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通过对复合材料固化度和温度相关黏弹性本构方程的分析,定义一个能综合反映固化度和温度等对复合材料黏弹性性能影响的无量纲参数De_m。当参数De_m都大于10~2时,复合材料基体处于流动状态;当参数De_m都小于10~(-2)时,复合材料为弹性状态;仅当部分参数De_m小于10~2而大于10~(-2)时,复合材料处于黏弹性状态。以AS4纤维/3501-6树脂复合材料为例,基于对其参数De_m在典型固化工艺过程中的演化,研究该复合材料黏弹性性能的发展过程,发现基于参数De_m分析得到的凝胶点时间与实验结果一致。根据复合材料黏弹性性能对残余应力发展的影响,将复合材料残余应力计算分为流动阶段和黏弹性阶段,并建立了相应的状态相关黏弹性本构模型。最后通过与原始模型预测结果的比较验证了提出的本构模型,表明本文提出的计算方法与原始黏弹性本构模型计算结果一致,但大大降低了计算所需的时间和存储空间。
Based on the analysis of constitutive equations of viscoelasticity and temperature, the dimensionless parameter De_m which can comprehensively reflect the influence of curing degree and temperature on the viscoelastic properties of composites is defined. When the parameters De_m are all greater than 10 ~ 2, the matrix of the composite material is in a flowing state; when De_m is less than 10 ~ (-2), the composite material is in elastic state; only when some parameters De_m is less than 10 ~ 2 and more than 10 ~ -2), the composite is in a viscoelastic state. Taking AS4 fiber / 3501-6 resin composite as an example, the development process of the viscoelasticity of the composite was studied based on the evolution of its parameter De_m in a typical curing process. It was found that the gel point time based on the De_m analysis The experimental results are consistent. According to the influence of composite viscoelastic properties on the development of residual stress, the calculation of residual stress in composite materials is divided into flow phase and viscoelastic phase, and corresponding state-dependent viscoelastic constitutive model is established. Finally, the proposed model is verified by comparison with the original model. The results show that the proposed method is consistent with the original viscoelastic constitutive model, but the computational time and storage space are greatly reduced.