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Journal : Civil Engineering Journal

Analysis of Tetrachiral Sandwich Structures at High-Velocity Impact: Influence of the Applied Material and Projectile Core Geometry Maulana, Sultan; Prabowo, Aditya Rio; Wibowo, Wibowo; Do, Quang Thang; Muttaqie, Teguh; Muhayat, Nurul; Fitri, Siti Nurlita
Civil Engineering Journal Vol 10, No 10 (2024): October
Publisher : Salehan Institute of Higher Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/CEJ-2024-010-10-017

Abstract

This research involved ballistic impact analysis on a tetrachiral sandwich structure in which the shapes of the circular nodes in the tetrachiral core are modified into polygonal shapes, namely a square, hexagon, and octagon. The objectives of this study were to observe the effect of a modified sandwich tetrachiral structure core, investigate the effect of the projectile geometry, and calculate the material performance of the structure. This research was conducted using numerical analysis utilizing the finite element method. The simulation methodology was validated through a benchmarking study, the results of which showed an error below 6%. The findings show that the material with the best performance was Armox 500T, at 5033 J. The most difficult projectile to withstand was conical, followed by ogive, hemispherical, and blunt. The results of the core modification on the tetrachiral sandwich structure show that the octagonal core had better energy absorption, by 2.8%, compared to the circular core. Modifying the node geometry in the tetrachiral core and then analyzing it with stress and strain contours are the novel aspects of this research. Doi: 10.28991/CEJ-2024-010-10-017 Full Text: PDF
Comprehensive Assessment for Liquefaction Vulnerability in Indonesia: Empirical and Element Simulation Approaches Fitri, Siti Nurlita; Sawada, Kazuhide
Civil Engineering Journal Vol 11, No 1 (2025): January
Publisher : Salehan Institute of Higher Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/CEJ-2025-011-01-019

Abstract

Historical liquefaction events have occurred at many locations, such as Yogyakarta and Lombok; the most significant flow side is in Palu. The standard Indonesian liquefaction assessment is based on a simplified empirical analysis. However, these methods only occasionally yield appropriate results. Contrastingly, the limited data from the cyclic test ensured that the liquefaction ratio could only partially support the liquefaction vulnerability. This research aims to re-examine the empirical approach that combines the constitutive model using LIQCA with a cyclic triaxial test (CXT) and cyclic simple shear (CSS). The empirical method was arranged using deterministic and probabilistic approaches, and the recommendation of the peak ground acceleration (PGA) threshold was validated. The results show a strong relationship between all calculation methods and the SPT value, which differs in the liquefaction strength ratio. This output offers the PGA recommendation results, reaching a 48% overestimation from the empirical method without considering the cyclic test. This research presents the development of a combination of the empirical method with the element simulation from CXT and CSS. This offers a comprehensive overview of the Indonesian requirement standard assessment for liquefaction vulnerability analysis. Doi: 10.28991/CEJ-2025-011-01-019 Full Text: PDF