Subsystems' Layout Change Method based on Analytical SEA for Vibration Reduction; Utilization for an Injection Pump of an Engine

Conventionally, noise and vibration problems arise in the latter stages of design or manufacturing, but it is necessary to develop a robust design process for low noise and vibration, especially in the early stage. To achieve this, the present authors have proposed a two-step design process based on energy propagation analysis. The first step focuses on the baseline (average) frequency response behavior of structures, and the second step focuses on the peak behavior of the frequency response. Because conventional approaches such as the finite-element method and the boundaryelement method can be used for the second step, the authors have focused more on developing the first design step, especially using analytical statistical energy analysis (SEA) and an optimization package. In the first step, using analytical SEA makes it possible to predict the noise and vibration response by mathematical expressions, and low noise and vibration can be realized at the initial design stage without the detail like. However, in previous reports the design flexibility was limited; the shape of each subsystem could be designed but the layout of each unit could not be changed. In this paper, an initial design step is proposed that is applicable to an arbitrary layout. The proposed use of analytical SEA enables one to change and set each subsystem, including the input subsystem and the vibration source, at optimal locations in terms of SEA for low vibration. As an example, the proposed method is used to reduce the vibration of a mock-up of an injection-pump structure, and the feasibility is examined through numerical simulation. Consequently, each subsystem including the input is located at its optimal position and the vibration of the target subsystem is reduced.