Noise and Vibration Control in Automotive Bodies

3Noise and Vibration Control for Local Body Structures

3.1 Noise and Vibration Problems Caused by Vehicle Local Structures

3.1.1 Classification and Modes of Local Body Structures

The vibration and control of the overall body structure is introduced in Chapter 2. Chapter 3 describes vibration, sound radiation, and control of the local body structures. In this book, the local body structures are divided into four categories: panel structures, acoustic cavity structures, accessory structures, and secondary‐beam (or sub‐beam) structures, as shown in Figure 3.1. The local structures have their own local modes and can generate vibration and noise. The local modes for the four kinds of structures are briefly described in the following sections.

Figure 3.1 Classification of local body structures.

3.1.1.1 Panel Structures

After the main frames and pillars, most of the rest of the body consists of various panel structures. The panels are connected with the body frames and pillars by welding or other means, forming a closed body, and they include fixed panels and movable panels. Fixed panels include the dash panel, roof, floor, side panels, fenders, wheelhouse, rear package tray, and windshield, whereas movable panels include the doors, engine hood, and trunk lid.

The panels are major contributors of body vibration and noise. Their corresponding modes are called local panel modes. ...