Category: Chapter 2: Modeling and Designing Intent

Introduction

Subsurfaces are lines, rectangles, or ellipses defined in the UW coordinates on an OpenVSP model surface. These features are honored by the CompGeom, CFD Mesh, and DegenGeom functions and may be used to model inlet/outlet boundary conditions, control surfaces, material properties, surface roughness, etc. This video provides an overview of the Subsurface panel in the OpenVSP GUI and demonstrates some basic use.

Introduction

Linear parameter linking in OpenVSP is establishing a linear relationship between any two parameters according to a scale and offset by B = A*Scale + Offset where B is the dependent variable and A is the independent or driving variable. Setting up a linear link is relatively simple. Users may choose parameters from the dropdown menus or drag-and-drop a parameter onto the Parm A or Parm B variable selections and then click the Add Link button. All linear links will be displayed under the Parm Link List header. Note that you should use Links when specific linear relationships, including equality, are needed in your model but should avoid linking every parameter by default. As with many features in OpenVSP, less is often more.

Introduction

Creating a linear link is very straightforward. Open the Model > Link menu and choose your A and B parameters to be linked. Recall that Parm B is the driven or dependent variable in the relationship. You may choose to set a Scale and/or Offset at the creation of the Link as well as any constraints on Parm B. Click Add Link to create the link and update the model.

To modify a Link, click on the Link in the Parm Link List and then alter the relationship using the activation buttons or entry fields.

Introduction

Parametric clones are essentially when components are made to be identical to a parent component by linking all of the Design group parameters. This can be done quite easily by choosing Groups for two matching components and clicking Link All. However, in order for this process to work, each component must have the same number and type of Group so that the links relate directly to the parameters of the parent. This tutorial demonstrates creating clones with a Pod; a very simple example in which only the Design group parameters need to be linked to create a clone. A wing, on the other hand, requires that each component has the same number of sections, the same cross-section types, etc.

In some cases, users may wish to only link all of a certain group of parameters and allow others to remain free. In such a case, you may either pick and choose individual parameters one at a time or Link All for the chosen Group.

Introduction

In this tutorial, a multi-hinged arm is demonstrated by altering a single user parameter linked to multiple Hinge components and solid cylinders. Each of the Hinge angles are set with linear links to the user parameter as a fraction of fully deployed. In this way, a single user parameter can be used to perform combinations of translation and rotation about multiple coordinate systems to achieve complex motion. Creating and adjusting linear Links in OpenVSP is not covered in detail in this tutorial.