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This paper reports an experimental study on the damage evaluation of quartz woven fabrics during needle punching process under different needle punching densities. The straight fiber bundles begin appearing in Z direction at 50 punches · cm−2 and the “U-shaped” fiber bundles begin being observed at 210 punches · cm−2. The retention ratio of mean breaking force (RRMF) of the needle-punched quarts woven fabrics in warp direction decreases from 100% to 49.4% with an increase in needle punching density from 0 to 10 punches · cm−2, and that in weft direction decreases from 100% to 50.21% with the same increments in needle punching density, but the RRMF in warp direction decreases from 49.4% to 0.35% when the needle punching density increases from 10 to 245 punches  ·  cm−2 and that in weft direction decreases from 50.21% to 0.19% with the same increments in needle punching density; obviously, the initial needle punching density increments (0 to 10 punches  ·  cm−2) seem to have weakened tensile property more significantly compared with needle punching density increments from 10 to 245 punches · cm−2. The retention ratios in warp and weft directions are 0.61% and 0.34%, respectively, at 210 punches · cm−2, which are roughly equal with those at 245 punches · cm−2. Therefore, it could be concluded that the tensile property has reached the minimized at 245 punches · cm−2. In addition, there is an obvious paired similarity existing in the macro damage morphologies, the load–displacement curve trend at the adjacent needle punching density from 70 to 245 punches · cm−2 in 35 punches · cm−2 increments, also such similarity exists when the needle punching density is at 10 to 60 punches · cm−2.

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In order to analyze the thermal and mechanical properties of the carding quartz fiber web and the needle-punched quartz fiber preform containing the carding quartz fiber web, we propose a ‘three-step’ method to establish a three-dimensional quartz carding fiber web model containing large slenderness ratio fibers. First, the thickness and areal density of the carding quartz fiber web were measured and statistical analysis of fiber length and orientation distribution was carried out, which provided data support for establishing the three-dimensional carding fiber web model. Based on the wide application of Python language in finite element software, then spatial layered fibers of the beam element were generated by running Python scripts in finite element software; second, the three-dimensional carding fiber web model of beam element was established through a deposition and compression process by the explicit method of the finite element software; finally, the three-dimensional carding fiber web model of the beam element was converted into the solid element model for heat transferring analysis by Python. The converted process is the reconstruction process. Furthermore, anisotropic heat transmission of the three-dimensional carding fiber web model that includes temperature distribution and heat flux distribution were analyzed. Meanwhile, anisotropic thermal conductivity of the three-dimensional carding fiber web model was predicted in finite element software. A hot-disk thermal analyzer was used to measure the anisotropic thermal conductivity of the three-dimensional carding quartz fiber web. Experimental anisotropic thermal conductivity showed an excellent agreement with anisotropic thermal conductivity predicted by the finite element method. Moreover, the method in this paper is not only suitable for any other fibrous materials with randomly distributed fibers and large slenderness ratio fibers, but also is more efficient and low cost to obtain detailed heat conductions and anisotropic thermal conductivity.

The uniformity of the monofilament diameter plays a key role in the performance of continuous filament yarns and their subsequent products. However, traditional methods for measuring fiber or filament diameters focus on estimating the arithmetic mean data, and only part of the diameter data can be obtained. Additionally, most of these traditional methods require complex sample preparations, such as by making cross-sectional slice samples. This study intends to present a simple method for measuring almost all of the monofilament diameters in a single yarn. It is not necessary to make slice samples. After the yarn sample or fabric sample is taken and prepared, synthetic laser images can be obtained directly by scanning the cross section of the sample with a 3D laser scanning confocal microscope. According to the results of many experiments, more than 90% of the monofilament diameters of a single yarn can be measured. The result also shows that the difference in the diameter data between the traditional method and the synthetic laser imaging method is less than 2%. This method presents the differences between the majority of monofilament diameters, and the yarn clustering property can be evaluated by the sum of the monofilament diameters and the yarn cross-sectional area.