Numerical prediction of the stiffness and strength of medium density fiberboards

Published Date
December 2014, Vol.79:73–84, doi:10.1016/j.mechmat.2014.08.005

Author 

Janis Sliseris ^a,c,,

Heiko Andrä ^a

Matthias Kabel ^a

Brigitte Dix ^b

Burkhard Plinke ^b

Oliver Wirjadi ^a

Girts Frolovs ^c

aFraunhofer Institute for Industrial Mathematics (ITWM), Germany

bFraunhofer Institute for Wood Research (WKI), Germany

cRiga Technical University (RTU), Latvia

Received 21 May 2014. Revised 15 August 2014. Available online 16 September 2014.

Highlights

• We simulate medium density fiberboard (MDF) behavior in tensile and bending loads.
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  We obtained fiber orientation tensor, density profile, fiber length and diameter using μCT.
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  A two scale approach is appropriate tool for MDF simulation.
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  Proposed model is used to analyze fiber orientation influence on stiffness.

Abstract 

A numerical two scale method for the prediction of tensile and bending stiffness and strength of medium density fiberboards (MDF) is proposed with the aim to study the fiber orientation influence on mechanical properties of MDF. The method requires less experimental data to optimize MDF and to improve industrial manufacturing technology of MDF. A new method for computing orientation tensors of the compressed fiber network is proposed. First, the virtual microstructure is generated by simulations of a fiber lay-down and a subsequent compression to obtain the necessary density. The density profile, fiber length, thickness, and orientation are used for the microstructure generation, which are obtained from  CT images and image analysis tools. Then a new damage model for the wood fiber cell walls and joints is introduced. The microstructural problem is formulated as a Lippmann–Schwinger type equation in elasticity and solved by using Fast Fourier Transformation (FFT). The macroscopic three point bending test is simulated with hexahedral finite elements and analytical methods based on Euler–Bernoulli theory. The difference between bending strength and stiffness numerically obtained and corresponding experimentally measured values is less than 10%. This study lays a foundation for the optimal design of MDF fiber structures and the optimization of industrial manufacturing processes. The first results show an increase of up to 60% for bending stiffness in the case of strongly oriented fibers.

Graphical abstract

Keywords

• Wood-based panels
• MDF
• Numerical analysis
• Experimental testing

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  Corresponding author at: Fraunhofer Platz 1, Kaiserslautern 67663, Germany. Tel.: +49 631316004738.
  
  

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