Regulation of Conjugate Rigid Plane Structure to Achieving Transformation of Fluorescent Recognition Properties

Bisbenzimidazole is an important class of fluorescence molecular probe materials with environmental, clinical and biological systems. Meanwhile, different bisbenzimidazole derivatives due to excellent coordination property and various fluorescence characteristic, were...

STATIC STABILITY OF AERODYNAMICALLY SUPPORTED PLATFORMS MOVING ABOVE WATER

The motion stability is the most important problem of high-speed marine vehicles that utilize aerodynamic support. A simplified analysis and calculations of longitudinal static stability of several basic platforms moving above water are carried out in this study. The analysis is based on the extreme ground effect theory and the assumption of hydrostatic deformations of the water surface. Effects of the underlying surface type, Froude number, and several geometrical parameters on main aerodynamic characteristics, including the static stability margin, are presented. If the underlying surface is water instead of a rigid plane, the static stability worsens for platforms with flat or S-shaped lower surfaces, but it slightly improves for a horizontal platform with a flap. The static stability margin remains positive for S-shaped profiles at sufficiently low Froude numbers, while it is negative for other configurations.

On the asymptotic behavior of solutions of anisotropic viscoelastic body

The quasistatic problem of a viscoelastic body in a three-dimensional thin domain with Tresca’s friction law is considered. The viscoelasticity coefficients and data for this system are assumed to vary with respect to the thickness ε. The asymptotic behavior of weak solution, when ε tends to zero, is proved, and the limit solution is identified in a new data system. We show that when the thin layer disappears, its traces form a new contact law between the rigid plane and the viscoelastic body. In which case, a generalized weak form equation is formulated, the uniqueness result for the limit problem is also proved.

A Static Friction Model for Unlubricated Contact of Random Rough Surfaces at Micro/Nano Scale

A novel static friction model for the unlubricated contact of random rough surfaces at micro/nano scale is presented. This model is based on the energy dissipation mechanism that states that changes in the potential of the surfaces in contact lead to friction. Furthermore, it employs the statistical theory of two nominally flat rough surfaces in contact, which assumes that the contact between the equivalent rough peaks and the rigid flat plane satisfies the condition of interfacial friction. Additionally, it proposes a statistical coefficient of positional correlation that represents the contact situation between the equivalent rough surface and the rigid plane. Finally, this model is compared with the static friction model established by Kogut and Etsion (KE model). The results of the proposed model agree well with those of the KE model in the fully elastic contact zone. For the calculation of dry static friction of rough surfaces in contact, previous models have mainly been based on classical contact mechanics; however, this model introduces the potential barrier theory and statistics to address this and provides a new way to calculate unlubricated friction for rough surfaces in contact.

FFT-Based Numerical Method for Non-Linear Elastic Contact

Based on FFT, a numerical method suitable for elastoplastic and hyperelastic frictionless contact is proposed in this paper, which can be used to solve 2D and 3D contact problems. The non-linear elastic contact problem is transformed to linear elastic contact considering residual deformation (or equivalent residual deformation). Numerical simulations for elastic, elastoplastic and hyperelastic contact between hemisphere and rigid plane are compared with the results of finite element method (FEM) to verify the accuracy of the numerical method. Compared with the existing elastoplastic contact numerical methods, the calculation efficiency is improved while ensuring a certain calculation accuracy (pressure error does not exceed 15% while calculation time does not exceed 10 minutes in a 64×64 grid). For hyperelastic contact, the proposed method reduces the dependence of the approximation result on load as in linear elastic approximation. Despite a certain error, the simplified numerical method shows a better approximation result than linear elastic contact approximation, which can be used for the fast solution in engineering applications. Finally, taking the sealing application as an example, the contact and leakage rate between 3D complicated rough surfaces are calculated.