Papers by Author: Matthias Brenneis

Abstract: Smart structures consisting of a load carrying structure and smart materials with actuatory and sensory capabilities feature high potential in numerous applications. However, to master the assembly conditions of smart structures, there is a need to integrate additional design parameters such as prestress of the smart material, critical loads and electric contacting as well as insulation into the process development. This paper focusses on the design of an incremental bulk forming process to integrate piezoceramic components into an aluminum tube simultaneously to the manufacturing process. Axial forces imposed on the piezoceramic are investigated numerically and experimentally to verify the design of critical components and the process control. Within this investigation, in situ measurement of the direct piezoelectric effect provides a method to validate the numerical design with regard to failure of the piezo tube and the functional properties of the overall structure.

Abstract: In all areas of technology, the demand for high-quality, competitive and more valuable products is rising steadily. One approach to increase the value of manufactured products is the integration of electronic components in load carrying structures. These new products, which combine electrical and mechanical components synergistically, are called smart products. They consist of a passive structure and integrated electronics or smart materials. In addition to their mechanical properties they are also able to sense, to actuate or to transmit energy or data. The resulting product architecture requires both a mechanical and an electronic design in order to save subsequent assembly costs. Since further components are required to evaluate and control as well as to supply energy, all of those components need to be connected and integrated into the smart product. However, the main prerequisite for the marketability is the possibility of low-cost manufacturing and a robust mass production. Nowadays processes for the manufacturing of smart products do not fulfill the requirements for a sustainable mass production in a satisfying way as long as metallic structures are used. The authors deploy the forming technologies roll forming and sheet metal hydroforming to form sheets with applied flat electronics. Since the components are applied prior to the forming process, small and difficult to access installation spaces can be used effectively in the product architecture. The incremental bulk forming process rotary swaging is employed to integrate piezoceramics during the forming procedure without any additional joining elements. Challenges resulting from the chosen integrative manufacturing approach are the prevention of new kinds of failure modes and additional requirements for defined residual stress states. These challenges lead to extended process design requirements, which will be discussed in the paper in detail.

Abstract: Today, a wide variety of methods to deal with uncertainty in load-carrying system exists. Thereby, uncertainty may result from not or only partially determined process properties. The present article proposes a classification of methods to control uncertainty in load-carrying systems from different disciplines within mechanical engineering. Therefore, several methods were collected, analysed and systematically classified concerning their characteristic into the proposed classification. First, the classification differs between degrees of uncertainty according to the model of uncertainty developed in the Collaborative Research Centre CRC 805. Second, the classification differs between the aim of the respective method to descriptive methods, evaluative methods or methods to design a system considering uncertainty. The classification should allow choosing appropriate methods during product and process development and thus to control uncertainty in a systematic and holistic approach.

Abstract: Today, the components of smart structures consisting of structural and smart materials are generally produced separately and assembled in additional processes afterwards. An alternative approach, which combines the forming of metallic parts and the assembly of the structures in one process step, is proposed in this paper. Incremental forming processes are applied for this operation. Significant joining mechanisms will be analyzed and some applications of this combined forming and assembly process are shown. As sensors, smart components allow a monitoring of appearing loads, as actuators they allow an active influencing on appearing disturbances. The research contains numerical analyses and experimental tests.