Polylactic acid (PLA), despite its widespread use in three-dimensional (3D) printing technique, is lacking in the literature on creep behavior due to the printing parameters. Also, the potential use of carbon fiber-reinforced composites as 3D printing materials is remarkable as it improves mechanical properties of the produced parts. Therefore, it is important to find out the positive/negative effects of composite filaments on creep strength. The main purpose of this research is to examine the creep behaviors of PLA and PLA composite produced with 3D printer and to reveal the effects of the printing parameters on the short-term creep.

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Purpose The purpose of this paper is to determine the optimum nozzle diameter for parts production with polylactic acid using a three-dimensional printer. The additive manufacturing method used was fused filament fabrication. Design/methodology/approach Designers and researchers have focused on the effects of these parameters on part strength. Additionally, production time is one of the disadvantages of this manufacturing method that researchers are trying to overcome. The production parameters that stand out at this point are nozzle diameter and layer thickness. Findings As a result of the study, it was determined that the increased nozzle diameter led to increased part strength. At the same time, layer thickness had the most significant effect on surface quality. The increased nozzle diameter and part density led to decreased production time. It was concluded that larger nozzle diameter and lower layer thickness should be used for parts with superior properties. Research limitations/implications The experimental printing parameters used in the study were nozzle diameter (0.2, 0.4, 0.6, 0.8, 1.0 and 1.2 mm), layer thickness (0.1, 0.2 and 0.3 mm) and printing orientation (0°, 45° and 90°). The effects of printing parameters on part strength, dimensional accuracy, surface quality and part density were analyzed experimentally. Originality/value The effects of several printing parameters have been examined in the literature. However, the effect of different nozzle diameters has been ignored. There are limited experimental studies that examine the effect of nozzle diameter on mechanical properties, surface roughness, dimensional quality and production time. In this regard, the results obtained from various nozzle diameters used in this study will significantly contribute to the literature.

3D printing technology has grown in the past decades. Faster and cheaper techniques are developed to produce complicated parts. It is also known that the hybrid material approach is beneficial in material selection. In this way, the mechanical properties are improved by using the materials instead of using them alone. In this study, TPE (Thermoplastic Elastomer) þ Air and TPE þ Foam hybrid materials are designed to get better performance than those obtained during only TPE material using. TPE are produced by 3D printer using FDM (Fused Deposition Modeling) technique. Fabricated hybrid materials are exposed to compression test according to ASTM D695 standard. The effect of different filling ratios and infill patterns are investigated. As a result of the study, the highest compressive strength is acquired with triangle infill pattern. These mechanical characteristics are increased in all infill patterns with increasing filling ratio. When TPE þ Air and TPE þ Foam hybrid materials are compared, higher Young's modulus and compressive yield strength values (about 95% increasing) are procured with TPE þ foam hybrid materials. This hybrid material approach, rapid prototyping, and the combined use of foam material are provided a significant increment in compressive strength and a wide range of material properties can be obtained.

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