环圈光纤的失效预测

以光纤的机械可靠性为主线综述了光纤材料中固有裂纹的生长和传播所导致的光纤断裂机制.在该断裂力学的基础上推导了传统通信光纤在平直应用中的寿命预测模型.继而分析了处于弯曲构型中的传感环圈光纤表面的应力分布,然后在与传统理论相同的基本断裂机理下,类比于通信光纤可靠性模型的推导,据此应力分析给出了评估这种环圈光纤的机械可靠性的一般模型.进而从工程应用的角度简化了所推导出的一般模型,使之能够快速简单地给出环圈光纤失效概率的保守评估.在此简化模型的基础上,数值计算了目前常见的几种传感环圈中的光纤在服役期间的累积失效概率;其结果同时也显示了该环圈光纤的失效概率对光纤参量、环圈参量以及工艺参量的依赖关系.根据这一依赖关系,不仅可以快速评估在各种服役应力条件下具有不同寿命要求的光纤环圈的失效概率,同时也能对这些环圈的设计提供参考.

Failure Prediction of Coiled Fibers

The mechanism of crack occurrence and propagation in optical fibers were reviewed with emphasis on the reliability of optical fibers. The lifetime prediction model of communication optical fibers were given on the basis of the fracture mechanics. The stresses distribution of optical fibers in the configuration of fiber coils was analyzed. A general model was derived for evaluating the mechanical reliability of this kind of coiled sensing fibers. The model was then simplified to an alternative model for engineering applications. This simplified model would bring the conserved results out rapidly and simply. Several numerical calculations of the failure probability in service time of various fiber coils with different fiber radius and bending radius were carried out using the simplified model. The results displayed the dependence of the failure probability on the parameters of the fibers, coils, and the process. According to the relation, the failure probability and the lifetimes could be estimated for fiber coils installed. Meanwhile, the relations provided the guidelines to various design solutions of the fiber coils with deferent geometric configurations and service conditions in the future.