No abstract

Spirality arising from loop distortion in single-jersey knitted fabrics is discussed. Test methods for measuring fabric spirality in knitted fabrics are outlined. Results of an experimental investigation are statistically analyzed considering the effects of yarn/fabric construction factors on the spirality behavior of laboratory produced single-jersey fabrics. The study reveals that the steady-state loop shape for the washed/tumbledried knitted specimens is not unique. Accordingly, the construction factors considered in the statistical analyses are yarn linear density, yarn twist factor, fabric tightness factor, and fabric loop shape. The analyses reveal the importance of the yarn twist factor as well as the fabric tightness factor in promoting fabric spirality. Multiple linear regression equations of practical importance for predicting fabric spirality are derived from the experimental results.

In this study the effect of electrode material was studied to avoid resulting residual stresses, the surface roughness and cracks resulted during Electrical Discharge Machining (EDM). Two types of EDM electrode materials were chosen, Dura graphite 11 and Poco graphite EDMC-3. Two grades of tool steels are chosen as test materials, DIN 1.2080 and DIN 1.2379. Different machining methods were chosen ''rough, medium, and soft'', it was found that the Dura graphite 11 exhibits more surface cracks upon DIN 1.2379 less micro-cracks appeared on the surface than on DIN 1.2080 while the higher surface roughness appeared in DIN 1.2080 using Dura Graphite 11 electrode, also Residual stresses were studied upon the surface and it was found that POCO Graphite EDMC-3 electrode results higher residual stresses compared with Dura Graphite 11 electrode. Also Soft EDM machining exhibits higher residual stresses as a result of higher pulse on duration time. Ó 2015 Faculty of Engineering, Ain Shams University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).