The Development of Vibration Damping Steel Sheets for Inner Panels of Automotive Vehicles 911083
Vibration damping steel sheets (VDSS), which have sandwich structures with intermediate layers of resin, have been studied.
The most important characteristics of VDSS for inner panels of automotive vehicles are the vibration damping properties, press formability and spot weldability.
Vibration damping properties, which are quantified by loss factor,η, were influenced by both tanδ, which indicates damping capacity of resins, and elastic modulus of core resin. From a view point of vibration damping properties, resins with larger tanδ and relatively lower elastic modulus were favorable. Because these mechanical characteristics vary considerably with temperature, it is important to select the most suitable resin for the service temperature range.
The relationship between noise reduction effect and loss factor of VDSS were also studied. It was experimentally confirmed that noise reduction effect of VDSS is proportional to the logarithm of their loss factor.
Press formability of VDSS is strongly influenced by adhesive strength of the core resin, thus higher adhesive strength gives better press formability. It is important and difficult to achieve good balance of damping properties and press formability of VDSS, particularly in order to develop VDSS which are used at room temperature.
It is also required that VDSS for inner parts of automotive vehicles can be directly spot welded as well as ordinary steel sheets. In this study it was found that spot weldability of VDSS depends upon the amount and the size of the metal powder in the resin layer and that spot weldability doesn't depend upon the kind of the metal.
As the result of above studies, VDSS for inner panels of automotive vehicles was developed, which showed excellent balance between vibration damping properties and press formability and also showed spot weldability similar to ordinary steel sheets.