Evaluating Mechanical Behavior of PLA Under Varied Strain Rates Using Stereolithography 3D Print Method

Abstract

Poly-L-lactic acid (PLA), a type of aliphatic polyester, has garnered significant attention in recent years due to its favorable mechanical properties, biocompatibility, and biodegradability. Derived from renewable resources such as corn starch and sugarcane, PLA is a sustainable alternative to petroleum-based plastics, aligning with global efforts to reduce environmental impact. The resin's ability to degrade into non-toxic lactic acid in biological environments makes it particularly suitable for medical applications, including sutures, drug delivery systems, and orthopedic implants. Focus of this study is evaluation of the comparative mechanical properties of PLA at varied low strain rates (quasi-static) through tensile and compression testing. The aims of this study are analyzing the strain rate sensitivity of PLA, defining the constitutive model of PLA, validating the viscoelastic constitutive model for PLA by comparing the experimentally tested mechanical response with the constitutive model. ASTM D695.6642 was applied for compressive testing with varied strain rate 10-3 s-1 and 10-4 s-1, resulted the difference of average Young’s Modulus and average yield stress 18.81% and 19.88% respectively. ASTM-D638-03 was applied for tensile testing, showed the difference of Young’s Modulus and yield stress 9.76% and 43.82% respectively. Simplified Zhu – Wang – Tang constitutive model was derived from the experimental data, resulted the R2 value 0.993 in elastic region. Lastly, the Mohr – Coulomb failure criterion was applied to define the failure between compressive and tensile behavior.