Protective properties of warp-knitted spacer fabrics under impact in hemispherical form. Part II: effects of structural parameters and lamination

This part aims to investigate the effects of structural parameters and lamination on the impact force attenuation properties of warp-knitted spacer fabrics developed for impact protectors. A series of warp-knitted spacer fabrics was produced on a double-needle bar Raschel machine by varying their structural parameters including spacer monofilament inclination and fineness, fabric thickness, and outer layer structure. The effects of fabric structural parameters, impact energy levels, and laminated layers on the protective performance of the spacer fabrics were tested and analyzed based on the assessment of the peak transmitted force. The results showed that all the structural parameters significantly affect the impact force attenuation properties of the warp-knitted spacer fabrics. It was also found that lamination of the spacer fabrics can effectively improve the force attenuation performance. Three layers of the developed warp-knitted spacer fabrics in a total thickness of about 2.5cm can meet the requirement of the transmitted force lower than 35kN at an impact energy of 50J according to the European Standard BS EN 1621-1:1998.