Shale swelling can cause a series of problems during the exploitation of shale gas. However, because of the complex fabric of shale, a thorough understanding of shale swelling has not been gained. In this work, an experimental multiscale approach is employed to characterize the swelling properties of a shale sample from Sichuan basin of China. Wetting/drying tests are performed by environmental scanning electron microscopy (ESEM), and deformation of the material is measured by analyzing the ESEM micrographs using digital image correlation (DIC) techniques. Investigations are conducted at three distinct scales, enabling the macroscopic behavior to be linked to the microscopic mechanisms (e.g., the role of inclusions, the behavior of clay particles). The macroscopic swelling of the tested shale is less than 2%. This limited swelling is mainly due to the presence of nonswelling inclusions as well as the low swelling capacity of the clay inside the shale. Microcracking is evidenced along both the wetting and the drying paths. It is demonstrated that the clay particles swell rather undirectionally perpendicular to their orientation. Moreover, a preferred orientation of the clay particles is found parallel to the bedding plane, which finally leads to a moderate anisotropy of the macroscopic swelling.

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The moving track of journal bearing changes with the time in the condition of dynamic loading. The force balance equation of journal bearing is established, and the generalized Reynolds equation, the oil film thickness equation of spiral oil wedge journal bearing under dynamic loading are gained, which is based on axial inertia force, bearing capacity and dynamically loading. By finite difference method, Euler method and Reynolds boundary condition, the generalized Reynolds equation and force balance equations are solved simultaneously, the periodic moving track of journal bearing at different times is solved. The results show that the circumferential pressure, axis displacement, axis velocity, axis acceleration velocity of journal bearing change periodically as time goes. The influence of dynamical loading on pressure distribution of oil film and axis locus is analyzed.

The plastic deformation during flash-butt welding (FBW) and its effects on weld quality are investigated by using numerical and experimental methods. The electro-thermo-mechanical coupling model of FBW is validated by comparing the calculated temperature and plastic deformation to measured one, obtaining reasonable agreement. The calculation results reveal that a thin liquid metal film forms at the contact interface during accelerating flash stage to provide temperature conditions for upsetting. The length of liquid metal (including burning and expelled losses) is 29.7 mm for one piece pipeline tube under the given condition. The stress and strain at contact surface are both almost zero at the initial stage of upsetting due to the thin liquid metal film existing at the contact interface, and they rapidly increase to 58.0 MPa and 17.7, respectively, while the liquid metal are excluded from the contact interface between two tubes to be welded. The maximum plastic deformation is 18.1 mm at the given condition under the action of upsetting force. The experimental results illustrate that the microstructure of X65 FBW joints consists of massive ferrite, grain boundary pre-eutectic ferrite, pearlite, and widmannstatten, while the microstructure in heat-affected zone is fine ferrite and pearlite. The coarse grain size and gray spots in the butt joint severely decrease the tension strength and impact toughness.