Mulsim/Nl Theoretical and Programmer's Manual

By Zipf, R. Karl, Jr.

Book Id: WPLBN0000192091
Format Type: PDF eBook:
File Size: 3.64 MB
Reproduction Date: 2005

Title:	Mulsim/Nl Theoretical and Programmer's Manual
Author:	Zipf, R. Karl, Jr.
Volume:
Language:	English
Subject:	Health., Medical research, Medical reports
Collections:	Medical Library Collection
Historic Publication Date:
Publisher:	Centers for Disease Control and Prevention


Citation APA MLA Chicago Karl Zipf, Jr, B. R. (n.d.). Mulsim/Nl Theoretical and Programmer's Manual. Retrieved from http://gutenberg.cc/

Excerpt
ABSTRACT: MULSIM/NL (multiple scams, nonlinear) is a three-dimensional boundary-element method (BEM) program developed at the U.S. Bureau of Mines for stress and displacement analysis of coal mines and thin metalliferous veins. It can analyze one to four parallel seams that can have any orientation with respect to the Earth's surface. Three main new features distinguish MULSIM/NL from its predccessors: (1) nonlinear material models, (2) multiple mining steps, and (3) energy release and strain energy computations. MULSIM/NL has six material models for the in-seam material: (1) linear elastic for coal, (2) strain softening, (3) elastic plastic, (4) bilinear hardcning, (5) strain hardening, and (6) linear elastic for gob. Detailed checks show that numerical stress and displacement calculations compare well to known analytic solutions for simple problems. The total energy release calculated by MULSIM/NL is comprised of three basic terms: (1) strain energy release from the mined-out material, (2) linear kinetic energyrelease due to change in gravitational potential over the mined-out area, and (3) nonlinear kinetic energy release due to nonlinear materials in the total backfill and gob area. The strain energy release term is modified to account for nonlinear stress-strain behavior in the unmined materials. Comparisons of these numerical energy release rate calculations with known analytic solutions show excellent agreement.

Table of Contents
CONTENTS Abstract. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Purpose and objective. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 MULSIM/NL enhancements 2 Scope 3 Origins and previous versions of MULSIM/NL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Historical review 3 Sinha's MULSIM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 MULSIM/BM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Itasca additions 5 Nonlinear material properties in MULSIM/NL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 General mechanics of boundary-clement method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Basic equations of boundary-element method 8 Application of boundary conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Some notes on BEM boundary conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Six material models for MULSIM/NL 10 Linear clastic for coal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Linear elastic for gob . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Strain-softening for coal . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Elastic-plastic for coal 11 Bilinear hardening for gob 11 Strain-hardening for gob. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Total-stress formulation for MULSIM/NL 12 Induced-stress boundary conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Total-stress boundary conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Illustration of convergence schemes 15 FORTRAN implementation of material nonlinearities .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Equation-solver logic 16 Material property subroutine structure 17 Nonlinear energy calculations in MULSIM/NL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Evolution of energy release rate concepts 18 Recent energy release rate concepts 19 Programming energy release calculations in MULSIM/NL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Intermediate stress-displacement files 22 Local energy calculations 22 Global energy calculations 23 Three special cases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Subroutine energy logic diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 MULSIM/NL program checks and behavior 26 Some simple analytic solutions 26 Rigid boundary effects 26 Element size effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Nonlinear effects 31 Subroutine ENERGY checks and behavior 31 Analytic checks on energy release caleulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .