J328 6061-T6 Load Factor Evaluation

A method of developing more representative test factors and respective minimum cycles is proposed in practices such as J328 and J2530. The method includes recent 6061-T6 material fatigue characterization from specimens originating in wheels. The characterization uses a fully reversed (R=−1) loading method and the specimen is in un-notched condition. Results of finite element analyses of different wheel designs are observed to verify the proposition of usage of R= −1 as appropriate for such material characterization. The results of recent fatigue response of 6061-T6 indicate that the accelerated test load factors found in SAE J328 and SAE J2530 can be reduced by 10%, while rendering at least the same structural margin as that of other ferrous and nonferrous materials. SAE J2562 illustrates a methodology for testing the structural adequacy of a wheel design using loads and cycles that more closely replicate on-vehicle service than those of J328 and J2530. Some wheel tests run to SAE J2562 load requirements, when compared against J328 or J2530 test criteria, demonstrate that wheels designed to proposed (lower) load factors and minimum cycles continue to exceed the life expectations of on-vehicle service.