Predicting the Strength of Additively Repaired Amorphous Thermoplastics Using Polymer Healing Theory

Fused filament fabrication (FFF) is a widely used additive manufacturing technique. Several printing parameters, including the print speed and print (extrusion) temperature, influence the properties of the 3D printed material. For instance, reducing print speed and increasing print temperature can improve the material's fracture strength, but they also result in longer print times and higher energy consumption. Optimizing these parameters is essential to achieve a balance between material performance and manufacturing efficiency. However, determining the optimal parameters remains a challenge. Current methods often rely on complex thermal histories of the deposited material to predict the fracture strength of 3D printed polymers, which can be time-consuming and imprecise. To address this challenge, we propose a novel equation derived from polymer healing theory to predict the fracture strength of thermoplastic polymers manufactured via FFF for given print speeds and print temperatures. The material constants in the derived equation were found experimentally using three-point bending experiments for acrylonitrile butadiene styrene (ABS) to validate the equation. Infrared thermography and microcomputed tomography were employed to analyze the underlying assumptions. The findings demonstrate that the proposed equation accurately predicts the fracture strength within the conventionally accepted 90% precision. The proposed equation reduces the reliance on time-consuming simulations and costly experimental testing. It also enables rapid evaluation of trade-offs between print speed, print temperature, mechanical performance, and other factors like print time, energy consumption, and dimensional accuracy, accelerating decision-making, and enhancing process efficiency.