关键词: 机织物, 过滤, 数值模拟, 动态形变, 孔径分布

Abstract:

Objective Woven filter materials are privileged amongst solids-liquid filtration materials by virtue of their superior strength, durability, superior filtration precision, ease of residue disposal, and soon. The efficacy of woven fabric filtration hinges upon the weave aperture, with both the fiber inner aperture and yarn interlace aperture influencing the filtration efficiency and resistance. In addition, yarns are typically elastomeric materials, and their weave behaviors under varying pressure contribute to further alterations in the fabric structure hence impacting the filtration efficiency and resistance. Consequently, the comprehension of deformation mechanisms of textiles under high pressure holds pivotal implications for enhancing the design and optimization of filter cloth.

Method This paper presents a comprehensive study on an archietypal plain woven filtration fabrics using VHX-500 super high-depth digital microscope for imaging the cross section of the fabric, and Image J software for collecting data regarding yarn curvature wave height and yarn spacing. Experiments were conducted to validate the model's accuracy under diverse pressure conditions. The fabric models were established via Solid Works software and a finite element analysis method was employed to simulate deformation of high density woven filter under varying pressures utilizing ANSYS Workbench's Mechanical module, which was adopted to analyze factors such as maximal deformation quantity, form contour curve progression, and hole diameter changing trends.

Results The simulation results indicated that maximum deformation of the fabric took place at the original form, with a gradual decline in deformation along the diameter. The fabric underwent an escalating deformation as pressure was increased. Within a certain threshold, a non-linear increase in maximum deformation of filter fabrics residing centrally was proportional to the applied pressure. Initially, lesser pressure induced substantial deformations in the fabric, but further increments in pressure resulted in a diminished incremental deformation. The longitudinal and latitudinal profile of the fabric showed congruent deformation, with the center contour curve conforming to the sine function pattern.

The strain demonstrated a maximum at the outermost regions of the fabric, where it diminished progressively from the center to the edge, with excrescent strain along the warp yarns towards both sides from the core. For individual thread, it was observed that the interlacing region illustrated lesser strain than the noninterlacing region. The strain distribution across various positions within the same circumference of the fabric varied with the strain on the warp yarns augmenting steadily and the weft yarns decreasing gradually. The mismatch between warp and weft strain not only amplified the size difference but also alters the shape. With similar warp and weft exerted strain, there occurred an equivalent increase in the post-deformation pore dimension compared to the unvaried pore. On the other hand, the significant disparity in the strain of the warp and weft underwent greater deformation in one direction relative to the other, thereby inducing a change in the pore's shape and dimension. In accordance with the fabric's strain pattern, the compressibility manifested different pore dimensions throughout the fabric, with the pore being larger in the central position rather than in the outer regions. Moreover, the size and shape of the pore across the same direction would also vary post compressing.

Through the deployment of a textile surface deformation experiment, it was established that the maximum strain measured for plain weave fabric under diverse pressure conditions paralleled with the simulation's prediction, with an error rate less than 10%. This substantiated the accuracy of the simulation. Additionally, the fabric curve deformations were fitted to follow a sine function, corroborating with the the simulation result.

Conclusion This study employs finite element software ANSYS Workbench to simulate the deformation of high-density filter fabrics under various pressures, scrutinizing the fabric's maximum deformation quantity, distortional profile, and pore size distribution post-deformation. A validating experiment for this simulation was conducted through an actual fabric deformation test, demonstrating accurate predictive capability. The outcomes suggest that 1) the maximum deformation quantity is located at the circle center, decreasing in a gradient manner as per diameter; 2) within a particular range, the maximum deformation at the center of the filter fabric increases non-linearly with pressure augmentation; 3) further, the contoured curve of polyamide 66 woven fabric resembles a sine wave pattern significantly; and 4) as pressure acts on the fabric, the pore size expands, with larger pore size at the central region compared to apices away from the center, simultaneously modifying the dimensions and shape of periodic pores. This research aids in comprehending the dynamic deformation and pore size variation of woven fabrics under compressive conditions, thus offering a valuable reference for the custom design and analysis of filtration fabrics.

Key words: woven fabric, filtration, numerical simulation, dynamic deformation, pore size distribution