title: Simulation of mechanical behavior and optimization of simulated injection molding process for PLA based antibacterial composite and nanocomposite bone screws using central composite design.
abstract: In this study, injection molding of three poly lactic acid (PLA) based bone screws was simulated and optimized through minimizing the shrinkage and warpage of the bone screws. The optimization was carried out by investigating the process factors such as coolant temperature, mold temperature, melt temperature, packing time, injection time, and packing pressure. A response surface methodology (RSM), based on the central composite design (CCD), was used to determine the effects of the process factors on the PLA based bone screws. Upon applying the method of maximizing the desirability function, optimization of the factors gave the lowest warpage and shrinkage for nanocomposite PLA bone screw (PLA9). Moreover, PLA9 has the greatest desirability among the selected materials for bone screw injection molding. Meanwhile, a finite element analysis (FE analysis) was also performed to determine the force values and concentration points which cause yielding of the screws under certain conditions. The Von-Mises stress distribution showed that PLA9 screw is more resistant against the highest loads as compared to the other ones. Finally, according to the results of injection molding simulations, the design of experiments (DOE) and structural analysis, PLA9 screw is recommended as the best candidate for the production of biomedical materials among all the three types of screws.
authors: Applied Science Nano Research Group, ASNARKA, P.C. 1619948753, Tehran, Iran.
authors: Behzad Shiroud
authors: BS
authors: Heidari
authors: Applied Science Nano Research Group, ASNARKA, P.C. 1619948753, Tehran, Iran.
authors: Erfan
authors: E
authors: Oliaei
authors: School of Chemical Engineering, Iran University of Science and Technology, Narmak, Tehran, Iran.
authors: Hadi
authors: H
authors: Shayesteh
authors: Applied Science Nano Research Group, ASNARKA, P.C. 1619948753, Tehran, Iran. Electronic address: mohdvi@gmail.com.
authors: Seyed Mohammad
authors: SM
authors: Davachi
authors: Applied Science Nano Research Group, ASNARKA, P.C. 1619948753, Tehran, Iran.
authors: Iman
authors: I
authors: Hejazi
authors: Department of Chemical Engineering, Shahrood Branch, Islamic Azad University, P.O. Box 36155-163, Shahrood, Iran.
authors: Javad
authors: J
authors: Seyfi
authors: Macromolecular Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136, United States.
authors: Mozhgan
authors: M
authors: Bahrami
authors: Department of Biotechnology, School of Chemical Engineering, College of Engineering, University of Tehran, Tehran, Iran.
authors: Hamid
authors: H
authors: Rashedi
mesh_terms: D000900:Anti-Bacterial Agents / Q000032:analysis*; D001863:Bone Screws; D020342:Finite Element Analysis; D053761:Nanocomposites / Q000032:analysis*; D011091:Polyesters / Q000032:analysis*; D013314:Stress, Mechanical
chemical_list: D000900:Anti-Bacterial Agents; D011091:Polyesters; C033616:poly(lactide)
keywords: Central composite design; Injection molding simulation; PLA bone screw; Shrinkage and warpage; Structural analysis