A pinboard by
Omar Amhimmid

PhD student, Swinburne University of Technology


This research investigates and develops mathematical models for the functionality of 3D built parts

Fused deposition modeling (FDM) process has become a leading additive manufacturing process over the past few years because it gives designers the possibility to fabricate physical parts of any complexity of geometry entirely in a wide range of engineering thermoplastic materials without the need for special tools. However, as a relatively new manufacturing technology, it is still under research and development phase and not ready for actually replacing conventional manufacturing processes as the resulting properties of the manufactured products are not yet strong enough for a variety of industrial applications. FDM process has its own drawbacks related to part accuracy, mechanical properties and surface roughness. Hence, there are significant challenges faced this process with respect to the quality and functionality of the manufactured parts. To achieve a desired quality and functionality of the part, it is important to understand key issues and weaknesses of the process and identify the process parameters affecting the part quality. No reliable and systematic studies have been made in the previous studies to understand the influence of FDM process parameters on the mechanical properties of the part under dynamic and cyclic loading conditions. Consequently, for wider application of FDM technology, a detailed investigation on the effect of fabrication parameters is required. Unlike all previous studies, this study presents results of the experimental investigation on the effect of the main FDM process parameters on different part quality measures such as dimensional accuracy, build time, material consumption, dynamic mechanical properties and rheological properties for FDM newly developed material. In this research, the effect of independent and interactive effects of FDM parameters on these properties is comprehensively investigated and the optimum process parameters are determined, validated and applied upon real parts, and the results will be analyzed, discussed, and evaluated. The main contribution of this research is to build up a new relationship between the FDM fabrication parameters and various quality characteristics of PC-ABS material. This research also introduces for the first time the use of definitive screening design in AM problem-solving. The results show that there is a substantial effect of FDM fabrication parameters on the quality and functionality of the processed parts with a good improvement in them using optimized process parameters


Materials, Vol. 9, Pages 895: Analytical Modelling and Optimization of the Temperature-Dependent Dynamic Mechanical Properties of Fused Deposition Fabricated Parts Made of PC-ABS

Abstract: Fused deposition modeling (FDM) additive manufacturing has been intensively used for many industrial applications due to its attractive advantages over traditional manufacturing processes. The process parameters used in FDM have significant influence on the part quality and its properties. This process produces the plastic part through complex mechanisms and it involves complex relationships between the manufacturing conditions and the quality of the processed part. In the present study, the influence of multi-level manufacturing parameters on the temperature-dependent dynamic mechanical properties of FDM processed parts was investigated using IV-optimality response surface methodology (RSM) and multilayer feed-forward neural networks (MFNNs). The process parameters considered for optimization and investigation are slice thickness, raster to raster air gap, deposition angle, part print direction, bead width, and number of perimeters. Storage compliance and loss compliance were considered as response variables. The effect of each process parameter was investigated using developed regression models and multiple regression analysis. The surface characteristics are studied using scanning electron microscope (SEM). Furthermore, performance of optimum conditions was determined and validated by conducting confirmation experiment. The comparison between the experimental values and the predicted values by IV-Optimal RSM and MFNN was conducted for each experimental run and results indicate that the MFNN provides better predictions than IV-Optimal RSM.

Pub.: 04 Nov '16, Pinned: 31 Jul '17

Effect of Process Parameters on Dynamic Mechanical Performance of FDM PC/ABS Printed Parts Through Design of Experiment

Abstract: In fused deposition modeling (FDM) additive manufacturing process, it is often difficult to determine the actual levels of process parameters in order to achieve the best dynamic mechanical properties of FDM manufactured part. This is mainly due to the large number of FDM parameters and a high degree of interaction between the parameters affecting such properties. This requires a large number of experiments to be determined. This paper presents a study on the influence of six FDM process parameters (layer thickness, air gap, raster angle, build orientation, road width, and number of contours) on the dynamic mechanical properties of the FDM manufactured parts using the fraction factorial design. The most influential parameters were statistically obtained through the analysis of variance (ANOVA) technique, and the results indicate that the layer thickness, the air gap, and the number of contours have the largest impact on dynamic mechanical properties. The optimal parameters for maximum dynamic mechanical properties were found to be layer thickness of 0.3302 mm, air gap of 0.00 mm, raster angle of 0.0°, build orientation of 0.0°, road width of 0.4572 mm, and 10 contours. Finally, a confirmation experiment was performed using optimized levels of process parameters, which showed good fit with the estimated values.

Pub.: 10 Jun '16, Pinned: 31 Jul '17

Mathematical modeling and FDM process parameters optimization using response surface methodology based on Q-optimal design

Abstract: Fused deposition modeling (FDM) is a growing 3D printing technique widely practiced around the world in various industrial applications because of its ability to create complex 3D objects and geometries. Reduction of build time and feedstock material consumption without compromising the mechanical performance is the major concern in most industrial applications affecting the cost and the functionality of the manufactured part. One of the key issues of FDM process is how to select the correct parameters to reduce the build time and to reduce feedstock material consumption while maintaining high dynamic mechanical properties. In this study, influence of critical FDM parameters - layer thickness, air gap, raster angle, build orientation, road width, and number of contours - are studied using Q-optimal response surface methodology. Their effects on build time, feedstock material consumption and dynamic flexural modulus are critically examined. Mathematical models have been formulated to develop a functional relationship between the processing conditions and the process quality characteristics. Analysis of variance (ANOVA) technique was employed to check the adequacy and significance of mathematical models. Moreover, the optimal setting of process parameters was determined. A confirmation test was also conducted in order to verify the developed models and the optimal settings. The results show that Q-optimal design is a very promising method in FDM process parameter optimization. The results also confirm the adequacy of the developed models.

Pub.: 09 Jul '16, Pinned: 31 Jul '17