The tyre of the lunar rover is the research background of this study.
Lot of research going in improve structural performance, design and structure of flexible spokes and rolling resistance. While driving spokes in tyre undergo tension-compression cyclic load. Spokes are like array presented between vertical walls. Different shape of spokes is proposed for NPT they are square, hexagonal, kagome, triangle, mixed squares and triangles, and diamond shape. Triangular, kagome and diamond cell honeycomb are good for high modulus structural designs. Square and hexagonal cell honeycombs are known to be good for flexible structure.3. LITERATURE REVIEWAvinash Kolla,Jaehyung Ju,Joshua D.
Summer 1 They proposed the chiral honeycomb with 4 and 6 ligament attachments. The objective of the study is to find an ideal geometry for the shear layer while meeting its requirements of shear properties, about 6.5 MPa shear modulus and 0.15 maximum effective shear strain with polycarbonate as base material Prabhu Shankar,Jaehyung Ju,Joshua D.Summer, John C Ziegert 2 They proposed the auxetic honeycomb meso structure with sinusoidal re-entrant wall. They conducted the comparative study between the ability of sinusoidal meso structure over the auxetic meso structure for high shear flexure. The sinusoidal introduces nonlinearity with increase in cell wall thickness and shear strain.
This nonlinearity causes the sinusoidal auxetic meso structure to have low shear flexure at a high shear modulus which is higher than about 10MPa. However, it is marginally better than auxetic meso structure at a low shear modulus which is 10MPa and less. Jaehyung Ju,Joshua D.Summer,John C Ziegert,George Fadel3 To attain the maximum effective shear modulus in hexagonal honeycomb meso-structure they used various ratio in vertical cell length, h to inclined length.They described the basic design constraints like t ? 0.1mm (manufacturing constraint), t/l ? 0.25. The negative Poisson ratio honeycomb have a higher density, but may be good to avoid nonlinear elastic buckling.
Mohammad Fazelpour, Joshua D.Summer4 The evaluation started with ideation method, then continued with the known topologies such as honeycomb and proposed new shapes like S-type. They discussed about 12 types of meso-structure in detail like how is generate, difference between present and previous type, describe its property, Physical prototype testing.
From the literature survey different types of hexagon shape are investigated but octagon shape is new for spoke design. So octagon shape is selected for this project. The objective of this study is study the physical behavior of the shape and analysis its mechanical propertieS