Analysis And Optimization Of The Mechanical Properties For FDM Specimens Based On PLA Filament

Fused deposition modeling (FDM) process is a class of widely used technique in the field of rapid prototyping manufacturing. It plays an important role in the production of engineering parts and medical devices. The molding precision of FDM process has always been a hot topic, but few of studies about the mechanical properties of the forming parts have been carried out. With the emergence of new materials, and the continual increasing of actual project requirements, more users began to focus on the mechanical properties of the forming parts. To improve the bonding strength and other mechanical properties of the forming parts become the main research focus for FDM process, as well as the whole field of rapid prototyping.Firstly, from the micro-level, combining with new polylactic acid (PLA) material’s inherent properties, this paper describes the adhesive mechanism of liquid crystal state polymer. Then based on the principles of heat welding, it derives the theoretical model for bonding strength and monolithic cured layer’s stress-strain relation equation, these works provide a useful theoretical basis for the subsequent analysis of the mechanical properties of molded parts.According to the different influencing parameters like modelling direction, forming temperature, layer thickness, contour width, raster width, and extruding speed, three sets of test parameters with 135 specimens have been made. By the combining of microscopic image observation and tensile test method, ultimate tensile strength, the Young’s modulus and tensile strain have been analyzed and compared respectively, the factors affecting the nature of the mechanical properties of the molded article, while PLA material to provide an effective data reference in the field of rapid prototyping applications. After analyzing the test results obtained in XZY molding direction, mechanical properties when molding temperature of 210℃ when the specimen is superior molded specimens of other parameters, the above process parameters specific impact on the mechanical properties remain to be analyzed.Furthermore, to further analyze the effect of layer thickness, contour width, raster width, and extruding speed on the mechanical properties of the order, the four parameters of multi-index comprehensive optimization. According to the experimental design of the nine groups of orthogonal tensile test, this paper takes the ultimate tensile strength, elastic modulus and increase quantity of tensile strain as the optimization target. Using the grey correlation to analyze the test results, it obtains the effect order of the comprehensive process parameters, and optimizes the combination of multi-objective optimal parameters; in addition, using fuzzy reasoning method on the further analysis to the data and the comparative analysis of the results, the main difference between the two methods of analysis are obtained. Finally, the results of the test proved that the use of fuzzy reasoning method, the result is more practical and effective.