| { |
| "structure_type": "<str> Identifier for the truss topology used in this instance.", |
| "dimension": "<int> Number of spatial dimensions of the truss (2 for planar, 3 for space trusses).", |
| "num_bars": "<int> Total number of bars in the truss structure.", |
| "num_nodes": "<int> Total number of nodes in the truss structure, including supports.", |
| "num_loading_conditions": "<int> Number of independent external loading conditions the structure must withstand.", |
| "num_free_dofs": "<int> Number of unconstrained nodal displacement directions across all free nodes.", |
| "num_linking_groups": "<int> Number of groups of symmetrically located bars that must share the same cross-sectional area.", |
| "linking_groups": "<list[dict], length num_linking_groups> Groups of bars required to receive identical cross-sectional areas due to structural symmetry.", |
| "nodes": [ |
| { |
| "node_id": "<int> Unique identifier for this node.", |
| "x": "<float> Horizontal coordinate of the node.", |
| "y": "<float> Vertical coordinate of the node.", |
| "is_support": "<bool> Whether this node is a fixed support with no freedom of movement.", |
| "fixed_dofs": "<list[str]> Coordinate directions in which this support node is fixed (present only for support nodes)." |
| } |
| ], |
| "bars": [ |
| { |
| "bar_id": "<int> Unique identifier for this bar.", |
| "node_i": "<int> Node at the start end of the bar.", |
| "node_j": "<int> Node at the finish end of the bar.", |
| "length": "<float> Physical length of the bar computed from node coordinates.", |
| "direction_cosines": "<list[float], length dimension> Cosines of the angle between the bar's orientation and each coordinate axis." |
| } |
| ], |
| "degrees_of_freedom": [ |
| { |
| "dof_id": "<int> Unique identifier for this degree of freedom.", |
| "node": "<int> Node to which this degree of freedom belongs.", |
| "direction": "<str> Coordinate direction of this degree of freedom." |
| } |
| ], |
| "material_properties": { |
| "modulus_of_elasticity": "<float> Young's modulus of the bar material, relating stress to strain.", |
| "cost_density": "<float> Cost per unit volume used to compute the total structural cost." |
| }, |
| "discrete_areas": "<list[float], length num_discrete_areas> Candidate cross-sectional areas from which exactly one must be chosen for each bar.", |
| "num_discrete_areas": "<int> Number of candidate cross-sectional areas available for selection.", |
| "stress_bounds": { |
| "lower": "<float> Default minimum allowable stress in any bar (negative denotes compression).", |
| "upper": "<float> Default maximum allowable stress in any bar (positive denotes tension)." |
| }, |
| "bar_specific_stress_bounds": [ |
| { |
| "bar_id": "<int> Bar to which these stress limits apply.", |
| "lower": "<float> Minimum allowable stress for this bar.", |
| "upper": "<float> Maximum allowable stress for this bar." |
| } |
| ], |
| "displacement_bounds": { |
| "lower": "<float or null> Minimum allowable nodal displacement at any free degree of freedom, or null if unbounded.", |
| "upper": "<float or null> Maximum allowable nodal displacement at any free degree of freedom, or null if unbounded." |
| }, |
| "loading_conditions": [ |
| { |
| "load_id": "<int> Unique identifier for this loading condition.", |
| "description": "<str> Human-readable summary of the applied loads.", |
| "loads": [ |
| { |
| "node": "<int> Node at which this external force is applied.", |
| "direction": "<str> Coordinate direction of the applied force.", |
| "dof_id": "<int> Degree of freedom at which the force acts.", |
| "force": "<float> Magnitude and sign of the applied external force." |
| } |
| ] |
| } |
| ], |
| "expected_optimal_mass": "<float> Known best objective value for this instance from the literature." |
| } |
|
|
