Selective laser melting (SLM) is well suited for the efficient manufacturing of complex structures because of its manufacturing methodology. The optimized process parameters for each alloy has been a cause for debate in recent years. In this study, the hatch angle and build orientation were investigated. 304L stainless steel samples were manufactured using three hatch angles (0°, 67°, and 105°) in three build orientations (x-, y-, and z-direction) and tested in compression. Analysis of variance and Tukey’s test were used to evaluate the obtained results. Results showed that the measured compressive yield strength and plastic flow stress varied when the hatch angle and build orientation changed. Samples built in the y-direction exhibited the highest yield strength irrespective of the hatch angle; although, samples manufactured using a hatch angle of 0° exhibited the lowest yield strength. Samples manufactured with a hatch angle of 0° flowed at the lowest stress at 35% plastic strain. Samples manufactured with hatch angles of 67° and 105° flowed at statistically the same flow stress at 35% plastic strain. However, samples manufactured with a 67° hatch angle deformed non-uniformly. Therefore, it can be concluded that 304L stainless steel parts manufactured using a hatch angle of 105° in the y-direction exhibited the best overall compressive behavior.
Sandwich composite structures are comprised of a low-density core (commonly honeycomb) and facesheets. They are typically used in applications that require lightweight for efficient design, such as in the marine and aerospace industries. This work investigates the feasibility of adopting triply periodic minimal surface (TPMS) cellular structures as the core for sandwich composites. Sandwich structures were manufactured using a carbon fiber-reinforced polymer (CFRP) facesheet and three different 304 L stainless steel core structures (honeycomb, gyroid TPMS, and diamond TPMS). Three mechanical tests, namely edgewise compression, three-point bend, and impact test, were carried out to evaluate the performance of each sandwich configuration. The experimental results of the non-traditional sandwich configurations were compared against those of a honeycomb core sandwich composite. The edgewise compression test showed that the ultimate edgewise compressive strength increased by 7% when the honeycomb core was replaced by the gyroid core and reduced by 2% when the diamond core replaced the honeycomb core. The three-point bend test showed that the traditional honeycomb core sandwich configuration had a higher shear yield stress when compared to the non-traditional sandwich structures. The shear yield stress was reduced by 54% when non-traditional sandwich cores were used. The shear ultimate stress was reduced by 41% and 37% when the honeycomb core was replaced by the gyroid and diamond structure, respectively. Impact test results, on the other hand, showed that the peak force recorded during the impact event was reduced, while the absorbed energy was increased when non-traditional cores were used. Peak force was reduced by 28% and 39%, while the absorbed energy was increased by 9% and 16% when the honeycomb core was replaced by the gyroid and diamond cores, respectively.
Hydrokinetic turbines extract energy from free-flowing water, such as river streams and marine currents. For river applications, the typical deployment location is highly space-constrained due to both the nature of the river (i.e., its natural width and depth) and the other usages of the river. Therefore, a modified design of a conversion device is desired to accommodate these space limitations. The objective of this work is to derive optimum design criteria for a coaxial horizontal axis hydrokinetic turbine system utilizing both numerical and experimental approaches. Single-turbine systems configured with different sizes of untwisted untapered blades were numerically studied to obtain the optimum solidity and to examine the blockage effects on the various-solidity rotors. The numerical modeling was, then, extended to analyze the performance of the coaxial multi-turbine system (equipped with optimum-solidity rotors) and characterize its ambient flow. The numerically predicted power outputs were validated against those measured with torque and rotational speed sensors in a water tunnel for both single-turbine and multi-turbine systems. Particle image velocimetry was also utilized to evaluate the wake structure and validate the numerical results of the flow characteristics. The optimum-solidity for the single-turbine system was found to be 0.222 48. An optimum-solidity three-turbine axial system can increase power output by 47% when compared to an optimum-solidity single-turbine system. Increasing the number of rotors from three to five only enhanced efficiency by about 4%. The study of wake structures behind a three-turbine system showed that the highest velocity deficit occurs behind the second rotor rather than the third rotor.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.