【作者】 张波；

【导师】 张乐年；

【作者基本信息】 南京航空航天大学 ， 航空宇航制造工程， 2021， 硕士

【摘要】 复合材料构件正朝着大型化、整体化发展,其使用部位由非承力、次承力构件向主承力构件过渡,大厚度复材构件在各领域得到广泛应用。结合国家自然科学基金项目和航空企业重大实际需求,本文针对现有方法固化大厚度复材零件过程中存在较大温度梯度和热冲击,影响成型质量的问题进行深入研究。论文主要成果如下:(1)提出大厚度复合材料分层自阻电热固化方法。对大厚度复材零件逐层独立馈能,以非均匀馈能实现零件厚向温度场均匀化调控。为分析分层层厚等因素对厚向温度场影响规律,建立了分层自阻电热固化过程电、热、化学多物理场耦合有限元模型。基于模型验证分层自阻电热方法提升复材构件厚向固化温度均匀性的有效性。(2)针对固化过程中的热冲击问题,结合多层独立控温特点,优化设计分层自阻电热方法各层固化工艺。基于各层差异化控温思想设计分层自阻电热工艺。在有限元模型基础上,建立用于快速预测的径向基函数代理模型。通过遗传算法对固化过程中热冲击峰值温度、厚向最大温差、固化周期进行多目标优化,获得优化后各层独立控温工艺。(3)对大厚度复合材料分层自阻电热工艺进行实验验证。由于分层独立控温,分层自阻电热升温阶段平均温差和保温稳定温差仅1.83℃和2.63℃,相较整体自阻电热(10.22℃和11.01℃)分别降低82.1%和76.1%。固化结束时,非均匀分层自阻电热固化方法的最大固化应变仅为-183.04με,相较烘箱(-438.01με)大幅降低。相较推荐工艺,优化的分层工艺热冲击峰值温度降低6.8℃,固化周期缩短33 min。经测试绝缘层的添加小幅度降低了构件的层间剪切强度。更多还原

【Abstract】 Carbon fiber reinforced polymer(CFRP)components are developing towards large-scale and integration,and their use parts are also transitioning from non-bearing and secondary load-bearing components to primary load-bearing components.Thick CFRP parts are widely applicated in various fields.Combining the practical demands of Natural Science Foundation of China and the aviation enterprises,the problems of large through-thickness temperature gradient and thermal overshoot during the curing of thick CFRP parts by existing methods that affect the curing quality are studied in this paper.The main achievements are as follows:(1)A novel layered self-resistance electric(L-SRE)heating method to cure thick laminates is proposed.Thick composite is fed independently layer by layer,and the through-thickness temperature field is uniformly controlled by non-uniform energy supply.A multi-physical coupling finite element model(FEM)of electrical,thermal,and chemical multi-physical fields of L-SRE process is established that can analyze the influence of the layer thickness and other factors in the through-thickness temperature field.And the effectiveness of the L-SRE in improving the through-thickness temperature uniformity of the CFRP laminate is verified based on the model.(2)Aiming at the thermal overshoot during the curing process of thick CFRP parts,combined with the characteristics of multi-layer independent temperature control,the L-SRE heating method is optimized for curing process of each layer.With the idea of differentiated temperature control of each layer,the L-SRE process is designed.Based on the FEM,a surrogate model of radial basis function neural network model(RBF)for rapid prediction is established.Multi-objective optimization of the peak temperature of thermal overshoot,the maximum through-thickness temperature difference,and the curing time during the curing process is carried out by genetic algorithm(GA),and the independent temperature control process of each layer after optimization is obtained.(3)Some experiments had been conducted to verify the process of L-SRE heating for thick CFRP laminate.Due to the layered independent temperature control,the average temperature difference during the heating stage and the stable temperature difference of the L-SRE are 1.83 ℃ and 2.63 ℃,which are respectively 82.1% and 76.1% lower than that of the integrated self-resistance electric heating(SRE)(10.22 ℃ and 11.01℃).At the end of curing,the maximum cure-induced strain of the U-L-SRE method is only-183.04 με,which is significantly lower than that of the oven(-438.01 με).Compared with the recommended process,the optimized layering process reduces the peak temperature of thermal overshoot by 6.8 ℃ and shortens the curing time by 33 min.It was tested that the addition of the insulating layer reduces the interlaminar shear strength of the laminate in a small extent.更多还原