SAE International Virtual Prototyping in Redesign and Durability Test Assessment 2008-01-0862

The durability of a new cost saving frame for the E-Z-GO ST 4×4 utility vehicle is investigated based on known road test data and durability information for the current frame. To validate the concept of the frame redesign, reduce the number of prototypes, shorten test duration and save lab costs, virtual prototyping is applied. Road test data is acquired and processed by nCode software including rainflow cycle counting with different turning points for fatigue estimation. FEA structure analysis is processed in ANSYS. Optimization analysis is used for correlating real road load with simplified FEA model for the entire vehicle. Based on the correlated FEA model, the estimation of the durability for the current frame and redesigned frame is conducted. Results of both, the stress analysis under peak load and the fatigue prediction for vehicle riding history, are used for relative comparison between the new frame and current design. Fatigue life distribution has been investigated, and possible failure areas have been diagnosed. Fatigue estimation with constant load tests is conducted and is correlated with the predicted life based on compressed cycling loading data. An acceleration test assessment, applying a constant step load, is suggested. An accelerated durability test is conducted to validate the redesign based on the durability assessment instead of a formal four-poster test. Static structure analysis, DOE and fatigue estimation are applied to the reliability investigation and to acquire a satisfactory result on both of frame durability and acceleration test settings. Virtual prototyping not only improves redesign, but also saves time and reduces the cost of redesign verification.