The drag is a crucial factor in reducing the speed of movement and increasing unnecessary energy loss. In this work, inspired by dolphins, five bionic flexible coatings with drag reduction performance were designed and manufactured. First and foremost, the mixed solution, composed of the polydimethylsiloxane and ethyl acetate, was sprayed on aluminum disks with a spray gun, and the bionic flexible coatings were obtained by heating the aluminum disks sprayed with the mixed solution. Afterward, the mechanical properties and surface characteristics of the flexible coatings were characterized. The experimental results for the flexible coatings of drag reduction performance were obtained by using the drag force device. Above all, the parametric study focusing on the flexible coating of the mechanical properties affects the station of flow, which is performed to analyze the impact on drag reduction. Selecting the aluminum disk without any coating as a reference, numerical simulation methods were introduced to explore the drag reduction mechanism of the bionic flexible coating. The results evidence that the drag reduction ratio is 21.6% at the rotation velocity 50 rpm. Under the action of frictional resistance, the coating of elastic deformation caused by the viscoelasticity of the coating like the dolphin skin results in a decrease in frictional resistance of the wall.
Extensive brittle failures in the weld zone of the beam bottom flange in composite joints of SMRFs were observed during the Northridge earthquake and the Kobe earthquake. One of the main reasons is the large tensile strain demand generated at the beam bottom flange zone under positive bending. The key to accurately understanding the mechanical properties of composite joints is the effective width of the slab. However, researchers have no consensus on the flange slab’s effective width for composite joints, even with the simplest solid concrete slab. Therefore, the best way to design the composite joint specimen is by following the current design specifications. However, each specification implements different ideas and approaches for specifying an effective slab width. This paper presents comparisons of the effective flange width provisions in China, the United States, Australia/New Zealand, and the European Union. The characteristics of each provision are briefly described and summarized. Numerical comparisons for positive and negative moment regions of continuous spans follow. Based on the commonalities and main differences among all these provisions, we propose a recommended equation for calculating the effective width of a solid concrete slab, reflecting the specification differences. The reliability of the recommended equation was verified with ABAQUS software analysis. The recommended equation can meet the fast and secure design requirements for composite joints in tests with concrete slabs.
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.