Robert Fleischhauer

Thermomechanical modeling of fiber reinforced material including interphasial properties and its application to epoxy/glass composites

Purpose – The purpose of this paper is to investigate of interphasial effects, including temperature dependency, within fiber reinforced polymers on the overall composite behavior. Providing theoretical and numerical approaches in terms of a consistent thermomechanical finite element method framework are further goals of this research. Design/methodology/approach – Starting points for achieving the aims of this research are the partial differential equations describing the evolution of the displacements and temperature within a continuum mechanical setting. Based on the continuous formulation of a thermomechanical equilibrium, constitutive equations are derived, accounting for the modeling of fiber reinforced thermosets and thermoplastics, respectively. The numerical solutions of different initial boundary value problems are obtained by a consistent implementation of the proposed formulations into a finite element framework. Findings – The successful theoretical formulation and numerical modeling of the t...

Simulation-based development of adaptive fiber-elastomer composites with embedded shape memory alloys:

Fiber-reinforced composites are currently being used in a wide range of lightweight constructions. Function integration, in particular, offers possibilities to develop new, innovative products for a variety of applications. The large amount of experimental testing required to investigate these novel material combinations often hinders their use in industrial applications. This paper presents an approach that allows the layout of adaptive, fiber-reinforced composites by the use of numerical simulation. In order to model the adaptive characteristics of this functional composite with textile-integrated shape memory alloys, a thermo-elastic simulation is considered by using the Finite Element method. For the numerical simulation, the parameters of the raw materials are identified and used to generate the model. The results of this simulation are validated through deflection measurements with a specimen consisting of a glass fiber fabric with structurally integrated shape memory alloys and an elastomeric matrix system. The achieved experimental and numerical results demonstrate the promising potential of adaptive, fiber-reinforced composites with large deformation capabilities.

Hygro- and Thermo-Mechanical Modeling of Wood at Large Deformations: Application to Densification and Forming of Wooden Structures

The contribution at hand provides a basis for modeling hygro- and thermo-mechanical processes, especially at large deformations. Therefore, hygro- and thermo-mechanical fundamentals of wood are introduced under consideration of moisture, temperature and displacement dependent processes. The influence of moisture on the density of wood is taken into account as well as a characterization of the interaction of temperature and moisture. Finite element formulations are derived,s together with constitutive laws, as a basis for the numerical solutions. A verification as well as a validation of the specific formulations for the hygro- and thermo-mechanical behavior of different wood species is presented. Finally, the applicability of the proposed finite element descriptions is demonstrated at the densification and forming process of wood.