Purpose -The present work aims to focus on the simulation of tensile, shear and bending deformation of the plain-weft knitted fabrics in an analogous manner to the tests performed on the Kawabata Evaluation System for Fabrics. Design/methodology/approach -The simulation of the tests is based on the modelling of the fabric microstructure and the application of the boundary conditions and the equivalent loading that correspond to each mechanical test, with a respect to the contact phenomena. A three-dimensional model consisting of three bodies in contact represents the unit cell of the fabric microstructure. Finite element analysis is used for the prediction of fabric performance since the complexity of the structure, the anisotropic properties of the yarns and the interaction phenomena between the yarns at the contact areas preclude the use of analytical methods. Findings -The proper definition of the boundary conditions and the appropriate load is of great significance for the realistic simulation of the mechanical tests under examination. The results of the simulated deformations compared to the respective measurements of the laboratory tests are correlated very well and this enables the consideration of the computational analysis as a powerful textile design tool. Originality/value -The prediction of the mechanical properties of the knitted fabrics based on the computational modelling supports the estimation of the fabric hand during the design stage and before its manufacturing.

The surface of the textile fabrics is not absolutely flat and smooth. Its geometrical roughness within certain extents is considerable. The surface roughness influences the fabric hand and it plays a significant role in the end use of the fabric. In parallel, the periodic variations of the fabric surface level due to the regular interlaced patterns of the yarns cause a respective variation of the geometrical roughness measurement. Thus, the fabric roughness data measured using the Kawabata Evaluation System for Fabrics and imposed to a certain process of numerical calculations result into the retrieval of the structural parameters of the fabric. The principle of the method has a non-destructive character and can be applied to woven or knitted fabrics.

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PurposeThe target of the current work is the creation of a model for the prediction of the air permeability of the woven fabrics and the water content of the fabrics after the vacuum drying.Design/methodology/approachThere have been produced 30 different woven fabrics under certain weft and warp densities. The values of the air permeability and water content after the vacuum drying have been measured using standard laboratory techniques. The structural parameters of the fabrics and the measured values have been correlated using techniques like multiple linear regression and Artificial Neural Networks (ANN). The ANN and especially the generalized regression ANN permit the prediction of the air permeability of the fabrics and consequently of the water content after vacuum drying. The performance of the related models has been evaluated by comparing the predicted values with the respective experimental ones.FindingsThe predicted values from the nonlinear models approach satisfactorily the experimental results. Although air permeability of the textile fabrics is a complex phenomenon, the nonlinear modeling becomes a useful tool for its prediction based on the structural data of the woven fabrics.Originality/valueThe air permeability and water content modeling support the prediction of the related physical properties of the fabric based on the design parameters only. The vacuum drying performance estimation supports the optimization of the industrial drying procedure.

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Polymers such as polyvinylidene difluoride, polypropylene and polyamide-11 show great promise for providing light-weight, flexible and fibrous piezoelectric materials that can be integrated into technical textile fabric structures for energy harvesting applications. Durability is an important parameter for the textiles and especially for functional and smart materials. This research work provides an insight on the piezoelectric behaviour of polypropylene, polyamide-11 and polyvinylidene difluoride in terms of peak-to-peak voltage generation capabilities after washing at 40°C with the addition of detergent as described in test method BS EN ISO 105-C06:2010. It was observed that the peak-to-peak voltage generated by polypropylene monofilaments retained similar values with only slight differences, while the monofilaments of polyvinylidene difluoride and polyamide-11 showed higher peak-to-peak voltage generation after washing. These changes have been explained using the changes in the crystallinity and phase, as determined by Fourier transform infrared spectroscopy analysis.