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LocalConstraints2 - Source Code¶
File: userfiles/TwoBarTruss/subsystem2/LocalConstraints2.py
# Copyright (C) The DistributedDesignOptimizer Contributors
# Licensed under the GNU General Public License v3.0. See LICENSE file for details.
"""Local constraints module for Two-Bar Truss subsystem 2.
Defines the buckling stability constraint for bar 2 (compression member)
in the Two-Bar Truss problem.
"""
from typing import List
from Distributed_Design_Optimizer.subsystem import LocalSubSystemBasis
from Distributed_Design_Optimizer.subsystem.optimization.designproblem import LocalConstraintsInterface
from Distributed_Design_Optimizer.subsystem.tools import ScalerBasis, ScalerConstraint
class LocalConstraints2(LocalConstraintsInterface):
"""Local constraints class for Two-Bar Truss subsystem 2.
Evaluates the Euler buckling stability constraint for bar 2.
Attributes:
None specific to this class; inherits from LocalConstraintsInterface.
"""
def __init__(self) -> None:
"""Initialize LocalConstraints2 instance."""
pass
def evaluateEqualityLocalConstraints(self, subsystem: LocalSubSystemBasis) -> None:
"""Evaluate equality constraints for subsystem 2.
Args:
subsystem: The local subsystem basis containing state information.
"""
responses: List[float] = subsystem.get_Responses_Unscaled() # unscaled values
scalers: List[ScalerBasis] = subsystem.get_Scalers()
equality_unscaled = []
# append any equality Local constraints to this list using the responses
################################################################
### USER CODE: Equality constraints ###
################################################################
# equality_unscaled.append(responses[...])
# scale equality Local constraint evaluation
scl: List[ScalerConstraint] = [scalers[5]]
# equality: List[float] = [scl[i].transform(equality_unscaled[i]) for i in range(len(equality_unscaled))]
# or if no Equality Local constraints exist:
equality = None
# equality Local constraints needs to be a scaled01 quantity
################################################################
### END USER CODE ###
################################################################
subsystem.set_EqualityLocalConstraintsValue(equality)
def evaluate_Jacobian_EqualityLocalConstraints(self, subsystem: LocalSubSystemBasis) -> None:
"""Evaluate the Jacobian of the local equality constraints.
Args:
subsystem: The local subsystem basis containing state information.
"""
return None
def evaluate_Hessians_EqualityLocalConstraints(self, subsystem: LocalSubSystemBasis) -> None:
"""Evaluate the Hessians of the local equality constraints.
Args:
subsystem: The local subsystem basis containing state information.
"""
return None
def evaluateInEqualityLocalConstraints(self, subsystem: LocalSubSystemBasis) -> None:
"""Evaluate inequality constraints for subsystem 2.
Computes the buckling constraint (sigma2 / sigma_Euler)**2 - 1 <= 0,
magnitude-compressed via a sign/zero-crossing preserving power map so
the feasible set is unchanged (see power_ratio below).
Args:
subsystem: The local subsystem basis containing state information.
"""
responses: List[float] = subsystem.get_Responses_Unscaled() # unscaled values
scalers: List[ScalerBasis] = subsystem.get_Scalers()
inequality_unscaled = []
# append any inequality Local constraints to this list using the responses
################################################################
### USER CODE: Inequality constraints ###
################################################################
# Buckling constraint (sigma2 / sigma_Euler)**2 - 1 <= 0. At infeasible
# designs (thin bar + large nodal force) the squared stress ratio reaches
# O(1e10+), pushing the scaled value outside ScalerConstraint(-500, 500).
# Compress the magnitude with a sign/zero-crossing preserving power map
# EXPR -> sign(EXPR) * |EXPR|**exponent (strictly increasing, EXPR=1 -> 1)
# so power_ratio(EXPR, p) - 1 <= 0 has the SAME feasible set as EXPR - 1 <= 0.
def power_ratio(expr: float, exponent: float) -> float:
"""Return sign(expr)*|expr|**exponent: magnitude-compressed, sign/zero-crossing preserving."""
return (1.0 if expr >= 0.0 else -1.0) * abs(expr)**exponent
inequality_unscaled.append(power_ratio((responses[0] / responses[1])**2, 1.0 / 4.0) - 1.0)
# scale the inequality Local constraint evaluation
scl: List[ScalerConstraint] = [scalers[6]]
inequality: List[float] = [scl[i].transform(inequality_unscaled[i]) for i in range(len(inequality_unscaled))]
# inequality Local constraints needs to be a scaled01 quantity
################################################################
### END USER CODE ###
################################################################
subsystem.set_InequalityLocalConstraintsValue(inequality)
def evaluate_Jacobian_InEqualityLocalConstraints(self, subsystem: LocalSubSystemBasis) -> None:
"""Evaluate the Jacobian of the local inequality constraints.
Args:
subsystem: The local subsystem basis containing state information.
"""
# No closed-form Jacobian available (complex physics); return None to let
# the framework fall back to its internal finite-difference computation.
return None
def evaluate_Hessians_InEqualityLocalConstraints(self, subsystem: LocalSubSystemBasis) -> None:
"""Evaluate the Hessians of the local inequality constraints.
Args:
subsystem: The local subsystem basis containing state information.
"""
# No closed-form Hessian available (complex physics); return None to let
# the framework fall back to its internal finite-difference computation.
return None