Experimental Study and Investigation of Thrust Force and Delamination Damage of Drilled Ramie Woven Reinforced Composites

One of the machining failures in composite materials is delamination damage. In this paper, machining parameters and delamination damage caused by the drilling process on ramie woven reinforced composite material with an unsaturated polyester matrix were investigated. The ramie woven used is ramie yarn type 12S/3. The machining process used 1.5 kW Pillar drills, where variations in the diameter of the "brad & spur" drill are 4 mm, 6 mm, 8 mm, and 10 mm, respectively. In this work, focuses on the influence of machining parameters like feeds rate and spindle speed. Holes quality was analyzed in terms of thrust force and delamination failure. From the results of this study, the thrust force value obtained at the time of drilling is very closely related to the delamination damage that happens. Delamination damage occurs on both sides of the holes drill.

Influence of Technological Parameter for Ramie Yarn Hairiness on Compact Spinning with Suction Groove

The application of compact spinning technology with suction groove for ramie was studied. This technology improved ramie yarn hairiness, breaking strength and so on. The performance of the yarn hairiness was analyzed in detail through contrast test of the compact spinning technology with suction groove and the traditional ring spinning for ramie fiber. At the same time, the comprehensive performances of ramie yarn spinning by the two kinds of spinning technologies were contrasted and analyzed. The results showed that the spinning technology with suction groove can be significantly improved ramie yarn properties: hairiness and breaking strength etc. In the spinning technology with suction groove, the optimal technological parameter for producing least yarn hairiness, A1 B1 C1 D1, is acquired, where the spindle speed A is 6600 r/min, twist B is 608 T/m, the value of negative pressure C is -3.1 kPa, and traveler D is 21 # (yarn Nm 36).