Testing and analysis of Anisogrid Prepreg element specimens under uniaxial tension and compression

This paper reports on test results and analysis of element sized Anisogrid Prepreg knot and rib specimens under uniaxial tension and compression.Anisogrid or Lattice structures consist of intersecting, integral manufactured ribs with different directions (circumferential, axial, and/or helical) and optionally a load bearing skin. The classical manufacturing method for aerospace grid structures is wet-filament winding. For airframes, an Anisogrid Prepreg structure concept has been developed considering high quality assurance demands and the need of a qualified automated manufacturing process (Advanced Fibre Placement). The Prepreg layers feature 60% fibre volume ratio for high stiffness properties, but need to be cut in the point of intersecting rib directions. The pattern of cut and uncut layers in the rib knot alternates for all rib directions over the height.Due to the special stacking of the ribs with rectangular cross-section and very narrow ply widths, a wide reference testing program is performed additionally. As result, an answer is given which stiffness and strength properties in tension and compression can be expected for this Anisogrid Prepreg structure concept.