细观尺度下推进剂/衬层/绝热层界面多角度拉伸过程中的变形测量与分析

Measurement and analysis on deformation of propellant/liner/insulation interface during multi-angle tensile process at meso-scale

为了研究细观尺度下推进剂/衬层/绝热层界面多角度拉伸过程中的变形特点与破坏模式,使用拉压力传感器、三目金相显微镜等设备获取多角度拉伸过程中的应力数据与界面形貌演化图像,采用数字图像相关技术对多角度拉伸过程的图像序列进行处理,获取了细观尺度下界面多角度拉伸过程中的应变场演化情况。实验结果表明,粘接试件在0°拉伸时的抗拉强度最大,90°拉伸时的伸长率最大;随着拉伸角度的增加,应力-应变曲线的加载段和卸载段均逐渐变缓,表面的应变集中区域由衬层/绝热层界面附近,变化为推进剂/衬层界面附近,最后两个界面附近均出现了明显的应变集中现象;45°拉伸时,推进剂与衬层表面应变随拉伸载荷的增加而增加,绝热层的模量高,应变变化幅度小,推进剂表面的平均正应变高于衬层,平均切应变低于衬层。所采用的实验方法可较好地测量界面在多角度拉伸过程中的变形,为发动机粘接结构的完整性分析提供参考。

In order to study the deformation characteristics and failure modes of the propellant/liner/insulation interface during the multiple angle tensile process at meso-scale,tension and pressure sensors,trinocular metallographic microscope and other equipments were used to obtain stress data and interface morphology evolution images.Digital image correlation technology was used to process the image sequences of the multi-angle tensile process,and the strain field evolution during the multi-angle tensile process was obtained at meso-scale.The experimental results show that the tensile strength of the bonded specimen is the largest at 0°and the elongation is up to the largest value at 90°.With the increase of tensile angle,the stress-strain curve of the loading and unloading sections gradually slows down,and the strain concentration area on the surface changes from vicinity of liner/insulation interface to vicinity of propellant/liner interface.Finally,obvious strain concentration phenomenon appears near both interfaces.When the tensile angle is 45°,the surface strain of propellant and liner increases with the increase of tensile load.The modulus of insulation layer is high,and variation of strain is small;the average normal strain of propellant surface is higher than that of liner,and the average shear strain is lower than that of liner.The experimental method can better measure the interface deformation during multi-angle tensile process and provide a reference for the integrity analysis of motor bonding structure.