The Effect of 3D Printing Process Parameters on the Mechanical Properties of PLA Parts

Taking the PLA molded by FDM as the research object, the influence of various process parameters on mechanical properties is investigated through comparative experiments, which provides reference and help for the promotion and application of FDM molding technology. During the molding process, the PLA material undergoes the process of melting to solidification, thus the performance of the molded part is worse than the original due to thermal shrinkage and other reasons. To improve the quality and mechanical properties of the molded parts, the experiment is designed using an orthogonal test method in parallel with nine different sets of process parameters (layer thickness, build direction, filling speed, and infill density, etc.). Ultimately, the mechanical properties of PLA are tested and the results are analyzed respectively to determine the main factors affecting the mechanical properties and their optimal level combination. Among them, fill rate is the crucial factor in compressive property, while build direction has a significant effect on surface roughness, tensile property and bending property.

Temperature and Stress Effects on the Compressive Creep Behavior of Parallel Strand Bamboo

Parallel strand bamboo (PSB) is an engineered bamboo product fabricated using crushed bamboo fiber bundles. Recently, this product finds applications in the civil engineering field. It is expected that the use of this composite will continue to grow because of its excellent mechanical performance, relatively low variability in material properties, and shape standardization. Modern bamboo structures made from PSB composites may be subjected to temperature variations during service. So far, however, there has been little discussion about the temperature-dependent creep. In this study, an investigation was carried out on the short-term behavior of the compressive property of PSB. A stress range of 8 to 64 MPa over a temperature range of 25°C to 75°C was considered in the 24-hour creep tests. In addition, Burgers model was adopted to describe the short-term creep behavior of PSB. Temperature and stress effects on the creep compliance of the Burgers model were also discussed.

Mechanical Properties of Spark Plasma Sintering-Processed Pure Ti and Ti-6Al-4V Alloys: A Comparative Study between Harmonic and Non-Harmonic Microstructures

Microstructure characteristics and compressive property relationships of so-called harmonic (composed by fine and coarse grains) and conventional pure titanium (Ti) and Ti-6Al-4V alloy processed by powder metallurgy route are presented in the present work. Electron backscatter diffraction (EBSD) analysis was performed to characterize the as-processed microstructures. The harmonicity structure of selected samples is described, and relevant EBSD maps are presented. The bulk samples’ hardness is reported, along with compressive responses at quasi-static and intermediate strain rates, ranging from 0.005 s−1 to 16 s−1. The strain rate sensitivity of these metallic samples is discussed, and the benefits in terms of mechanical properties of the harmonic microstructures compared with the non-harmonic conventional ones are highlighted. Finally, a modified Johnson–Cook model was shown to predict fairly the experimental results.