The DDA Method

Deformation Analysis ◽

Short Overview ◽

Abrupt Changes ◽

Iteration Technique

“DDA” stands for “Discontinuous Deformation Analysis”, suggesting that the displacement field of the analyzed domain shows abrupt changes on the element boundaries in the model. This chapter introduces the theoretical fundaments of DDA: mechanical characteristics of the elements together with the basic degrees of freedom, contact behavior, the equations of motion and their numerical integration with the help of Newmark's beta-method taking into account contact creation, loss and sliding with the help of an open-close iteration technique. Finally, a short overview on practical and scientific applications for masonry structures is given.

Vertex Displacement-Based Discontinuous Deformation Analysis Using Virtual Element Method

Materials ◽

10.3390/ma14051252 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1252

Author(s):

Hongming Luo ◽

Guanhua Sun ◽

Lipeng Liu ◽

Wei Jiang

Keyword(s):

Degrees Of Freedom ◽

Deformation Analysis ◽

Virtual Element Method ◽

Time Step ◽

Element Space ◽

Displacement Mode ◽

Virtual Element ◽

Element Method

To avoid disadvantages caused by rotational degrees of freedom in the original Discontinuous Deformation Analysis (DDA), a new block displacement mode is defined within a time step, where displacements of all the block vertices are taken as the degrees of freedom. An individual virtual element space V1(Ω) is defined for a block to illustrate displacement of the block using the Virtual Element Method (VEM). Based on VEM theory, the total potential energy of the block system in DDA is formulated and minimized to obtain the global equilibrium equations. At the end of a time step, the vertex coordinates are updated by adding their incremental displacement to their previous coordinates. In the new method, no explicit expression for the displacement u is required, and all numerical integrations can be easily computed. Four numerical examples originally designed by Shi are analyzed, verifying the effectiveness and precision of the proposed method.

Parallelization of spherical discontinuous deformation analysis (SDDA) for geotechnical problems based on cloud computing environment

Science China Technological Sciences ◽

10.1007/s11431-020-1768-3 ◽

2021 ◽

Author(s):

Yu-Yong Jiao ◽

ZeYang Wu ◽

Fei Zheng ◽

Qiang Zhao ◽

Long Wang ◽

...

Keyword(s):

Cloud Computing ◽

Deformation Analysis ◽

Computing Environment ◽

Cloud Computing Environment ◽

Geotechnical Problems

Formulations of the three-dimensional discontinuous deformation analysis method

Acta Mechanica Sinica ◽

10.1007/bf02486719 ◽

2004 ◽

Vol 20 (3) ◽

pp. 270-282 ◽

Cited By ~ 24

Author(s):

Liu Jun ◽

Kong Xianjing ◽

Lin Gao

Keyword(s):

Three Dimensional ◽

Deformation Analysis ◽

Analysis Method ◽

Discontinuous Deformation

Numerical modeling of complex hydraulic fracture networks based on the discontinuous deformation analysis (DDA) method

Energy Exploration & Exploitation ◽

10.1177/0144598720981532 ◽

2021 ◽

pp. 014459872098153

Author(s):

Yanzhi Hu ◽

Xiao Li ◽

Zhaobin Zhang ◽

Jianming He ◽

Guanfang Li

Keyword(s):

Hydraulic Fracturing ◽

Hydraulic Fracture ◽

Fracture Network ◽

Deformation Analysis ◽

Fracture Networks ◽

Proposed Model ◽

Shale Reservoirs ◽

Dda Method

Hydraulic fracturing is one of the most important technologies for shale gas production. Complex hydraulic fracture networks can be stimulated in shale reservoirs due to the existence of numerous natural fractures. The prediction of the complex fracture network remains a difficult and challenging problem. This paper presents a fully coupled hydromechanical model for complex hydraulic fracture network propagation based on the discontinuous deformation analysis (DDA) method. In the proposed model, the fracture propagation and rock mass deformation are simulated under the framework of DDA, and the fluid flow within fractures is simulated using lubrication theory. In particular, the natural fracture network is considered by using the discrete fracture network (DFN) model. The proposed model is widely verified against several analytical and experimental results. All the numerical results show good agreement. Then, this model is applied to field-scale modeling of hydraulic fracturing in naturally fractured shale reservoirs. The simulation results show that the proposed model can capture the evolution process of complex hydraulic fracture networks. This work offers a feasible numerical tool for investigating hydraulic fracturing processes, which may be useful for optimizing the fracturing design of shale gas reservoirs.