Novel stitch-bonded sandwich composite structures

Sandwich construction with composite skins and a variety of core materials is getting popular for a range of structural applications. These structures are subjected to various impact loads, such as accidental dropping of objects, vehicular collisions, drilling for traditional fastening or routing electrical cables etc. For example, lateral penetration of a blunt tool results in severe debonding of the bottom skin, which is not always visible/accessible and hence not easy to repair. In the present work, stitch-bonded sandwich structures have been developed using commercial close-cellular core and woven broadcloth. Traditional sewing machines are not suitable for relatively hard and thick core materials. The authors, using tufting and weft insertion techniques, derived from the textile industry, developed a novel stitch-bonding technique. A number of sandwich samples were prepared and subjected to quasi-static indentation tests, for optimising the stitch geometry.