微波固化成型三维中空复合材料结构的力学性能

MECHANICAL PROPERTIES OF 3D FABRIC COMPOSITES MANUFACTURED BY MICROWAVE CURING

为了改善三维中空复合材料结构微波固化成型的固化均匀性,提出了添加外部导热附加模具和内部微波吸收剂两种不同的方法。通过试验研究了附加模具的材料、厚度以及微波吸收剂种类和含量对三维中空复合材料结构力学性能的影响。结果表明,结构的平压失效模式包括芯柱失稳和压溃,剪切失效模式为芯材剪切失效和界面脱粘,短梁弯曲的失效模式为面板/芯材界面的脱粘后屈曲破坏。相比于未添加附加模具,AlN和Al_2O_3陶瓷均可以提高结构的力学性能,但AlN的增强效果更显著。AlN模具厚度的增加不利于结构的力学性能,模具厚度从0.5 mm增加到1.5 mm时,结构的平压、剪切和芯材剪切强度均随之降低。微波吸收剂的添加均可提高中空结构的力学性能,其中剪切和芯材剪切强度随着石墨含量的增加而增加,平压强度随着石墨含量的增加先增加后降低,而Fe_3O_4含量变化则对结构力学性能的影响不显著。

Aiming at improving the curing uniformity of microwave curing process of 3D spacer fabric composites,two different methods were proposed,i. e.,additional mould for external heat-conducting and microwave absorber for internal heat-conducting. Compression test,shear test and short-beam flexural test were utilized to study the effect of material and thickness of addition mould and the kind and content of microwave absorber on the mechanical properties of spacer fabric composites. The experimental results indicate that the failure modes of compression includes the instability and crushing of core,and the failure modes of shear test are the shear failure of core and interfacial debonding,while the failure mode of short-beam flexure is the buckling after interfacial debonding. Compared with the specimens with no additional mould,the mould of AlN and Al2O3 could both improve the mechanical properties of the 3D spacer fabric composites,and the reinforcing effect of AlN mould is more significant. However,increasing the thickness of AlN mould is adverse to the mechanical properties. When the thickness is increased from 0.5mm to 1.5mm,the compression,shear and core shear strength were all decreased. The addition of microwave absorber could improve the mechanical properties. The shear and core shear strength increased with the increasing of graphite’s content,while the compressive strength first increased then decreased. The change of Fe3O4 ’s content didn’t affect the mechanical properties significantly.