Effects of Printing Interval Time on the Structural Performance of 3D-Printed Beams Under Four-Point Bending Loads (2025-10)¶

This study examines the effects of printing interval time on the performance of 3D-printed beams under bending loads. Two reinforced 3D-printed beams, each with dimensions of 210 mm in width, 360 mm in depth, and 2200 mm in length, were tested using a four-point bending load. One beam was printed continuously, while another beam possessed a 60-minute interval time at the printed interface located at the mid-depth of the beam. The load-carrying capacity of the 3D-printed beam is significantly influenced by the printing interval time between each printed layer. The beam with a 60-minute interval at the mid-depth layer exhibited a much lower load-carrying capacity compared to the continuously printed beam. Both beams demonstrated a ductile failure mode. Horizontal cracks were observed at the mid-depth layer interface in the beam printed with a 60-minute interval time, whilst there was no horizontal crack observed at the mid-depth layer of the continuous printed beam. It is noted that both beams exhibited horizontal cracks along the interface where reinforcing bars were installed. Notably, the continuous printed beam exhibited both flexural and shear cracks, followed by crushing of the printed mortar at one of the loading points whilst the printed beam with 60-minute interval time failed by the sliding of the printed layer at the interface at the beam mid-depth and at the rebar layers.