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112 lines
2.7 KiB
Markdown
112 lines
2.7 KiB
Markdown
# 2D Problem Definition Version 1 (PD2v1) Specification
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A format for defining shapes that humans and machines can read.
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I think it should have a better name.
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## Usage
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### Beam Elements (BE)
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Beam element problem definitions use points to represent nodes and links to represent
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beams.
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A given point (node) can be connected to any number of links (beams).
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### Finite Elements (FE)
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Finite element problem definitions use points to represent nodes and links to represent
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edges.
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A given point (node) can only be connected to two links (edges).
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### Mesh
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The spec can also be used to export meshes by using fixed boundary conditions and definining a set
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of `LINK_PROPS` that can be ignored (i.e. `LINK_PROPS ignore 0 0`).
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## Types
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### REAL
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A real number
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#### Examples
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```
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0
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-1
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1
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-1.0
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1.0
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9999999.999999
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```
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### IDs (`ID`)
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String that can include numbers, letters, underscores (`_`), and dashes (`-`).
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### Boundary condition types (`BC_TYPE`)
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- `NONE`
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- `FIXED`
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- `FORCE <VEC_ID>`
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## Syntax
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### Comments
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```
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// comments begin with // and end at the end of a line
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```
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### Definitions
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Each definiton goes on its own line.
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Definitons cannot refer to IDs of objects that are defined in latter lines.
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Every ID given for every object must be unqiue amongst its object type but not between types (although it is fine if it is).
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All definitions are immutable.
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| Object Type | Syntax |
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|--------------------|----------------------------------------------------------|
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| Boundary Condition | `BOUNDARY_CONDITION <ID ID> <BC_TYPE BC_TYPE>` |
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| Link | `LINK <ID ID> <ID LINK_PROPS> <ID NODE_ID> <ID NODE_ID>` |
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| Link Properties | `LINK_PROPS <ID ID> <ID MATERIAL> <REAL AREA>` |
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| Material | `MATERIAL <ID ID> <REAL YOUNGS_MODULUS>` |
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| Point | `POINT <ID ID> <ID VEC_ID> <ID BOUNDARY_CONDITION>` |
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| Vector | `VEC <ID ID> <REAL X> <REAL Y>` |
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## Example
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### Beam Element
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```
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// Define a fixed boundary conditon as it can be shared by all fixed points
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BOUNDARY_CONDITION bc_fixed FIXED
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MATERIAL aluminium 210000000000 250000000
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LINK_PROPS beam_props aluminium 0.0019635
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// Define the first node
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VEC point1_pos 0 0
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POINT point1 point1_pos bc_fixed
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// Define node with force boundary condition
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VEC point4_pos 1.7321 1
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VEC bc4_mag 14142 14142
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BOUNDARY_CONDITION bc4 FORCE bc4_mag
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POINT point4 point4_pos bc4
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// Define rest of the nodes
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VEC point2_pos 0 1.1547
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POINT point2 point2_pos bc_fixed
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VEC point3_pos 0 4.4641
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POINT point3 point3_pos bc_fixed
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// And finally link the nodes together to create the beams
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LINK link1 beam_props point1 point4
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LINK link2 beam_props point2 point4
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LINK link3 beam_props point3 point4
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```
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