Modellierung und Simulation eines Verbunds von Sandwichplatten zur Entwicklung einer mechanischen Verbindungstechnik

  • Modelling and Simulation of Sandwich-Composites with Regards to the Development of a Mechanical Joining Technology

Torsakul, Sirichai; Feldhusen, Jörg (Thesis advisor)

Aachen] : Lehrstuhl u. Inst. für Allg. Konstruktionstechnik des Maschinenbaus (2007)
Dissertation / PhD Thesis

In: Schriftenreihe Produktentwicklung und Konstruktionsmethodik
Page(s)/Article-Nr.: IX, 122 S. : Ill., graph. Darst.

Zugl.: Aachen, Techn. Hochsch., Diss., 2007

Abstract

The use of sandwich materials can lead to economical advantages in many applications by means of weight reduction. In spite of its large demand, its distribution in the field of mechanical engineering is constrained due to unsolved problems in the connection technology and uncertainties in the mechanics of such structures. Hence, in this filed, there exists a demand for the support of design engineers in designing of sandwich structures. Today, the Finite-element-method (FEM) for the simulation of the mechanical behaviours of complex structures is well established at the CAD-workstation; however the particularities of composite materials require advanced modelling- and analysis strategies. This work shall give the design engineer hints, with which a suitable FEM-system can be chosen for appropriate modelling of the loading cases and for evaluating the calculated results. To achieve this, simulations were carried out with different FEM-systems, whose results are validated by experiments. In the framework of this thesis, only plate materials with steel face and a PUR foam core that is very common in the mechanical engineering applications are considered. The simulated loading case is the four-point-bending-test according to DIN 53293, which is established as a test procedure and creates a practice relevant stress condition. After describing the possible approaches for FE-Modelling of the loading case, results of the simulation of a 3D-CAD/FEM-Integration with the FEM-Systems ANSYS, ABAQUS and ALGOR and their corresponding working steps are presented. Here the sandwich plate was created either completely through volume elements or through volume elements and shell/plate elements. In the experimental part of the work, the simulated loading case was experimentally repeated on the servo-hydraulic test machine as test series, whereby the linear elastic behaviour and the different failure of sandwich plate were investigated. The results obtained with aid of the FEM were compared to the analytical and experimental results. It shows that the computed stress values have a very good agreement with the analytical results and experiments. In terms of accuracy of the calculated results, ANSYS seems to be the most suitable one; however ALGOR has the best characteristics with regard to the usability. In each case, it has been proved that the described modelling strategies can be achieved with a reasonable effort and it delivers useful results to understand the deformation behaviour of sandwich structures. Also for the observation of different failure modes of the sandwich plate, the linear elastic FEM-Simulation seems to be a suitable tool. The face wrinkling at the places of the load transmission is investigated with the help of experiments. It is determined that, with the results of the FEM-calculation, the appearance of this special, partially unstable phenomenon can be predicted and explained. Additionally a core shear failure could also be investigated by a modification of this experiment, which could also be predicted with the help of FEM-simulation.

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