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Compressive Properties of a Closed-Cell Aluminum Foam as a Function of Strain-Rate and Temperature.

Description: The compressive deformation behavior of a closed-cell Aluminum foam (ALPORAS) manufactured by Shinko Wire. Co. in Japan was evaluated under static and dynamic loading conditions as a function of temperature. High strain rate tests (1000 - 2000/s) were conducted using a split-Hopkinson pressure bar(SHPB). Quasi-static and intermediate strain rate tests were conducted on a hydraulic load frame. Little change in the flow stress behavior as a function of strain rate was measured. The deformation behavior of the Al-foam was however found to be strongly temperature dependent under both quasistatic and dynamic loading. Localized deformation and stress state instability during testing of metal foams will be discussed in detail since the behavior over the entire range of strain rates indicates nonuniform deformation.
Date: January 1, 2001
Creator: Gray, G. T. (George T.), III; Liu, C. (Cheng); Trujillo, C. P. (Carl P.); Jacquez, B. (Benito); Mukai, T. & Cady, C. M. (Carl McElhinney)
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Ductile damage evolution and experimental simulation under high rates of strain in 10100 copper.

Description: The high strain-rate damage evolution and Eracture behavior of half-hard 10 LOO Cu was investigated by experiments and computer simulations. Testing of uniaxial stress and axisymmetric notched bars of the Hancock-Mackenzie geometries were performetl using a momentum trapped tensile split Hopkinson pressure bar. Specimens were. tested to fracture and to several stages of incipient failure prior to fracture. Recovered specimens were sectioned and metallographically examined using image analysis and optical profilornelry to quantify the resulting damage. The quantified damage is described by spatially resolved porosity distributions, spatially resolved volumetric number densiries, and spatia Ily resolved void size distributions. Concurrent to mechanical testing, explicit finite element simulations of the tensile split Hopkinson pressure bar experiments were perfornicd to quantify the local stress-state and strain-state within the material and to determine the evolution of damage within the notch region. The coinpressive plasticity behavior of the material was fit to the mechanical threshold stress constitutive model, and was used in the simulations. The quantified damage was coniprued with damage model (TEPLA) predictions and used to refine model parameters and damage nucleation criteria. The simulation results also show that the maximum stress triaxiality in the specimens quickly enlarges after the onset of plastic flow or tensile instability to almost twice that of the Bridgman predicted levels.
Date: January 1, 2001
Creator: Thissell, W. R. (W. Richards); McKirgan, J. B. (John B.); Chen, S. R. (Shuh-Rong); Trujillo, C. P. (Carl P.) & Macdougall, D. A. S. (Duncan A. S.)
Partner: UNT Libraries Government Documents Department