热场效应下聚酰亚胺纤维力学性质有限元分析

利用COMSOL Multiphysics 5.3软件构建了聚酰亚胺纤维三维有限元模型。 该模型实现了固体传热和表面对表面辐射传热产生的温度场中聚酰亚胺纤维固体力学的计算,重点分析了孔洞的大小、位置和热膨胀系数的差异对聚酰亚胺纤维力学性能的影响。 结果表明,聚酰亚胺(PI)纤维在两端固定约束的条件下,在固体传热和表面对表面辐射传热产生的温度场中呈现相似的应力变化趋势,即聚酰亚胺纤维出现孔洞,使纤维的力学性能降低,孔洞越大,应力分布越不均衡,越不利于纤维性质的稳定;温度越高,应力越大;但随着负轴向热膨胀系数的增加,应力逐渐减小。

Finite Element Analysis of Mechanical Properties of Polyimide Fiber under Thermal Field

Using COMSOL Multiphysics 5.3 package,we establish a three-dimensional finite element model to calculate the mechanical properties of polyimide fibers with the temperature field generated by the solid heat transfer and surface radiation heat transfer.We analyze the effects of the size and location of holes and the difference of thermal expansion coefficient on the mechanical properties of polyimide fibers.The results indicate that under the condition of polyimide fiber with fixed constraints at both ends,the stress exhibits the similar trends in the temperature fields generated by solid heat transfer and surface radiation heat transfer.The holes in the polyimide fiber reduce the mechanical properties,which results in the larger holes corresponding to the more unbalanced stress distribution.This is more unfavorable to the stability of the polyimide fibers.Meanwhile,the stress decreases with the increase of negative axial coefficient of thermal expansion.