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All Journal Civil Engineering Journal Mekanika: Majalah Ilmiah Mekanika
R. Ridwan
Universitas Merdeka Madiun
Civil Engineering, Building, Construction & Architecture

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Effect of Holding Time and Temperature of Hot Pressing on Tensile Strength of Biodegradable Plastic Made of Carrageenan Fitrian Imaduddin; Palgunadi Sastra; Wijang Wisnu Raharjo; Putri Wullandari; Ridwan Ridwan
Mekanika: Majalah Ilmiah Mekanika Vol 21, No 2 (2022): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v21i2.64292

Abstract

The most significant environmental problem was caused by plastic. One way to handle plastic waste was using biodegradable plastic because it faster decomposes naturally. Biodegradable plastic can be made from carrageenan by the hot press method. This method can make biodegradable plastic with large dimensions. However, the plastic quality depended on the holding time, temperature, and pressure selected during the hot pressing process. Therefore, this research is conducted to determine the effect of holding time and temperature in the hot press process on the tensile strength of biodegradable plastic made from carrageenan. The composition of the biodegradable plastic material used was 35% carrageenan, 35% polyvinyl alcohol (PVA), and 30% glycerol. In the manufacture of composites, the holding time was varied: 10, 20, 30, and 40 minutes, as well as the process temperature varied from 100, 110, 120, and 130 °C. The tensile strength of the composite was observed through tensile testing using a Universal Testing Machine. FTIR, XRD, and SEM tests were also conducted to sharpen the analysis. The addition of holding time led to an increase in the tensile strength of biodegradable plastics. The highest tensile strength was obtained at a holding time of 30 minutes with a value of 4.45 MPa. After 30 minutes, the tensile strength of the biodegradable composite decreased. Meanwhile, the addition of process temperature caused a decrease in the tensile strength of biodegradable plastics. The highest tensile strength was obtained at a process temperature of 100 °C with a value of 5.28 MPa.
Forecasting the Effects of Failure Criteria in Assessing Ship Structural Damage Modes Aditya Rio Prabowo; R. Ridwan; T. Tuswan; Fitrian Imaduddin
Civil Engineering Journal Vol 8, No 10 (2022): October
Publisher : Salehan Institute of Higher Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/CEJ-2022-08-10-03

Abstract

The failure to achieve satisfactory results will cause immense losses in major projects. Nevertheless, the modeling limitations and phenomenon assumptions represented by failure criteria can significantly influence the final results—e.g., the damage mode, affecting its quantification—thus representing an interesting topic for technical assessment. This work aims to forecast the effects of several failure criteria on the damage occurring due to structural loading schemes, such as compression, torsion, and tensile tests. Failure criteria are taken based on the proposal of pioneer researchers and include those of Peschmann (P), Germanischer Lloyd (GL), Liu (LIU), and Rice–Tracey and Cockroft–Latham (RTCL). A series of nonlinear finite element analyses (NLFEA) are conducted by inputting these criteria into different loading schemes. To obtain reliable validation, the proposed models are designed based on previous laboratory experiments. The numerical results of NLFEA in the forms of damage mode, i.e., tearing, plastic deformation, and torsion, are cross-checked with experimental data. The results show that numerical modeling using the LIU criterion produces slightly larger discrepancies compared with experimental data. This indication is founded on the analysis of stress–strain, load–displacement, and shear stress–strain during the tensile test, compressive load, and torsion load, respectively. According to this work, we formulate recommendations based on the forecast tendency and accuracy for each damage mode subjected to failure criteria. Therefore, future works can adopt the findings in our current work when choosing to apply specific criteria in structural modeling and load idealization. Doi: 10.28991/CEJ-2022-08-10-03 Full Text: PDF
Failure Criteria in Crashworthiness Analysis of Ship Collision and Grounding Using FEA: Milestone and Development Hermes Carvalho; Ridwan Ridwan; Sudarno Sudarno; Aditya Rio Prabowo; Dong Myung Bae; Nurul Huda
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 DNV RP-C204 criterion, Germanischer Lloyd criterion, Peschmann, RiceTracey 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.
Evaluating the Influence of Environmental Factors and Parameters on Advancements in Welding and Joining Processes: A Review Sudarno Sudarno; Quang Thang Do; Haris Nubli; Dandun Mahesa Prabowoputra; Nur Candra Dana Agusti; Ridwan Ridwan; Anggi Vandika
Mekanika: Majalah Ilmiah Mekanika Vol 22, No 2 (2023): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v22i2.75378

Abstract

This review article presents a comprehensive overview of welding, including its environmental influence, common welding failures, welding parameters, and predictions of development regarding welding and corrosion. The quality and integrity of welds can be significantly affected by environmental factors such as temperature, humidity, and atmospheric contaminants. Moreover, welding failures can occur due to various reasons, such as improper welding techniques, inadequate preparation, corrosion, or material defects, leading to structural weaknesses and compromised joint integrity. Furthermore, notable progress has been achieved in welding system technology, encompassing automation, robotics, and real-time monitoring. These advancements underscore the vital role of welding parameters in transforming control, precision, and productivity within the welding process. The integration of innovative welding systems has led to improved welding efficiency, reduced human error, and increased overall process reliability. This review consolidates knowledge from diverse sources, making it a valuable resource for researchers, practitioners, and industries involved in welding.
Numerical Analysis of Openings in Stiffeners under Impact Loading: Investigating Structural Response and Failure Behavior Ridwan Ridwan; Sudarno Sudarno; Haris Nubli; Achmad Chasan; Iwan Istanto; Pandu Sandi Pratama
Mekanika: Majalah Ilmiah Mekanika Vol 22, No 2 (2023): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v22i2.76774

Abstract

As the demand for lightweight ships continues to rise, there is a growing necessity to explore innovative methods that can reduce the weight of ship structures without altering the materials used. This research addresses this challenge by investigating the effect of opening in stiffener under impact loading. The research aims to provide valuable insights into optimizing weight reduction strategies while ensuring the ship's overall strength and performance remain uncompromised. To achieve this goal, the study employed the finite element method as a solver. By simulating impact scenarios and analyzing stiffener responses, the numerical analysis quantified the structural behavior and failure modes. The focus was on understanding the impact of openings on the structural integrity and how it relates to their positioning relative to the impact point. The results of the study indicate that opening slightly distant from the impact point exhibit greater strength, showcasing a counterintuitive relationship between opening placement and structural response.
Co-Authors Achmad Chasan Aditya Rio Prabowo Anggi Vandika Dandun Mahesa Prabowoputra Dong Myung Bae Fitrian Imaduddin Fitrian Imaduddin Haris Nubli Hermes Carvalho Iwan Istanto Nur Candra Dana Agusti Nurul Huda Palgunadi Sastra Pandu Sandi Pratama Putri Wullandari Quang Thang Do Sudarno Sudarno T. Tuswan Wijang Wisnu Raharjo