Waviness
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Recent papers in Waviness
The quality of the surface of the piston ring and cylinder tribo pair affects significantly its performance and its dynamic characteristics. Manufacturing errors in terms of waviness and straightness can lead to a series of defects on the... more
The quality of the surface of the piston ring and cylinder tribo pair affects significantly its performance and its dynamic characteristics. Manufacturing errors in terms of waviness and straightness can lead to a series of defects on the surfaces of the piston ring and the cylinder respectively. In this work a tribological model of a piston ring- cylinder package is presented using CFD analysis. In the proposed model, the piston ring waviness and cylinder straightness are included. Smooth and artificially textured surfaces of the ring are also considered. Configurations of the waves are formed as a sum of sinusoidal waves with different amplitude and length in order to study the relationship between the waviness of the ring and the cylinder bore. The results of the simulations carried out show the reduction of the friction force by increasing the percentage of the waviness or straightness amplitude.
Effective elastic properties for carbon nanotube reinforced composites are obtained through a variety of micromechanics techniques. An embedded carbon nanotube in a polymer matrix and its surrounding interphase is replaced with an... more
Effective elastic properties for carbon nanotube reinforced composites are obtained through a variety of micromechanics techniques. An embedded carbon nanotube in a polymer matrix and its surrounding interphase is replaced with an equivalent fiber for predicting the mechanical properties of the carbon nanotube/polymer composite. The effects of an interphase layer between the nanotubes and the polymer matrix as result of effective interphase layer is investigated. A modeling analysis investigating the effect of the aspect ratio on the tubes reinforcement mechanism has been carried out. The variations of mechanical properties with tube reduce, interphase thickness and waviness is investigated. Furthermore in this work, the classical theory concerning the mechanical efficiency of a matrix embedding finite length fibers has been modified by introducing the tube-to-tube Random Contact which explicitly accounts for the progressive reduction of the tubes effective aspect ratio as the filler content increases.
Material imperfection, especially struts waviness attributed to fabrication and service phase, may cause the decay of the fracture resistance of lattice structures. Accordingly, a cautionary step must be taken to ensure the correct... more
Material imperfection, especially struts waviness attributed to fabrication and service phase, may cause the decay of the fracture resistance of lattice structures. Accordingly, a cautionary step must be taken to ensure the correct fracture properties are employed in the analysis and design of lattices before further utilized in applications. Hence, strut waviness effects on the fracture toughness, K C , of square lattices with respect to numerous loading orientations are of concern in this paper. To examine these effects, square lattices with struts in flat (planar) and biaxially woven configurations are numerically considered. K C is assessed by introducing plane-tension to centrally-cracked lattices for various relative densities ( ̄𝜌= 0.05, 0.1, 0.15, and 0.2) and loading directions ( 𝛼= 0°–90°). In all cases, K C of planar lattices are greater than those woven, with as high as 91.7% of performance knockdown in the latter due to the waviness and loading direction effects. In general, K C correlates directly with relative density but inversely with loading direction. K C enhancement is greater in planar lattices compared to those woven when the relative density is increased. Both lattices exhibit anisotropic K C , in which the effects on the planar lattices are more evident. Failure modes of both lattices are found to be independent of relative density but greatly influenced by loading orientations. A shifting in failure mode from plane-tension to plane-shear can be noticed in accordance with the transition angle 𝛼= 𝛼t as the loading orientation increases.
Mode II fracture toughness, KIIC, of single-ply triaxially woven fabric (TWF) composite due to tow waviness and anisotropy effects were numerically and experimentally studied. The numerical wavy beam network model with anisotropic... more
Mode II fracture toughness, KIIC, of single-ply triaxially woven fabric (TWF) composite due to tow waviness and anisotropy effects were numerically and experimentally studied. The numerical wavy beam network model with anisotropic material description denoted as TWF anisotropic was first validated with experimental Mode II fracture toughness test employing the modified compact tensile shear specimen configuration. 2D planar Kagome and TWF isotropic models were additionally constructed for various relative densities, crack lengths, and cell size parameters for examining effects due to tow waviness and anisotropy. KIIC generally increased with relative density, the inverse of cell size, and crack length. It was found that both the waviness and anisotropy of tow inflict a drop in KIIC of TWF. These effects were more adverse due to the waviness of tow compared to anisotropy.
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