Stress distributions in compacted powders in convergent and stepped dies

•Neutron diffraction is used to map axisymmetric stress distributions in granular materials.•Stress distributions from materials compacted within stepped and taped dies are presented.•Comparisons between ductile iron powder and brittle quartz sand are made.

Neutron diffraction techniques are used to measure a series of bulk stress distributions in granular materials undergoing high stress die compaction. Two different granular materials are studied: a ductile material in the form of iron powder and a brittle material in the form of quartz sand. The behaviour of these two materials is examined in terms of the resulting stress distribution within two dies of different geometry: an axisymmetric converging die and a stepped cylindrical die. These measured distributions are examined and discussed to highlight both similarities and differences in the mechanical response of these contrasting materials at high consolidating loads. The potential for neutron diffraction techniques to provide full-field information on the mechanical response and stress within granular samples is demonstrated.

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