Experimental Evaluation of S‐N Curves for Drake ACSR Conductor

This paper reports on an experimental effort to generate S‐N (dynamic stress‐fatigue life) curves for a Drake ACSR (aluminum conductor steel reinforced) conductor. In the testing, aeolian vibrations were simulated by mechanical means in a controlled laboratory environment for one set of line conditions. Fatigue data for the first five strand breaks were evaluated, and S‐N curves for the first through fifth strand breaks were fit to the data using linear regression analyses. A minimum of four duplicative tests at each stress level tested were conducted to allow an evaluation of the statistical parameters and to provide statistical credibility to the results. A pseudo endurance limit of 21.31 MPa (3.09 ksi) was estimated from the S‐N data. The S‐N curves generated in this study provide much needed information for transmission line designers on the fatigue characteristics of Drake ACSR conductors. It is recommended that the S‐N curves be used in conjunction with a probabilistic approach in designing transmission lines for aeolian fatigue.