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Analisis Karakteristik Akustik Dan Dinamik Micro-Perforated Panel Dengan Struktur Honeycomb Mengunakan FEM Debby Perkasa; Afdhilla Afdhilla; Meifal Rusli
Jurnal Teknik Mesin Vol 15 No 2 (2022): Jurnal Teknik Mesin
Publisher : Politeknik Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30630/jtm.15.2.941

Abstract

This study focuses on the discussion of the correlation of acoustic and dynamic characteristics of hybrid panels, namely Micro-perforated Panel (MPP) and Honeycomb (HC) structures. Acoustic characteristics in experimental studies are obtained by the sound absorption coefficient and Sound Transmission Loss. Meanwhile, the dynamic characteristics are obtained by the mode and frequency response analysis of numerical simulation methods. The results of these two characteristics serve as a benchmark for the development of experimental data studies/analysis. The purpose of this study is to obtain dynamic characteristics using mode and frequency response analysis through the finite element method. The development of this experimental study/analysis data is to overcome the drawbacks of experimental testing. The weakness obtained from experimental studies is that the stages are complicated and require a very large amount of money. The method in this study was carried out by numerical simulation using the finite element method using the Ansys 2019 R3 program. The results of this study obtained dynamic characteristics from the development of experimental study analysis methods using numerical simulations through the finite element method. Numerical simulation on the hybrid panel provides efficiency at the experimental testing stage. The results of the mode and frequency response analysis obtained by numerical simulation methods have similarities in the frequency range of high and low frequency values of sound absorption coefficient and soundtransmission loss.
The Analysis of Loosening of Bolt Connection Due to Structural Vibration Through Changes in Dynamic Characteristics Rahmatsyah Maksum Ramsi; Meifal Rusli; Mulyadi Bur
Jurnal Teknik Mesin Vol 16 No 1 (2023): Jurnal Teknik Mesin
Publisher : Politeknik Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30630/jtm.16.1.1091

Abstract

Bolted joints are generally used to connect two or more mechanical structures due to their ease of assembly and disassembly for maintenance. However, the problem of vibration is one of the main challenges when the tightness of the bolted joints is insufficient, causing failures such as looseness and resulting in disconnection. Looseness is the most common cause of dynamically loaded bolted joint structure failure. This study tested a simple bolt joint structure to observe the looseness indication of the bolt joint after it was vibrated using a shaker in a single-frequency excitation. A freely fixed beam consisting of two beams connected by a bolt and subjected to varying bolt tightening torques. Then the response measurement is carried out by recording the FRF graph obtained from loosening and tightening bolt torque effects. Modal parameters such as personal frequency and damping ratio were collected through experimental modal analysis (EMA). It was found that the structure’s vibration could change the conditions of loosening or lower tightening torque indicated by shifting the structure’s natural frequency. In addition, the damping characteristics are also affected by changes in the tightening torque. Especially when conditions are loose, the damping ratio becomes much higher than that of tightening.
PENGARUH CLEARANCE DAN PEMBEBANAN RADIAL TERHADAP PERPINDAHAN, DISTRIBUSI BEBAN KONTAK, DAN KEKAKUAN ELEMEN ROL PADA SPHERICAL ROLLER BEARING Hendery Dahlan; Rahmi Safitri; Meifal Rusli; Mulyadi Bur
Jurnal Rekayasa Mesin Vol. 14 No. 1 (2023)
Publisher : Jurusan Teknik Mesin, Fakultas Teknik, Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/jrm.v14i1.1065

Abstract

This study aims to determine the effect of clearance and loading regarding to the displacement, distribution of contact loads and stiffness of spherical roller bearings at rest. The displacement formulation of the inner ring of the bearing was developed by defining the angle of inclination of the roller element to the axis of shaft. The comparison between exact calculations using the Matlab program and numerical modeling with MSC Marc for the displacement has an error value of less than 10%. Therefore, the displacement formulation of the inner ring of the bearing is used to calculate the exact distribution of contact load and stiffness of the spherical roller bearing and numerical modeling. The results revealed that the effect of clearance and loading on the displacement of the inner ring of the spherical roller bearing is directly proportional. The contact load of the bearing roller element is distributed over the part of the roller element that is in contact with its path, where the largest contact load occurs at the position of the roller element parallel to the axis of the shaft at rest. Meanwhile, bearing stiffness will decreases with increasing the value of clearance.  
Bolted Joint Loosening Analysis Due to Structural Vibrations using Short-Time Fourier Transform and Wavelet Transform Rahmatsyah Maksum Ramsi; Meifal Rusli; Feblil Huda
METAL: Jurnal Sistem Mekanik dan Termal Vol. 9 No. 2 (2025): Jurnal Sistem Mekanik dan Termal (METAL)
Publisher : Department of Mechanical Engineering, Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/metal.9.2.130-138.2025

Abstract

This research investigates the influence of bolt loosening on the dynamic behavior of a steel beam structure under continuous vibration excitation for 30 minutes. Bolted joints play a critical role in maintaining structural integrity; however, loosening caused by vibration remains one of the most common failure mechanisms in mechanical structures. To capture the effect of bolt loosening, acceleration responses were analyzed using time-domain inspection, Fast Fourier Transform (FFT), Short-Time Fourier Transform (STFT), and Continuous Wavelet Transform (CWT). The experimental setup involved controlled vibration excitation applied to a steel beam with bolted connections, and response signals were recorded at different stages of loosening progression. The time-domain analysis showed a gradual reduction in acceleration amplitude as bolt tightness decreased, indicating energy dissipation and stiffness loss. FFT provided an overview of frequency content but lacked sensitivity to localized variations. STFT and CWT enabled a more detailed examination of the time-frequency domain, revealing a loss of high-frequency components and significant redistribution of energy patterns during the loosening process. Both methods successfully identified shifts in natural frequencies and variations in response amplitude. Especially, CWT exhibited superior resolution in detecting early-stage loosening compared to STFT, making it more effective for practical monitoring applications. These results highlight the potential of time-frequency analysis as a diagnostic tool for vibration-based Structural Health Monitoring (SHM) systems. Early detection of bolt loosening through non-destructive vibration analysis can improve safety, reduce maintenance costs, and extend the service life of mechanical structures.