Appl. Mech., Volume 5, Issue 3 (September 2024) – 3 articles

Laser additive manufacturing with mixed powders of aluminum alloy and silicon carbide (SiC) or boron carbide (B₄C) is investigated in this experiment. With various mixing ratios of SiC/Al to form metal matrix composites (MMC), their mechanical and physical properties are empirically investigated. Parameters such as laser power, scan speed, scan pattern, and hatching space are optimized to obtain the highest density for each mixing ratio of SiC/Al. The mechanical and thermal properties are systematically investigated and compared with and without heat treatment. It shows that 2 wt% of SiC obtained the highest strength and Young’s modulus. Graded composite additive manufacturing (AM) of MMC is also fabricated and characterized. Various types of MMC devices, such as heat sink using graded SiC MMC and grid type three-dimensional (3D) neutron collimators using boron carbide (B₄C), were also fabricated to demonstrate their feasibility for applications. Full article

This literature review provides an in-depth exploration of the research conducted on residual stresses (RS) in Wire Arc Additive Manufacturing (WAAM) products, particularly focusing on how process parameters influence the phenomenon. The motivation of the study is the growing focus on WAAM technology and the observation that RS plays a crucial role in determining the mechanical behavior and structural integrity of WAAM components. Thus, the review is intended to provide a better understanding of the relationship between process parameters and RS to optimize the WAAM process and ensure the durability of the final products. It also summarizes key findings, measurement techniques, challenges, and future directions in this evolving field. The review also analyzes measurement techniques used to characterize RS in products fabricated by WAAM as a function of process parameters. Experimental measuring techniques and numerical analysis of RS to determine the impacts of RS in mechanical responses in products of WAAM were discussed. Experimental measuring techniques, such as X-ray diffraction, neutron diffraction (ND), contour and ND, digital image correlation, thermomechanical coupling and contour, and hole-drilling methods, along with numerical simulations like finite element analysis, are discussed to determine the impacts of RS on the mechanical responses of WAAM products. Additionally, it addresses the influence of thermal cycles, cooling rates, and deposition strategies on RS formation. The role of material properties, such as thermal conductivity and expansion coefficients, in RS development is also considered. By offering a comprehensive overview of current research trends and insights, this review serves as a valuable resource to guide future investigations, fostering the advancement of WAAM as a robust and efficient manufacturing technology. The review also underscores the importance of interdisciplinary approaches combining experimental and numerical methods to tackle the complex issues of RS in WAAM, aiming to enhance the performance and reliability of additively manufactured components. Full article

Reinforced Concrete (RC) members in existing RC structures are susceptible to shear-critical due to their under-reinforced design. Thus, implementing a retrofitting technique is essential to eliminate the casualties that could arise from sudden and catastrophic collapses due to these members’ brittleness. Among other proposed techniques, using Carbon-Fiber Reinforced Polymers (C-FRP) ropes to increase the shear strength of RC structural elements has proved to be a promising reinforcement application. Moreover, an Electro-Mechanical Impedance (EMI-based) method using Lead Zirconate Titanate (PZT-enabled) was employed to assess the efficiency of the strengthening scheme. Initially, the proposed technique was applied to C-FRP rope under the subjection of pullout testing. Thus, a correlation of the rope’s tensile strength with the EMI responses of the PZT patch was achieved using the Root Mean Square Deviation (RMSD) metric index. Thereafter, the method was implemented to the experimentally acquired data of C-FRP ropes, used as shear reinforcement in a rectangular deep beam. The ropes were installed using the Embedded Through Section (ETS) scheme. Furthermore, an approach to evaluate the residual shear-bearing capacity based on the EMI responses acquired by being embedded in and bonded to the ropes’ PZTs was attempted, demonstrating promising results and good precision compared to the analytical prediction of the C-FRP ropes’ shear resistance contribution. Full article