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All Journal Civil Engineering Journal Mekanika: Majalah Ilmiah Mekanika
Carvalho, Hermes
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Civil Engineering, Building, Construction & Architecture

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Effect of Cu and SiO₂ on a Remelted-Recycled Piston Alloy Under Vertical Centrifugal Casting Conditions Triyono, Teguh; Surojo, Eko; Prabowo, Aditya Rio; Triyono, Triyono; Djordjevic, Branislav; Carvalho, Hermes; Adie, Prayoga Wira; Sholehuddin, Muhammad Ilham
Civil Engineering Journal Vol. 12 No. 1 (2026): January
Publisher : Salehan Institute of Higher Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/CEJ-2026-012-01-020

Abstract

Functionally graded aluminum matrices produced by means of centrifugal casting offer a route to location-specific properties, yet sustainable feedstocks and dual-density reinforcements are less well explored. In this work, we evaluate vertical centrifugal casting (VCC) of a remelted, recycled piston alloy reinforced with silica (SiO₂) and copper (Cu) particulates selected for their contrasting densities relative to the matrix. Castings were produced at 1000 rpm for 5 minutes using a 500 °C preheated mold and an 800 °C pour temperature. Cu was added at 1–4 wt.% and SiO₂ was added at 0–9 wt.%. Bulk density/porosity measurements, Vickers hardness testing, and optical/SEM microstructural analysis were employed to characterize the resulting gradients. The density increased with the radial distance from the rotation axis, accompanied by a monotonic decrease in porosity, consistent with centrifugal separation. Microstructurally, SiO₂ concentrated toward the inner region near the rotation center; in comparison, Cu was enriched at the outer periphery. Correspondingly, hardness exhibited a spatial gradient: SiO₂-reinforced zones were hardest near the inner region, whereas Cu-rich outer zones were hardest at the external rim. These results demonstrate that VCC of a recycled Al–Si feedstock can be used to reliably tailor its microstructure and properties through density-driven particle segregation, enabling controllable, bidirectional functional grading using environmentally friendly starting materials.
Failure Criteria in Crashworthiness Analysis of Ship Collision and Grounding Using FEA: Milestone and Development Carvalho, Hermes; Ridwan, Ridwan; Sudarno, Sudarno; Prabowo, Aditya Rio; Bae, Dong Myung; Huda, Nurul
Mekanika: Majalah Ilmiah Mekanika Vol 22, No 1 (2023): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v22i1.70959

Abstract

This study presents reviews of the failure criteria to capture the resulting response due to the catastrophe of ship collision and grounding using the finite element. Researchers have introduced several failure criteria, for instance, the Det Norske Veritas (DNV) RP-C204 criterion, Germanischer Lloyd criterion, Peschmann, Rice-Tracey and Cockcroft-Latham (RTCL), Bressan-Williams-Hill (BWH) instability criterion, and Liu criterion. As in the mathematical formula, each criterion has a difference. The choice of failure criteria will depend on the simulation's specific requirements and the analysis's goals. Liu's criterion can be used to evaluate the failure of materials in ship collision simulations, for example, when large element sizes (i.e., 20 mm) are considered in the simulation.
Co-Authors Adie, Prayoga Wira Aditya Rio Prabowo Bae, Dong Myung Djordjevic, Branislav Eko Surojo Nurul Huda Ridwan, Ridwan Sholehuddin, Muhammad Ilham Sudarno Sudarno Teguh Triyono Triyono Triyono