Development of Code, PNFENT, Based on Using Finite Elements for Neutron Transport

2009 ◽  
Author(s):  
Ahmad Zolfaghari ◽  
Hamid Minuchehr ◽  
Mohammadreza Abbasi
Keyword(s):  
Finite Element ◽  
Neutron Transport ◽  
Anisotropic Scattering ◽  
Free Form ◽  
Group Method ◽  
Maximum Principles ◽  
Finite Element Program ◽  
Boltzman Equation ◽  
Variational Treatment ◽  
Element Program

A variational treatment of the finite element method for neutron transport is used based on a version of the even parity Boltzman equation for the general case of anisotropic scattering and sources. The theory of maximum principles is based on the Cauchy-Schwartz inequality and the properties of a leakage operator G and a removal operator C. For system with extraneous sources a maximum principle is used in boundary free form to ease finite element computations. The global error of an approximate variational solution is shown. The energy dependence of the angular flux is treated by the multi-group method. In this paper the spatial dependence of the angular flux is given in a finite element representation. The directional dependence of angular flux is represented preferably by a spherical harmonic expansion. The above method has been developed and implemented in the finite element program PNFENT. A homogenous slab of a pure absorber along edge-cell and a two dimensional problems are solved with an accuracy as good as the best problem techniques.

scholarly journals The impact of drilling and slitting construction on damage field: evolution characteristics in low-permeability coal seam

2021 ◽  
Vol 37 ◽  
pp. 205-215
Author(s):  
Heng Chen ◽  
Hongmei Cheng ◽  
Aibin Xu ◽  
Yi Xue ◽  
Weihong Peng
Keyword(s):  
Finite Element ◽  
Rock Mass ◽  
Damage Mechanics ◽  
Effective Strain ◽  
Secondary Development ◽  
Distribution Area ◽  
Finite Element Program ◽  
Element Program ◽  
Mining Face ◽  
The Impact

ABSTRACT The fracture field of coal and rock mass is the main channel for gas migration and accumulation. Exploring the evolution law of fracture field of coal and rock mass under the condition of drilling and slitting construction has important theoretical significance for guiding efficient gas drainage. The generation and evolution process of coal and rock fissures is also the development and accumulation process of its damage. Therefore, based on damage mechanics and finite element theory, the mathematical model is established. The damage variable of coal mass is defined by effective strain, the elastoplastic damage constitutive equation is established and the secondary development of finite element program is completed by FORTRAN language. Using this program, the numerical simulation of drilling and slitting construction of the 15-14120 mining face of Pingdingshan No. 8 Mine is carried out, and the effects of different single borehole diameters, different kerf widths and different kerf heights on the distribution area of surrounding coal fracture field and the degree of damage are studied quantitatively. These provide a theoretical basis for the reasonable determination of the slitting and drilling arrangement parameters at the engineering site.

Finite Element Analysis on the Deformation of Energy-Saving Wire-Mesh Frame Wallboard

2014 ◽  
Vol 501-504 ◽  
pp. 731-735
Author(s):  
Li Zhang ◽  
Kang Li
Keyword(s):  
Finite Element ◽  
Energy Saving ◽  
Theoretical Basis ◽  
Steel Wire ◽  
Wire Mesh ◽  
Design Parameters ◽  
Element Analysis ◽  
Finite Element Program ◽  
Element Program ◽  
Influence Degree

This paper analyzes the influence degree of related design parameters of wire-mesh frame wallboard on deformation through finite element program, providing theoretical basis for the design and test of steel wire rack energy-saving wallboard.

scholarly journals Numerical Analyses of Earthquake Induced Liquefaction and Deformation Behaviour of an Upstream Tailings Dam

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Muhammad Auchar Zardari ◽  
Hans Mattsson ◽  
Sven Knutsson ◽  
Muhammad Shehzad Khalid ◽  
Maria V. S. Ask ◽  
...  
Keyword(s):  
Finite Element ◽  
Seismic Event ◽  
Deformation Behaviour ◽  
Ground Surface ◽  
Tailings Dam ◽  
Limited Extent ◽  
Northern Sweden ◽  
Finite Element Program ◽  
Dynamic Analyses ◽  
Element Program

Much of the seismic activity of northern Sweden consists of micro-earthquakes occurring near postglacial faults. However, larger magnitude earthquakes do occur in Sweden, and earthquake statistics indicate that a magnitude 5 event is likely to occur once every century. This paper presents dynamic analyses of the effects of larger earthquakes on an upstream tailings dam at the Aitik copper mine in northern Sweden. The analyses were performed to evaluate the potential for liquefaction and to assess stability of the dam under two specific earthquakes: a commonly occurring magnitude 3.6 event and a more extreme earthquake of magnitude 5.8. The dynamic analyses were carried out with the finite element program PLAXIS using a recently implemented constitutive model called UBCSAND. The results indicate that the magnitude 5.8 earthquake would likely induce liquefaction in a limited zone located below the ground surface near the embankment dikes. It is interpreted that stability of the dam may not be affected due to the limited extent of the liquefied zone. Both types of earthquakes are predicted to induce tolerable magnitudes of displacements. The results of the postseismic slope stability analysis, performed for a state after a seismic event, suggest that the dam is stable during both the earthquakes.

A preprocessor for the finite element program SAP IV

1981 ◽  
Vol 17 (12) ◽  
pp. 1779-1789
Author(s):  
E. Haugeneder ◽  
W. Prochazka ◽  
P. Tavolato
Keyword(s):  
Finite Element ◽  
Finite Element Program ◽  
Element Program

Abstract 2871: Saddle-Shaped Annuloplasty Reduces Mitral Leaflet Stress: A Real-Time 3D Echocardiographic Study

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Aaron S Blom ◽  
Chun Xu ◽  
Liam P Ryan ◽  
Benjamin Jackson ◽  
Landi M Parish ◽  
...  
Keyword(s):  
Finite Element ◽  
Real Time ◽  
Stress Reduction ◽  
Heart Association ◽  
Posterior Leaflet ◽  
Volume Data ◽  
Medical Systems ◽  
Annuloplasty Ring ◽  
Finite Element Program ◽  
Element Program

Objectives: High leaflet and chordal stresses contribute to recurrent mitral regurgitation after repair procedures. We hypothesized that a saddle-shaped annuloplasty ring would reduce leaflet stress compared to a similarly sized flat annuloplasty ring. To test this hypothesis we used a novel 3D echocardiographically-based finite element modeling (FEM) technique for quantifying regional mitral valve stress. Methods: Real-time 3D echocardiography was performed in 8 sheep before and after placement of either a 30mm flat annuloplasty (n=4) or a 30mm saddle-shaped annuloplasty. Full-volume data sets of the MV were obtained using an IE33 platform(Philips Medical Systems, Andover, Massachusetts) and exported to Cardio-View (Tomtec Imaging Systems, Munich, Germany) for image analysis. Individual leaflet data were then interpolated using Matlab (The Mathworks, Natick, Massachusetts). Triangulated leaflet surfaces were extracted and the data imported into a commercial finite element program (ABAQUS/Explicit 6.3, HKS Inc. Pawtucket, RI) to quantify regional stress distributions in all segments (P1, P2, P3 and A1, A2, A3) of the MV. Results: Peak anterior and posterior leaflet stresses after flat annuloplasty placement were 0.20±0.001MPa and 21±0.02MPa. Peak anterior and posterior leaflet stress after saddle-shaped annuloplasty placement was 0.19±0.02MPa and 13±0.01MPa (p<0.05 for the posterior leaflet stresses) Conclusions: Saddle-shaped annuloplasty design results in greater stress reduction in the posterior leaflet than standard flat annuloplasty rings and may, therefore, result in more durable repairs. This research has received full or partial funding support from the American Heart Association, AHA Great Rivers Affiliate (Delaware, Kentucky, Ohio, Pennsylvania & West Virginia).

Study on Crashworthiness Characteristics of Several Concentric Thin Wall Tubes

2010 ◽  
Author(s):  
Parisa Hosseini Tehrani ◽  
Sajad Pirmohammad
Keyword(s):  
Finite Element ◽  
Optimum Combination ◽  
Thick Wall ◽  
Thin Wall ◽  
Finite Element Program ◽  
Linear Dynamic ◽  
Wall Structures ◽  
Moving Body ◽  
Oblique Loading ◽  
Element Program

There is a growing interest in the use of thin-wall structures as a means of absorbing the kinetic energy of a moving body. Multi-layered thin-wall structures are more efficient and lighter than thick-wall structures, and show better crashworthiness characteristics. In this task, several concentric aluminum thin wall tubes as energy absorber under axial and oblique loading are studied and optimum combination of these tubes is presented. The weight of the tubes is optimized while crashworthiness of tubes is not compromised. The commercial finite element program LS-DYNA that offers non-linear dynamic simulation capabilities was used in this study.

scholarly journals Numerical Derivation of Iso-Damaged Curve for a Reinforced Concrete Beam Subjected to Blast Loading

2018 ◽  
Vol 149 ◽  
pp. 02016 ◽  
Author(s):  
Yehya Temsah ◽  
Ali Jahami ◽  
Jamal Khatib ◽  
M Sonebi
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Shock Waves ◽  
Concrete Beam ◽  
Blast Loading ◽  
Reinforced Concrete Beam ◽  
Structural Elements ◽  
Finite Element Program ◽  
Element Program ◽  
Structural Engineers

Many engineering facilities are severely damaged by blast loading. Therefore, many manufacturers of sensitive, breakable, and deformed structures (such as facades of glass buildings) carry out studies and set standards for these installations to withstand shock waves caused by explosions. Structural engineers also use these standards in their designs for various structural elements by following the ISO Damage Carve, which links pressure and Impulse. As all the points below this curve means that the structure is safe and will not exceed the degree of damage based on the various assumptions made. This research aims to derive the Iso-Damage curve of a reinforced concrete beam exposed to blast wave. An advanced volumetric finite element program (ABAQUS) will be used to perform the derivation.

Sign in / Sign up

Export Citation Format

Share Document