Li Zhao, Ke Wei, Liu Mingyao, Zhou Yang
School of Mechanical and Electronic Engineering, Wuhan University of Technology, Wuhan 430070, China.
State Key Laboratory of New Textile Materials and Advanced Processing Technologies, Wuhan Textile University, Wuhan 430200, China.
Polymers (Basel). 2022 Oct 17;14(20):4368. doi: 10.3390/polym14204368.
Thermal residual strains/stresses cause several defects in hybrid structures and various studies have reported the reduction of residual strain. This paper describes a method for reducing thermal residual strains/stresses in metal-CFRP-metal hybrid tubes (MCMHT). The proposed axial preload tool provides two ways to reduce the thermal residual strains/stresses during the co-cure bonding process: pre-compressing of the metal layers and pre-stretching of the unidirectional carbon fiber reinforced polymer (CFRP) layers. An online measurement technique with embedded optical fiber Bragg grating (FBG) sensors is presented. Thermal residual strains are evaluated based on classical lamination theory with the assumption of plane stress. The theoretical calculations and measurement results agree well. Furthermore, the dynamic characteristics of the MCMHTs are tested. The results show that the reduction of residual strain increases the natural frequency of the MCMHT, but is detrimental to the damping capability of the MCMHT, which imply that the intrinsic properties of the metal-composite hybrid structure can be modified by the proposed axial preload tool.
热残余应变/应力会在混合结构中导致多种缺陷，并且已有多项研究报道了残余应变的降低。本文描述了一种用于降低金属 - 碳纤维增强塑料 - 金属混合管（MCMHT）中热残余应变/应力的方法。所提出的轴向预载工具提供了两种在共固化粘结过程中降低热残余应变/应力的方法：对金属层进行预压缩以及对单向碳纤维增强聚合物（CFRP）层进行预拉伸。提出了一种采用嵌入式光纤布拉格光栅（FBG）传感器的在线测量技术。基于平面应力假设，根据经典层合理论对热残余应变进行评估。理论计算与测量结果吻合良好。此外，还测试了MCMHT的动态特性。结果表明，残余应变的降低提高了MCMHT的固有频率，但对MCMHT的阻尼能力不利，这意味着所提出的轴向预载工具可以改变金属 - 复合材料混合结构的固有特性。
