Reduction of Whole Body Shake on a Luxury Sports Convertible 2008-01-0571
One of the engineering challenges in the development of convertible vehicles is to minimise low frequency vibrations without significant compromise in other attributes, for instance, vehicle dynamics, package and weight. This low frequency vibration is normally perceived through the driver's interfaces such as the steering wheel, seat and A-pillars. The frequency of the vibration is typically between 10-20Hz. This vibration is often called “shake” and tends to cause annoyance to the driver and passengers as many parts of the human body have a high sensitivity to this frequency region.
From studies carried out in the past, the major contributing factors of the shake are well known to be suspension dynamics, body stiffness and modal behaviour of the body, sub-systems and powertrain as well as combinations thereof. However, most of these characteristics are defined by the fundamental structural elements within the vehicle that are fixed in the early design stages of a program, and significant engineering work is required to rectify these later in the vehicle's development.
This paper details how the engineering team achieved the required shake target through the application of test, analysis, identification and optimisation for each of the contributing factors.