In this study, the dynamic puncture behavior of nonwoven needle-punched polyester geotextiles has been studied using video processing technique. Twenty-seven needle-punched geotextile samples were produced by changing areal weight, needle penetration depth and punch density as independent variables. Cone drop test was carried out on the samples. In addition to measuring the hole diameter (HD), the video processing technique with a high frame rate camera was employed to calculate the energy absorbed by geotextile fabric up to puncture point (Ep) and the hole expansion energy (Ee). Multiple linear regression method was used to develop the predicting relationships between independent and reply variables. The models showed that an increase in areal weight results in an increase in Ep, whereas it causes a decrease in Ee and HD. Moreover, increasing punch density and needle penetration depth, leads to less Ep, and more Ee and HD. In addition, it was also found that significant relationships exist for Ep-HD and Ee-HD.
Random-velour needling technology uses not only a modified needle loom in which the bed-plate is replaced by a moveable brush conveyor but also specially designed needles known as fork needles are employed. In this study, in order to measure the net force exerted on fork needles and contributing forces due to factors such as vibration, inertia and resistances of brush and fibrous matt, a twin force measuring unit was developed. It was found that the magnitude of the contributing forces is strongly related to factors such as loom vibration, needle inertia and rigidity of both the conveyor surface and the fibrous matt. Quantification of the net punching force and the related factors are of vital importance in the engineering design of fork needles and random-velour looms, which in turn leads to production of high performance products at lower costs.
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