Sensitivity of Road Test Simulator Drive Files to Convertible Roof Configurations

Automotive companies are now offering the option of Hard-top (folding panel) or Soft-top (cloth) convertible roofs. It is therefore necessary to develop Road Test Simulator tests for four roof configurations: 1) Hard-top / Roof Down, 2) Hard-top / Roof Up, 3) Soft-top / Roof Down, and 4) Soft-top / Roof Up. This extends both the data acquisition and drive file development phases of the test. The objective of this paper is to examine whether the drives developed from one configuration (Hard-top / Roof Up) are valid for the other three configurations, assuming no suspension parameter changes. The changes in roof configurations are quantified by the relative difference in a) global body stiffness in torsion and bending, b) vehicle weight distribution, and c) roof center-of-gravity. The responses at the Proving Grounds and on the Rig are measured by: i) spindle loads and accelerations, ii) wheel-to-body displacement, iii) body acceleration, and iv) roof structural strains. The changes in these responses are analyzed in terms of Normalized Severity. It is concluded that Hard-top / Roof Up drive files iterated under recommended conditions, can be successfully used to drive the other three configurations.