Comparison of Tensile and Compressive Creep-Fatigue Damage Behavior of Cellular Composites

Abstract

The damage behavior of cellular composites under creep and cyclic tensile loading conditions is investigated. Tensile cyclic tests at 1 Hz and 20 Hz test frequency and creep tests are performed and compared to previous investigations under compressive loading. In contrast to the compressive loading, no frequency effect is identified in tensile loading and the fatigue curves have steeper slopes. The damage behavior is analyzed by means of scanning electron microscope (SEM) and high resolution 3D X-ray tomography. It is found that microcracks are forming in the glass foam granules first; the final failure is caused by a macrocrack passing through the glass foam granules and the matrix. The damage evolution is measured in terms of stiffness loss of the specimen and is found to have different behavior than in compression.

A Continuum Damage Mechanics Model for the Static and Cyclic Fatigue of Cellular Composites

“…The cellular composite described in [ 9 , 10 , 11 ] was manufactured from epoxy laminating resin EPIKOTE™ MGS LR 285 (Hexion Speciality Chemicals GmbH, Iserlohn-Letmathe, Germany) and EPIKURE™ MGS 286 curing agent (Hexion Speciality Chemicals GmbH, Iserlohn-Letmathe, Germany) as matrix material by the low pressure infiltration (0.03–0.05 MPa) of a mold filled with granules. Glass foam granules with the grain-size fraction 1–2 mm (Dennert Poraver GmbH, Schlüsselfeld, Germany) are used as filler material.…”

“…The fatigue behavior of cellular composites under uniaxial static and cyclic tensile, compressive, and reversal loading was investigated in [ 9 , 10 , 13 ]. Figure 2 shows the test setup.…”

“…The damage evolution behavior is different for tension and compression loading [ 10 ]. In tensile tests, the main damage growth occurs in Stages I and II.…”

“…In case of the cellular composite, static and cyclic damage have the same effect on the microcrack growth in the glass foam granules [ 9 , 10 , 13 ]. Furthermore, both damage types can interact and therefore accelerate the damage process, which has been observed in the case of many materials [ 36 ].…”

“…The static and fatigue behavior of the presented cellular composite (recycled glass foam granules in epoxy resin) is analyzed in [ 9 , 10 , 11 ] for uniaxial compression and tension. Epoxy resin enables a good connection with glass granules without specific coatings.…”