Direct Measurement of the Dynamic Side Forces on the Automotive Suspension Strut

Measuring side forces on the automotive suspension strut damper is critical in assuring the satisfaction of the design criteria. The advanced modeling and analysis technology has been used to design and validate the side force characteristics of the strut dampers, but the experimental verification method has not been sufficiently developed. The application of the strain gages on the reservoir tube of the strut damper has been used to measure the side forces. This conventional method features that the reservoir tube of the strut damper being used as the sensing element. However, the reservoir tube of the strut damper is in the path of the various external loads, and the strain output of the reservoir tube is affected by the unwanted source of forces. A method of the direct measurement of the side forces exactly on the force application point has been developed. The inner components of the strut damper are modified and sensorized to measure directly the forces acting on the rod guide and on the piston inside of the strut damper. The major side forces acting on the strut damper is two-axial, longitudinal and lateral in the vehicle coordinates; each sensor is composed of the independent two-axis load cell structure. The piston sensor is calibrated prior to assemble the strut damper, and the rod guide sensor is calibrated after all the components are assembled. The strut damper assembly is loaded with different load cases and stroke intervals, and the performance is evaluated. The side force measurement using the proposed and the conventional method has been performed on the proving ground, and the result is analyzed under various road events.