Some techniques in 2D mapped meshing
Structural Engineering
Large Lateral Deflection of Unequal Stiffness Springs
A two-spring system is subjected to a force F as shown below. l=10 cm, k1=8N/cm, and k2=1N/cm. F=5*2^0.5N. Determine the strain energy of the system and the displacements δx and δy. The solution to this problem is best obtained by adding mass and using the "slow dynamics" technique with approximately critical damping. Combination elements (COMBIN40) are … Continue reading Large Lateral Deflection of Unequal Stiffness Springs
3D Stationary Crack Analysis: J-integral and Stress Intensity Factor Calculation
We talked about 2D stationary crack analysis using KSCON in the last post. This time let's have a look at the 3D model using solid elements. A long plate with a centre crack is subjected to an end tensile stress. The sketch of the problem is as follows. A one-quarter model is used because of symmetry. … Continue reading 3D Stationary Crack Analysis: J-integral and Stress Intensity Factor Calculation
2D Stationary Crack Analysis: J-integral and Stress Intensity Factor Calculation
We talked about calculating J-integral and K1 using XFEM in the last post. XFEM is a powerful method as it eliminates the need to remesh crack-tip regions. However, there are some limitations. For example, material behaviour is assumed to be linearly elastic. The available fracture criteria are valid only for cracks in homogeneous linear elastic … Continue reading 2D Stationary Crack Analysis: J-integral and Stress Intensity Factor Calculation
XFEM-Based Stationary Crack Analysis
This post presents an example of stationary crack analysis based on the extended FEM (XFEM). A common way to model the stress concentration at a crack tip is using KSCON command which specifies a keypoint about which an area mesh will be skewed. For stationary crack analysis, reasonable accuracy can be achieved using KSCON, although … Continue reading XFEM-Based Stationary Crack Analysis
Contact analysis: a bolted flange connection
A typical bolted flange connection (see Fig.1) is modeled in this example. Fig.1. The geometry of the model. Only the 1/4 model is created due to symmetry. The challenges in this example are as follows: Complicated geometry. Applying pretension to bolts. Multiple load steps. Modeling contact. It is worth mentioning that a special element Prentension179 … Continue reading Contact analysis: a bolted flange connection
Nonlinear analysis of a cable-membrane structure: from shape-finding to static and modal analysis
Fig.1. A typical cable-membrane structure The following assumptions are made in this example: Cables are discretized using LINK10 elements. The membrane is discretized using triangular SHELL41 elements with 'cloth' feature turned on. No slip between cables and membrane. The material complies with Hooke’s Law. The material is orthotropic and elastic. The two principal axes of … Continue reading Nonlinear analysis of a cable-membrane structure: from shape-finding to static and modal analysis
Torsional limit analysis of a container
Fig.1. A typical container This problem is to analyze the torsional limit of an open container (without lid). It is a typical problem in structural nonlinear buckling analysis. As an alternative to the Newton-Raphson method, the arc-length method will be used. Fig.2. A simplified model of the container body Some assumptions and simplifications in this … Continue reading Torsional limit analysis of a container
Wear analysis of casing coupling
Fig.1. Typical casing couplings Because the reciprocating and rotary motion of the drill pipe in the casing is eccentric, the radial and axial friction between the drill pipe and the casing causes serious wear on the outer surface of the drill pipe and the inner surface of the casing. This wear mostly occurs at the … Continue reading Wear analysis of casing coupling
The Analysis of Piston Rubber Film of Pneumatic Brake Device
Fig.1. Typical piston rubber films (with central hole) Fig.2. A typical piston rubber film Fig.3. A typical piston rubber film (edge can be fixed with bolts) Typical piston rubber films in a pneumatic brake device that is commonly used in drilling operations are shown in Fig.1-Fig.3. When the brake device is activated, the piston rubber … Continue reading The Analysis of Piston Rubber Film of Pneumatic Brake Device
Xutao Sun 