【摘要】 金属材料应变疲劳基本材质参数。σ_f′、ε′_f、b、c、K′和 n′的测定是低循环疲劳研究的重要内容,它为运用局部应力应变法估算构件的疲劳寿命提供了最基本的数据。本文较详细地叙述了在MTS 伺服闭环系统上以LY12CZ棒材试件测定上述参数的过程及有关技术细节,同时以该材料板材静力力学指标估算了板材的六个参数。试验结果及估算证明:该种材料在双对数坐标上循环稳定的应力幅（σ_a）和塑性应变分量(ε_pa)之间,疲劳寿命（ZN_f）和弹性应变分量(ε_ea)之间及疲劳寿命和塑性应变分量(ε_pa)之间存在着线性函数关系;Muanson的四点关联法估算的材质参数比通用斜率法更逼近试验结果,是有相当精度的估算方法。更多还原

【Abstract】 The measurement of strain fatigue parameters of metal material is an im-portant problem in low cycle fatigue. The basic strain fatigue parameters suchas fatigue strength coefficient σ_f’, fatigue ductility coefficient ε_f’, fatigue strengthexponent b, fatigue ductility exponent c, cyclic strength coefficient K’, andstrain hardening exponent for cyclic loading n’ provide the essential data forthe fatigue life evaluation in local strain approach, because if we have thesesix parameters of a certain material, we can obtain stable stress-strain curve,stable stress-strain hysteresis loop, and strain-life relationship during cyclicloading of the same material. This paper presents the procedures and some technical details of measuringthese six parameters of LY12CZ bar with MTS closed loop servo-system. Thispaper also deals with the method of using static properties of LY12CZ sheetto evaluate the basic strain fatigue parameters （σ_f’, ε_f’, b, c, K’ and n’） ofLY12CZ sheet. In order to evaluate these six parameters by using the staticproperties of the material, we derive calculating equations and point out thatthis method of evaluating cyclic strength coefficient K’ and strain hardeningexponent for cyclic loading n’ must be verified by more experimental data. As far as LY12CZ aluminium alloy is concerned, the experimental resultsand evaluated values bear out that, on logarithmic graph paper, there are thefollowing linear relationships: between stable cyclic stress amplitude σ_a andstrain of plastic component ε_pa; between fatigue life （or reversals to failure）2N₁ and strain of plastic component ε（pa）. We find that the four-point correlationmethod suggested by Manson, S. S. is superior to the universal slope method,because the values of parameters （as mentioned above） evaluated by the four-point correlation method are closer to the experimental results than thoseevaluated by the universal slope method,更多还原