دانلود رایگان مقاله مدل مساله خروج تک فیبر شبه استاتیکی

abstract

A theoretical analysis for the single-fiber pullout with unload process is presented based on the energybased debonding criterion and the modified analysis of stress transfer between fiber and matrix(Qing [1]). The relationship between the applied stress and the interfacial relative displacement is expressed as a function of the radial residual thermal stress, fiber pullout rate and volume content as well as the length of reverse frictional sliding. The influence of fiber pullout rate on interfacial frictional coefficient is also taken into consideration. The calculation results show that the applied stress result in further debonding increases with the increase of the radial residual thermal stress and the fiber volume content and the decrease of the fiber pull-out rate. There is a drop for the applied stress when the interface debonding close to the model length and the drops of short models are larger than those of long models. Under different conditions, the model length almost has no influence on the debonding and reverse sliding in unloading processes at the initial debonding region.

4. Conclusions

A theoretical model is developed to establish the relationship between the applied stress and relative displacement during the loading-unloading process based on the debonding criterion of energy release rate and the modified analysis of stress (Qing, 2013). The influence of radial residual thermal stress, fiber pullout rate, fiber volume contents and model length on loading and unloading processes is investigated through the theoretical model. The study results show that both normal deformation along the radial and circumferential directions as well as shear deformation should be taken into account to calculate the elastic strain energy for single fiber pullout model. The model length almost has no influence on the debonding and unloading processes at the initial debonding region under different conditions of radial residual thermal stress, fiber pullout rate and fiber volume contents. There is a drop for applied stress when the debonding close to model end, and the drop decreases with the increase of the model length. When the unloading stops(u ¼ l), the unloading stress increases with the increase of radial residual thermal stress, fiber pullout rate and fiber volume content.