Investigating the forming limits of a flax fibre-reinforced polypropylene composite in different water treatment conditions

The forming limits of natural fibre composite through stretch forming tests have been studied where hourglass samples of varying widths are formed using a hemispherical punch. This study proposes a new failure criterion which uses fibre strain and strain ratio. This new failure criterion is more effective than a conventional strain-based failure criterion in detecting failure in woven natural fibre composites as it can successfully eliminate the path dependency effect. This innovative method of examining failure can be applied to structural design of composite materials as long as their failure mechanisms are dominated by fibre fracture.