Abstract: The draping of fabrics is mostly tested without distinguishing between directions, generally, it is to research the overall draping. However, the same fabric has significant differences in draping due to different warp and weft yarn densities or distinct fabric structures. Therefore, researching the draping of different directions is necessary. This topic provides an evaluation method for the investigate of multi-directional draping performance of fabrics. In this paper, the traditional method of umbrella-shaped measurement is improved. First,15 common fabrics were chosen and marked in the 0°, 90 °, 45 °, and 135 ° thread directions to test, then use XDP-1 fabric draper to test the fabric's draping and obtain a drape projection image, process and analyze the image to obtain the maximum widening, projection area and drape coefficient in four directions. Finally, the bending length and bending stiffness of the fabric are tested, and the relationship between drape and bending length and bending stiffness in various directions of the fabric is analyzed. 
The maximum widening, projected area and drape coefficient are compared with the bending length and bending stiffness in four directions. Results show that the new indicators have high correlation with both bending length and bending stiffness, with a high correlation at a significance level of 0.01, and the three new indicators are positively correlated with the bending length and bending stiffness. The harder the fabric, the greater its maximum widening and projection area. In other words, the poorer the drape of the fabric, the less prone it is to bending, and the greater its ability to resist bending deformation. The equation between projected area and bending length is a linear function: Y=0.482X1+2.759, R2=0.71, where Y represents the bending length (mm) and X1 represents the projected area (cm2). And the equation between drape coefficient and bending length is a cubic function: Y=0.180X2+10.272, R2=0.70, where Y is the bending length (mm) and X2 is the drape coefficient (%). Then, based on the umbrella method, the anisotropy of fabric drape is analyzed and two indicators are extracted: the maximum widening ratio A1 of warp and weft and the maximum widening ratio A2 of oblique direction. Anisotropy analysis is conducted by combining the drape projection shapes of different fabrics.
The results show that all three new indicators have good correlation with bending length and bending stiffness. The direction of fabric stiffness is prone to wave peaks, while the direction of softness is prone to wave valleys. The better the drape of the fabric in a certain direction, the easier it is to bend, and the smaller the bending resistance in that direction. Therefore, the drape projection of a circular sample can be used to estimate the bending performance of the fabric in a certain direction. It is feasible to measure the drape anisotropy of the fabric using the umbrella method.

Key words: fabric, drape coefficient, maximum widening, projected area, fabric drape, bending property

摘要： 为研究织物悬垂性能的各向差异性，对传统的伞式测量法进行改进。选取15种常见织物，采用XDP-1织物悬垂仪对织物0°、90°、45°、135°4个方向的悬垂性进行测试并获取悬垂图像；基于所得图像提出最大展宽、投影面积和悬垂系数3个新指标；最后分析织物各向悬垂性与弯曲长度和抗弯刚度的关系。结果发现：这3个新指标与弯曲长度和抗弯刚度均具有较好的相关性；织物硬挺的方向易形成波峰，柔软的方向易形成波谷，织物某方向的悬垂性越好，越易弯曲，该方向的抗弯能力越小。这表明通过一块圆形试样的悬垂投影可以预估织物某方向的弯曲性能，利用改进的伞式法可以测量织物悬垂性能的各向差异性。

关键词: 织物, 悬垂系数, 最大展宽, 投影面积, 悬垂性, 弯曲性