Shahrekord UniversityAdvanced Structural Mechanics3060-804X2120251201A Study on Improving the Vibration Performance of the Smart Moment Frame (Produced by PACO Company in USA) using the Proposed Brace under Modal Analyses in the Frequency11411611710.22034/asm.2024.14754.1022ENMasoudMahdaviPhD Student, K. N. Toosi University of Technology, Tehran , Iran0009-0005-9385-7525AbbasBabaafjaeiMSc Student, K. N. Toosi University of Technology, Tehran , Iran0009-0004-6268-8602SeyyedRezaHosseiniMSc Student, K. N. Toosi University of Technology, Tehran , IranJournal Article20240417Reducing the vibration of the steel structure is one of the most important issues in evaluating its dynamic performance. There are various methods to reduce the vibration of the structure such as structural bracing systems. Modern concentrically braced systems<br>are among the latest methods used to reduce structure vibration. In the present paper, with the finite element method and ABAQUS software, the steel frame is improved with rhombus and Super X braces. The smart steel frames are manufactured by PACO<br>Engineering Company in the USA. The smart braced frames are investigated using modal analyses in the frequency domain. The results show that the rhombus bracing system improves the vibration performance in the PACO smart frames with the Super X<br>bracing system. The proposed rhombus bracing system in the smart moment frame reduces von Mises stress by 8.04%, displacement by 30.02%, natural frequency by 10.64%, and eigenvalue by 10.95% compared to the smart moment frame equipped<br>with a Super X bracing system. The results of the present paper are suggested to PACO Company in the USA and engineers in Iran as a means to improve the vibration of the steel moment frame.https://asm.sku.ac.ir/article_116117_23f20ad7a1ba6b02703294432df88417.pdfShahrekord UniversityAdvanced Structural Mechanics3060-804X2120251201Numerical and Experimental Investigation of Perforation of Flat- ended Fragment Tungsten Heavy Alloy into Thin Metallic Targets152811662410.22034/asm.2026.14892.1024ENPouyaPiraliAssistant Professor, Faculty of Materials and Manufacturing Technologies, Malek Ashtar University of Technology, Tehran, Iran.MostafaHaghighatpourFaculty of Materials and Manufacturing Technologies, Malek Ashtar University of Technology, Tehran, Iran.Journal Article20260125Tungsten heavy alloys (WHAs) are high density materials widely used in ballistic applications because of their superior mechanical strength and high impact resistance. In this study, the perforation behavior of tungsten heavy alloy flat nosed projectiles with a W90–Ni7–Fe3 composition, manufactured via powder metallurgy, was investigated through combined experimental and numerical approaches. Flat nosed projectiles with specified dimensions (5.8 mm in diameter and 6.7 mm in length) were launched toward St37 steel targets with thicknesses of 1.5 mm and 3 mm at a controlled impact velocity of 260 m/s. Ballistic experiments were performed using a gas gun system to measure the projectile residual velocity and the Maximum back face deflection (BFD). Experimental results indicated that complete perforation did not occur for the 3 mm thin target and Maximum back face deflection was 5 mm. In contrast, complete perforation accompanied by plug formation was observed for the 1.5 mm thick target, with residual projectile velocities ranging from 123 to 135 m/s. Numerical simulations of the perforation process were performed using the LS DYNA finite element code. The Johnson–Cook constitutive and failure models were employed to describe the material behavior of both the projectile and the target. The numerical simulations accurately reproduced the projectile deformation mechanisms and the corresponding failure modes of the target, including plug formation. The numerical simulations showed consistent agreement with the experimental observations.https://asm.sku.ac.ir/article_116624_82d458df824372299b0359749da9fee8.pdf