Novel mechanical models of tensile strength and elastic property of FDM AM PLA materials: Experimental and theoretical analyses

In order to develop FDM additive manufacturing and promote the application of this technology, the essential mechanical properties including tensile strength and elastic property of PLA material fabricated by FDM additive manufacturing are studied deeply this time. Two novel theoretical models have been built to predict the tensile strength and Young's modulus of FDM additive manufacturing PLA material with different printing angles and layer thicknesses in this study. Firstly, strength theoretical model is established based on transversely isotropic material hypothesis and Tsai-Hill strength criterion. Then, Young's modulus theoretical model is established based on orthotropic material hypothesis under plane stress state. Test data indicates that the tensile strength and Young's Modulus of FDM additive manufacturing PLA material increase as the printing angle increases or the layer thickness decreases. Relative Error (RE) between theoretical results and test data is put forward as a criterion to evaluate the accuracy of the theoretical models quantitatively. All the Relative Error are so small (≤0.14) that is satisfactory in engineering applications. Therefore, one can confirm that the theoretical models established during this research can predict the tensile strength and Young's modulus of FDM additive manufacturing PLA material with different printing angles and layer thicknesses precisely.