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通过试验测试与数值模拟相结合的方法对三维六向编织复合材料的螺栓连接性能进行了研究。首先,通过拉伸试验对不同侧向约束螺接方式连接件的连接强度进行了测试。测试结果表明:单搭连接结构的二次弯曲现象明显,连接强度与侧向约束有一定的关系,使用垫片可有效提高连接强度,螺栓拧紧力矩增加对连接强度影响不大;连接结构的破坏模式包括挤压破坏和拉伸破坏,在孔径较小时其主导破坏模式是挤压破坏。随后,基于测试中发现的破坏模式,建立了基于点应力准则的分析模型,并使用升温法实现螺栓拧紧力矩的施加。通过数值结果与试验结果的比较验证了分析模型的可靠性。最后,利用得到验证的分析模型,分析了单搭连接的二次弯曲现象,获得了侧向约束面积、螺栓拧紧力矩及连接平板厚度对单搭单螺栓连接结构力学性能的影响规律。分析结果表明:当侧向约束应力增加时,连接强度表现为先增加后降低的规律。
The bolting performance of three-dimensional six-directional braided composites was studied through a combination of experimental tests and numerical simulations. First of all, through the tensile test of different lateral restraint screw connection connection strength test. The test results show that the secondary bending phenomenon of single-connection structure is obvious, the connection strength has a certain relationship with lateral restraint, and the use of shims can effectively improve the connection strength. The increase of bolt tightening torque has little effect on the connection strength. Modes include crush and tensile failure, and the dominant mode of failure is crush failure at smaller apertures. Then, based on the failure mode found in the test, an analytical model based on the point stress criterion was established, and the application of the screw tightening torque was realized by using the temperature rising method. The reliability of the analytical model is verified by comparing the numerical results with the experimental results. Finally, using the validated analytical model, the secondary bending phenomenon of single-ended connection was analyzed and the influence of lateral restraint area, bolt tightening torque and connecting plate thickness on the mechanical properties of single-seat single-bolt connection structure was obtained. The analysis results show that when the lateral restraint stress increases, the connection strength first increases and then decreases.