PSI - Issue 53

Mohammad Reza Khosravani et al. / Procedia Structural Integrity 53 (2024) 264–269 Author name / Structural Integrity Procedia 00 (2023) 000–000

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dimensional accuracy of the most 3D-printed parts is approximately ± 0.2 mm and it depends on several parameters including nozzle diameter, utilized layer thickness, model fill strategy, and feed rate. The primary stages of 3D printing with the FDM method are: preparation, printing, and post-processing. Each of these stages includes particular variables that a ff ect how the FDM 3D-printed part behaves mechanically. Preparation factors: design of a component is the first step. In this case, di ff erent parameters depend on the ap plication of 3D-printed parts. In addition, resolution of the part is directly related to its application. The material preparation, file format, and translating the 3D model for printing are examples of preparatory parameters. Printing parameters: these parameters are mostly responsible for mechanical behavior of 3D-printed parts. The printing parameters can be classified into four main categories: material, machine, process, and environment. For instance, machine calibration and accuracy are related to the machine, but layer thickness and raster orientations are examples process parameters. Post-processing techniques: di ff erent techniques such as cleaning, removing support structures, panting, and pol ishing which should be performed after printing process. Post-processing is often expensive, particularly if it is done by hand. It is noteworthy that performing an appropriate post-processing can make a 3D-printed part more durable and improve its physical properties. FDM process has proved its benefits compared to other techniques. Particularly, the overall complexity of the FDM process is very low. Indeed, process simplicity and a good cost-to-production ratio can be considered as the main advantages of the FDM process. In addition, capability of using various materials, cloud server printing, and high printing speed are documented as benefits of the FDM technique. Although di ff erent types of materials can be used in the FDM process, it should be taken into account that FDM works better with polymers that are amorphous in nature compared to he highly crystalline polymers. Because of low processing shrinkage, PLA material is the easiest to utilize in the FDM process. It is noteworthy that developing suitable standards and metrics for FDM process is a necessity which can guide industries and researchers to a better quality assurance and process consistency.

3. Specimen fabrication

In the present study, PLA material was used to print specimens based on the FDM process. Particularly, the speci mens with three di ff erent geometries were designed and printed: (i) dumbbell-shaped, (ii) smooth, and (iii) V-notched specimens were designed in a Computer-Aided Design (CAD) system, transferred into a slicer software and then saved in ”.stl” format. The files were utilized to extrude and deposit molten PLA which is built up in layers from a horizon tal base. The main parameters of the printing process were as follows: layer thickness: 0.15 mm, printing speed: 55 mm / s, nozzle temperature: 215 ◦ C, and infill density: 100%. The fabricated specimens with di ff erent geometries are illustrated in 1.

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R 60

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90 °

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Fig. 1. PLA 3D-printed specimens with di ff erent geometries (Dimensions in mm).