Large Amplitude Oscillatory Shear (LAOS) Experiments on Colloidal Ceramic Paste Formulated for Robocasting Applications

Abstract

As a branch of direct 3D printing technique, Robocasting is a promising candidate to fulfil multiple material printing [1]. Currently, the Robocasting community commonly utilizes small amplitude oscillatory shear (SAOS) tests to evaluate the printability and stiffness of the pastes for Robocasting, while large amplitude oscillatory shear (LAOS) test has been neglected. However, SAOS experiments restrict the information about the rheological properties within the linear viscoelastic regime, providing information regarding the internal microstructure of the pastes at rest, i.e., before they start to flow. From the previous study on large amplitude oscillatory shear (LAOS) tests of polymer solutions and powder suspensions [2, 3], the Lissajous–Bowditch curves illustrate the gradually changing flow behaviours of those complex fluids. By imposing variable frequencies and shear strains to inks with both high elastic and viscous moduli, the same approach is used to assess their complex theological behaviours, aiming at further understanding their effects on the Robocasting process.