g. cleat run) tests in well defined tire stand-alone test rigs measure the accumulated tire force acting on the wheel center. While some tests are designed to induce local deformations (e.g. vertical stiffness on cleats), no measurement of local reactions (e.g. sidewall displacement or rim strain) are performed in a standardized way - apart from footprint and contour tests.

The level of detail in structural FEA tire models renders them unfeasible for most full vehicle applications due to the implied computational effort; however, dedicated tire stand-alone scenarios are well within reach of today's R&D IT infrastructures. While their applicability for transient simulations (such as cleat runs) is still under investigation, quasi-static and steady-state simulations are common practice in the tire industry. Of course, without access to the proprietary information on constructional and material data of the tire industry, vehicle OEM departments, R&D suppliers and universities need to rely on reverse engineering techniques to parameterize their FE tire models.

The main focus of this paper is the introduction of a newly developed structural MBD tire model with dedicated descriptions of the main constructional elements of a tire such as belt, carcass and bandage layers with cords. It was specifically designed to combine the prediction quality of quasi-static and steady-state FEA models with the computational performance of MBD tire models. A parameter identification procedure is introduced that explicitly excludes cleat runs and focuses instead on a mixture of static, steady-state and local geometrical measurements. This procedure is not targeted at replacing today's standard procedures, but to allow for cases where standard tire measurements (such as cleat runs) are not available due to present day limitations of test facilities with respect to e.g. tire size or preload restrictions. However, the authors see some potential that these methods can eventually eliminate the need for cleat run tests in parameter identification also for passenger car tires - and as such allow them to be validation tests only.