三维柔性间隔织物压缩非线性变形的材料与细观结构耦合机理

3-D spacer fabric which is a flexible sandwich structure formed by intermeshing monofilament and multifilament has good cushioning performance and energy absorption capacity. In this project, the material/mesostructure coupling mechanisms for nonlinear compressive deformation of spacer fabrics will be investigated. A series of spacer fabrics with different fiber materials and fabric constructions will be manufactured. In-situ compression testing with micro-computed tomography scanning will be employed to reconstruct and digitally visualize complex deformation of fabric constructions and post-buckling processes of spacer monofilaments to analyze the deformation behavior of fabric structures. Mesostructure geometric models for the spacer fabrics will be established by using the micro-computed tomography results. The effect of fabric constructions on post-buckling behavior of spacer monofilaments will be studied based on the results of numerical simulation, theoretical calculation and in-situ tests at meso scale. By employing monofilaments with different constitutive relationships, the influence of fiber materials on the deformation mechanisms of fabric constructions will also be investigated by comparing the experimental and simulation results of compressive deformation of macro-scale fabric constructions and the change of mesostructure. The spacer monofilament post-buckling and fabric construction deformation mechanisms will be revealed by examining the coupling effects between mesostructure deformation and fiber material property on different fabric compression deformation states, by virtue of numerical simulation and theoretical calculation. From the investigation of this project, the relationships between compression deformation of spacer fabrics and the three factors including fiber material constitutive relationship, fabric construction and mesostructured will be established, for the application in the design of cushioning performance of spacer fabrics.

三维间隔织物是单/复丝相互捆绑串套的柔性夹芯结构，具有优异的缓冲吸能效果。本项目将研究压缩时该织物非线性变形的纤维材料特性与细观结构耦合机理：织造不同规格纤维材料和组织结构特征间隔织物，用断层扫描动态检测织物压缩过程，在线测量织物组织结构和间隔丝屈曲变形，分析织物结构压缩变形模式；构建织物细观结构几何模型，采用细观结构层面数值模拟、理论计算和变形在线检测结果，揭示织物组织结构对压缩过程中间隔丝屈曲变形的影响规律；结合不同规格间隔丝纤维本构方程，采用织物宏观压缩变形和细观结构变化的实验测量与数值模拟结果，发现纤维材料影响织物结构变化机理；研究各压缩变形状态时织物细观结构变形与纤维材料特性耦合对应性，结合数值模拟和理论计算结果，揭示间隔织物压缩变形中间隔丝屈曲变形和组织结构非线性变化机理。项目将建立纤维材料本构、织物组织结构、细观结构三因素与间隔织物压缩变形间的联系，应用于织物缓冲性质设计。

三维间隔织物是单/复丝相互捆绑串套的柔性夹芯结构，具有优异的缓冲吸能效果，已经广泛应用作床垫和汽车通风座椅等产品的缓冲材料。本项目通过实验观测和理论分析相结合，研究了压缩时间隔织物非线性变形的纤维材料特性与细观结构耦合机理。织造了不同规格纤维材料和组织结构特征间隔织物，用断层扫描定量分析了织物的几何结构，计算了单丝的曲率和挠率分布，并使用在线断层扫描动态检测织物压缩过程，在线测量织物组织结构和间隔丝屈曲变形，分析织物结构压缩变形模式，直接观察间隔织物的压缩机制，实验结果表明间隔织物不同循环单元的间隔单丝形态不一致，单丝长度、曲率和挠率均有较大差异，说明织物在拉幅热定型过程中间隔单丝和单丝线圈之间有转移，施加在单丝上的张力分布不匀，所以单一单元建模无法精确预测织物的变形机理。基于构建织物细观结构几何模型，采用细观结构层面数值模拟、理论计算和变形在线检测结果，揭示了织物组织结构对压缩过程中间隔丝屈曲变形的影响规律，结果表明不同形态单丝的旋转自由度不相同，竖直单丝相比倾斜单丝绕织物横向的旋转自由度较小，对织物的抗压性能起主要作用，表面密实型间隔织物单丝间的相互作用对织物的压实阶段影响较大，而对线性和平台段影响较小，而网眼型间隔织物单丝的相互作用较密实型间隔织物对织物总体抗压性能要小。研究了单丝纺丝工艺、超分子结构和力学性能的关系，结合不同性能间隔丝纤维本构方程，采用织物宏观压缩变形和细观结构变化的实验测量与数值模拟结果，发现纤维材料影响织物结构变化机理。从间隔织物单丝屈曲大变形、单丝自身拉压小变形、单丝与织物表层线-面接触及其单丝之间的相互接触四个方面，定量揭示了间隔织物的压缩变形机理。项目初步建立了纤维材料本构、织物组织结构、细观结构三因素与间隔织物压缩变形间的联系，对于间隔织物的缓冲性质设计具有指导意义。