Mechanical Characterization of a Graphite/Epoxy IsoTruss
| Autor: | Thomas Jared Weaver, David W. Jensen |
|---|---|
| Rok vydání: | 2000 |
| Předmět: |
Toughness
Materials science business.industry Mechanical Engineering Aerospace Engineering Torsion (mechanics) Truss Structural engineering Epoxy Mandrel Buckling visual_art Tetrahedron visual_art.visual_art_medium General Materials Science Graphite Composite material business Civil and Structural Engineering |
| Zdroj: | Journal of Aerospace Engineering. 13:23-35 |
| ISSN: | 1943-5525 0893-1321 |
| DOI: | 10.1061/(asce)0893-1321(2000)13:1(23) |
| Popis: | Graphite/epoxy IsoTruss specimens were filament wound and experimentally tested to failure under simple compression, tension, and torsion and compared with simple analytical predictions. Failed speci- mens were subsequently retested to gain further insight into the mechanical interaction of the various components of the IsoTruss. Simple analytical techniques were used to predict the approximate strength of the IsoTruss. A total of 15 five inch (12.7 cm) diameter, five-bay IsoTruss specimens were filament wound on a reusable, silicone inner mandrel. Nine 3-tow specimens with a nominal member cross-sectional area of 0.27 in. 2 (1.7 cm 2 ) and six 5-tow specimens with a corresponding area of 0.45 in. 2 (2.9 cm 2 ) were fabricated and tested. Axial and torsion loads, axial displacements, and rotations were synchronized with axial strain gauge data from the three main regions of the IsoTruss (axials, tetrahedrons, and the cross-zone). Additionally, four 3-tow IsoTruss spec- imens with various lengths tested in simple compression showed that global buckling does not affect a five inch (12.7 cm) IsoTruss six bays in length or less, and that the failure of a single bay has little or no effect on the capacity of the remaining IsoTruss to resist compressive loads. The results indicate the relative contributions of primary and secondary load members. The influence of the secondary load members increases after failure of a primary load member. The redundancy of the structure coupled with the influence of the secondary load members causes a ductile type failure to occur for all load types, but it is most pronounced in torsion. In all load types, failure was initially isolated to a single bay. Generally, reloaded specimens were only minimally affected by the prior damage. Finally, increased fiber interconnectivity at the nodes of the IsoTruss yields higher ultimate stresses and greater toughness in IsoTruss structures. of the descending helical members with the axial. The axial members located between these two cross-sectional slices through the IsoTruss are excluded from the region, remaining part of the group labeled axials, as described above. The third region, the cross-zone, refers to the section between the tet- rahedron regions along the length of the IsoTruss. In this re- gion, helically wound members intersect on flat planes to form a hexagonal cross section. APPROACH In this study, two different IsoTruss configurations were in- vestigated, differing only in the cross-sectional area of the members, the second having nearly double the area of the first. The 3-tow IsoTruss was tested more extensively, focusing on three basic load types (compression, tension, and torsion). The 5-tow IsoTruss was tested only selectively, to gain additional insights on the effect of member diameter and node intercon- nectivity. Fig. 2 shows a picture of a 5-tow IsoTruss. Both types were manufactured using a carbon/epoxy system and measured approximately 5 in. (12.7 cm) in diameter (outer tetrahedron node to outer tetrahedron node, through the central axis) and about 40 in. (102 cm) in length. Each employed a 607 internal angle (measured between the two opposing planes of the legs of a tetrahedron), with 2.5 in. (6.35 cm) long bays (repeating units). A combination of analytical and experimental techniques |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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