Numerical simulation of the natural fragmentation of explosively loaded thick walled cylinders
40
Citation
10
Reference
10
Related Paper
Citation Trend
Abstract:
The ability to predict the natural fragmentation of an explosively loaded metal casing would represent a significant achievement. Physically-based material models permit the use of small scale laboratory tests to characterise and validate their parameters. The model can then be directly employed to understand and design the system of interest and identify the experiments required for validation of the predictions across a wide area of the performance space. This is fundamentally different to the use of phenomenologically based material algorithms which require a much wider range of characterisation and validation tests to be able to predict a reduced area of the performance space. Eulerians numerical simulation methods are used to describe the fragmentation of thick walled EN24 steel cylinders filled with PBXN-109 explosive. The methodology to characterise the constitutive response of the material using the physically based Armstrong–Zerilli constitutive model and the Goldthorpe path dependent fracture model is described, and the results are presented. The ability of an Eulerian hydrocode to describe the fragmentation process and reproduce the experimentally observed fragment mass and velocity distributions is presented and discussed. Finally the suitability of the current experimental analysis methodology for simulation validation is addressed.Keywords:
Fragmentation
A 3D simulating model for calculating casing in fracturing wells is established based on the casing force-summing analysis. The laws of casing stress changes caused by inner casing pressure changes are calculated by simulation. According to the calculation the factors of fracturing influencing on casing failure are analyzed. It is considered that the casing failure is the result of combined action caused by many factors. Through analyzing the data of casing failure wells, the causes of casing failure in the fracturing wells are compared analytically, by which theoretical bases are provided for preventing casing failure under special operation condition.
Cite
Citations (1)
This paper advances a new optimization method about material constitutive equation on the basis of physical simulation and numerical simulation results which basic thinking can be described as the following: through comparing the results of the material deformation process under actual experimental conditions and virtually simulated by the finite element numerical simulation method with the constitutive equation established on the basis of the physical simulation, the constitutive equation established by the experimental data is optimized in turn. Based on it, this paper advances a visco/plastic constitutive equation to depict the semi-solid thixo-forming and the constitutive equation is analyzed and optimized through coupling of the physical simulation and numerical simulation. It is observed that this method can effectively eliminate the influence of the factor outside material itself on the constitutive equation. So, it can exactly depict the deformation behavior of the materials and improve the accuracy and reliability of the numerical simulation.
Cauchy elastic material
Basis (linear algebra)
Cite
Citations (3)
Explosive lining is simplified as an axisymmetric problem. Using DYNA 2D commercial program, the change of displacements of mortar and soil with time during the explosive lining are analyzed by numerical simulation. The numerical simulation results meet the on site experiment results. Research indicates that mortar and soil could be pressured into a stable lining structure through explosive lining. Free face is one of the important factors influencing shape of the lining shell.
Cite
Citations (0)
The interactions between the high-speed waterjet of 500 m/s and the condensed explosive have been simulated by LS-DYNA3D code with Lagrange method.The pressure distributions in the explosive at different times and the pressure histories at different elements of the explosive have been calculated.On the basis of numerical simulation,the sound speeds of the explosive have been determined.The numerical simulation results accord with the theoretical analysis.During the process of the interaction between the high-speed waterjet and the condensed explosive,the numerical simulation results show that the pressure decreases with the increase in the radial distance of the element and the maximum pressure occurs nearby or in front of the head of the penetrating waterjet.
Shock front
Cite
Citations (0)
Degradation of the casing strength in relation with thermal cycles of steam injection process is still less explored in literature. In this paper, three-dimensional finite element (FE) analysis of casing strength degradation in thermal environment of steam injection wells is presented. 3D FE models consisting of casing-cement-formation system are developed in this study. Grade N80 casing is employed with the casing length of 3.048 m. In the analysis, cyclic thermal stresses induced on the casing in thermal environment of steam injection wells from 25 °C to 360 °C are first examined to verify the feasibility of the 3D FE models. Degradation of the casing strength in the thermal environment is subsequently investigated by applying an external pressure that represents formation pressure to the casing-cement system. The results show that the casing capability to resist the pressure is lowering as the number of thermal cycles extends, thus causing casing strength degradation in the thermal application. It is also shown that the casing may fail under external pressure below its specified collapse strength i.e. 10 % lower than the reference casing strength obtained at 360 °C.
Steam injection
Degradation
Cite
Citations (4)
在 build 节的中间的 casings 服从于严重在扩大活动范围的钻穿。这篇论文为在中间的 casing 上预言一条 wear 沟的深度论述一个新方法。根据精力，原则和 casing 的动态累积由工具关节穿，一个模型被建立在 casing 的内部墙上计算 wear 区域。在 wear 沟深度和区域之间的关系功能基于在 drillstring 和 wear 节和假设之间的几何学关系被获得 casing 穿沟是新月形的。casing 的变化在不同尺寸的 drillstrings 下面穿沟深度对钻的英尺数也被讨论。一个机械模型为预言 casing 被建议穿地点，它基于井轨道和 drillstring 运动。casing 穿一口计划的井的沟深度与 casing 的倒置被预言从钻的井穿因素并且必然修订了为钻的井和计划的井之间的差别改进预言精确性。为预言 casing 的方法在扩大活动范围的钻穿通过实际案例研究被验证。casing 上的 drillstring 尺寸的效果穿应该在 casing 被考虑穿预言。
Cite
Citations (2)
In this papcr.3D numerical simulation on the explosive driving to certain column charge within a hollow is a- chieved by using ANSYS/LS-DYNA program,and the change history of fragment velocity is obtained.Otherwise,a test of the explosive driving on this charge is carried out.and its results and simulation ones are accorded very well.
Shaped charge
LS-DYNA
Cite
Citations (1)
Abstract In order to study the performance of reinforced concrete (RC) beams Subjected to continuous explosive load, the numerical model of RC beam is established by LS-DYNA finite element program. And the numerical model experiences two explosive cases continuously. The reliability of the numerical model is verified by comparing with the field test results of a RC beam under the same explosive cases. It provides a reference for the future numerical simulation and experimental research of Building components under continuous explosive load.
Cite
Citations (0)
In this paper,the numerical simulation of the dynamic response inside partially-buried structures is studied out by the LS-DYNA3D program．During the simulation of the explosive loads,there are two meth- ods．One is that equivalent pressure time-histories inside explosive cavity are used to simulate the loads．The other is that using a piece of DYNA3D material specifically designed for simulating high explosive detonation (ALE)．The results indicate that the numerical simulated precision of method and the precision of Lagrangian method is very close．The precision of the ALE method is much higher than the above metioned two methods, but more computing time is required．So the equivalent pressure time-histories inside explosive cavity method is superior in practice．
Dynamic pressure
Dynamic simulation
Cite
Citations (3)
Casing strength under the complex geological conditions is one of the major problems urgently to be solved at home and abroad. Catching the main characteristics and trends of casing collapse under the complex geological conditions, and based on which, carrying out the method study of casing strength analysis under the inhomogeneous load, as well as consideration of the law about how the non-uniformity load and the casing eccentricity influence on casing strength are of great significance. Setting a suit of method and theory about casing strength under the complex geological conditions has certain reference value. This paper affords a new sight for the casing strength design and safety assessment under the complex geological conditions by research on the relevance between the casing strength and the complex geological conditions. Meanwhile, consideration gives the non-uniformity load and the law about how the casing eccentricity influences on the casing strength. The results show that the increasing off-center distance will aggravate the non-uniformity of the loads when the casing skews along the relative off-center direction of 90° and 270°, thus the casing collapse risk goes up evidently.
Eccentricity (behavior)
Cite
Citations (9)