|
Journal of Technology and Social Science (JTSS, J. Tech. Soc. Sci.) An international open-access peer-reviewed journal ISSN 2432-5686
Vol.9, No.1
TABLE OF CONTENTS
Articles
Sound insulation and radiation sound analysis for car floor carpet using FE method Yoshio Kurosawa, Tsuyoshi Yamashita, Tetsuya Ozaki, Naoyuki Nakaizumi, Yuki Fujita, and Manabu Takahashi Journal of Technology and Social Science, Vol.9, No.1, pp.1-9, 2025. Abstract: The performance enhancement of the acoustic insulation is demanded for the high frequency for interior noise of automobile. A carpet having urethane adhered to a rubber skin is generally laminated on a floor panel of an automobile. In order to elucidate noise and vibration for this structure, the vibration transmission rate was measured using a test apparatus in which a carpet was laminated on a panel simulating the floor of an automobile. In addition, we modeled this experimental apparatus with finite elements (FE) and analyzed the vibration during displacement excitation. Biot-Allard model was used for felt and urethane. We calculate using separately identified Biot parameters and compare with experimental results and introduce the change of vibration and obtained findings when material is changed. In the low frequency range, the values changed significantly when the skin density, Young's modulus and loss factor of urethane were changed.
Acoustic analysis of car cabin space assuming in-vehicle speakers Yoshio Kurosawa, Kohei Shibuya, Manabu Sasajima, and Mitsuharu Watanabe Journal of Technology and Social Science, Vol.9, No.1, pp.10-15, 2025. Abstract: In order to improve the quietness of the automobile interior, trims such as the ceiling often use a structure with high sound absorption performance. In addition, leather and fabric have different effects on interior noise. The purpose of this research is analyzing the influence of the sound absorption at the time of reflecting in a ceiling, a wall, or a sheet using the FE method and a sound ray method, when the sound emitted from the automobile speaker reaches a crew member's ear. In order to analyze how the sound emitted from a car's speakers changes due to the effects of the ceiling, walls, floor, seats, etc., we created a simple FE model of the interior of the car and performed calculations. We will report the results compared with the experimental results. In addition, in order to perform high-speed calculations up to the high frequency range, we used the acoustic ray method.
Vibro-acoustic analysis of automotive air ducts using porous materials Yoshio Kurosawa, Tsuyoshi Yamashita, Tetsuya Ozaki, Naoyuki Nakaizumi, Yuki Fujita, and Manabu Takahashi Journal of Technology and Social Science, Vol.9, No.1, pp.16-21, 2025. Abstract: The electrification of automobiles has progressed in response to environmental problems. Accordingly, the number of automobiles equipped with large and large-capacity batteries, such as electric vehicles and hybrid vehicles, is increasing. These batteries take in air from the passenger compartment using ducts for cooling. However, since the cooling fan operates regardless of the running condition, sound may leak into the car interior through the ducts. To reduce such cabin noise, we examined the use of sound-absorbing ducts. We developed four types of test pieces using conventional polypropylene resin, compression felt, and film on the inside and outside of the compression felt. We measured the insertion loss in two ways: one on the opposite side and the other on the outside from the entrance of the duct. Acoustic attenuation was measured. The results of creating and calculating a similar FE model were then reported.
Transmission loss analysis of acoustic metamaterial using finite element models Yoshio Kurosawa, Kazuki Fukui, and Kazuya Harayama Journal of Technology and Social Science, Vol.9, No.1, pp.22-28, 2025. Abstract: FE models used for measurement of transmission loss (size 300mm×300mm) and impedance tube were created by using an acoustic metamaterial in which films were laminated on top and bottom of polypropylene processed into a honeycomb structure. Numerical calculation of sound transmission loss, comparison with experimental results, and various parameter studies were conducted. In the calculation of the transmission loss of the FE model of the impedance tube, it was possible to obtain a value close to the experimental result by changing the value of the spring stiffness which is the boundary condition. The attenuation of the boundary spring has no effect on the transmission loss of FE model. The hardness of the spring affects the low frequency stiffness line and the first dip (about 100Hz). The first dip is the effect of the vibration mode in which the entire honeycomb deforms out of plane.
Soundproof analysis of porous material covers for automotive parts Yoshio Kurosawa, Tsuyoshi Yamashita, Tetsuya Ozaki, Naoyuki Nakaizumi, Yuki Fujita, and Manabu Takahashi Journal of Technology and Social Science, Vol.9, No.1, pp.29-35, 2025. Abstract: Some automobile transmissions (AT, CVT, etc.) generate noise, and a soundproof material cover is attached to the transmission body reduce the noise by offering sound absorption and insulation. However, the sound radiating from the cover may affect the transmission of vibrations. In this study, we attached a simply shaped cover to a jig to represent a transmission body and measured the vibration acceleration and sound pressure level when the jig was vibrated. The jig and cover were modeled by FEM, and vibro–acoustic analysis was performed. The material of the cover was felt or grow wool, and sound propagation was simulated using the Biot–Allard model. This report describes the changes in vibration acceleration and sound pressure level when the method of fixing the cover and cover material are changed.
Finite Element Analysis for Damping Properties of a System Having Liquid, Elastic Body and Viscoelastic Body Takao Yamaguchi, Chihiro Kamio, and Takeo Nakaie Journal of Technology and Social Science, Vol.9, No.1, pp.36-43, 2025. Abstract: An analytical method is proposed to calculate damping properties for a system involving liquid, elastic body and viscoelastic body in a three-dimensional region. Particle velocity is selected as an unknown parameter for the proposed method. Further, damping effects of viscoelastic body on the system are analyzed. Water, a steel water tank and damping layers were used for analysis as liquid, elastic body and viscoelastic body. When damping layers were attached on tank’s wall, modal loss factors increase for coupled modes between elastic deformation of the tank’s walls and resonance of the water.
Analysis of Damped Vibration by MSKE Method for Structures Having Porous Layer Sandwiched by Double Walls with Acoustic Black Hole in Cover Plate Takao Yamaguchi, Chihiro Kamio, and Yuta Hisamura Journal of Technology and Social Science, Vol.9, No.1, pp.44-53, 2025. Abstract: Vibration suppression is an important technology both industrially and environmentally to realize a comfort industrial product with a safe structure. In this paper, we carried out numerical simulation of damped vibration for a structure having a porous material sandwiched by double walls. The cover plate in double walls has a Krylov type acoustic black hole. All edges where the black hole exists, have free boundaries. Damping material is laminated on the surface of the black hole. Numerical analysis is performed to clarify changes of vibration reduction and vibration transmission from the base plate to the cover plate due to the acoustic black hole using FEM and MSKE method proposed by Yamaguchi et al.
Introduction of a Herbert Pendulum Hardness Tester Equipped with Raspberry Pi and Research on a Method for Converting Hardness Values Obtained from It Ryosuke Suzuki, Masaaki Matsubara, Takumi Tagaya, and Tetsushi Kaburagi Journal of Technology and Social Science, Vol.9, No.1, pp.54-59, 2025. Abstract: Present paper introduces a Herbert pendulum hardness tester equipped with a wire-less accelerometer and a Raspberry Pi. The configuration of the tester is shown. The tester can evaluate hardness stand-alone without relying on any external system. Touch screen operation makes it easy to evaluate hardness with the tester. Hardness tests with an accelerometer and a laser displacement meter are performed based on the test procedures described in the paper. The devices give different Matsubara hardness values. Matsubara hardness conversion method is shown when the swing angle of the Herbert hardness tester was measured by different methods.
Nonlinear Numerical Analysis of Insertion Loss for Structures Having a Compressed Softened Porous Layer Sandwiched by Double Walls under Acoustic Excitation Takao Yamaguchi, Tetsuya Ozaki, Tsuyoshi Yamashita, Chihiro Kamio Journal of Technology and Social Science, Vol.9, No.1, pp.60-69, 2025. Abstract: We perform nonlinear numerical simulation of insertion loss for structures having compressed porous layers sandwiched by double walls under acoustic excitation. The double walls are consisted of a steel base plate and a plastic cover plate. We compare the insertion loss including Urethane foam with felt. These porous layers are compressed by a heavy frame around the cover plate. As increasing weight of the frame, Urethane foam has soft-hardening characteristics in its restoring force. If we set appropriate weight of the frame to get 33% compression, lower rigidity is obtained for Urethane foam. This leads to softer porous layer for the double walls. And vibration and sound decrease from the base plate to the cover plate. For felt, the hardening characteristics appear. This leads to the higher rigidity and the more transmission. In the numerical calculation using LS-Dyna as a nonlinear FEM code, geometric nonlinearity is considered. For compressed porous materials, Storaker model is adopted in consideration of material nonlinearity with hysteresis. Sound pressure on the surface of the base plate was computed in a reverberation box where there exists a sound source by our FORTRAN FEM code. Sound radiation powers from the cover plate were also calculated. We evaluated effects of compression on them.
|
|||||
|
© Copyright 2016 | e-JIKEI Network Promotion Institute. All Rights Reserved. |