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应用梁试件的疲劳试验和梁底拉应变的连续测定,对4种半刚性基层材料在疲劳加载过程中的模量衰变规律进行了研究。在总结梁试件底部应变增长规律的基础上,提出应变稳定增加转折点和极限破坏转折点的确定方法。结果表明:半刚性基层材料的模量衰变分为3个阶段,即迅速衰减阶段、稳定降低阶段和快速破坏阶段;第1阶段模量衰变至初始模量值的60%左右,占总疲劳寿命的15%~20%;第2阶段衰变较为缓慢,与作用次数呈线性关系,占总疲劳寿命的60%~75%;第3阶段占总疲劳寿命的10%~20%,模量急剧减小;各种材料的衰变率与所加应力水平的大小有关系,应力水平越大,衰变率越大;不同半刚性基层材料的模量衰变规律差异主要集中在初始模量值不同以及各阶段衰变的幅度不同。
The fatigue tests of the beam specimens and the continuous determination of the tensile strain of the beam bottom were carried out to study the modulus decay laws of the four kinds of semi-rigid base materials during fatigue loading. On the basis of summarizing the law of strain growth at the bottom of the beam specimens, a method of determining the turning points of the turning point and the ultimate failure point of stability increase is proposed. The results show that the modulus decay of the semi-rigid base material is divided into three stages, that is, the rapid decay stage, the stable decay stage and the rapid rupture stage. The first stage modulus decays to about 60% of the initial modulus value, accounting for the total fatigue life Of the total fatigue life of 60% -75%; the third stage of the total fatigue life of 10% to 20%, the modulus decreased sharply Small; the decay rate of various materials and the size of the stress level is related to the larger the stress level, the greater the decay rate; different semi-rigid base material modulus decay law mainly in the different initial modulus values and the various stages The magnitude of the decay is different.