Abstract
Thai Microelectronics Center fabricates micropillar sheets from soft lithography techniques and roll-to-roll process which were used as superhydrophobic and superoleophobic surfaces coated on marine structures and medical devices. This research aimed to study appropriate constitutive models and mechanical behaviours of PDMS micropillar sheets with two substrate thicknesses of 1,910 mu m and 150 mu m under compressive loading using ANSYS Mechanical APDL program. The constitutive models consisted of Mooney-Rivlin (2, 3 and 5 parameters), Ogden (1st, 2nd and 3rd orders), Neo-Hookean, Polynomial (1st and 2nd orders), Arruda-Boyce, Gent and Yeoh (1st, 2nd and 3rd orders) models were curved fitting with experiment data from uniaxial compression test. We found that the most accurate constitutive model was Mooney-Rivlin 5 parameter model for the low strain range (epsilon(z) <= 0.225). The compressive strength and the lateral collapse of micropillars depended on substrate thickness were studied. The lateral collapse of micropillars was found when the substrate thicknesses were 150 mu m and 1,910 mu m. As the substrate thickness decreased, the compressive strength decreased while the elastic stiffness increased. The maximum compressive forces per one micropillar were 21.060 mu N and 18.549 mu N for the 1,910 mu m and 150 mu m thick substrates respectively.
