Muammel M. Hanon

This study presents a comparative analysis of the tensile properties of 3D-printed polymer specimens with different standard geometry shapes. The objective is to assess the influence of printing orientation and geometry on the mechanical performance. Rectangular-shaped ASTM D3039 specimens with angles of 0°, 15°, and 90° are compared to various tensile test specimens based on ASTM and ISO standards. All specimens are fabricated using polyethylene terephthalate glycol (PETG) material through fused deposition modeling (FDM). Two printing orientations, flat and on-edge, are investigated, and tensile strength, elastic modulus, strain, and elongation at break are measured. The study examines the weak spot commonly found at the neck of the specimens and evaluates the broken areas. Additionally, a numerical analysis using the finite element method (FEM) is performed to identify stress risers’ locations in each specimen type. Experimental results show that the ASTM D3039-0° specimen printed in the on-edge orientation exhibits the highest tensile properties, while the flat orientation yields the best results in terms of the broken area. The ISO 527-2 specimens consistently display lower tensile properties, irrespective of the printing orientation. The study highlights the enhanced tensile properties achieved with the rectangular shape. Specifically, the tensile strength of ASTM D3039-0° was 17.87% and 21% higher than that of the ISO 527 geometry shape for the flat and on-edge orientations, respectively. The numerical analysis indicated that the ISO 527-2 specimen had either no or minimal stress raisers, and the higher stresses observed in the narrow section were isolated from the gripping location. The findings contribute to understanding the relationship between standard geometry shapes, printing orientation, and the resulting tensile properties of 3D-printed polymer specimens.

The current work presents a study of the tribological properties of composite materials designed based on polyethylene terephthalate (PET), which has an important role in the structures of machines, represented by tribological couplings made of composite polymers. The paper examined the effect of two factors, namely recycled waste heating time (HT) and weight percentage (wt. %), on the improvement of the abrasive wear resistance of micro-filler-reinforced epoxy composites. The current research aims to develop epoxy composites by improving abrasive wear resistance while ensuring low cost and weight. Improving wear resistance due to the use of epoxy composites to connect joints that operate under conditions without lubrication in various industrial fields will increase their operational life. The signal-to-noise ratio was analyzed to find out the effect of test parameters HT and wt. % on the wear rate of epoxy composites. Using MINITAB 19 software, regression equations were obtained for each variable to compare it with the Artificial Neural Network (ANN) results. Predictive models based on the regression equation and artificial neural network were developed to predict the wear rate of epoxy composites, and to determine which model is more efficient, their results were compared and the most appropriate model with the low error was determined. The results of the current research showed that the wear resistance of epoxy composites reinforced with RCCF improved by 41 % when increasing wt. % and HT, and also showed that the ANN model is more suitable than the regression model for predicting the wear rate of epoxy composites