دانلود رایگان مقاله آسیب فرسودگی فشاری و مکانیزم شکست فیبر مواد سیمانی

Abstract

The fiber reinforced cementitious material with high ductility has potential use in particular environments and structures that undergo repeated or fatigue loads. In this study, a series of monotonic and fatigue tests were performed to investigate the compressive fatigue behavior of this material. It is found that the fatigue life of this material is higher than that of plain concrete and steel fiber reinforced concrete under the same stress level. In addition, the failure deformation of fiber reinforced cementitious material with high ductility under fatigue load was larger than the monotonic envelope, while the envelope coincides with the monotonic loading curve for concrete or fiber reinforced concrete. The failure surface and damage process were investigated and a new failure mode of polyvinyl alcohol fiber with crushed end was discovered. The fatigue failure surface could be divided into three regions, including fatigue source region, transition region and crack extension region.

4. Conclusions

A series of monotonic and fatigue tests were performed in this study to investigate the fatigue behavior of ultra-high toughness cementitious composites under compression. The fatigue life of UHTCC specimens is shown to follow a Weibull distribution and the S - N relationship was given, which indicates that the fatigue life of this material is higher than that of plain concrete and steel fiber reinforced concrete under the same stress level. In addition, the maximum deformation of UHTCC at failure under fatigue load was larger than that of the monotonic envelope, while the envelope coincides with the monotonic loading curve for concrete or fiber reinforced concrete, and the fatigue life of UHTCC is much smaller than that of plain concrete and fiber reinforced concrete at the same secondary strain rate. The failure surface and damage process of UHTCC were investigated. A new failure mode of PVA fiber with crushed end was discovered with the help of SEM analysis and EDS analysis. This failure mode forms by the ruptured ends of fibers experiencing repeated crushing. The fatigue failure surface could be divided into three regions, including fatigue source region, transition region and crack extension region. During the fatigue failure process, micro cracks initiate in the fatigue source region, propagate in the transition region and form main cracks in the crack extension region.