Added Lippmann Mahrenholz

pyroll/neutral_point_estimator/__init__.py

@@ -15,4 +15,5 @@ class Config:
 from . import sims_neutral_point_estimator
 from . import equal_neutral_line_estimator
 from . import lichansky_polyakov_ribbed_profile_neutral_point
-from . import napatov_ribbed_profile_neutral_point
+from . import napatov_ribbed_profile_neutral_point
+from . import lippmann_mahrenholz

pyroll/neutral_point_estimator/lippmann_mahrenholz.py

@@ -0,0 +1,29 @@
+import numpy as np
+
+from . import Config
+from .utils import chosen_estimator
+from pyroll.core import SymmetricRollPass, Hook
+
+SymmetricRollPass.Roll.relative_neutral_angle = Hook[float]()
+"""Relative Neutral angle defined by Lippmann and Mahrenholz for the roll pass."""
+
+@SymmetricRollPass.Roll.relative_neutral_angle
+def relative_neutral_angle(self: SymmetricRollPass.Roll):
+    rp = self.roll_pass
+    mean_flow_stress = (rp.in_profile.flow_stress + 2 * rp.out_profile.flow_stress) / 3
+    abs_rel_draught  = abs(rp.rel_draught)
+    back_tension_model_definition = -rp.back_tension
+    front_tension_model_definition = -rp.front_tension
+    relative_tension = (back_tension_model_definition - front_tension_model_definition) / mean_flow_stress
+
+    p1 = np.sqrt((1 - abs_rel_draught) / abs_rel_draught)
+    p2 = 1 / 2 * np.sqrt(rp.out_profile.equivalent_height / self.working_radius) * (relative_tension + np.log(1 - abs_rel_draught))
+    p3 = 1 / 2 * np.arctan(np.sqrt(abs_rel_draught / (1 - abs_rel_draught)))
+
+    return p1 * np.tan(p2 + p3)
+
+
+@SymmetricRollPass.Roll.neutral_angle
+def neutral_angle(self: SymmetricRollPass.Roll):
+    if chosen_estimator(Config.ESTIMATOR, "lippmann-mahrenholz"):
+        return self.entry_angle * self.relative_neutral_angle

test/test_solve_lippmann_mahrenholz.py

@@ -0,0 +1,89 @@
+import logging
+import webbrowser
+from pathlib import Path
+
+from pyroll.core import Profile, PassSequence, RollPass, Roll, CircularOvalGroove, Transport, RoundGroove, root_hooks
+
+
+def test_solve_lippmann_mahrenholz(tmp_path: Path, caplog, monkeypatch):
+    caplog.set_level(logging.INFO, logger="pyroll")
+
+    import pyroll.neutral_point_estimator
+    monkeypatch.setenv("PYROLL_NEUTRAL_POINT_ESTIMATOR_ESTIMATOR", "LIPPMANN-MAHRENHOLZ")
+
+    root_hooks.add(Roll.neutral_point)
+
+    try:
+        in_profile = Profile.round(
+            diameter=30e-3,
+            temperature=1200 + 273.15,
+            strain=0,
+            material=["C45", "steel"],
+            flow_stress=100e6,
+            density=7.5e3,
+            thermal_capacity=690,
+        )
+
+        sequence = PassSequence([
+            RollPass(
+                label="Oval I",
+                roll=Roll(
+                    groove=CircularOvalGroove(
+                        depth=8e-3,
+                        r1=6e-3,
+                        r2=40e-3
+                    ),
+                    nominal_radius=160e-3,
+                    rotational_frequency=1
+                ),
+                gap=2e-3,
+                coulomb_friction_coefficient=0.4,
+                back_tension=0,
+                front_tension=5e6
+            ),
+            Transport(
+                label="I => II",
+                duration=1
+            ),
+            RollPass(
+                label="Round II",
+                roll=Roll(
+                    groove=RoundGroove(
+                        r1=1e-3,
+                        r2=12.5e-3,
+                        depth=11.5e-3
+                    ),
+                    nominal_radius=160e-3,
+                    rotational_frequency=1
+                ),
+                gap=2e-3,
+                coulomb_friction_coefficient=0.4,
+                back_tension=5e6,
+                front_tension=0
+            ),
+        ])
+
+        try:
+            sequence.solve(in_profile)
+
+            assert sequence[0].roll.neutral_point < 0
+            assert sequence[2].roll.neutral_point < 0
+
+        finally:
+            print("\nLog:")
+            print(caplog.text)
+    finally:
+        root_hooks.remove(Roll.neutral_point)
+
+    try:
+        import pyroll.report
+
+        report = pyroll.report.report(sequence)
+
+        report_file = tmp_path / "report.html"
+        report_file.write_text(report, encoding="utf-8")
+        print(report_file)
+        webbrowser.open(report_file.as_uri())
+
+    except ImportError:
+        pass

test/test_solve_lippmann_mahrenholz3.py

@@ -0,0 +1,89 @@
+import logging
+import webbrowser
+from pathlib import Path
+
+from pyroll.core import Profile, Roll, ThreeRollPass, Transport, RoundGroove, CircularOvalGroove, PassSequence, root_hooks
+
+
+def test_solve_lippmann_mahrenholz3(tmp_path: Path, caplog, monkeypatch):
+    caplog.set_level(logging.DEBUG, logger="pyroll")
+
+    import pyroll.neutral_point_estimator
+    monkeypatch.setenv("PYROLL_NEUTRAL_POINT_ESTIMATOR_ESTIMATOR", "LIPPMANN-MAHRENHOLZ")
+
+    root_hooks.add(Roll.neutral_point)
+
+    in_profile = Profile.round(
+        diameter=55e-3,
+        temperature=1200 + 273.15,
+        strain=0,
+        material=["C45", "steel"],
+        flow_stress=100e6,
+        density=7.5e3,
+        thermal_capacity=690,
+    )
+
+    sequence = PassSequence([
+        ThreeRollPass(
+            label="Oval I",
+            roll=Roll(
+                groove=CircularOvalGroove(
+                    depth=8e-3,
+                    r1=6e-3,
+                    r2=40e-3,
+                    pad_angle=30
+                ),
+                nominal_radius=160e-3,
+                rotational_frequency=1
+            ),
+            gap=2e-3,
+            coulomb_friction_coefficient=0.4,
+            back_tension=0,
+            front_tension=5e6
+        ),
+        Transport(
+            label="I => II",
+            duration=1
+        ),
+        ThreeRollPass(
+            label="Round II",
+            roll=Roll(
+                groove=RoundGroove(
+                    r1=3e-3,
+                    r2=25e-3,
+                    depth=11e-3,
+                    pad_angle=30
+                ),
+                nominal_radius=160e-3,
+                rotational_frequency=1
+            ),
+            gap=2e-3,
+            coulomb_friction_coefficient=0.4,
+            back_tension=5e6,
+            front_tension=0
+        ),
+    ])
+
+    try:
+        sequence.solve(in_profile)
+
+        assert sequence[0].roll.neutral_point < 0
+        assert sequence[2].roll.neutral_point < 0
+    finally:
+        root_hooks.remove(Roll.neutral_point)
+
+        print("\nLog:")
+        print(caplog.text)
+
+    try:
+        import pyroll.report
+
+        report = pyroll.report.report(sequence)
+
+        report_file = tmp_path / "report.html"
+        report_file.write_text(report, encoding="utf-8")
+        print(report_file)
+        webbrowser.open(report_file.as_uri())
+
+    except ImportError:
+        pass