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Simulation of a Multifunctional Hybrid Composite with Continuous Steel and Carbon Fiber Reinforcement on the micro-level

Thursday (27.09.2018)
15:45 - 16:00 S1/01 - A2
Part of:

Due to their superior weight-specific mechanical properties, carbon fiber

reinforced polymers (CFRP) are increasingly used in automotive industry. One of

the main reasons is the compensation of the penalty weight caused by the

components for the electrification of the passenger cars. However, the brittle

failure behavior of CFRP limits its structural integrity and damage tolerance in

case of impact and crash events. Furthermore, the electrical conductivity of

CFRP structures is insufficient for certain applications.

Former research attempts tried to resolve the mechanical and electrical deficits

of CFRP by modifying the resin system (e.g. by addition of conductive particles

or toughening agents), but could not prove sufficient enhancements. A novel

approach is the incorporation of highly conductive and ductile continuous metal

fibers into the CFRP. The basic idea of this hybrid material concept is to address

both the electrical and load-bearing capabilities of the integrated metal fibers to

improve the electrical conductivity and the failure behavior of the composite.

To understand the complex interaction of carbon and metal fibers of a loaded

hybrid composite, a micromechanical model of unidirectional and multiaxial

laminates is build up using the structure generators of the software GeoDict. For

each constituent material, separate user defined material models (UMAT) with

individual failure criterions are developed and implemented to simulate the

macroscopic material behavior. Through the modelling of the microscopic

structure and damages the strength of the laminate could be determined using

the GeoDict module ElastoDict. This module uses a solver called FeelMath

which is developed at the Fraunhofer Institute for Industrial Mathematics. This

fast and memory efficient solver is capable to handle the huge number of

elements required for such accurate micromechanical simulations. Additionally,

the electrical conductivity of the different laminates is simulated using the

GeoDict module ConductoDict.

The numerical study is validated with experimental test results on unidirectional

and multiaxial specimens with different steel-carbon-fiber-ratios. The simulation

results are in a good accordance with the experimental data and give

additionally a detailed insight in the micromechanics of this complex hybrid

composite material.

Additional Authors:
  • Benedikt Hannemann
    Institut für Verbundwerkstoffe GmbH
  • Dr. Matthias Kabel
    Fraunhofer Institute for Industrial Mathematics ITWM
  • Dr. Sebastian Schmeer
    Institut für Verbundwerkstoffe GmbH