The influence of infill pattern and infill density on the (tensile, flexural and impact) strength of 3D printed polymers

This manuscript describes the effect of the infill pattern and its density (infill percentage) on the tensile behavior of three dimensional printed polymer (polylactic acid-PLA). The polymer filaments were manufactured into 3D prints using locally-made 3D printer, and the specimens were designed by a software that transfers design patterns into the moving printer head with a nozzle that pushes the melted polymer into the final shape. Tensile test specimens were prepared according to the standard specification ASTM D-638, and different infill patterns were made (gyroid, linear and trihexagonal) with different infill densities (30, 50, and 70%). The tests were carried out on 3 specimens for each test to get the optimum results, and the results showed that the specimens with infill ratio 70% and linear infill pattern had the highest tensile strength in the case of Tensile Test compared with other specimens. And the values of Young’s modulus obtained by tensile test show that 70% infill density has the highest value, and the linear infill pattern has the highest value, followed by trihexagon and gyroid patterns respectively. But in the case of Flexural Test and Impact Test the Tri-hexagon infill pattern proved to have the highest values of Flexural strength and Impact strength.