弯曲载荷下碳/玻复合材料抽油杆失效机制

Failure mechanism of carbon/glass composite rod under bending load

由于碳/玻复合材料抽油杆在挤压、弯折、扭转和冲击载荷下,极易发生界面剥离、芯材剪切、纤维断裂等问题,严重影响抽油杆使用寿命,故基于碳/玻复合材料抽油杆复合结构,以Hashin准则和Puck准则为纤维材料和基体材料的失效判据,结合界面内聚力模型,编写ABAQUS子程序建立三点弯曲载荷下碳/玻复合材料抽油杆三维数值模型,通过室内三点弯曲试验验证仿真模型的准确性;同时结合扫描电子显微镜(SEM)分析结果,从微观尺度阐释碳/玻复合材料抽油杆在弯曲载荷作用下的失效特征与损伤机制。结果表明:以最大弯曲载荷为评价指标,碳/玻复合材料抽油杆三维数值仿真模型误差为3%,满足工程分析精度需求;弯曲载荷下碳/玻复合材料抽油杆首先出现“压头状”损伤,随着载荷增大,抽油杆底端出现裂纹并迅速贯穿杆体,最终在垂直于纤维方向发生断裂。

Due to the extrusion,bending,torsion and impact loads applied on the carbon/glass composite sucker rod,it is easy to cause problems such as the interface peeling,the core shearing and the fiber fracture,which seriously affect the service life of the rod.Therefore,based on the composite structure of this carbon/glass composite sucker rod,a three-dimensional numerical model under the three-point bending load was established by writing the ABAQUS subroutine using the Hashin criterion and the Puck criterion as failure criteria of fiber and matrix combined with the interface cohesion model.At the same time,the failure characteristics and damage mechanism of the carbon/glass composite sucker rod under the bending load were analyzed from the viewpoint of microscopic scale based on the scanning electron microscope(SEM).The results show that,taking the maximum bending load as the evaluation index,the error of the numerical simulation model is within 3%,which meets the requirement of analysis accuracy in engineering.Moreover,at first there is "press-head" damage which appears in the carbon/glass composite sucker rod.With the increase of the load,cracks appear at the bottom of the composite rod and rapidly pass through the rod,and finally they are fractured in the direction perpendicular to the fiber.