Anisogrid lattice cylinders made of thermoplastic composite under buckling loading

Claudia Papa,Daniele Santoro,Denise Bellisario,Fabrizio Quadrini,Leandro Iorio,Loredana Santo,Marco Regi,Nicola Gallo

doi:10.25518/esaform21.2798

Abstract

Anisogrid lattice cylinders have been produced by means of an innovative out-of-autoclave (OOA) process by using thermoplastic prepreg. Unidirectional thermoplastic tapes with polypropylene matrix and glass fibers were wound on cylindrical mandrels at room temperature. Composite consolidation was achieved by using the compression of a heat-shrink tube during its shape recovery in oven. A cylindrical anisogrid lattice structure was manufactured and mechanically tested under vertical loading. Results from the buckling test revealed the optimal adhesion between prepreg layers after the out-of-autoclave molding. Numerical modelling of buckling has been performed to correlate the structural behavior of the anisogrid lattice cylinder with composite material properties and geometrical features. A parametric model of the lattice structure has been defined for this aim. The proposed manufacturing technology combines the advantages of thermoplastic composites (reparability, easy handling, easy storage, long prepreg life, productivity) with the designing potential of anisogrid lattice structures in terms of lightness and stiffness.

Highlights

Anisogrid composite lattice structures (ACLSs) are composed of dense system of unidirectional composite helical, circumferential and axial ribs made by continuous filament winding
The present work aims at presenting the results of buckling tests performed on cylindrical ACLSs, extending the results showed in [10]
The limit point has been reached at about 1.5 mm of displacement, with force peak of 4874.8 N. At this point the ACLS exhibit a substantial collapse in the upper part, close to the upper compression plate. This determined a reduction of ACLS ability to bear axial load with slight rise of stiffness at 2.4 mm

Summary

Introduction

Anisogrid composite lattice structures (ACLSs) are composed of dense system of unidirectional composite helical, circumferential and axial ribs made by continuous filament winding. They are used mainly in the form of cylindrical or conical shells. Axial compression loads can cause local or global structural instabilities [2]. Many contributions discussed these aspects, focusing on their numerical prediction via finite element method (FEM). In [4] the authors predicted the axial deformability of filament-wound composite anisogrid lattice tubular body of the spacecraft subjected to compressive loading. Experimental tests on anisogrid specimen cells have been proposed in [7], where a multi-failure theory is proposed, including global buckling, local in-plane buckling, local out-of-plane buckling, Euler buckling and material failure

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Results

Conclusion