No abstract

SUMMARY

A stress-rupture apparatus was designed and built for testing filaments and wires having a diameter of 20 mils or less in a controlled atmosphere to prevent oxidation. Four tests may be run simultaneously at different stresses and temperatures (to 1427°C), and the stress-rupture life of each filament can be measured independently and automatically.

The observed critical aspect ratio for pullout specimens of tungsten wire in a copper matrix tested in stress rupture at 649 and 816 C was slightly greater than for tension tests at the same temperature. Time for failure of the stress rupture specimens was controlled by the properties of the fiber (tungsten) at aspect ratios greater than the critical aspect ratio and by the properties of the matrix (copper) at aspect ratios less than the critical ratio.