Commits on Nov 03, 2017

Abaqus_uel_continuum_beam.in

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+%
+%             Demonstration input file for simple general purpose FEA code EN234FEA
+%                                    A.F. Bower, August 2017
+%                                               HW10
+%
+%              Input file to test a continuum beam element
+%              The file solves a cantilever beam 10 units long that is clamped at x1=0 and has a point force at x1=10
+%              Element is assumed to be coded as an ABAQUS UEL
+%
+%
+% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% MESH DEFINITION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%
+    MESH
+
+%    The NODE command defines properties of the nodes.  
+%    The parameters are # of coords, # of DOF, and an optional integer identifier
+       NODES
+%    The parameters are # of coords, # of DOF, and an optional integer identifier
+       PARAMETERS, 2, 3, 1
+%      Specify which nodal DOF are displacements.  In the example, DOF 1 is the x displacement, 2 is the y displacement, 3 is the z displacement
+       DISPLACEMENT DOF, 1, 2
+%    Enter x,y,z coords of nodes.   The node number is optional, and is ignored in the code.
+         COORDINATES
+%  Coords 
+      1,           0.,           0.
+      2,           1.,           0.
+      3,           2.,           0.
+      4,           3.,           0.
+      5,           4.,           0.
+      6,           5.,           0.
+      7,           6.,           0.
+      8,           7.,           0.
+      9,           8.,           0.
+     10,           9.,           0.
+     11,          10.,           0.   
+        END COORDINATES
+      END NODES
+%
+%     The ELEMENT command defines properties of elements
+%     The parameters are no. nodes on the element, total no. state variables (4*# integration points), integer identifier
+
+      ELEMENTS, USER
+        PARAMETERS, 2, 3, U1
+%       Define element properties - the values are passed to user subroutine elstif in the order they are listed here
+%       For the example provided, the params are beam thickness h, width w,  Youngs Modulus, Poissons ratio
+        PROPERTIES
+         1.2d0, 1.d0, 100.d0, 0.3d0
+        END PROPERTIES
+%     Define element connectivity
+%     The element number (first number in the list) is optional, and is ignored in the code
+        CONNECTIVITY, zone1
+ 1,  1,  2
+ 2,  2,  3
+ 3,  3,  4
+ 4,  4,  5
+ 5,  5,  6
+ 6,  6,  7
+ 7,  7,  8
+ 8,  8,  9
+ 9,  9,   10
+ 10, 10,  11
+        END CONNECTIVITY
+
+%     The PROPERTIES, PARAMETERS, CONNECTIVITY keywords can be repeated here to define more set of elements with different properties
+
+        END ELEMENTS
+      END MESH
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% BOUNDARY CONDITIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%     The BOUNDARY conditions key starts definition of BCs
+      BOUNDARY CONDITIONS
+
+%       The HISTORY key defines a time history that can be applied to DOFs or distributed loads
+        HISTORY, force_history
+          0.d0, 0.d0                  % Each line gives a time value and then a function value
+         1.d0, 0.01d0
+        END HISTORY
+
+%       The NODESET key defines a list of nodes
+        NODESET, left
+           1
+        END NODESET
+        NODESET, right
+           11
+        END NODESET
+
+
+%      The ELEMENTSET key defines a list of elements
+       ELEMENTSET, end_element
+           1
+       END ELEMENTSET
+
+%       The DEGREE OF FREEDOM key assigns values to nodal DOFs
+%       The syntax is node set name, DOF number, VALUE/HISTORY/SUBROUTINE, value/history name/subroutine parameter list name.
+%     
+        DEGREES OF FREEDOM
+           left, 1, VALUE, 0.d0
+           left, 2, VALUE, 0.d0
+           left, 3, VALUE, 0.d0
+        END DEGREES OF FREEDOM
+
+        FORCES
+          right, 2, HISTORY, force_history
+        END FORCES
+
+
+   END BOUNDARY CONDITIONS
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Mesh printing, error checking %%%%%%%%%%%%%%%%%%%%
+
+%  Print the initial mesh to a file named initial_mesh.dat
+
+%  PRINT INITIAL MESH, Output_files\initial_mesh.dat
+
+%   TIME, VALUE, 0.d0        % Use this to specify the initial time
+%   TIME, INCREMENT, 0.01d0  % Use this to specify a time increment (often needed for check stiffness)
+
+%   The CHECK STIFFNESS key tests the element subroutine to ensure that
+%   the residual force vector is consistent with the stiffness
+       CHECK STIFFNESS, U1
+
+%       STOP
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Analysis %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+   %   The STATIC STEP key initializes a static load step
+
+     STATIC STEP
+
+
+          INITIAL TIME STEP, 1.d0       
+          MAX TIME STEP, 1.d0
+          MIN TIME STEP, 0.001d0
+          MAX NUMBER OF STEPS, 1
+          STOP TIME, 10.d0
+          USER PRINT STEP INTERVAL, 1
+
+
+%        The SOLVER key controls the equation solver and Newton-Raphson iterations
+%        The options are FACTOR for direct solver, CONJUGATE GRADIENT for cg solver
+%        Factor will work on anything but might be slow for large equation systems.   
+%        Conjugate gradient works well for elasticity problems but (with the diagonal preconditioner used here) is not so good for unsymmetric matrices
+%                        LINEAR for linear equations, NONLINEAR for nonlinear equations
+%                        For nonlinear solver, must specify convergence tolerance and max # iterations
+%                        UNSYMMETRIC  (optional - only for unsymmetric stiffness)
+
+
+         SOLVER, DIRECT, NONLINEAR, 1.d-05,15
+
+         USER PRINT FILES
+             Output_files\beam_displacements.dat
+             Output_files\beam_forces.dat
+         END USER PRINT FILES
+         USER PRINT PARAMETERS
+                10 % Specify the HW problem number
+         END USER PRINT PARAMETERS
+
+
+
+
+        END STATIC STEP
+
+
+   STOP