Journal of Acoustics and Vibration Research

A Framework for Predicting Nonlinear Frequency Response Functions of a Bolted Beam using Force-Controlled Technique in MSC NASTRAN SOL128

2025-12-31T04:50:24+00:00

This paper investigates nonlinear dynamic behaviour in a bolted beam. Force-Controlled Technique (FCT), implemented in MSC NASTRAN SOL128, is used to predict the Nonlinear Frequency Response Functions (NLFRFs) of the beam. The predicted NLFRFs are analysed to determine softening or hardening trends resulting from the bolted joint-induced nonlinearity. The results show that the adopted FCT framework can identify amplitude-dependent changes in resonance frequency and damping, which are in line with established results reported in previous studies. This study provides a practical approach and reliable means for identifying nonlinear dynamic behaviour in bolted structures, and also supports improved modelling of bolted joint-induced nonlinearity

Characterisation of Deproteinised Natural Rubber Latex Foam for Enhanced Acoustic and Vibration Isolation

2025-12-31T05:31:23+00:00

Natural acoustic foams used in recording studios, auditoriums, cinemas, etc., are largely of petrochemical origin and cause environmental and health problems. The current research explores the application of natural rubber (NR) latex foam as a substitute material. Three types of NR latex foams low ammonia (LATZ), deproteinized (DPNR), and epoxidized (ENR)were developed and characterized for their acoustic and mechanical performance. Sound performance was tested in an impedance tube to ISO 10534-2, for sound absorption coefficient (SAC), noise reduction coefficient (NRC), and sound transmission loss (STL). Results indicate that STL is a rising function of foam density, while SAC in the low-frequency range is a function of density but in high frequencies of morphological structure. Among the foams, high-density DPNR latex foam possessed the highest his paper investigates nonlinear dynamic behaviour in a bolted beam. Force-Controlled Technique (FCT), NRC, surpassing ENR and LATZ foams and commercial memory foam. Further mechanical evaluation of the DPNR foam revealed increased resilience, as evidenced by a maximum ball rebound and minimum hysteresis loss compared to polyurethane (PU) and memory (PM) foams. DPNR latex foam was also successfully manufactured in the configuration of seat cushions through the Dunlop batch process. Pressure-relief performance, as measured by a CONFORMatTM sensor system and mannequin, showed that DPNR cushions were lower in peak pressure than PU foam and were comparable with PM foam. Vibration transmissibility tests, as conducted in accordance with ASTM D3580-95, showed that the lowest attenuation frequency for DPNR latex foam resulted from low stiffness and high resilience. These findings identify DPNR latex foam as a highly potential, eco-friendly acoustic insulation and ergonomic cushioning material particularly for electric vehicle (EV) seat applications.

Progression of Cutting Tool Wear and Vibration Emission in the Grinding Process

2025-12-31T05:43:46+00:00

This study investigates the progression of cutting tool wear in grinding by analysing vibration emissions. The measurement was conducted under a repeated single operating condition. A cylindrical carbon steel workpiece was ground using a CNC grinding machine with coolant. Vibrations were measured along the X, Y, and Z axes using a Dytran 3-axis piezoelectric accelerometer, with data collected via NI DAQ 9234 at 12.8 kHz. A total of 70 grinding cycles were performed at 3000 rev/min (50 Hz). Root mean square (RMS) values of vibration signals were extracted as well as kurtosis, skewness and variance, to evaluate the correlation between tool wear progression and vibration characteristics. The findings highlight the sensitivity of vibration response to gradual tool wear. This study demonstrates the potential of using vibration measurement as a reliable indicator for monitoring grinding performance, improving process stability, and enhancing product quality.

Performance of dry rubber foam as a sound absorbing material

2025-12-31T06:06:17+00:00

The present study aims to investigate the actual sound-absorbing capability of dry rubber foam. Two sound-absorbing foam materials were produced from dry synthetic rubbers known as ethylene-propylene-diene monomer (EPDM) and nitrile butadiene rubber (NBR). The acoustical efficiencies of dry rubber foams and commercially available acoustic foams; polyurethane and melamine were studied. The results showed a significant influence of the sound absorption properties of the different dry rubber foams and acoustic foams. EPDM reached a peak absorption coefficient of 0.94, while NBR peaked at 0.75, both occurring at frequencies below 1500 Hz. In contrast, acoustic foams reached their sound absorption peak at frequencies exceeding 2000 Hz. These properties were governed by the physical and microstructural properties of the foams. This study can be helpful and valuable for designing a dry rubber foam with optimum non-acoustical properties to achieve the desired acoustical properties in various service applications.

Response Surface Methodology-Based Optimisation of Finite Element Model Updating for Disc Brake Dynamic Behaviour: A Review

2025-12-31T06:32:56+00:00

Accurate modelling and prediction of disc brake dynamic behaviour are essential for addressing vibration and noise issues in automotive braking systems. Finite element model updating (FEMU) has been widely adopted to improve the correlation between numerical simulations and experimental modal data; however, conventional updating approaches are often limited by iterative trial-and-error procedures, high computational cost, and insufficient consideration of parameter interactions. In recent years, Response Surface Methodology (RSM) has emerged as a promising surrogate-based optimisation technique to enhance the efficiency and robustness of FEMU frameworks. This paper presents a comprehensive review and synthesis of RSM-based optimisation approaches integrated with FEMU for disc brake dynamic analysis. Key developments in surrogate modelling, design of experiments, and hybrid optimisation strategies are critically examined, with particular emphasis on their capability to manage high-dimensional parameter spaces and complex nonlinear phenomena such as frictional contact and thermo-mechanical coupling. The role of advanced experimental modal analysis techniques in improving model fidelity and supporting optimisation accuracy is also discussed. Based on the reviewed literature, current limitations and research gaps are identified, including challenges related to nonlinear behaviour modelling, experimental–numerical integration, and automation of optimisation workflows. Finally, future research directions are outlined, highlighting the need for comprehensive, adaptive, and multi-physics RSM–FEMU frameworks to support reliable, efficient, and sustainable disc brake design and analysis.