Novel sheet metal parts with sensor and actuator mode of operation

Increasing demands on lightweight-construction and functional integration lead to new material and design concepts. Examples are sandwich structures with layers of plastics or fiber-reinforced plastics used within a multi-material lay-up. Moreover, new products with increased functionalities are replacing assembly groups in order to solve the conflicting goals of comfort and lightweight requirements, e.g. in car bodies. In this field the noise vibration harshness (NVH) characteristics of lightweight materials always have to be considered. The paper presents two different process chains for the integration of piezoceramicsin sheet metal structures. One process chain allows the integration of piezomodules in sandwich structures, using different curing states of a lubricating adhesive for an improved formability of the piezo-metal-sandwiches. This production method provides a relative movement between the piezomodule and the sheet metal during the forming operation, while a hydrostatic pressure inside the compound is ensured with a special design of the semi-finished part. Result is a 3D-shaped sandwich with integrated piezomodules. Such parts offer complex geometries in combination with a high stiffness, high passive structural damping and low weights. Additionally the integrated piezomodules enable a sensor and actuator functionality which can be used for an active reduction of extrinsically excited vibrations. The second process chain is based on the integration of bar-shaped piezoceramic fibers into micro-structured sheet metals. A stiff connection between piezoceramic and aluminum sheet metalis achieved by form and force fit without any elastic interlayers and hence allows a good coupling of elongations resulting from direct orinverse piezoelectric effect.