使一个光纤光栅的两段分别具有不同的包层直径,在正确的应用条件下可解决工程中的应变、温度交叉敏感难题。对不同包层直径光栅在有、无涂覆层两种情况下的应变传感特性进行了深入的力学分析,推导得出了结构实际应变与两段光栅相对波长变化的关系表达式,并数值仿真分析了直径比和长度比对其应变灵敏特性的影响。研究结果有利于指导实际应用时光栅的结构选择和参数设计。此外指出,在实际工程应用中无论采用何种封装形式或复合方式,要从应变、温度的混合信息中提取出结构体的真实应变,必须使不同包层直径光栅满足两端拉伸的受力条件。

In engineering applications the difficulties of strain and temperature cross-sensitivity can be resolved by using FBG with two different cladding diameters on condition that a certain usage mode is adopted. The mechanical analyses of strain sensing characteristics of bare and coated FBG with two different cladding diameters were performed, and the relational expressions between the actual strain of structure and the relative wavelength change of two FBG segments were deduced respectively. Simulation analyses were also carried out to study the influence of different diameter ratio and length ratio on the strain sensing sensitivity. The results help to direct the structure selection and parameters design in practical applications. It was also proposed that no matter which package form or bonding style were adopted in practical engineering applications; the measured strain can be picked up from the mixed information of strain and temperature only if tensile force was applied on the FBG at both ends.