Estimation of fiber system orientation for nonwoven and nanofibrous layers: local approach based on image analysis

Abstract

Analysis of textile materials often includes measurement of structural anisotropy or directional orientation of textile object systems. To that purpose, the real-world objects are replaced by their images, which are analyzed, and the results of this analysis are used for decisions about the product(s). Study of the image data allows one to understand the image contents and to perform quantitative and qualitative description of objects of interest. This paper deals in particular with the problem of estimating the main orientation of fiber systems. Firstly, we present a concise survey of the methods suitable for estimating orientation of fiber systems stemming from the image analysis. The methods we consider are based on the two-dimensional discrete Fourier transform combined with the method of moments. Secondly, we suggest abandoning the currently used global, that is, all-at-once, analysis of the whole image, which typically leads to just one estimate of the characteristic of interest, and advise replacing it with a “local analysis”. This means splitting the image into many small, non-overlapping pieces, and estimating the characteristic of interest for each piece separately and independently of the others. As a result we obtain many estimates of the characteristic of interest, one for each sub-window of the original image, and – instead of averaging them to get just one value – we suggest analyzing the distribution of the estimates obtained for the respective sub-images. The proposed approach seems especially appealing when analyzing nonwoven textiles and nanofibrous layers, which may often exhibit quite a large anisotropy of the characteristic of interest.

Characterisation of carbon fibre-reinforced polymer composites through radon-transform analysis of complex eddy-current data

“…This presents a problem for many traditionally effective NDT methods such as ultrasonic testing (UT) as they require contact with the test material through a coupling medium or for the sample to be submerged in water. Potential in-line non-destructive testing techniques include optical sensing with image processing methods to measure fibre alignment [6,7,8,9]. Such approaches are fast and low cost but cannot measure orientation in $ sub-surface plies.…”

Fibre direction and stacking sequence measurement in carbon fibre composites using Radon transforms of ultrasonic data

“…Many techniques for detecting fibres and measuring their orientation are seen in the literature [9], spanning many scientific fields. Examples include techniques based on structure tensor [22][23][24][25][26][27][28], Radon transform [29][30][31][32], Fast Fourier Transform (FFT) [14,[33][34][35][36][37][38], rotated filter [39][40][41][42][43][44], and image moment [45][46][47] methods.…”

GPU-accelerated ray-casting for 3D fiber orientation analysis

“…The methods involving the analysis of spatial frequency components of the 2D Fourier spectrum enabled to reveal a global orientation of presented structures. They were applied to quantify direction of nanofibrous and nonwovens layers of textile materials [ 9 , 10 ], amorphous cast iron fibers [ 11 ], actin fibers and myofibroblasts [ 12 ], scleral fibers in normal rat eyes [ 13 ], fibers in electrospun materials [ 14 – 16 ], collagen fibers [ 17 , 18 ], and fibroblast proliferation [ 19 ]. Another way to utilize the 2D Fourier spectrum is to fit a line into the thresholded spectrum to infer orientation from a line slope [ 20 ] to estimate the direction of α-actin fibers [ 21 ].…”