Low cycle fatigue analysis of temperature and frequency effects in eutectic solder alloy

Low cycle isothermal mechanical fatigue testing of a euteutic alloy 63Sn/37 Pb was carried out in a systematic manner over a wide range of frequencies (10(-4)-1 Hz) and temperatures (-40 to 150 degrees C) with the total strain set at different values (1-50%). The low cycle fatigue behavior of the eut ectic solder was found to be strongly dependent on test temperature and fre quency. If the Coffin-Manson model is used to describe such fatigue behavio r, the fatigue exponent in and ductility coefficient C in the model are fou nd to be a function of temperature and frequency rather than numerical cons tants. The plastic flow law was employed to explain the temperature and fre quency dependence. The frequency-modified Coffin-Manson model was tried and found to be able to eliminate the frequency dependence of the numerical "c onstants" but not the temperature dependence. To have a full description of the temperature- and frequency-dependent fatigue behavior, a set of empiri cal formulae was derived based on the frequency-modified Coffin-Manson mode l. (C) 2000 Elsevier Science Ltd. All rights reserved.