The Loader
This example consists of a simplified model of a tractor front-end loader. The model consists of the following five FE Parts which can be downloaded here.
- Loader Front Frame
- Lifting Arm
- Bucket
- Bell crank
- Bucket link
The hydraulic cylinders are represented by Axial Springs while the joints are represented by Revolute joint objects.
Basic lifting operation
The model is activated with a time-dependent function for the spring elongation.
The model is loaded by increasing the mass in the bucket.
Model and solver control using the Python API
To create and solve this model, the following items needs to be imported from the fedempy module.
from fedempy.fmm_solver import FmmSolver
from fedempy.modeler import FedemModeler
from fedempy.enums import FmDof, FmDofStat, FmLoadType, FmType, FmVar
Low-code modelling and solving
Here is a complete python script that creates and runs the Loader model. Make sure to unzip the file with the FE models before running the script.
from os import mkdir, path
from pathlib import Path
from fedempy.fmm_solver import FmmSolver
from fedempy.modeler import FedemModeler
from fedempy.enums import FmDofStat, FmLoadType, FmType
# Global constants
RELATIVE_PATH = '00-loader-base_case/'
MODEL_FILE = '00-loader-base_case.fmm'
PARTS_PATH = 'parts/'
# Prepare run directory (=RELATIVE_PATH)
model_file = Path(RELATIVE_PATH) / MODEL_FILE
if not path.isdir(model_file.parent):
mkdir(model_file.parent)
# Create a new FEDEM model
my_model = FedemModeler(str(model_file), force_new=True)
# Load the FE parts
p1 = my_model.make_fe_part(PARTS_PATH + 'Front.flm')
p2 = my_model.make_fe_part(PARTS_PATH + 'Boom.flm')
p3 = my_model.make_fe_part(PARTS_PATH + 'Bucket.flm')
p4 = my_model.make_fe_part(PARTS_PATH + 'BellCrank.flm')
p5 = my_model.make_fe_part(PARTS_PATH + 'BucketLink.flm')
# Edit some part properties
my_model.edit_part([p1, p2, p3, p4, p5], alpha2=0.00286, component_modes=0, consistent_mass=True)
my_model.edit_part(p2, Tx=0.01080263, Tz=-0.77487206)
my_model.edit_part(p3, Tx=-0.64636636, Tz=-2.0328088, Ry=-30, Rz=-180)
my_model.edit_part(p4, Tx=-3.2499752, Ty=-2.8376081, Tz=0.04694241, Ry=21.814096)
my_model.edit_part(p5, Tx=-2.041544, Ty=-0.92750001, Tz=0.12191465, Ry=-4.9156169)
# Create revolute joints coupling the FE parts together and to ground
joints = []
joints.append(my_model.make_joint('Rev1', FmType.REVOLUTE_JOINT, 8))
joints.append(my_model.make_joint('Rev2', FmType.REVOLUTE_JOINT, 11))
joints.append(my_model.make_joint('Rev3', FmType.REVOLUTE_JOINT, 19, 7))
joints.append(my_model.make_joint('Rev4', FmType.REVOLUTE_JOINT, 24, 6))
joints.append(my_model.make_joint('Rev5', FmType.REVOLUTE_JOINT, 38, 22))
joints.append(my_model.make_joint('Rev6', FmType.REVOLUTE_JOINT, 33, 17))
joints.append(my_model.make_joint('Rev7', FmType.REVOLUTE_JOINT, 49, 21))
joints.append(my_model.make_joint('Rev8', FmType.REVOLUTE_JOINT, 48, 20))
joints.append(my_model.make_joint('Rev9', FmType.REVOLUTE_JOINT, 56, 47))
joints.append(my_model.make_joint('Rv10', FmType.REVOLUTE_JOINT, 55, 35))
my_model.edit_joint(joints[2], Ry=90, Rz=-90)
[my_model.edit_joint(id, Rx=90) for id in joints[3:]]
# Create functions
f1 = my_model.make_function('Lift Cylinders',
frequency=0.625, amplitude=0.15, delay=0.25, mean_value=0.15, end=0.8)
f2 = my_model.make_function('Boom Cylinder',
slope=-0.5, start_ramp=0.5, end_ramp=1.2)
f3 = my_model.make_function('Rotation Front',
frequency=0.5, amplitude=0.262, delay=0.25, mean_value=0.262, end=1.0)
f4 = my_model.make_function('Bucket Load',
slope=50000, start_ramp=0.7, end_ramp=1.2)
my_model.edit_joint(joints[0], constraints={'Rz' : FmDofStat.SPRING},
spring={'Rz' : 1.0e9}, length={'Rz' : f3})
cyl = my_model.make_spring('Lift cylinder', [(9, 23), (10, 18)],
init_Stiff_Coeff=1.0e9, length=f1)
cyl.append(my_model.make_spring('Boom cylinder', (5, 50),
init_Stiff_Coeff=1.0e9, length=f2))
my_model.make_load('Load', FmLoadType.FORCE, 39, (0, 0, -1), fn=f4)
my_model.fm_solver_setup(t_inc=0.01, t_end=1.6)
my_model.close(True, True)
# Solver setup and execution
my_solver = FmmSolver()
my_solver.solve_all(str(model_file), True, True)
No-code modeling
It is also possible to create the FEDEM model without writing python code. Instead, the model is described using YAML-syntax.
To create this model, execute the command:
$ python -m fedempy.yaml_parser -f loader_model.yaml
target_file: 02-loader-y100.fmm
file_exists: OVERWRITE!
fe_parts:
p1: [parts/Front.ftl]
p2: [parts/Boom.ftl]
p3: [parts/Bucket.ftl]
p4: [parts/BellCrank.ftl]
p5: [parts/BucketLink.ftl]
triads_from_fe_parts:
Front_fix_bottom: [Front bottom bearing housing to ground, p1, node, 441]
front_fix_top: [Front top bearing housing to ground, p1, node, 211]
front_right_housing: [Front right bearing housing, p1, node, 38]
front_left_housing: [Front left bearing housing, p1, node, 58]
front_top_cylinder_attachment: [Front top cylinder attachment point, p1, node, 18]
front_right_cylinder_attachment: [Front right cylinder attachment point, p1, node, 222]
front_left_cylinder_attachment: [Front left cylinder attachment point, p1, node, 235]
boom_rear_right_houding: [Boom right rear bearing housing, p2, node, 1038]
boom_rear_left_housing: [Boom left rear bearing housing, p2, node, 178]
boom_front_right_housing: [Boom right front bearing housing, p2, node, 715]
boom_front_left_housing: [Boom left front bearing housing, p2, node, 5]
boom_right_bellcrank_housing: [Boom right bearing housing to BellCrank, p2, node, 545]
boom_left_bellcrank_housing: [Boom left bearing housing to BellCrank, p2, node, 424]
boom_right_cylinder_attachment: [Boom right cylinder attachment point, p2, node, 829]
boom_left_cylinder_attachment: [Boom left cylinder attachment point, p2, node, 119]
bucket_right_housing: [Bucket right housing, p3, node, 509]
bucket_mid_housing: [Bucket midt housing, p3, node, 451]
bucket_left_housing: [Bucket left housing, p3, node, 284]
bellcrank_top_housing: [BellCrank top housing, p4, node, 420]
bellcrank_bottom_housing: [BellCrank bottom housing, p4, node, 14]
bellcrank_right_housing: [BellCrank right housing, p4, node, 276]
bellcrank_left_housing: [BellCrank left housing, p4, node, 244]
bucketlink_rear_houding: [BucketLink rear housing, p5, node, 575]
bucketlink_front_housing: [BucketLink front housing, p5, node, 174]
edit_fe_parts:
p1: &link_property
alpha2: 0.00286
component_modes: 0
consistent_mass: True
p2:
<<: *link_property
Tx: 0.01080263
Tz: -0.77487206
p3:
<<: *link_property
Tx: -0.64636636
Tz: -2.0328088
Ry: -30
Rz: -180
p4:
<<: *link_property
Tx: -3.2499752
Ty: -2.8376081
Tz: 0.04694241
Ry: 21.814096
p5:
<<: *link_property
Tx: -2.041544
Ty: -0.92750001
Tz: 0.12191465
Ry: -4.9156169
joints:
j01: [Front bottom to ground, BALL_JOINT, Front_fix_bottom]
j02: [Front top to ground, BALL_JOINT, front_fix_top]
j03: [Front to boom right, BALL_JOINT, front_right_housing, boom_rear_right_houding]
j04: [Front to boom left, BALL_JOINT, front_left_housing, boom_rear_left_housing]
j05: [Boom to bucket right, BALL_JOINT, boom_front_right_housing, bucket_right_housing]
j06: [Boom to bucket left, BALL_JOINT, boom_front_left_housing, bucket_left_housing]
j07: [Bucket link rear, BALL_JOINT, bucketlink_rear_houding, bellcrank_bottom_housing]
j08: [Bucket link front, BALL_JOINT, bucketlink_front_housing, bucket_mid_housing]
j09: [Boom to bellCrank right, BALL_JOINT, boom_right_bellcrank_housing, bellcrank_right_housing]
j10: [Boom to BellCrank left, BALL_JOINT, boom_left_bellcrank_housing, bellcrank_left_housing]
hydraulic_cylinders: # User-defined function
Top_cylinder: [Top cylinder, front_top_cylinder_attachment,
bellcrank_top_housing, 0.15, 0.12, 0.05, 0.7, 0.7, 1.0e+4]
Right_cylinder: [Right cylinder, front_right_cylinder_attachment,
boom_right_cylinder_attachment, 0.15, 0.12, 0.05, 0.7, 0.7, 1.0e+6]
Left_cylinder: [Left cylinder, front_left_cylinder_attachment,
boom_left_cylinder_attachment, 0.15, 0.12, 0.05, 0.7, 0.7, 1.0e+6]
fedem_objects:
p10:
kind: PART
ORIGINAL_FE_FILE: parts/Front.ftl
COORDINATE_SYSTEM:
- [1.0, 0.0, 0.0, 1.0]
- [0.0, 1.0, 0.0, 1.0]
- [0.0, 0.0, 1.0, 1.0]
DESCR: Front no. 2 | tagging_2