OPTUMCompute
1 Getting started
When OPTUM Compute has been installed, open the application and login using your email and password. You will then be greeted by a minimalistic console, geometry window, and visualization window.
Direct interaction with the application is very limited, and all commands for modelling, analyzing, and viewing results are issued using Python. OPTUM Compute comes with a Python API (OptumCompute.py
) and several examples. If the default directory was chosen for the installation, the Python scripts can be found here:
C:\Program Files\OPTUM CE\OPTUM C 2020\Python
In the current directory, the files are readonly. In order to edit them, copy the code to a new Python script (.py
) in a new folder. To run the appended examples:
 Open them up in a Python environment (Spyder, PyCharm, Visual Studio Code or similar)
 Run OPTUM Compute
 Press
Run
in the Python environment
1.1 OptumCompute.py
The OPTUM Compute Python API should be imported to the Python script:
import OptumCompute as oc
With this, all the different functions and methods for building a model, running calculations, and viewing results are available within the script.
The file contains all the methods available for OPTUM Compute. The input to most of the methods is shown in the file as well, with the exception of the materials, where the material parameters are
defined by calling the appropriate names. For example, the method for creating an Nprism as seen in OptumCompute.py
:
The method has a total of 4 inputs, and the 4th input is a location, which can be specified using oc.axis
as follows:
which creates vertical 16sided nprism with a height of 59.5 metres and a radius of 3.9 metres with the base center located at (0, 0, 20.5 m).
2 Working with OPTUM Compute
Before building a model, specifying materials, etc. a Python script has to be created and the OPTUM Compute Python API imported as shown above. The workflow in OPTUM Compute then follows a few general steps as outlined below:
 Creating a material A material is created by specifying the material type and parameters as shown in Section 5. OPTUM Compute comes with two basic categories of materials, Solids and Shells. These are listed in Sections 6 and 7. A Shear Joint material can also be specified for interfaces.
 Create stages, analysis type and meshing The
oc.setStageProperties
method specifies the stage name, analysis type, number of elements and the element type to be used in the analysis. Mesh options can also be specified within the method as shown in Section 11.1. Similarly, theoc.newStage
command is used to create a new stage. It also allow for specifying from which previous stage the analysis should be carried out from. Section 11 outlines the methods for creating stages.  Creating a geometry For 3D volumes, the geometry of a material can be specified via the
oc.makeBox
oroc.makeNprism
methods. More complex shapes can be created with theoc.makeFace
,oc.makeWire
andoc.extrude
commands. For 2D faces, theoc.makeRect
methods can be used to specify a planar geometry. Geometries can be edited or deleted with theoc.removeInterior
,oc.partition
andoc.DeleteShape
commands.  Assigning a geometry to a material A geometry is assigned a material via the
oc.assignSolid
method for Solids,oc.assignShell
for Shells andoc.assignShearJoint
for Shear Joints.  Specify boundary conditions A face or a boundary on a geometry is assigned supports with the
oc.assignSupport
method. Other methods are also available to directly specify full, normal or tangential supports.  Assign loads The
oc.assignLoad
method is used to assign a loading vector to a selected face of a geometry. The loading can be nonfixed for limit analysis and multiplier elastoplastic (MEP) problems or fixed for a standard singlestep elastoplastic (EP) analysis.  Running the analysis and viewing results After completing the above steps, the analysis is run and the results stored in a list by e.g. writing
results = oc.runAnalysis
. The analysis progress can be monitored in the Console window of OPTUM Compute. When the analysis is completed the results can be accessed in theresults
list as shown in Section 13. Section 12 specifies which plotting options are available via theos.plot
function for visualization.
2.1 Functions Overview
An overview of the available methods and functions in OPTUM Compute is given below.
Function  Description 

oc.assignFullSupport

Assign full supports to the given shapes 
oc.assignLoad

Assign the given load to the given shapes 
oc.assignNormalSupport

Assign normal supports to the given shapes 
oc.assignShearJoint

Assign the given shear joint material to the given shapes 
oc.assignShell

Assign the given shell material to the given (surface) shapes 
oc.assignSolid

Assign a solid material to a geometry in the current stage 
oc.assignSupport

Assign the given support to the given shapes 
oc.assignTangentialSupport

Assign tangential supports to the given shapes 
oc.axis

Axis with given point, normal vector (local Z) and primary vector (local X) 
oc.boundBox

Bounding box to test against 
oc.camera

Camera settings 
oc.clear

Clear everything the current project 
oc.currentStage

Access current stage information 
oc.deleteShape

Delete a signel selected object in the current stage 
oc.deleteShapes

Delete multipile selected objects in the current stage 
oc.extractEdges

List all edge shapes in current stage 
oc.extractFaces

List all surface shapes in current stage 
oc.extractVertices

List all vertex shapes in current stage 
oc.extrude

Extrude the given 2D shape to a 3D geometry 
oc.linear

Specify a linearly varying field 
oc.loads

List of all defined load attributes in current stage 
oc.makeBox

Bounding box to test against 
oc.makeFace

Create a 2D face in the current stage 
oc.makeMaterial

Create a new material in the current stage 
oc.makeNprism

Create a Nprism in the current stage 
oc.makeRect

Create a 2D rectangle in the current stage 
oc.makeVertex

Create a vertex point in the current stage 
oc.makeWire

Create a wire object in the current stage 
oc.material

Write out the material with the given id 
oc.materials

Write out all materials 
oc.newStage

Create a new stage 
oc.partition

Parition the selected geometries 
oc.plane

Plane containing global point (x, y, z) with normal vector (nx, ny, nz) 
oc.plot

Plot a specific result of the analysis 
oc.profile

Specify a piecewise linearly varying field 
oc.project

Access current project information 
oc.removeInterior

Remove the interior of the selected object 
oc.runAnalysis

Run the analysis using the stage parameters 
oc.select

Select objects within the specified domain 
oc.selectAll

Select all objects in the current stage 
oc.setCamera

Set the projection of the camera in the current stage 
oc.setStageProperties

Set the current stage properties 
oc.shapes

List all shapes in current stage 
oc.shearJoints

List of all defined solid attributes in current stage 
oc.shells

List of all defined shell attributes in current stage 
oc.solids

List of all defined solid attributes in current stage 
oc.stages

Access all stages information 
oc.supports

List of all defined support attributes in current stage 
oc.vector

Vector in global coordinates 
3 Coordinate system
OPTUM Compute uses a standard Cartesian coordinate system. The directions of the global coordinate system are shown upon startup in the lower left corner of the Geometry window. This along with the naming conventions used for the global and local coordinate systems is shown below.
3.1 Local axis
The oc.axis
method specifies the location and orientation of a local coordinate system relative to the global origo:
oc.axis(P, normal, primary)
P

Point of local csys origo, , relative to the global csys, default is or global origo 
normal

Normal vector, N, of the local csys, default is N = , i.e. local normal is in the direction of global coordinate 
primary

Primary vector, V, specifying the direction of the local csys, default is V, i.e. local direction is in the global direction 
A local coordinate system with origo at , a normal in the direction of global and V pointing along global is defined as:
at = oc.axis(P=[1, 1, 15], normal=[0, 1, 0], primary=[0, 0, 1])
The above method is for example used to specify a reference point for geometries.
3.2 Defining a plane
The oc.plane
method defines a local plane containing the global point with a normal vector :
oc.plane(P=[0,0,0], normal = [0,0,1])
P

Point of local csys origo, , relative to the global csys, default is or global origo 
normal

Normal vector, N, of the local csys, default is N = , i.e. local normal is in the direction of global coordinate 
Similar as to the oc.axis
method, a local plane with origo at and a normal in the direction of global can be specified as:
oc.plane(P=[1, 1, 15], normal = [0, 1, 0])
3.3 Defining a vector
The oc.vector
method defines a vector in the global coordinate system:
oc.vector(x, y, z)
x

magnitude of vector in global direction, default is 0 
y

magnitude of vector in global direction, default is 0 
z

magnitude of vector in global direction, default is 0 
Defining a vector is required as an input to methods that e.g. specify the magnitude and direction of loading or extrusion of a 2D surface into a 3D volume.
4 Analysis Types
OPTUM Compute comes with four types of analyses: Limit Analysis, Initial Stress, Elastoplastic and Multiplier Elastoplastic analysis. Additionally, a Mesh analysis type is also available. In this section an overview of the different analysis types is given. A complete list of the available options for the different analysis types is found in a section on Stage Options.
4.1 Mesh
This analysis type is atypical in that it involves no physics but only generates a mesh for the current stage. Mesh analysis can be specified through the oc.setStageProperties
method by specifying "analysisType": oc.AnalysisType.Mesh
as given in a section on Stage Options:
oc.setStageProperties({ "name": "Mesh", "analysisType": oc.AnalysisType.Mesh, "meshTargetCount": 1000, "elementFamily": 'mixed' })
The desired number of elements is here set to 1000 and a mixed element is used in the discretization.
Note: all analyses involve the automatic generation of a mesh. As such the Mesh analysis type is meant only to gauge the eventual mesh that would be used in an analysis with the same mesh settings.
4.2 Limit Analysis
The most basic analysis type in OPTUM Compute is Limit Analysis. This allows for the robust assessment of the stability or bearing capacity of geostructures without having to perform an exhaustive stepbystep elastoplastic analysis.
Both Fixed and Multiplier loads are applicable. In Limit Analysis, the former are kept constant while the latter are amplified until a state of incipient collapse is attained. The factor by which the multiplier loads need to be amplified in order to cause collapse is also referred to as the collapse multiplier.
The solution to a given Limit Analysis problem can be bracketed by using lower bound, upper bound and mixed elements. Using the lower bound element in Limit Analysis gives a solution which fulfills equilibrium and the yield conditions. To identify the upper bound a material specific flow rule and stressstrain relation is used. The mixed element type then implements a combination of the two.
A Limit Analysis stage can e.g. be specified as:
oc.setStageProperties({ "name": "LA", "analysisType": oc.AnalysisType.LimitAnalysis, "meshTargetCount": 5000, "adaptIterations": 3, "meshStartCount": 1000, "elementFamily": 'mixed' })
where a mixed upper and lower bound solution is specified via the "elementFamily": 'mixed'
and three mesh adaptation iterations are used.
Before running a Limit Analysis stage with the oc.runAnalysis()
method, a multiplier loading must be specified:
oc.assignLoad(shape, oc.vector(0,0,1), isFixed=False)
where the isFixed=False
input denotes a multiplier loading. The Limit Analysis will then give as an output a collapse multiplier on the 1 kN loading in the direction corresponding to a mixed upper and lower bound solution. Furthermore, a failure mechanism can be identified from the analysis. It should be noted that fixed loads and gravity are also included in the Limit Analysis but are not assigned a multiplier, i.e. they are held constant.
4.3 Initial Stress
The initial stresses in the ground are in many cases an important aspect of strength and deformation analysis. In problems involving complex geometries and/or constitutive models, a complete description of the initial stress state may be unavailable by simple methods.
The Initial Stress analysis ( analysis) in OPTUM Compute determines a stress field which satisfies the equilibrium and boundary conditions specified while also complying with the yield conditions of the materials and the earth pressure condition.
It is recommended to perform a Initial Stress analysis in an initial stage before proceeding to do an elastoplastic analysis. Initial stress analysis can be specified as:
oc.setStageProperties({ "name": "InitialStress", "analysisType": oc.AnalysisType.InitialStress, "meshTargetCount": 1000, "elementFamily": "mixed" })
Note: Usually, the number of elements is not particularly critical and the computed stress fields will rarely improve significantly by increasing the number of elements above 1000. The mixed element type is recommended for this type of analysis.
4.4 Elastoplastic
A singlestep Elastoplastic analysis entails that the failure criteria for all solid and structural elements are included in the analysis. Only fixed loads are processed while multiplier loads are ignored. Gravity is automatically included.
Elastoplastic is the appropriate analysis for both the situation where the deformations in response to a load of a given magnitude are to be computed and in the case where the analysis involves several linked stages in a staged construction scenario (e.g. excavation, embankment construction, etc). For example, after performing a analysis a new stage can be conducted as an elastoplastic analysis:
oc.newStage({ "name": "EP", "analysisType": oc.AnalysisType.ElastoPlastic, "meshTargetCount": 1000, "fromStage": "K0", "elementFamily": 'mixed' })
where "fromStage": "K0"
specifies that the analysis should continue from an initial stress analysis stage named "K0"
.
In Elastoplastic analysis the mixed element is usually an appropriate choice. However, the elements Lower and Upper may also be used to compute a response that underestimates (Lower) or overestimates (Upper) the true strength as well as stiffness.
4.5 Multiplier Elastoplastic
Multiplier Elastoplastic (MEP) analysis may be seen as combining the Limit Analysis and Elastoplastic analysis types. As in Limit Analysis, the Multiplier loads are amplified until collapse while Fixed loads and gravity are kept constant. This is done in a stepbystep elastoplastic manner with deformations computed at each load step.
Multiplier Elastoplastic analysis is for example useful in determining a LoadDisplacement curve as shown in an example in [sec:MonopileTrescaMEP]. Before running a Multiplier Elastoplastic analysis stage with, a multiplier loading must be specified similarly as for Limit Analysis. An example of specifying a MEP stage starting from an Initial Stress analysis is given below:
oc.newStage({ "name": "MEP", "analysisType": oc.AnalysisType.MultiplierEP, "meshStartCount": 1500, "steps": 6, "w": 20, "adaptSteps" : [[0, 1, 1500], [1, 1, 1750], [2, 1, 2000], [3, 1, 2500], [4, 1, 3000], [5, 1, 5000]], "fromStage": "K0" })
In the above "analysisType": oc.AnalysisType.MultiplierEP
specifies that the analysis should be conducted as MEP type. The "meshStartCount": 1500
input sets the starting number of elements in the mesh to 1500. Unique to the MEP analysis is the number of load steps to be run, "steps": 6
, and the prescribed work for each step, "w": 20
, here set at 6 and 20 kJ respectively. Using "fromStage": "K0"
ensures that the analysis is to continue from an Initial Stress stage which has been run beforehand. For the MEP analysis, it is possible to select precisely which steps should be used for mesh adaptivity using the option adaptSteps
, which is an array of lists containing step number, number of adaptations, and the target number of elements.
5 Creating a material
A new material is added using the following command:
oc.makeMaterial({...})
All materials are created with the same command, and the type of material is specified in the input.
5.1 Linearly varying material parameters
Linearly varying fields can be defined using the linear
method, e.g.:
oc.linear(48, z=6.4, zref=40.0)
which defines a field which takes the value of 48 at and decrease with the coordinate, e.g. at the field will evaluate to 304. This field can be assigned to a material parameter, e.g. as the shear strength of a Tresca material for limit analysis:
soil = oc.makeMaterial({ 'type': 'Tresca', 'specificWeight': 20.5, 'su': oc.linear(48, z=6.4, zref=40), 'color': '#ff0000' })
where 'color': '#ff0000'
defined the color of the Tresca material in HEX format, i.e. the chosen color corresponds to bright red in this case.
The linear
method can vary in all three directions. The full list of input can be seen below:
constant

Value at reference point 
x

Gradient in the direction 
y

Gradient in the direction 
z

Gradient in the direction 
xref

Reference coordinate 
yref

Reference coordinate 
zref

Reference coordinate 
5.2 Material parameter profile
Piecewise linearly varying fields can be defined using the profile
method which takes two lists as input, e.g.:
oc.profile([5, 15, 40, 50], [1.5, 1.0, 1.0, 0.5])
which defines a field that takes the value of 1.5 at , decrease linearly to 1.0 at , stays constant between and , and decrease to 0.5 at . For coordinates lower than 5 or higher than 50, the nearest value will be used, i.e. 1.5 for and 0.5 for . Defining a profile with a single point is equivalent to a constant field.
The profile can be assigned to material parameters, e.g. the cohesion of a MohrCoulomb material or as for an AUS material:
soil = oc.makeMaterial({ 'type': 'AUS', 'specificWeight': 18, 'suc': 30, 'sue': 18, 'K0': oc.profile([5, 15, 40, 50], [1.5, 1.0, 1.0, 0.5]), 'color': '#100010' })
The full list of input can be seen below:
z

coordinates 
values

Values at each coordinate 
Both z
and values
are lists, i.e. defined using square brackets as seen above. The number of coordinates and values must be identical otherwise an error message will be shown.
5.2.1 Solids
5.2.1.1 Rigid solid
In order to define a rigid material, the type must be defined as “RigidSolid”:
oc.makeMaterial({'type': 'RigidSolid', ...})
The only parameter that can be defined for a rigid material is the unit weight:
specificWeight
Unit weight [kN/m³, default = 0 kN/m³]
5.2.1.2 MohrCoulomb
Currently, only MohrCoulomb materials with associated flow rule are available. In order to define a MohrCoulomb material, the type must be defined as “MohrCoulomb”:
oc.makeMaterial({'type': 'MohrCoulomb', ...})
Strength related parameters (for Limit Analysis):
specificWeight

Unit weight [kN/m³, default = 18 kN/m³] 
c

Cohesion [kPa, default = 5 kPa] 
phi

Friction angle [°, default = 25°] 
Stiffness related parameters (for Elastoplastic Analysis):
E

Young’s modulus [MPa, default = 30 MPa] 
nu

Poisson’s ratio [, default = 0.25] 
K0

K0 for initial stress analysis [, default = 0.5] 
Optional parameters:
ft

Tension cutoff [kPa] (included only if “ft” is defined) Default is no tension cutoff. 
5.2.1.3 DruckerPrager
In order to define a DruckerPrager material, the type must be defined as “DruckerPrager”:
oc.makeMaterial({'type': 'DruckerPrager', ...})
Strength related parameters (for Limit Analysis):
specificWeight

Unit weight [kN/m³, default = 18 kN/m³] 
k

Cohesion [kPa, default = 5 kPa] 
M

Friction coefficient [, default = 0.7] 
Stiffness related parameters (for Elastoplastic Analysis):
E

Young’s modulus [MPa, default = 30 MPa] 
nu

Poisson’s ratio [, default = 0.25] 
K0

K0 for initial stress analysis [, default = 0.5] 
5.2.1.4 Tresca
In order to define a Tresca material, the type must be defined as “Tresca”:
oc.makeMaterial({'type': 'Tresca', ...})
Strength related parameters (for Limit Analysis):
specificWeight

Unit weight [kN/m³, default = 18 kN/m³] 
su

Shear strength [kPa, default = 30 kPa] 
Stiffness related parameters (for Elastoplastic Analysis):
E

Young’s modulus [MPa, default = 30 MPa] 
nu

Poisson’s ratio [, default = 0.25] 
K0

K0 for initial stress analysis [, default = 0.5] 
Optional parameters:
ft

Tension cutoff [kPa] (included only if “ft” is defined) Default is no tension cutoff. 
5.2.1.5 AUS
In order to define a AUS material, the type must be defined as “AUS”:
oc.makeMaterial({'type': 'AUS', ...})
Strength related parameters (for Limit Analysis):
specificWeight

Unit weight [kN/m³, default = 18 kN/m³] 
suc

Undrained shear strength in triaxial compression [kPa, default = 30 kPa] 
sue

Undrained shear strength in triaxial extension [kPa, default = 18 kPa] 
Stiffness and hardening related parameters (for Elastoplastic Analysis):
Eur

Initial undrained Young’s modulus [MPa, default = 30 MPa] 
epsilonC50

Axial plastic strains halfway to failure in triaxial compression [, default = 0.005] 
epsilonE50

Axial plastic strains halfway to failure in triaxial extension [, default = 0.020] 
alpha

Fitting parameter for small strain stiffness, typically [, default = 0.6] 
K0

K0 for initial stress analysis [, default = 0.5] 
Optional parameters:
resetParameter

Defines the degree of small strain stiffness reset: Value between 0 and 1 where 
1: Full stiffness used. Independent of initial stress state  
0: Stiffness reduced accordingly. Dependent on the intial stress state  
A value of 1 is used per default if resetParameter is not given.
 
ft

Tension cutoff [kPa] (included only if “ft” is defined) Default is no tension cutoff. 
5.2.1.6 Hardening MohrCoulomb (HMC)
The Hardening MohrCoulomb material includes small strain stiffness and a nonassociated flow rule. For elastoplastic analysis, several parameters must therefore be defined.
In order to define a Hardening MohrCoulomb material, the type must be defined as “HMC”:
oc.makeMaterial({'type': 'HMC', ...})
Strength related parameters (for Limit Analysis):
specificWeight

Unit weight [kN/m³, default = 18 kN/m³] 
c

Cohesion [kPa, default = 0 kPa] 
phi

Friction angle [°>, default = 35°] 
Stiffness and hardening related parameters (for Elastoplastic Analysis):
E0ref

Initial stiffness at reference pressure [MPa, default = 200 MPa] 
E50ref

Stiffness halfway to failure at reference pressure [MPa, default = 34 MPa] 
nu

Poisson’s ratio [, default = 0.25] 
dilationRule

Either “Taylor” or “Constant”. Use the provided class for setting the flow rule (Default is “Taylor”): 
'dilationRule': oc.HMCdilationRule.Taylor
 
'dilationRule': oc.HMCdilationRule.Constant
 
psi

Dilation angle [°, default = 5°] 
epsilonvcr

Volumetric dilation cap [, default = 0.01] 
pressureDependency

Defines how and depend on the pressure. Use the provided class for setting the pressure dependency (Default is "MinorPrincipal"): 
'pressureDepedency': oc.HMCpressureDependency.MinorPrincipal
 
'pressureDepedency': oc.HMCpressureDependency.MeanStress
 
'pressureDepedency': oc.HMCpressureDependency.Triaxial
 
referencePressure

Reference pressure for elastic moduli [kPa, default = 100 kPa] 
m

Exponent for the pressure dependency, [, default = 0.5] 
alpha

Fitting parameter for small strain stiffness, typically [, default = 0.6] 
K0

K0 for initial stress analysis [, default = 0.5] 
Optional parameters:
resetParameter

Defines the degree of small strain stiffness reset: Value between 0 and 1 where 
1: Full stiffness used. Independent of initial stress state  
0: Stiffness reduced accordingly. Dependent on the initial stress state  
A value of 1 is used per default if resetParameter is not given.
 
ft

Tension cutoff [kPa] (included only if “ft” is defined) Default is no tension cutoff. 
5.3 Shells
Shell materials are defined using the same basic makeMaterial
command as for Solids.
5.3.1 Rigid shell
In order to define a rigid shell material, the type must be defined as “RigidShell”:
oc.makeMaterial({'type': 'RigidShell', ...})
The only parameters that can be defined for a rigid shell material are the thickness and density:
thickness

Thickness of shell [m, default = 0.1 m] 
specificWeight

Unit weight [kN/m³, default = 0 kN/m³] 
5.3.2 Von Mises shell
In order to define a Von Mises shell material, the type must be defined as “VonMisesShell”:
oc.makeMaterial({'type': 'VonMisesShell', ...})
Strength related parameters (for Limit Analysis):
thickness

Thickness of shell [m, default = 0.1 m] 
specificWeight

Unit weight [kN/m³, default = 0 kN/m³] 
fy

Yield strength [MPa, default = 300 MPa] 
mp

Yield moment [kNm/m, default = 100 kNm/m] 
Stiffness related parameters (for Elastoplastic Analysis):
E

Young’s modulus [MPa, default = 210,000 MPa] 
nu

Poisson’s ratio [, default = 0.3] 
6 Creating a geometry
Three basic types of shapes are available in OPTUM Compute: wires, 2D faces and 3D volumes. Furthermore, 2D geometries can be extruded to create more complex 3D volume shapes.
The following methods for creating a geometry all return a Python dictionary which can be stored as a variable or passed on to other functions to edit the shapes, assign materials, load specification etc.
Additionally, vertices can be added to faces for application of point loads. Partition is necessary for the added vertex to be a part of face and thereby be included in the meshing. In general, point loads should only be used on rigid shells or rigid solids. An example of this is given in a section on Load Specification.
6.1 3D Box
The oc.makeBox
method creates a rectangular box in the current stage:
oc.makeBox(dx, dy, dz, at)
dx,dy,dz

dimensions of rectangle [m, default is ] 
at

Axis location of first corner and orientation of box, default means origo and global axis 
The at
input attribute specifies the location and orientation of the object (see section on Coordinate System):
at = oc.axis(P, normal, primary)
By e.g. writing:
oc.makeBox(dx=30, dy=30, dz=10, at=oc.axis(P=[15, 15, 0]))
a 3D box is created with depth and width of 30 m and a height of 10 m. Using at=oc.axis(P=[15,15,0])
in the input places the box with it’s center coinciding with the global origo. If no input for at
is provided, the lower left corner of the box is by default placed at the global origo with its sides coinciding with the global coordinate system.
6.2 3D Nprism
The oc.makeNprism
method creates and returns a Nprism volume shape in the current stage:
oc.makeNprism(n, radius, height, at)
n

number of prism sides, [, default is ] 
radius

outer radius of prism, [m, default is m] 
height

height of prism from base to top, [m, default is m] 
at

location and orientation of base point, default global origo and global axis. The reference point is set at the prism center. 
For example, the above method can be called as:
oc.makeNprism(n=16, radius=3.9, height=59.5, at=oc.axis(P=[0, 0, 20.5]))
to create a vertical solid cylinder with a radius of 3.9 m and a height of 59.5 m, with its center located at m.
6.3 2D Rectangle
The oc.makeRect
method creates and returns a rectangular surface shape in the current stage:
oc.makeRect(width, height, at)
width

width of rectangle in primary direction, [m, default is 10 m] 
height

height of rectangle in secondary direction, [m, default is 10 m] 
at

axis location and orientation of base point, default is origo and global axis 
To create a 30 m wide and 20 m high 2D rectangular face, with a planenormal coinciding with the global direction, the above can be used as:
oc.makeRect(width=30, height=20, at=oc.plane(P=[10, 20, 30], normal=[0, 1, 0]))
where the location of the lower left corner of the rectangle is set at m.
6.4 2D Face
The oc.makeFace
method generates a planar face shape:
oc.makeFace(pathData, at)
pathData

2D points in the given planar coordinate system 
at

axis location and orientation of base point, default origo and global axis 
For example, to create a 30by30 m rectangle with a 20 m indentation on one side, the coordinates of the corners are specified as:
oc.makeFace([[0,0], [10,0], [10,20], [20,20], [20,0], [30,0], [30,30], [0,30]])
Notice that the planar coordinates, , should be placed inside brackets to ensure that the pathData
input is given as a Python list. As nothing is specified for at
the coordinates are in the global coordinate system.
6.5 Wire
The oc.makeWire
method creates a wire object:
oc.makeWire(pathData, at)
pathData

2D points in the given planar coordinate system, default is the global plane 
at

axis location and orientation of base point, default origo and global axis 
The pathData
input is specified in the same way as for the oc.makeFace
method. To create a 30by30 m hollow rectangle with a 10 m indentation on one side:
oc.makeWire([[0,0], [10,0], [10,20], [20,20], [20,0], [30,0], [30,30], [0,30], [0,0]])
6.6 Extrude a 2D face or wire
he oc.extrude
method extrudes a 2D face or wire:
oc.extrude(shapes, vector)
shapes

instance or collection of shape dictionaries, each with attribute id identifying the shape (output from e.g. oc.makeFace or oc.makeWire )

vector

vector in global coordinates specifying the direction and magnitude of the extrusion (use oc.vector )

The input attribute oc.vector
specifies a vector in the global coordinate system. This controls the direction of extrusion for the object. The oc.extrude
and vector
methods are illustrated in the figure below.
The shapes
input specifies the geometrical object to be extruded. For example, to create a 30by30 m box of height 20 m, the oc.makeFace
method is fed into the shapes
input:
oc.extrude(oc.makeFace( [[0,0],[10,0],[10,20],[20,20], [20,0],[30,0],[30,30],[0,30]]), oc.vector(z=20))
For more complex shapes, the oc.extrude
method along with the oc.makeWire
and oc.makeFace
provide an easy way to first create the planar layout and then extruding the 2D face to make a 3D volume object.
6.7 Partition shapes
Partitioning shapes in the current stage into a new set of nonoverlapping shapes is done via the oc.partition
method:
oc.partition(shapes)
where shapes
is an instance or collection of shape dictionaries, each with an attribute id identifying the shape. The method is illustrated below.
For example, a 30x30x20 m box can be partitioned into two parts by using a 2D plane:
s1 = oc.makeBox(dx=30, dy=30, dz=20) s2 = oc.makeRect(30, 30, at=oc.axis(P=[0, 0, 10])) oc.partition([s1, s2]) oc.deleteShapes(s2)
where after partitioning, the 2D plane used to cut the 3D volume is deleted via the oc.deleteShapes(s2)
method.
After partitioning, OPTUM Compute generates new object id’s for the geometries in the current stage. Therefore, a dictionary with the prepartitioned shape which is stored in a variable cannot be used as a reference after performing the partitioning.
6.8 Create a vertex
The oc.makeVertex
method creates a vertex at given location:
oc.makeVertex(x, y, z)
x,y,z

Vertex location in global coordinates 
The vertex method is for example used to ensure that a node is placed at a specific point on a geometry. This must be the case for point loads as shown in an example in a section on Load Specification.
6.9 Selecting shapes
electing shapes in the current stage is done via the oc.select
method:
oc.select(bound, level, partials)
bound

Bounding box to test against 
level

The (combination) of parts to select, i.e. Edge, Face etc. as: Edge : oc.Level.Edge

Face : oc.Level.Face
 
Shell : oc.Level.Shell
 
Solid : oc.Level.Solid
 
Vertex : oc.Level.Vertex
 
Wire : oc.Level.Wire
 
partials

Include shapes that overlaps the bounding box. If false, only include shapes fully contained in box. Default is partials=True .

The bound
input attribute is specified via the oc.boundBox(x, y, z, dx, dy, dz)
command where give the reference location of the bounding volume dimensions to be selected. Selecting a face within a bounding box is illustrated in the figure below.
To specify which type of geometry to select, the level
input is given as e.g. oc.Level.Solid
to select all solids within the domain.
For selecting only 2D faces within a 30 m wide, 30 m deep and 10 m high box, with its center at global origo:
oc.select(oc.boundBox(x=15, y=15, z=0, dx=30, dy=30, dz=10), oc.Level.Face, partials=False)
If multiple 2D faces are present within the bounding box, the method returns a list of dictionaries containing the description of the shapes. This includes the dimensions and reference point of the object along with its id and object type.
All shapes in the stage can be selected using the following method:
shapes = oc.selectAll()
where shapes
will be a list of all shapes in the current stage.
6.10 Replace shapes
To replace a given (volume) shapes in the current stage with their corresponding surface shell shapes the following method can be used:
oc.removeInterior(shapes)
where shapes
is a dictionary containing the volume to be replaced.
For example, to create a circular hollow section the oc.makeNprism
method along with oc.removeInterior
, oc.select
and oc.deleteShapes
can be used to create a hollow shell object as:
oc.removeInterior(oc.makeNprism(n=16, radius=3.9, height=59.9)) oc.deleteShapes(oc.select(oc.boundBox(z=59.9), oc.Level.Face) + oc.select(oc.boundBox(z=0.0), oc.Level.Face))
In the above the 16side prism with a radius of 3.9 m and height of 59.9 m is first created and then hollowed out/replaced by a shell object. Then, the top and bottom faces are selected and subsequently deleted.
6.11 Delete a single shape
Deleting a shape from the current stage is done with the following method:
oc.deleteShape(shape)
The input shape
can be a single object such as the rectangular face stored as a dictionary in s2
in the partitioning example above:
s2 = oc.makeRect(30, 30, at=oc.axis(P=[0, 0, 15])) oc.deleteShape(s2)
Another example for the use of the above command is when having selected multiple shapes but only a single shape in the list is to be deleted:
sel = oc.select(oc.boundBox(x=15, y=15, z=0, dx=30, dy=30, dz=10), oc.Level.Face, partials=False) oc.deleteShapes(sel[0])
Note in the above the the index in sel[0]
refers to the first element in the list, sel[1]
to the second etc.
6.12 Delete multiple shapes
Deleting multiple shapes is done via the oc.deleteShapes(shapes)
method as:
oc.deleteShapes(shapes)
If for example, all faces within a certain volume are to be deleted, the above method can be used in combination with the oc.select
method as:
sel = oc.select(oc.boundBox(x=15, y=15, z=0, dx=30, dy=30, dz=10), oc.Level.Face, partials=False) oc.deleteShapes(sel)
To delete only certain shapes within the list of selected shapes:
oc.deleteShapes(sel[0]+sel[3]+sel[5])
can be used to remove the first, fourth and sixth shape in the list respectively.
7 Boundary conditions
7.1 Assign supports
A general way to specify boundary conditions is via the oc.assignSupport
method as:
assignSupport(shapes, x, y, z, rotation, isLocal)
shapes

Instance or list of shape dictionaries, each with attribute id identifying the shape. 
x, y, z, rotation

Degree of freedom for each global or local axis 
isLocal

Degrees of freedom parameters are consider in the canonical local coordinate system for the shapes, default is False. 
It is considered good practice to always use symmetry in a model to reduce the computational cost. For example, a model including both solid and shell materials can be reduced to half by using one axis of symmetry. The shell boundary conditions can then be specified in the following way:
oc.assignSupport(shellEdge, x = oc.Support.Free, y = oc.Support.Fixed, z = oc.Support.Free, rotation = oc.Support.Fixed)
corresponding to symmetry about the global direction, where displacement in the direction and rotation is fixed.
7.2 Assign full supports
Boundary conditions can be directly assigned as fully fixed (global fixed) as follows:
oc.assignFullSupport(shapes)
where shapes
is a list containing the dictionaries holding the object description.
7.3 Assign normal supports
To specify a boundary condition directly with local and free but local fixed:
oc.assignNormalSupport(shapes)
where shapes
is a list containing the dictionaries holding the object description.
7.4 Assign tangential supports
To specify a boundary condition directly with local and fixed and local free:
oc.assignTangentialSupport(shapes)
where shapes
is a list containing the dictionaries holding the object description.
7.5 Standard fixities
Specifying the boundary conditions of the computational domain is essential when carrying out an analysis with a soil volume which is practically infinite. For example, the figure below shows a soil domain with standard fixities where the displacement normal to the plane is restricted for the sides of the soil domain whereas both normal and inplane displacements are restricted for the bottom face.
A general approach to add standard fixities to a model is shown in the Python code below:
tol = 1E5 sel = oc.select(oc.boundBox(151, 151, 0, 30+2, 30+2, 10+1), oc.Level.Face) bottoms = [] sides = [] for i in sel: b = i['bound'] x, y, z, dx, dy, dz = [b[c] for c in ['x', 'y', 'z', 'dx', 'dy', 'dz']] if abs(z) < tol and dz < tol: bottoms.append(i) elif abs(x)  foundation_w/2 < tol and dx < tol: sides.append(i) elif abs(y)  foundation_w/2 < tol and dy < tol: sides.append(i) elif abs(y) < tol and dy < tol: sides.append(i) oc.assignFullSupport(bottoms) oc.assignNormalSupport(sides)
This can be broken down in a few steps:
 Firstly, all 2D faces within a e.g. 30x30x10 volume are selected and a list for storing the faces representing the bottom and sides of the domain is initialized
 A loop is used to iterate through all the 2D faces in the selected volume and a nested conditional ifelif statement used to check whether a face corresponds to a side or a bottom
 Finally, the bottom faces are assigned full supports (global fixed) and the sides assigned normal supports (local free, global fixed)
Note that in the above a tolerance variable is introduced as tol=1E5
. This is to allow for conditional statements on the dimensions of the faces, which are stored as floating point numbers with double precision.
8 Load specification
To assign a given load to specific shapes the oc.assignLoad
method is used as:
assignLoad(shapes, vector, isFixed)
shapes

Instance or collection of shape dictionaries, each with attribute id identifying the shape 
vector

Load vector in global coordinates specified via oc.vector()

isFixed

Load is to be considered a fixed (nonmultiplier) load, default is False 
The units of the load vector depends on the shape to which it is applied: If the shape is a solid a volume load is applied (kN/m³), if the shape is a face a surface load is applied (kN/m²), if the shape is an edge an edge load is applied (kN/m), and, finally, if the shape is a vertex a point load is applied (kN).
Arrows are used to denote assigned loads in the Geometry window as shown in the figure below.
To apply a vertical multiplier load to a rectangular face stored in rect
(for e.g. Limit Analysis), the above method can be used as:
oc.assignLoad(rect, oc.vector(0,0,1), isFixed=False)
As the given shape
is a 2D face, the loading type is a surface load in units of kN/m.
For point loading, a node must be placed where the loading is assigned. This can be ensured by creating a vertex via the oc.makeVertex
method on the geometry. For example, to assign a 25 kN vertical point loading on the middle upper face of a 10x10x10 m box:
s1 = oc.makeBox(10,10,10,at=oc.axis([5,5,10])) v = oc.makeVertex() oc.partition([s1, v]) oc.assignLoad(v, oc.vector(0,0,25))
Generally, the s1
shape in this example is assigned a rigid solid or shell material. Note that the box and vertex must be partitioned via the oc.partition([s1, v])
method.
9 Stage options
The stage options define the calculations to be run. The following options are available:
analysisType

Use the provided analysisType class (Default analysis type is meshing):

oc.AnalysisType.Mesh : Meshing
 
oc.AnalysisType.LimitAnalysis : Limit analysis
 
oc.AnalysisType.ElastoPlastic : Singlestep elastoplastic analysis
 
oc.AnalysisType.InitialStress : Initial stress analysis
 
oc.AnalysisType.MultiplierEP : Multiplier elastoplastic analysis
 
elementFamily

Use the provided elementFamily class:

oc.AnalysisType.Upper : Upper bound elements
 
oc.AnalysisType.Mixed : Mixed elements
 
oc.AnalysisType.Lower : Lower bound elements (Currently not available)
 
name

Unique name for the stage (standard string) 
fromStage

Defines previous stage: Results are carried over and analysis continues with e.g. additional loads. The previous stage is referenced using the name. 
When using the AUS or HMC materials, socalled iterations are needed to ensure convergence for each step. Tolerances and maximum number of iterations can be provided:
tol

Defines the acceptance criterion for the multiplier, i.e. , default is tol = 0.01 
iterations

Defines the maximum number of iterations, default is 15 
For the multiplier elastoplastic (MEP) analysis additional parameters can be given:
steps

Number of load steps to be run, default is 1 
w

Prescribed work (kJ) for each step. Input can be either a single double or a list of doubles. Default value is 1.0. 
tol2

Defines the acceptance criterion for the dampening and step length 
9.1 Mesh options
When defining a stage, several options for the mesh and mesh adaptivity can be defined. Generally, the following options are available:
meshTargetCount

Desired number of elements [integer] 
meshStartCount

Initial number of elements when using mesh adaptivity [integer] 
adaptIterations

Number of mesh adaptations [integer] 
refinementFactor

Defines the degree of refinement, i.e. the minimum size of new elements compared to the old size [double, default = 0.25] 
coarseningFactor

Defines the degree of coarsening, i.e. the maximum size of new elements compared to the old size [double, default = 1.50] 
targetLowerBound

Defines the lowest number of elements accepted relative to the target number [double, default = 0.90] 
targetUpperBound

Defines the highest number of elements accepted relative to the target number [double, default = 1.10] 
For multiplier elastoplastic analysis, mesh adaptivity can be chosen for any number of steps:
adaptSteps

List of triplets [3 integers]: Each triplet specifies the step number (starting from 0), the number of adaptivity iterations, and the target number of elements. 
An example of performing initial stress analysis, creating a new stage with MEP analysis and using mesh adaptivity is given in the Examples section.
10 Plotting options
The results can be visualised in OPTUM Compute using the oc.plot
method. The following input parameters are available:
fieldSetName

Field to be plotted, e.g. stresses, displacements and so on 
layer

Toggle between regular elements and (collapsed) interface elements. Default: Regular elements are shown. 
include

Toggle between solids and shells. Default: Both are shown. 
displacementScale

Factor for the displacements (or normalized velocities for Limit Analysis) for better visualization. Default: 0. 
rangeMax

Maximum for shown values. Default: No maximum is used. 
rangeMin

Minimum for shown values. Default: No minimum is used. 
step

Display the MEP results for specified step. Default: Last step is shown. 
camera

Specify initial view using oc.camera , e.g. camera=oc.camera(location=oc.vector(100,100,50)) . Default: Topdown view is used.

clipPlane

Allow cutting through the model for better visualization, e.g. clipPlane=oc.plane(0,0,0,1,0,0) , where the first three inputs to plane specify a point and the next three specify the normal vector. Default: No clipping plane is used.

slicePlane

Similar to clipPlane , but only the intersection of the plane and elements is shown. Default: No slice plane is used.

filename

File name for export of view. Default: No file name is specified, thus, no image is exported. 
renderAttributes

Renders the boundary conditions on the result set. Default: False , i.e. not shown.

The result fields can be plotted by specifying the correct fieldSetName
:
u  Euclidian norm of the displacements (or normalized velocities for Limit Analysis). 
ux

Displacement in the direction. Not available for Limit Analysis. 
uy

Displacement in the direction. Not available for Limit Analysis. 
uz

Displacement in the direction. Not available for Limit Analysis. 
sx


sy


sz

sxy


syz


szx


s1

, largest principal stress, i.e. 
s2

, middle principal stress 
s3

, smallest principal stress 
mx

, moment in the direction (shells) 
my

, moment in the direction (shells) 
mxy

, twisting moment (shells) 
m1

, largest principal moment, (shells) 
m2

, smallest principal moment (shells) 
td

Total dissipation (solids) 
td

Shear dissipation (solids) 
Strains will be added to the result set in the nearest future.
The layer
input takes a string as input:
layer=

Default option, solids and shells are shown. 
layer='volumes'

Same as default option, solids and shells are shown. 
layer='interfaces'

Interface elements are shown. 
The include
input takes a string as input:
include=

Default option, solids and shells are shown. 
include='solids'

Solids shown. 
include='shells'

Shells are shown. 
11 Accessing the results
The result set is the output when an analysis is run:
results = oc.runAnalysis()
Displacements and strains are currently not made available in the result structure, but it will be added in the nearest future. Resulting nodal forces for each element will likewise be added soon.
11.1 Limit analysis
The results of a limit analysis run can be accessed as follows:
results[0].limitAnalysis.volumes.elements[EL #].points

Location of the solid or shell element 
results[0].limitAnalysis.volumes.elements[EL #].displacements

Displacement of the solid or shell element 
results[0].limitAnalysis.volumes.elements[EL #].stresses

Stresses of the solid or shell element 
results[0].limitAnalysis.volumes.elements[EL #].moments

Moments of the shell element 
11.2 Initial stress analysis
The results of an initial stress analysis run can be accessed as follows:
results[0].initialStress.volumes.elements[EL #].points

Location of the solid or shell element 
results[0].initialStress.volumes.elements[EL #].displacements

Displacement of the solid or shell element 
results[0].initialStress.volumes.elements[EL #].stresses

Stresses of the solid or shell element 
results[0].initialStress.volumes.elements[EL #].moments

Moments of the shell element 
11.3 Elastoplastic analysis
The results of an elastoplastic analysis run can be accessed as follows:
results[0].ep.volumes.elements[EL #].points

Location of the solid or shell element 
results[0].ep.volumes.elements[EL #].displacements

Displacement of the solid or shell element 
results[0].ep.volumes.elements[EL #].stresses

Stresses of the solid or shell element 
results[0].ep.volumes.elements[EL #].moments

Moments of the shell element 
11.4 Multiplier elastoplastic analysis
The multiplier elastoplastic analysis may contain several steps. The results for each step can be assessed using the first index (counting from zero):
First step:  
results[0].ep.volumes.elements[EL #].points

Location of the solid or shell element 
results[0].ep.volumes.elements[EL #].displacements

Displacement of the solid or shell element 
results[0].ep.volumes.elements[EL #].stresses

Stresses of the solid or shell element 
results[0].ep.volumes.elements[EL #].moments

Moments of the shell element 
Second step:  
results[1].ep.volumes.elements[EL #].points

Location of the solid or shell element 
Nth step:  
results[N1].ep.volumes.elements[EL #].points

Location of the solid or shell element 
12 Examples
12.1 Monopile with Tresca material
In this section, we will go through an example script for modelling and analysing a monopile. The script is included as an example in the installed version of OPTUM Compute as well.
First and foremost, we import OptumCompute
and set the camera to perspective. Moreover, several variables are defined to make the model parametric:
import OptumCompute as oc oc.setCamera(oc.CameraOption.Perspective) oc.clear() foundation_w = 50.0 foundation_h = 40.0 d = 19.5 pile_z = foundation_h  d pile_h = 40.0 + d pile_r = 3.9 tol = 1E5
Next, the materials are defined: The soil is modelled as a Tresca material with a shear strength, which increase with the depth and has the value of 48 kPa at ground level, while the monopile is modelled as a rigid shell.
solid1 = oc.makeMaterial({ 'type': 'Tresca', 'specificWeight': 20.5, 'su': oc.linear(48, z=6.4, zref=foundation_h), 'E': 50, 'nu': 0.0, 'K0': 0.5, 'color': '#ff0000' }) shellMaterial = oc.makeMaterial({ 'type': 'RigidShell', 'thickness': 0.080, 'color': '#60ff00' })
The model is encapsulated in a small method, as it needs to be defined twice; once for the initial stress analysis and once for the multiplier elastoplastic analysis. The geometry of the soil is created using the makeBox
method, while the monopile is created using the makeNprism
method. Due to the symmetry of the model, half is removed using a box to partition, and finally, the interior of the pile is removed above ground level.
def create_geometry(): shift = foundation_w/2 s1 = oc.makeBox(foundation_w, foundation_w, foundation_h, at=oc.axis(P=[shift, shift, 0])) s2 = oc.makeNprism(16, pile_r, pile_h, at=oc.axis(P=[0, 0, pile_z])) s3 = oc.makeBox(foundation_w+2, foundation_w/2+1, foundation_h+pile_h+1, at=oc.axis(P=[shift1, 0, 0])) oc.partition([s1, s2, s3]) # Remove half: sel = oc.select(oc.boundBox(shift+2, 1, 1, foundation_w+2, foundation_w/2+2, foundation_h+pile_h ), oc.Level.Solid) oc.deleteShapes(sel) # Hollow out pile above ground and delete face: sel = oc.select(oc.boundBox(z=pile_h + pile_z/2), oc.Level.Solid) oc.removeInterior(sel[0]) sel = oc.select(oc.boundBox(z=pile_h + pile_z/2), oc.Level.Face) oc.deleteShapes(sel[0])
With the geometry in place, materials can be assigned to the shapes. This is done by selecting a shape in the model using the select
method and then assigning materials. For the shells, two selections are used to be able to define interfaces between the pile and the soil. These interfaces means that a displacement discontinuity can occur. Finally, a shear joint is assigned at pile bottom, which again enables a displacement discontinuity.
# solid sel = oc.select(oc.boundBox(shift1, shift1, 0, foundation_w+2, foundation_w+2, foundation_h+1), oc.Level.Solid) oc.assignSolid(sel, solid1) # shell sel = oc.select(oc.boundBox(x = pile_r1, y=pile_r1, z=pile_z+1, dx=2*pile_r+2, dy=pile_r, dz=foundation_hpile_z2), oc.Level.Face) sel = list(filter(lambda s:s['bound']['dy'] > 1e5, sel)) oc.assignShell(sel, shellMaterial, plusMaterial=solid1, minusMaterial=solid1) sel = oc.select(oc.boundBox(pile_r1, pile_r1, foundation_h+1, 2*pile_r+2, pile_r+2, pile_h), oc.Level.Face) oc.assignShell(sel, shellMaterial) # shear joint at pile bottom: sel = oc.select(oc.boundBox(0, 1, pile_z), oc.Level.Face) oc.assignShearJoint(sel, solid1)
For the soil, standard fixities are used. This is done by selecting the faces of the soil domain and assigning full support for the bottom and normal supports for the sides. When using either the assignNormalSupport
or assignTangentialSupport
methods, the local coordinate system of the face is used.
# standard fixities sel = oc.select(oc.boundBox(shift1, shift1, 0, foundation_w+2, foundation_w+2, foundation_h+1), oc.Level.Face) bottoms = [] sides = [] for i in sel: b = i['bound'] x, y, z, dx, dy, dz = [b[c] for c in ['x', 'y', 'z', 'dx', 'dy', 'dz']] if abs(z) < tol and dz < tol: bottoms.append(i) elif abs(x)  foundation_w/2 < tol and dx < tol: sides.append(i) elif abs(y)  foundation_w/2 < tol and dy < tol: sides.append(i) elif abs(y) < tol and dy < tol: sides.append(i) oc.assignFullSupport(bottoms) oc.assignNormalSupport(sides)
Symmetry conditions must be applied to the pile itself. Again, this is done by selecting the relevant edges and applying supports using the assignSupport
method.
# shell BCs edges = [] edges.extend(oc.select(oc.boundBox(x = pile_r, y = 0, z = pile_z/2+foundation_h/2), oc.Level.Edge)) edges.extend(oc.select(oc.boundBox(x = pile_r, y = 0, z = pile_z/2+foundation_h/2), oc.Level.Edge)) edges.extend(oc.select(oc.boundBox(x = pile_r, y = 0, z = pile_z/2+foundation_h), oc.Level.Edge)) edges.extend(oc.select(oc.boundBox(x = pile_r, y = 0, z = pile_z/2+foundation_h), oc.Level.Edge)) edges.extend(oc.select(oc.boundBox(x = 0, y = 0, z = pile_z+foundation_h), oc.Level.Edge)) oc.assignSupport(edges, x=oc.Support.Free, y=oc.Support.Fixed, z=oc.Support.Free, rotation=oc.Support.Fixed) return
An initial stress stage is required when doing a multiplier elastoplastic analysis. A stage name is needed as reference for following stage. The analysis type is set to oc.AnalysisType.InitialStress
, and we will be using approximately 1500 mixed elements. The stage is run using oc.runAnalysis()
.
# STAGE 1 oc.setStageProperties({ "name": "K0", "analysisType": oc.AnalysisType.InitialStress, "meshTargetCount": 1500, "elementFamily": 'mixed' }) create_geometry() result = oc.runAnalysis()
With the initial stresses computed, we can create a new stage for the multiplier elastoplastic (MEP) analysis. With the new stage initiated, we recreate the geometry and define the load acting horizontally at the pile top. For the analysis, we want to run six steps starting at 1500 elements and adapt the mesh every step increasing the element count to 4000 for the final step.
For the MEP analysis, it is possible to select precisely which steps should be used for mesh adaptivity using the option adaptSteps
, which is an array of lists containing step number, number of adaptations, and the target number of elements.
# STAGE 2 oc.newStage({ "name": "MEP", "analysisType": oc.AnalysisType.MultiplierEP, "meshStartCount": 1500, "steps": 6, "w": 20, "adaptSteps" : [[0, 1, 1500], [1, 1, 1750], [2, 1, 2000], [3, 1, 2500], [4, 1, 3000], [5, 1, 5000]], "fromStage": "K0" }) create_geometry() sel = oc.select(oc.boundBox(0,0,pile_z+pile_h), oc.Level.Face) oc.assignLoad(sel, oc.vector(10,0,0), isFixed = False) result = oc.runAnalysis() oc.plot('U', displacementScale = 10)
The six steps of the MEP analysis yield the following load multipliers and maximum displacements:
MEP step 1 concluded: Multiplier = 11.2121, max displacement = 0.0862609 m MEP step 2 concluded: Multiplier = 17.3423, max displacement = 0.172418 m MEP step 3 concluded: Multiplier = 20.8508, max displacement = 0.258606 m MEP step 4 concluded: Multiplier = 22.9506, max displacement = 0.344827 m MEP step 5 concluded: Multiplier = 24.064, max displacement = 0.431041 m MEP step 6 concluded: Multiplier = 24.672, max displacement = 0.517284 m
Multiplying with the applied load of 10 kN/m² and the area of the pile top (23.282 m²), we get the following load displacement curve for the top of the pile:
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