Investigation on Fractal Characteristics of Disintegration Process and Strength of Rockfill under Water Pressure

The paper aimed to investigate internal mechanics between disintegration of the rockfill material and stability of the dam, and further provide scientific evidence for the design of rockfills, through the conducted disintegration of water pressure and triaxial test to analyze fractal characteristics, strength and deformation of the rockfill in whole disintegration procedure. As the results that the water pressure was low 0.2 MPa, the increasing water pressure would delay the disintegration rate of rockfill;while the water pressure was above 0.2 MPa, it would promote the disintegration rate of the rockfill. In addition, in the disintegration process, the cohesion force of rockfill rapidly slowed down at the beginning and then gradually increased. The internal friction angle increased gradually during the whole disintegration process. Furthermore, when the water pressure increased from 0 MPa to 0.6 MPa, the partial stress firstly decreased to a minimum level when the water pressure was 0.2 MPa, and then increased gradually with water pressure.

Integrated passage design based on extended free-form deformation and adjoint optimization

Inspired by the three-dimensional design of flow passages in turbomachinery,this study proposes the concept of integrated passage design.The capability of adjoint method for efficient optimization and the flexibility of the parameterization method based on extended free-form defor-mation have been considered to develop a feasible approach to design an integrated passage.This concept was applied to redesign a typical transonic fan,Rotor 67,and the results were analyzed by CFX.It is shown that the passage was adequately adjusted in all three dimensions and reduced the strength of shock wave and wake-induced flow.In particular,the secondary flow was appropriately reorganized and the corner separation was well controlled in the end wall region,leading to signif-icant improvements in adiabatic efficiency and diffusion.

Finite element simulations of deformation behavior in equal channel angular pressing using a rotated die

A new die design for equal channel angular pressing （ECAP） of square cross-section billet was proposed by a 45° rotation of the inlet and outlet channels around the channel axes. ECAP utilizing the rotated and conventional dies was simulated in three dimensions using the finite element method. Conditions with different material properties and friction coefficients were studied. The billet deformation behavior was evaluated in terms of the spatial distribution of equivalent plastic strain, plastic deformation zone and load history. The results show that the rotated die appears to produce billets with a smaller deformation inhomogeneity over the entire cross- section and a greater average of equivalent plastic strain at the cost of a slightly larger working load. The billet deformdtion enters into a Steady s^ate earlier in the case of the rotated die than the conventional die under the condition of a relatively large friction coefficient.