Fig. 4

Towards a J-shaped stress–strain curve combining wavy fibre deposition and preconditioning: a Optical microscope image of a poly(ε-caprolactone) (PCL) fibre sublayer fabricated at a deposition angle of 21° after one cycle of fibre deposition with continuous clockwise rod spinning. b Optical microscope image of a PCL fibre sublayer fabricated at a deposition angle of 21° after one cycle of fibre deposition with alternated rod spinning and after the preconditioning step. c Scanning electron microscopy (SEM) image of a series of 24 PCL fibre sublayers fabricated at a deposition angle of +/−67°. d SEM image of a series of 24 PCL fibre sublayers fabricated at a deposition angle of +/−67° with alternated rod spinning and after the preconditioning step. e Longitudinal stress–strain curve for a series of 24 PCL fibre sublayers fabricated with deposition angles of +/−21°, with and without a stretch preconditioning step of five cycles of loading/unloading at 30% strain and wavy fibre deposition using the alternating rod spinning during angled fibre deposition. The grey line represents previously published stress–strain mechanical behaviour of the media layer of the human coronary artery under longitudinal tensile testing¹¹. One independent experiment was conducted for each condition