NV prediction technology for excitation force and vibration transfer using Multi-Body Dynamics CAE in the development of electric drive unit

Toshio Kageyama (AVL JAPAN K.K.)

Effective measures for noise vibration are to reduce the excitation force and vibration transfer. In general, it's not easy to distinguish whether the root cause is the excitation force or the vibration transfer when an abnormal noise occurs in the final stage of prototyping. We use a multibody dynamics analysis model that simulates actual operating conditions, and this presentation will introduce these efforts.

Construction of numerical model for in-vehicle sound field based on the exploration of phase difference during reflection

Takayuki Masumoto･Masahiro Takekawa (CYBERNET SYSTEMS)･Kazushi Kuroyanagi･Akira Shigeta･Hiroyuki Kumakura (JVCKENWOOD)

An attempt was made to build a numerical model that reproduces measured SPL values at multiple points in a vehicle. In this report, surface impedances, which are variables in the model, were organized based on sound absorption coefficient and reflection phase difference and were assigned to wall groups roughly generated based on the components. Appropriate values those could reproduce measured SPLs were explored through parameter studies in which these values were varied. The sensitivity of the sound absorbent material and microphone position to the response was also confirmed.

Proposal of a New Unit Mode Extraction Method

Takafumi Mochizuki･Hiroyuki Suzuki･Takao Hirai･Kazuki Hidaka･Moe Hanashima (Estech)

We propose the idea that vibration characteristics can be decomposed into modes with simple shapes called “unit modes”. Analyzing with these modes make the vibration mechanism very clear. We have previously reported that it is possible to easily study response reduction by changing the resonant frequency of unit mode. This research introduces a new method that solves the problems encountered with conventional extraction methods.

The Influence of Mass and Stiffness Distribution on the Vibration Characteristics of Automobile Bodies

Ryo Ageba･Kazuhiko Higai･Tsuyoshi Shiozaki (JFE steel)

Approaches to improve the vibration damping of automobile bodies include measures to reduce vibrations from the source to evaluation points, as well as controlling the body’s natural frequencies. An example of the latter, focusing on the optimization of mass distribution, was reported in 2024. This report evaluates the impact of changes in stiffness at various locations, such as through bead application, on the overall vibration characteristics of the vehicle body.

Evaluation of Vibration Characteristics of Bolted Joints Using Aluminum Alloy Bolts and Titanium Alloy Bolts

Yuuki Kawaharabashi･Satoru Kuga･Yoshinao Kishimoto･Yukiyoshi Kobayashi･Tristan Samuel Britton (Fujimori)･Keisuke Inoue (Tokyo City University)

Bolted joints are relatively easy to assemble and disassemble, but the use of many steel bolts and nuts leads to an increase in the total weight of the car body. In this study, the effects of replacing steel bolts and nuts with aluminum alloy and titanium alloy bolts and nuts, which are lighter than steel bolts and nuts, on the vibration characteristics of bolted joints were evaluated by hammering tests and the finite element analysis.

Vibration Characteristics of Bolted Joints in Magnesium Alloy Based Multi-Material Structures

Tristan Samuel Britton (Fujimori)･Keisuke Inoue･Yoshinao Kishimoto･Yukiyoshi Kobayashi･Yuuki Kawaharabashi･Satoru Kuga (Tokyo City University)

Magnesium alloy is the lightest structural metal, and it is known for its high damping performance. Therefore, it is expected to be applied on next-generational body structures. This study has investigated the vibration characteristics of bolted joints in magnesium alloy based multi-material structures by hammering tests and finite element analyses in order to establish an analyzing method that is applicable for the vibration characteristics prediction.