Anm (Analysis Model) Class
This is an abstract super-class in the Object Oriented Programming (OOP) paradigm that generically specifies an analysis model in the LESM (Linear Elements Structure Model) program.
This super-class is abstract because one cannot instantiate objects from it, since it contains abstract methods that should be implemented in (derived) sub-classes.
Essentially, this super-class declares abstract methods that define the generic behavior of an analysis model in the LESM (Linear Elements Structure Model) program. These abstract methods are the functions that should be implemented in a (derived) sub-class that deals with specific types of analysis, such as a 2D truss, 2D frame, grillage, 3D truss or a 3D frame model.
An object of the Anm class "projects" the generic 3D behavior of linear element objects of the Elem class and node objects of the Node class to a specific model behavior. The implementations of an abstract method in each sub-class differ in the use of the degrees of freedom of each analysis model. Only one analysis model object is created during the analysis process.
Contents
Sub-classes
To handle different types of analysis models, there are five sub-classes derived from this super-class:
Class definition
Definition of super-class Anm as a handle class.
classdef Anm < handle
Public attributes
properties (SetAccess = public, GetAccess = public)
analysis_type = 0; % flag for type of analysis model
ndof = 0; % number of degrees-of-freedom per node
end
Constructor method
methods %------------------------------------------------------------------ function anm = Anm(type,ndof) anm.analysis_type = type; anm.ndof = ndof; end end
Abstract methods
Declaration of abstract methods implemented in derived sub-classes.
methods (Abstract) %------------------------------------------------------------------ % Assembles element d.o.f. (degree of freedom) rotation transformation % matrix from global system to local system. % Output: % rot: rotation transformation matrix % Input arguments: % elem: handle to an object of the Elem class rot = gblToLocElemRotMtx(~,elem) %------------------------------------------------------------------ % Initializes global d.o.f (degree of freedom) numbering ID matrix % with ones and zeros, and counts total number of equations of free % d.o.f.'s and total number of equations of fixed d.o.f.'s. % ID matrix initialization: % if ID(k,n) = 0, d.o.f. k of node n is free. % if ID(k,n) = 1, d.o.f. k of node n is constrained by support. % Input arguments: % drv: handle to an object of the Drv class setupDOFNum(anm,drv) %------------------------------------------------------------------ % Adds prescribed displacements (known support settlement values) % to global displacement vector. % Avoids storing a prescribed displacement component in a position % of the global displacement vector that corresponds to a free d.o.f. % Input arguments: % drv: handle to an object of the Drv class setupPrescDispl(~,drv) %------------------------------------------------------------------ % Assembles element stiffness matrix in local system. % Output: % kel: target element stiffness matrix in local system % Input arguments: % elem: handle to an object of the Elem class kel = elemLocStiffMtx(~,elem) %------------------------------------------------------------------ % Adds nodal load components to global forcing vector, % including the terms that correspond to constrained d.o.f. % Input arguments: % drv: handle to an object of the Drv class nodalLoads(~,drv) %------------------------------------------------------------------ % Assembles element fixed end force (FEF) vector in local system % for an applied distributed load. % Output: % fel: element fixed end force vector in local system % Input arguments: % load: handle to an object of the Lelem class fel = elemLocDistribLoadFEF(~,load) %------------------------------------------------------------------ % Assembles element fixed end force (FEF) vector in local system % for an applied thermal load (temperature variation). % Output: % fel: element fixed end force vector in local system % Input arguments: % load: handle to an object of the Lelem class fel = elemLocThermalLoadFEF(~,load) %------------------------------------------------------------------ % Initializes element internal forces arrays with null values. % Input arguments: % elem: handle to an object of the Elem class initIntForce(~,elem) %------------------------------------------------------------------ % Assembles contribution of a given internal force vector to % element arrays of internal forces. % Input arguments: % elem: handle to an object of the Elem class % fel: element internal force vector in local system assembleIntForce(~,elem,fel) %------------------------------------------------------------------ % Initializes element internal displacements array with null values. % Each element is discretized in 50 cross-sections, where internal % displacements are computed. % Input arguments: % elem: handle to an object of the Elem class initIntDispl(~,elem) %------------------------------------------------------------------ % Assembles displacement shape functions matrix evaluated at a % given cross-section position. % Output: % N: displacement shape function matrix % Input arguments: % elem: handle to an object of the Elem class % x: cross-section position N = displShapeFcnMtx(~,elem,x) %------------------------------------------------------------------ % Computes element internal displacements vector in local system, % in a given cross-section position, for the local analysis from % element loads (distributed loads and thermal loads). % Output: % del: element internal displacements vector in a given % cross-section position % Input arguments: % elem: handle to an object of the Elem class % x: cross-section position on element local x-axis del = lclAnlIntDispl(anm,elem,x) end
Public methods
methods %------------------------------------------------------------------ % Cleans data structure of an Anm object. function clean(anm) anm.analysis_type = 0; anm.ndof = 0; end end
end