ANSYS-Optimization Studies

What-if Study

Parameters and Design Points

– Let you run what-if studies

Progress can be monitored during Solve

Results can be Charted

Export a Design Point to automatically create and save a project for the Solve associated with that Design Point

Design Exploration

Extended Optimization Capabilities are available using Design Exploration

– Goal Driven Optimization

Best possible design obtained given goals set for parameters

– Parameter Correlation

Probabilistic sensitivities can be investigated using statistical correlation analysis

– Response Surface

Builds a response surface from the Design Points input and output values

– Six Sigma Analysis

Performs Six Sigma Analysis on input parameters that have uncertainties (e.g. room temperature)

Design Exploration: Surface Body Impact

Input Parameters

– Surface Body Thickness

– Yield Strength of Aluminum

Output Parameters

– Maximum Equivalent Plastic Strain

– Maximum rebound velocity

http://www.cadfamily.com/html/Article/ANSYS-Optimization%20Studies_819_1.htm

DesignModeler-Advanced 3D Geometry Part A

Modifying 3D Geometry

-3D Curve Feature

-Planar Bodies

-Boolean Operations

-Named Selection Base Objects

-Pattern Feature

-Advanced Features

-Advanced Tools

-Body Operations

-Mid Surface Extraction

Modifying 3D Geometry

Thin/Surface:

– The Thin/Surface feature has two distinct applications:

Create thin solids (Thin).

Create simplified shelling (Surface).

– Selections available from Details:

Faces to Remove: Selected faces will be removed from their bodies.

Faces to Keep: Selected faces will be kept, while unselected faces are removed.

Bodies Only: The operation will be performed on the selected bodies without removing any faces.

– When converting solids into thin solids or surfaces, you can specify a model's thickness in one of three offset directions:

1. Inward

2. Outward

3. Mid-Plane

Thin/Surface details:

Using the simple block shown here, let’s look at basic Thin/Surface behavior.

Notes on Thin/Surface:

– The Thin/Surface feature supports thickness > 0 if the selected faces are part of surface bodies.

– This allows for the “thickening” of an imported surface.

Mid Plane Option:

– This does not mean mid-plane extraction.

– Bodies will be hollowed, such that the inner and outer walls of the bodies are offset equal distances from the original faces.

– Example :

Fixed Radius Blend:

– The Fixed-Radius feature allows you to create blends on model edges.

– You can select or pre-select 3D edges and/or faces for blending.

Face selection applies blend to all the edges from that face.

– When pre-selecting, additional options are available from a RMB context menu

(face edge loop selection, smooth 3D edge chain)

– You can edit the blend radius in the Detail View. Clicking Generate completes the feature creation and updates the model.

Variable Radius Blend (same as above plus):

– Use the Detail View to change the start and end blend radius for each edge.

Also, the Detail View can set the transition between blends to smooth or linear. Clicking Generate completes the feature creation and updates the model.

Vertex Blend: allows surface or line body blending.

– Vertex must belong to surface or line body.

– Must connect to exactly 2 edges.

– Geometry surrounding vertex must be planar.

Chamfer:

– The Chamfer feature allows you to create planar transitions (or chamfer face) across model edges.

You can select or pre-select 3D edges and/or faces for chamfering.

If a face is selected, all the edges from that face are chamfered.

– When pre-selecting, additional options are available from a right mouse button context menu (face edge loop selection, smooth 3D edge chain)

Every edge on a face has a direction. This direction defines a right and left side.

– Chamfer is defined either by two distances from the edge for the planar transition (chamfer face), or by a distance (left or right) and an angle.

– The type of chamfer is set up in the Detail View along with the distances and angle.

http://www.cadfamily.com/html/Article/DesignModeler-Advanced%203D%20Geometry%20Part%20A_820_1.htm

http://www.cadfamily.com/html/Article/DesignModeler-Advanced%203D%20Geometry%20Part%20A_820_2.htm

DesignModeler-Advanced 3D Geometry Part B

http://www.cadfamily.com/HTML/Article/DesignModeler-Advanced%203D%20Geometry%20Part%20B_821.htm

ANSYS-Explicit Dynamics Meshing Part A

What is required of Meshes for Explicit Applications?

Uniform element size (in finest zoned regions)

– Smallest element size controls the time step used to advance the solution in time

– Explicit analyses compute dynamic stress waves that propagate throughout the entire mesh

Element size controlled by the user throughout the mesh

– Not automatically dependent on geometry

Implicit analyses usually have static region of stress concentration where mesh is refined (strongly dependent on geometry)

In explicit analyses, the location of regions of high stress constantly change as stress waves propagate through the mesh

– Mesh refinement is usually used to improve efficiency

Mesh transitions should be smooth for maximum accuracy

Hex-dominant meshing preferred

– More efficient

– Sometimes more accurate for slower transients

Mesh

Right-click Mesh in the Outline Tree to:

– Insert

Method

Sizing

-Important for Explicit

Contact Sizing

Refinement

Mapped Face Meshing

Match Control

Pinch

Inflation

– Update

– Generate Mesh

– Preview Surface Mesh

– Show Sweepable Bodies

– Preview Inflation

– Clean

– Rename

Meshing Methods

Solid Bodies

-Automatic

-Tetrahedron

-Hex Dominant

-Sweep

-Multizone

-CFX-Mesh

Surface Bodies (Shells)

-Quadrilateral Dominant

-Triangles

-Uniform Quad / Tri

-Uniform Quad

Line Bodies (Beams)

-Automatic

Meshing Methods – Solid Bodies

Tetrahedrons

– Advantages

An arbitrary volume can always be filled with tetrahedra

Can be generated quickly, automatically, and for complicated geometry

– Disadvantages

Element and node counts are higher than for a hex mesh with a similar mesh density

Generally not possible to align the cells with a flow direction

Not well suited for thin solids or annuli due to non-isotropy of geometry and nature of

Element

Tetrahedrons - Patch Conforming

-Default Tetrahedron Mesher

-All Faces, Edges, Vertices of the geometry are respected during mesh generation

-Delaunay Method

-Not good for Explicit Dynamics

Tetrahedrons - Patch Independent

-Recommended Tet mesher for Explicit

-Faces, Edges, Vertices not always respected

-Octree Method

-Element size Defined By

-Maximum Element Size

-Approx. number of Elements

Hex Dominant

– Useful for meshing bodies that cannot be swept

– Recommended for meshing bodies with large interior volumes

– The hex-dominant meshing algorithm creates a quad-dominant surface mesh first, then pyramid and tetrahedral elements are filled in as needed

Always check interior of mesh for good element structure

“Control Messages” will appear to warn you if volume may not be suitable for hex-dominant meshing

Hex Dominant

Sometimes produces a better (more uniform) mesh if a size control is placed on one or more edges / surfaces of a body

Mesh Methods – Sweeping

– Sweep

Sweeping from a single source face to a single target face

– Thin Sweep

Good at handling multiple sources and targets for thin parts

– Multizone

Uses a free decomposition approach

– Attempts to automatically slice geometry into sweepable regions

Supports multi-source and multi-target

Sweep methods for generating pure hex meshes

http://www.cadfamily.com/html/Article/ANSYS-Explicit%20Dynamics%20Meshing%20Part%20A_812_1.htm

http://www.cadfamily.com/html/Article/ANSYS-Explicit%20Dynamics%20Meshing%20Part%20A_812_2.htm

 

ANSYS-Explicit Dynamics Meshing Part B

http://www.cadfamily.com/HTML/Article/ANSYS-Explicit%20Dynamics%20Meshing%20Part%20B_813.htm

ANSYS-Explicit Dynamics Body Interactions Part A

Body Interactions

The Body Interactions folder, under Connections, is used to define global connection options for Explicit Dynamics

– Contact Detection

Trajectory (default)

– Formulation

– Shell Thickness Factor

– Tolerence

Proximity Based

– Pinball Factor

– Timestep Safety Factor

– Limiting Timestep Velocity

– Edge On Edge Contact

– Body Self Contact

– Element Self Contact

Trajectory Contact

Recommended option for impact and sliding contact between Solids, Shells and Beams.

The trajectory of nodes and faces are tracked during the computation cycle. If the trajectory of a node and a face intersects during the cycle a contact event is detected (see figure).

Trajectory based contact does not constrain the time step

– Often provides the most efficient solution.

Nodes which penetrate into another element at the start of the simulation will be ignored for contact and should be avoided.

– To generate duplicate conforming nodes across a contact interface

a) Use the multi-body part option in DesignModeler and set the Shared Topology Method to either Imprint or None

b) In Meshing use Arbitrary Match Control (Sweep) or Match mesh where possible (Patch Independent Tetrahedrons).

Shell Thickness Factor

– The Shell Thickness Factor (STF) defines the shell (surface body) thickness used for contact

A factor of 1.0 takes the true physical shell thickness into account, which means that the contact surface is positioned at half the true shell thickness on both sides of the shell mid plane.

A factor of 0.0 means that the shell has no contact thickness and the contact surface is positioned at the shell mid plane.

Value must be between 0.0 and 5.0

– For shell node on shell face impacts, the node is always located at the mid-surface of the shell.

Formulations

– Penalty Formulation (default, recommended)

A penalty force is calculated to push a penetrating node back to the face.

Penalty forces are calculated to conserve linear and angular momentum.

where D is the depth of penetration M is the effective mass of the node (N) and face (F)

?t is the simulation time step

Nodes will be pushed back towards the contact position, but it will usually take several cycles to satisfy the contact condition.

-Decomposition Response

All contacts that take place at the same point in time are first detected. The response of the system is then calculated to conserve momentum and energy. During this process, forces are calculated to ensure that the resulting position of nodes and faces does not result in further penetration at that time point

The decomposition response algorithm is more impulsive (in a given cycle) than the penalty method. This can in some situations give rise to large hourglass energies and energy errors.

Proximity Based Contact

Alternative option for impact and sliding contact between Solids, Shells and Beams

The external faces, edges and nodes of a mesh are encapsulated by a contact detection zone. If a node enters this zone, it is repelled using a penalty based force that conserves linear and angular momentum

http://www.cadfamily.com/html/Article/ANSYS-Explicit%20Dynamics%20Body%20Interactions%20Part%20A_814_1.htm

http://www.cadfamily.com/html/Article/ANSYS-Explicit%20Dynamics%20Body%20Interactions%20Part%20A_814_2.htm

http://www.cadfamily.com/html/Article/ANSYS-Explicit%20Dynamics%20Body%20Interactions%20Part%20A_814_3.htm

 

ANSYS-Explicit Dynamics Body Interactions Part B

 

http://www.cadfamily.com/HTML/Article/ANSYS-Explicit%20Dynamics%20Body%20Interactions%20Part%20B_815.htm

ANSYS Explicit Dynamics-Introduction to Workbench

ANSYS Workbench Overview

The Workbench environment supports two types of applications:

– Native applications (workspaces): Current native applications are Project Schematic, Engineering Data and Design Exploration.

Native applications are launched and run entirely in the Workbench window.

– Data Integrated Applications: current applications include Mechanical,Explicit Dynamics (Mechanical), Fluent, CFX, AUTODYN and others.

 

Starting Workbench

There are two methods of launching Workbench:

– From the Windows start menu:

The Workbench Environment

For most situations the Workbench GUI is divided into 2 primary sections (there are other optional sections we’ll see in a moment):

The Toolbox

-The toolbox contains 4 subgroups:Analysis systems: predefined templates that can be placed in the schematic.

-Component systems: various applications that can be accessed to build, or expand, analysis

systems.

-Custom Systems: predefined analysis systems for coupled applications (FSI, thermal-stress, etc.). -Users can also create their own predefined systems.

-Design Exploration: Parametric management and optimization tools.

The systems and components displayed in the toolbox will depend on the installed products.

Using the check boxes in the “View All / Customize” window, the items displayed in the toolbox can be toggled on or off.

The toolbox customization window is normally left closed when not in use.

The Project Schematic

The Workbench project schematic is a graphical representation of the workflow defining a system or group of systems.

The workflow in the project schematic is always left to right.

There are currently several applications which are native to Workbench, meaning they run entirely in the Workbench window:

–Project Schematic, Engineering Data and Design Exploration

Non-native applications (called data-integrated) run in their own window:

–DesignModeler, Mechanical (formerly Simulation), Mechanical APDL (formerly ANSYS), ANSYS AUTODYN, ANSYS Fluent, ANSYS CFX, Etc . . .

Blocks of cells can be deleted by RMB menu selection.

In this example an Explicit Dynamics analysis type is selected for the project schematic.

From the toolbox the selection can be dragged and dropped onto the schematic or simply double clicked.

By dropping applications and/or analyses into various locations in the schematic, an overall analysis project is defined

“Connectors” indicate the level of collaboration between systems.In the example below a structural system is dragged and dropped onto a thermal system at the Model cell (A4)

Before completing the operation notice there are a number of optional “drop” locations that will provide various types of linkage between systems (continued next page)

By completing the operation from the previous page, notice the linkage here is only at the Model level and above

In this case there would be no thermal/structural coupling

Notice each system block is given an alphabetic designation (A, B, C, etc)

By dropping the structural system at the “Solution” level we obtain a structural system that is coupled to the thermal solution.

http://www.cadfamily.com/html/Article/ANSYS%20Explicit%20Dynamics-Introduction%20to%20Workbench_807_1.htm

http://www.cadfamily.com/html/Article/ANSYS%20Explicit%20Dynamics-Introduction%20to%20Workbench_807_2.htm

http://www.cadfamily.com/html/Article/ANSYS%20Explicit%20Dynamics-Introduction%20to%20Workbench_807_3.htm

ANSYS-Explicit Dynamics Basics Part B

Initial Conditions

By default, all bodies in an Explicit Dynamics system are at rest, unconstrained and stress free.

At least one Initial Condition, Constraint or Load must be applied to the model.

– otherwise the initial solution is the final solution and there is need to Solve.Two forms of velocity are available as Initial Conditions for Explicit Dynamics:

– Velocity (Translational)

– Angular Velocity (Rotational)

Initial Conditions

Applied to single or multiple bodies in global or local Cartesian co-ordinate systems.

– If rotational and translational velocities are applied to the same body, the initial velocity of the body will be calculated as the sum of these two conditions

Loads and Constraints

Loads and constraints that can be applied for Explicit Dynamics analyses:

– Acceleration

– Standard Earth Gravity

– Pressure

– Force

– Line Pressure

– Fixed Support

– Displacement

– Velocity

– Impedance Boundary

Acceleration

– A constant body acceleration can be applied to all bodies in the model. This results in a body acceleration vector, defined via three Cartesian components being applied to all nodes in the model prior to any constraints

Any constraints applied to the model will over-ride an applied body accelerationStandard Earth Gravity

– Special case of an Acceleration load which is applied to all bodies.

– Magnitude of acceleration is fixed at standard earth gravitational acceleration

– Acting direction can be applied in ± x, y, z directions.

Any constraints applied to the model will over-ride any applied gravity

Pressure

– Constant and tabular Pressure loads can only be applied to faces of flexible bodies.

Pressure is applied normal to element faces of scoped bodies.

Direction of applied pressure rotates with deformation of faces.

Force

– Constant and tabular Force loads can be applied to flexible and rigid bodies.

Flexible bodies

– Force loads can be scoped to points, lines and faces.

Rigid bodies

– Force loads can only be scoped to bodies.

User defines total force load applied to mesh nodes of scoped bodies.

Force applied to each node is equal to total force

divided by number of mesh nodes in the scoping.

– Resulting distribution of force is mesh dependent.

When defining tabular forces, define the analysis end time first.

Force can be applied in global or local Cartesian co-ordinate systems.

Line Pressure

– Constant and tabular Line Pressure loads can be applied to edges of flexible bodies.

Applied in a specified direction.

Does not rotate with the deformation of the model.

Fixed Support

– A Fixed Support can be scoped to flexible and rigid bodies to constrain all degrees of freedom.

Flexible bodies:

– Fixed supports can be scoped to points, lines and faces.

Rigid bodies:

– Fixed supports can only be scoped to bodies.Displacement

– Constant and tabular Displacement constraints can be applied to flexible and rigid bodies.

Flexible bodies:

– Displacements can be scoped to points, lines and faces.

Rigid bodies:

– Displacements can only be scoped to bodies.

– Displacements are ramped linearly over analysis time.

For tabular displacements, the initial value at time zero should be zero.

– For rigid bodies, the rotational degrees of freedom will automatically be constrained if a displacement object is scoped to the body.

– Displacements can be applied in global or local Cartesian co-ordinate systems.

http://www.cadfamily.com/html/Article/ANSYS-Explicit%20Dynamics%20Basics%20Part%20B_809_1.htm

http://www.cadfamily.com/html/Article/ANSYS-Explicit%20Dynamics%20Basics%20Part%20B_809_2.htm