The present investigations on sealability evaluation for tubing and casing premium connections depend the FEM with testing. This paper proposed a theoretical model to evaluate of sphere-type connection based make-up torque, which combines Hertz contact pressure von Mises yield criterion calculating elastic–plastic distribution sealing interface adopts gas obtained from Murtagian’s experimental ...

Abstract As the main launch energy of barrel weapon, dynamic mechanical properties gun propellant is very important to evaluate safety. Through transverse drop hammer impact damage test at room temperature and initial vivacity ratio propellant, crack growth law fracture degree damaged were obtained separately. Based on Hertz-Mindlin bonding contact model, discrete element model rosette 19-hole ...

Since the introduction of Finite Element Tearing and Interconnecting (FETI) by 10 Farhat and Roux in 1991, the method has been recognized to be an efficient parallel technique 11 for the solution of partial differential equations. In 2003 Langer and Steinbach formulated its 12 boundary element counterpart (BETI), which reduces the problem dimension to subdomain 13 boundaries. Recently, we have ...

One-dimensional "sonic vacuum" type phononic crystals were assembled from a chain of polytetrafluoroethylene (PTFE,Teflon) spheres with different diameters in a Teflon holder. It was demonstrated that this polymer-based sonic vacuum, with exceptionally low elastic modulus of particles, supports propagation of strongly nonlinear solitary waves with a very low speed. These solitary waves can be d...

In order to improve the service life of needle roller bearing used in a precision cycloid reducer, and reveal skew collision phenomenon bearing, based on force analysis transmission mechanism reducer considering friction between wheel, roller, cage, crank shaft, dynamic contact rolling bodies is simulated by Hertz elastic contact, where cage pocket hole equivalent spring damping, nonlinear mode...

The coupling interaction between nonlinear solitary waves in one-dimensional granular chains and damaged composite material plates is considered. Based on Hertz contact law meso-mechanical model of stiffness reduction when the fiber breakage main damage mode, coupled differential equations particle are derived. By solving with Runge–Kutta method to get velocity displacement curves particles ana...

A boundary-domain integral equation for a coated half-space (elastically isotropic homogeneous substratum, possibly anisotropic coating layer) is developed. The half-space fundamental solution is used, so that the discretization is limited to the potential contact zone (boundary elements), the potentially plastic part of the substratum and the coating layer (domain integration cells). Steady-st...

– We investigated impacts of nearly elastic spherical gels (very soft balls) onto a solid substrate. The Hertz contact deformation expected in the static (elastic) limit was observed only at very small impact velocities. For larger velocities, a gel ball deformed into flattened forms like a pancake. We measured the size of gel balls at the maximal deformation and a contact time as a function of...

Living human corneal epithelial cells have been probed in vitro via atomic force microscopy, revealing the frictional characteristics of single cells. Under cell media, measured shear stresses of 0.40 kPa demonstrate the high lubricity of epithelial cell surfaces in contact with a microsphere probe. The mechanical properties of individual epithelial cells have been further probed through nanome...