Mineral-bonded composites
for enhanced structural impact safety

Mineral-bonded composites
for enhanced structural impact safety

Mineral-bonded composites
for enhanced structural
impact safety

A2/II Fiber and interphase modification for energy adsorption at high strain rates

The aim of this subproject is to make a numerical model of cement based composites which fibers are modeled explicitly and represented by embedded elements.

To this aim, our in-house program CaeFem has been developed to analyze simple regular discretization of heterogeneous mesoscopic continuum with discrete distinction of aggregates or void from a matrix with different discretization approaches and comparisons are made with a commercial FEM program-DIANA. A material model is implemented and assigned to bond element to connect embedded fibers to continuum which fibers are distributed randomly within the simply discretized continuum. The next three steps will be: modeling of random geometry (for position, orientation and length of fibers, position and size of aggregates, comparison of approaches to model continuum with embedded fibers and embedded smeared or discrete cracks using FEM (SDA and X-FEM), EFG and iso-geometric methods and implementation of physical nonlinearities regarding fiber, bond, aggregates, matrix. Incidentally, the behavior of composite under quasi-static loading, as a necessary prerequisite for dynamics, will be validate by experiment results provided by Institut für Baustoffe.

a) Force-displacement curve of sized PP-fibres pulled-out of cementitious matrix during dynamic single fibre pull-out test; b) SEM images, top: deformed, rough fibre surface in the case of increasing pull-out force, below: undeformed, smooth fibre surface for low pull-out forces
Approach for the fibre and interphase modification , a) application of particles by polymer dispersions; b) introduction of particles by a bicomponent-spinning process
It is the aim of the project to develope and implement concepts for a targeted interphase design to increase the impact resistance based on high plastic deformation of polymer fibers or in the polymer-based interphase in case of high-modulus fibers. The mechanical interlocking, which leads to shearing (high plastic deformation) of the polymer fibers, is initiated by the application of particles (e.g. aluminium oxide) from polymer dispersions (Fig. 2a), while the influence of particle type, particle size and application are systematically investigated, as well as the influence of the mineral-bonded matrix (e.g. geopolymers). The incorporation of particles into the polymer and the subsequent processing in the bicomponent-spinning process will also be studied as a possible solution (Fig. 2b). A similar approach is followed for increasing the roughness of coatings for carbon fibers, here also the degree of chemical crosslinking in the coating is varied. This approach will later be transferred to textile reinforcement structures and investigated on concrete composites under high strain rates.

Contributors

© Tin Trong Dinh

Doctoral Researcher
(2020-2023)

Mihaela-Monica Popa, M.Sc

Contact

Leibniz-Institut für Polymerforschung Dresden e.V.

Department of Reactive Processing
Hohe Straße 6
01069 Dresden
Germany

Principal Investigator

Prof. Dr.-Ing. Christina Scheffler

Contact

Institute of Textile Machinery and High
Performance Material Technology (ITM)

Hohe Straße 6, Room 138
01069 Dresden
Germany

in cooperation with

Univ.-Prof. Dr.-Ing. Viktor Mechtcherine

Contact

Institute of Construction Materials

Von-Mises-Bau, 3rd Floor, Room 315A Georg-Schumann-Straße 7
01187 Dresden
Germany