A material toughness testing apparatus includes a stylus having at least two cutting blades configured to engage with the sample and spaced apart to define a stretch passage therebetween and a stylus transport system configured to move the stylus along a path trajectory as the cutting blades cut the sample such that the sample is displaced on at least one side of the path trajectory. Each cutting blade has a blade dive surface and a blade lift surface that intersect to form a cutting edge configured to cut the sample along the path trajectory. Each blade dive surface and blade lift surface is configured to contact the sample when cutting the sample. The stylus is configured to separate the sample and configured to form a ligament in the stretch passage and to induce tension in the ligament due to opposing forces of the cutting blades and the sample.