Jörg Melcher

System Response of Nanotube based Actuators

The electromechanical characterization of carbon nanotube (CNT) papers, which are immersed in an aqueous electrolyte, is the main focus of this paper. The experimental set up consists of an ordinary three electrode cell, filled with the liquid electrolyte and using the CNT paper as working electrode. The in plain strain of the paper is measured and its quasi static and dynamic response to various electrical potential excitations has been investigated in a series of experiments. Additionally, the influence of different electrolytes, pre-stresses and types of carbon nanotubes (SWNT vs. MWNT) was studied.

Design, optimization and realization of smart structures

The paper starts with a discussion of the methods for the analysis of smart structures. A method is presented that does not require special finite elements for the analysis of structures with piezoelectric devices, but which uses conventional finite elements. This method can also be adapted to structures with integrated magnetostrictive materials. The second part of the paper deals with vibration suppression in form measuring machines. A smart solution is presented that actively counteracts the machines vibrations. For this purpose, the machine was equipped with a sensing system, an active interface and a special controller. This new concept has been successfully tested on a real form measuring machine.

The power of light: Self-organized formation of macroscopic amounts of silica melts controlled by laser light

CO2 laser systems with a power output of up to 12kW continuous wave have been employed for melting high purity amorphous silica (SiO2) powders. Under the intense light irradiation, the migration of matter on the silica sample has been observed. A net mass transport results in the formation of macroscopic structures in the liquid phase. Protrusions of up to 7mm height are formed against gravitational force and surface tension. For the first time, this work reports on the self-organized formation of macroscopic structures by viscous flow of a dielectric melt driven by laser light.

Structural optimization of printed structures by self-organized relaxation

Purpose This paper aims to present an additive manufacturing-based approach in which a new strategy for a thermally activated local melting and material flow, which results in densification of printed structures, is introduced. Design/methodology/approach For enabling this self-organized relaxation of printed objects by the viscous flow of material, two interconnected structures are printed simultaneously in one printing process, namely, Structure A actually representing the three dimensional object to be built and Structure B acting as a material reservoir for infiltrating Structure A. In an additional process step, subsequent to the printing job, an increase in the objects’ temperature results in the melting of the material reservoir B and infiltration of structure A. Findings A thermally activated local melting of the polymethylsilsesquioxane results in densification of the printed structures and the local formation of structures with minimum surface area. Originality/value The present work introduces an approach for the local relaxation of printed three-dimensional structures by the viscous flow of the printed material, without the loss of structural integrity of the structure itself. This approach is not restricted only to the materials used, but also offers a more general strategy for printing dense structures with a surface finish far beyond the volumetric resolution of the 3D printing process.