考虑纤维体积含量变化的纤维缠绕厚壁柱形结构的等强度设计

纤维缠绕厚壁柱形管道或容器在缠绕张力作用下会使缠绕纤维层的应力状态不断变化,形成沿壁厚力学性能非均匀的结构。依据缠绕过程中的纤维束应力状态分析和纤维束本构关系,获得了纤维体积含量与所受应力状态的关系。基于正交各向异性本构关系和双层筒模型的离散叠加法,建立了给定缠绕张力确定纤维缠绕厚壁柱形结构剩余张力的计算方法,并计算了等张力缠绕纤维层的纤维体积含量沿壁厚的分布。利用Tsai-Wu失效准则研究了纤维体积含量非均匀的厚壁柱形结构的纤维层强度。研究表明:缠绕工艺使内层纤维体积含量和强度均略高于外层,纤维缠绕厚壁柱形结构的强度分析和设计时应考虑这种影响;利用变化的缠绕张力设计可以实现强度比沿壁厚的均匀分布。

Constant strength design of filament wound thick-wailed cylindrical structure considering variation of fiber volume content

In filament wound thick-walled cylindrical pipe or vessel, the winding tension makes stress state of fiber layer change, which forms a non-uniform structure through thickness. According to the analysis of stress state and constitutive relation of fiber bundle in winding process, the relationship between the fiber volume content and the stress state was obtained. Based on the orthotropic constitutive relations and discrete superposition method of a double layered cylinder model, a calculation method to determine the residual tension for given winding tension in filament wound thick-walled cylindrical structure was established, where the distribution of fiber volume content through wall thickness was calculated for a constant winding tension. Using Tsai-Wu failure criteria, the strength of filament layer was investigated in thick-walled cylindrical structure with non-uniform fiber volume content. It is found that winding process makes the fiber volume content and strength of inner layer higher than those of the outer layer, where the influence of non-unform material property should be considered in analyzing and designing of filament wound thick-walled cylindrical structure. Uniform distribution of strength through thickness can be achieved by design of variational winding tension.