Numerical Investigation of Bundled RC Column under Impact Load

Dynamic impact load has an extensive application area in civil engineering, including highway, military, and marine structures. Many researchers have studied the performance of reinforced concrete (RC) columns under impact load. However, very limited work has been conducted on the effect of bundle reinforced concrete (BRC) columns subjected to lateral impact load. In this study, to examine the behavior of RC columns under impact load, numerical simulations of one with normal reinforcement distribution and three different bundles of reinforced concrete column specimens have been conducted using an explicit finite element (FE) analysis. In addition to the bundle reinforcement distribution, the parameters considered in the study are impact scenarios, impact velocity, pure axial load, and impact locations. From the numerical analysis, it has been found that bundling of longitudinal reinforcement does not only improve the impact capacity but also stabilizes the fluctuating response of impacted reinforced concrete columns. Both peak impact force and maximum lateral displacements of impacted BRC columns increase with increasing initial impact velocity. The numerical results also show that pure axial load slightly improved the impact capacity of the BRC columns. Finally, while the global failure of the RC column governs the response of repeatedly impacted BRC columns, failure characteristics of the single impacted columns are associated with local concrete damage at the impact zone.

Progress of Flake Powder Metallurgy Research

This paper reviewed several recent progresses of the new powder metallurgy technology known as flake powder metallurgy (FPM) including different processing routes, conventional FPM (C-FPM), slurry blending (SB), shift-speed ball milling (SSBM), and high-shear pre-dispersion and SSBM (HSPD/SSBM). The name of FPM was derived from the use of flake metal powders obtained by low-speed ball milling (LSBM) from spherical powder. In this case, the uniformity of reinforcement distribution leads to increased strength and ductility. Powder is the basic unit in PM, especially advanced PM, and its control is key to various new PM technologies. The FPM is a typical method for finely controlling the powder shape through low-energy ball milling (LEBM) to realize the preparation of advanced material structures. The present paper represents a review of the main results of research on FPM and indicates the potential for future studies devoted to the optimization of this processing route.

Static and free vibration analysis of functionally graded CNT reinforced sandwich plates using inverse hyperbolic shear deformation theory

In the present study, the static and free vibration analysis of functionally graded carbon nano-tubes reinforced (FG-CNTR) sandwich plates are studied in the framework of inverse hyperbolic shear deformation theory. The governing differential equations are derived using Hamilton’s principle and solved with the Navier’s solution technique. The analytical approach is used to obtain the deflections, stresses, natural frequencies, and corresponding mode shapes of FG-CNTR sandwich plates with different material properties, stacking sequences, span thickness ratios, core to face sheet thickness ratios, and loading conditions. Different types of reinforcement distribution such as uniformly distribution (UD) and functionally graded (FG) distribution of FG-O, FG-X, FG-/\, and FG-V are considered for the analysis. Also, the efforts are made to achieve the best possible arrangement for the stacking sequences and the appropriate reinforcement distribution that will produce improved static and free vibration responses for the FG-CNTR sandwich plates.

Microstructure and Mechanical Properties of Friction Stir Welded and Processed Joints with the Addition of Nanoparticles: A Review

Background: Friction Stir Welding (FSW) is an efficient process for solid-state joining of two different material without melting by using a non-consumable tool. FSW process was developed for the modification of metallic material microstructure. FSW requires a precise investigation of the process, microstructure, and the welds mechanical properties in order to be used in the fabrication of high- quality engineering components. Through the efforts of improving the weld's mechanical and microstructural properties and conveying the current knowledge of the friction stir to other applications, multiple new technologies have been developed over the time. One of the latest methods to fabricate high performance joints or Nanocomposites alloys is the addition of nano- reinforcements to the joint in Friction Stir Welding (FSW) or the metal matrix in Friction Stir Processing (FSP). Objective: In this study, an overview of effect of nanoparticles on mn this study, an overview of the effect of nanoparticles on microstructural and mechanical properties of the FSW/ FSP joints is presented. The review revealed that the most widely employed additions are SiC, SiO2, Al2O3, and graphite nano-powders. Microstructural evolutions, such as grain size, second phase particles, and reinforcement distribution, usually are investigated using optical methods and Scanning Electron Microscopy (SEM). Furthermore, the mechanical properties of the joints, such as tensile strength, hardness, and wear performance, are also investigated. Based on most of the researches, microstructural evolution associated with adding nanoparticles led to improve the joints mechanical properties.icrostructural and mechanical properties of the FSW/ FSP joints is presented. The review revealed that the most widely employed additions are SiC, SiO2, Al2O3, and graphite nano-powders. Microstructural evolutions such as grain size, second phase particles and reinforcement distribution usually are investigated using optical methods and scanning electron microscopy (SEM). Furthermore, the mechanical properties of the joints, such as tensile strength, hardness, and wear performance, are also investigated Based on most of researches, microstructural evolution associated with adding nanoparticles led to improve the joints’ mechanical properties.

Design and prototyping soft–rigid tendon-driven modular grippers using interpenetrating phase composites materials

Advances in soft robotics and material science have enabled rapid progress in soft grippers. The ability to 3D print materials with softer, more elastic materials properties is a recent development and a key enabling technology for the rapid development of soft robots. However, obtaining the desired mechanical properties (e.g., stiffness) of the soft joints and information about the parameters to select in 3D printers is often not straightforward. In this article, we propose the use of interpenetrating phase composites (IPCs) materials with mathematically generated topologies based on triply periodic minimal surfaces for the development of soft grippers with desired mechanical properties. The flexible joints of the gripper can be realized through two or more phases that are topologically interconnected such that each phase represents a standalone cellular structure. As a case study, we present the design and development of a two-finger soft gripper as an example to demonstrate the application scenario of our approach. The flexible parts with desired stiffness values are realized by using IPCs materials in which the reinforcement distribution can be regulated on the basis of mathematical models. We characterized the properties of the material through a set of quantitative experiments on IPCs material specimens, and then we realized qualitative grasping tests with the gripper and a set of objects with different shapes and sizes. We showed that by properly regulating the properties of IPCs material it is possible to design modular grippers with the same structure, but different closure motions. Grippers can be customized for different tasks by easily assembling and disassembling fingers.

Measurement of Friction and Wear in Aluminum Alloy Al7075/Sic & Gr Processed By Friction Stir Method

Aluminum proved its effective usage in various applications because of its light weight and high strength. This work highly focused on fabrication of aluminum alloy Al7075 with addition of (10 wt. %) of silicon carbide (SiC) and (10 wt. %) graphite (Gr) by using friction stir processing. Initially reinforcement distribution examined by using SEM and EDS analysis. Co efficient of friction and wear was examined by pin on disc Tribometer. Based on the experimental results, improved mechanical properties and tribological properties were obtained compare to the base metal Al7075 aluminum alloy.