Jörn Jaschinski

Numerical and experimental investigations on HYLITE sandwich sheets as an alternative sheet metal

Current developments show that in the field of sheeting alternative material concepts are successfully applied. In this context metal plastic sandwiches, which are composed of two thin metallic surface layers and a polymer core, represent an interesting group of semi-finished products. Compared to conventional sheet metal materials the structural modification caused by sandwich design provides an increased specific flexural rigidity. Extensive experimental and numerical investigations were carried out for the characterisation of this still young group of semi-finished products. The evaluation of suitable calculation methods represents a crucial step to a broad application of semi-finished metal plastic sandwiches within bulk production processes.

Investigations on the applicability of chemically deposited Ni-shell tools for deep-drawing processes

The paper introduces the results of an EFB (European Research Association for Sheet Metal Working) research project concerning the applicability of tools made of chemically deposited nickel shells with polymer supports for small and medium scale deep drawing production. Several investigations of the material behaviour and tribological response of the chemically deposited nickel shells were performed together with numerical analyses of the deep-drawing process in order to optimize the tools under the consideration of the specific characteristics of the nickel shell and the polymer support structure. Finally, an optimized tool prototype has been manufactured and tested in order to verify the design solutions under service conditions.

Shape alteration of large string instruments due to changing climate conditions

Large string instruments, such as cellos and double basses, are manufactured, bought and played all over the world. Thereby they are exposed to different climate conditions. This paper describes shape alterations using the example of a double bass stored at different climatic conditions. By means of an optical measurement these shape alterations were recorded and represented. The results clearly show spots with strong and without deformations. Thus, weak points of the construction are localised and improvements can be established for the construction of string instruments.

Mechanical Anisotropy of Aluminium Laminates Produced by ARB

The plastic anisotropy was studied on aluminium sheets with layers of different purity (A: 5N and B: 2N+) produced by accumulative roll bonding (ARB). Both material layers show a contrasting recrystallization behavior where A and B are discontinuously and continuously recrystallized, respectively. Global textures were measured by neutron diffraction. The mechanical anisotropy was measured by tensile testing after different numbers of ARB cycles. The planar anisotropy decreases with the number of ARB cycles while the normal anisotropy reaches a plateau after 4 cycles. Simulations of the Lankford parameters were carried out with the help of the viscoplastic self-consistent scheme (based on the global texture) and compared with the experimental data. Deviations of the simulated values from those of experiment are discussed with regard to through-thickness texture and material heterogeneities.

Plastic Anisotropy of Ultrafine Grained Al Alloy AA6016 Produced by Accumulative Roll Bonding

In order to quantify the plastic anisotropy of the ultrafine grained aluminium alloy AA6016 produced by accumulative roll-bonding (ARB) the Lankford parameter is measured by tensile testing as a function of the number of ARB cycles. The experimental results are compared with those from texture-based Taylor simulations. Increasing differences between experiment and theory at higher number of ARB cycles may be attributed to highly oriented microstructural features.