Análise da perda de torque entre dois fixadores diferentes em um conjunto de suspensão veicular

Abstract

Experimental validation is always very important for any product or component, even more so in the automotive industry. On the other hand, the costs involved to adequately instrument a component, provide a vehicle and labor for testing for long periods of time mean that the experimental methods are intended only in the final stages of product validation. This work was initially aimed at the acquisition of data, by means of the installation of load cells, referring to the clamping force in the spring clip of the suspension of a 10 ton micro bus subjected to dynamic stresses. With the focus on torque loss analysis, two types of fasteners were used in the spring clamp to compare their behavior, a standard thread profile fastener and a special thread profile fastener. With the instrumented clamps, a standard methodology was defined so that each cycle of data acquisition in the tracks of the Center of Technology Randon, had by variable only the fixing nut. The signal generated by the tracks was filtered and analyzed. The section of parallelepipeds was selected for the application of the cycle count rainflow method, because it presents alternating load amplitudes of alternating loads that the other tracks and not be of high severity as the track of holes. The loads for parameterization of the dynamic loading machine were analyzed analytically. The SWT criterion for medium force correction was used to operate with floating load under traction. A device was designed to simulate the clamping of the spring clip using as many components as possible of the vehicle tested. The laboratory test generated about 240,000 cycles which were analyzed in a comparative way between the two fasteners for the reduction of the clamping force. The results obtained in the test tracks and in the laboratory demonstrated a behavioral difference between the fasteners. In the field, the Spiralock nut registered greater loss in the clamping force when subjected to impact solicitations. On the other hand, the dynamic loading machine showed a greater efficiency of the Spiralock nut to the loss in the clamping force when subjected to alternating requests of continuous amplitude compared to the standardized nut. The importance of bench testing with the same joint rigidity of the vehicle and the capability of the data acquisition procedure was evidenced.(sic)