Import Bolt

Bolt Modeling1D Bolt > Import Bolt

Introduction

1D bolts can be created by importing bolt definition file. There are three blocks in this file called BOLT, HEAD_DEF and THREAD_DEF to define bolt, head and thread respectively. Lines that start with # are comment line. The file can have many of these blocks to define bolts between different bodies. Each BOLT definition block should refer to a head and thread definition.

Sample bolt definition file: 1D bolt definition file

Identifying bolt holes

When bolt definition file is imported, the following steps are carried out to identify the bolt holes and create rigids and bars.

  1. The contact faces between the head and thread body are identified based on the value defined by "GAP" in bolt definition file.

  2. The circles on these faces within the diameter range from "MIN_DIA" to "MAX_DIA" will be considered as bolt holes to create rigids. "MIN_DIA" to "MAX_DIA" are defined in bolt definition.

  3. The edges on other end of holes of head body is identified by considering an imaginary cylinder coaxial to the bolt hole. Diameter of the imaginary cylinder = "TOP_RBE_SCALE" x diameter of bolt hole. There is also a keyword "BOLT_HEAD_DIA" to define the diameter of bolt head. If this keyword is defined, then the diameter of imaginary cylinder will be diameter of bolt head. The faces which are intersecting with imaginary cylinder are assumed as bolt head sitting faces. The edge loop nearest to the circumference of imaginary cylinder is assumed as edges on end of bolt hole.

  4. The edges on other end of holes of thread body is identified by considering an imaginary cylinder coaxial to the bolt hole. Diameter of the imaginary cylinder = "BTM_RBE_SCALE" x diameter of bolt hole. There is also a keyword "NUT_DIA" to define the diameter of nut. If this keyword is defined, then the diameter of imaginary cylinder will be diameter of nut. The faces which are intersecting with imaginary cylinder are assumed as the faces at other end of bolt hole. The edge loop nearest to the circumference of imaginary cylinder is assumed as edges on end of bolt hole.

Bolt definition

BOLT - Keyword to define bolt

Keyword Value Description
BOLT_NAME Name of bolt definition
METHOD CIRCLE_BASED/CYLINDER_BASED Method to identify bolt

CIRCLE_BASED - Bolt holes between head and thread body is identified based on circular edge loops in contact faces.

CYLINDER_BASED - Matching bolt holes between head and thread body is identified based on matching cylinders.
HEAD_ENTITY Name of head body
THREAD_ENTITY Name of thread body.
GAP Gap between the contact faces of head and thread body.
HEAD_DEF_NAME Name of head definition.
THREAD_DEF_NAME Name of thread definition.
AXIS_INCLINATION_TOL Tolerance for axis inclination to identify matching bolt holes (Angle in degrees).
AXIS_SHIFT_TOL Tolerance for axis shift to identify matching bolt holes.
MIN_DIA Minimum diameter of bolt holes.
MAX_DIA Maximum diameter of bolt holes.
CONNECTION EQUIVALENCE/RBAR/MPC/PRETENSION Type of connection between head and thread.

EQUIVALENCE - End node of bar and/or master node of RBE between head and thread will be equivalenced.

RBAR - RBAR will be created between end node of bar and/or master node of RBE between head and thread.

MPC - MPC will be created between end node of bar and/or master node of RBE between head and thread. Keyword "ENFORCED_DISP" defines enforced displacement along the axial direction of bolt.

PRETENSION - Creates pretension force between head and thread. The additional keywords to define bar pretension under bolt definition are

  1. PRETENSION_FORCE
  2. LOCK
  3. PRETENSION_TYPE
  4. NUMBER_OF_BARS
ENFORCED_DISP Enforced displacement along the axis of bolt for MPC connection.
PRETENSION_FORCE Value for pretension force.
LOCK true/false Lock option for bolt.

true - Bolt will be locked for pretension.

false -Bolt will be unlocked for pretension.
BOLT_TYPE THREADED/THROUGH Type of bolt.

THREADED - Blind threaded hole.

THROUGH - Through hole.
NUMBER_OF_BARS Number of bar elements between head and thread RBE.

Keywords BOLT_NAME, HEAD_ENTITY, THREAD _ENTITY, GAP, HEAD_DEF_NAME, THREAD_DEF_NAME, AXIS_INCLINATION_TOL AXIS_SHIFT_TOL MIN_DIA, MAX_DIA, and PRETENSION_TYPE are mandatory. If anyone on this keyword is missing or not defined correctly, then that definition will be invalid. If other keywords are not defined/missed, default value will be assumed. The default value for each keyword is

METHOD = CIRCLE_BASED

CONNECTION = EQUIVALENCE

ENFORCED_DISP = 1.0

PRETENSION_FORCE = 100.00

LOCK = false

NUMBER_OF_BARS = 3

Head definition

HEAD_DEF - Keyword to define head

Keyword Value Description
NAME Name of head definition.
TYPE 1/2/3/4/5/6/7/8/9/10/11 Type of bolt.
  1. Top and bottom RBE with bar
  2. Top RBE with bar
  3. Bottom RBE with bar
  4. Bar without RBE
  5. Top RBE
  6. Bottom RBE
  7. Mid RBE
  8. Top and bottom RBE without bar
  9. Top and bottom RBE with bar_Special
  10. Equivalence top RBE to bottom RBE
  11. Equivalence bottom RBE to top RBE
TOP_RBE_SCALE An imaginary cylinder coaxial to the bolt hole is assumed. Diameter of this imaginary cylinder = "TOP_RBE_SCALE" x diameter of bolt hole. Nodes on bolt head sitting faces and inside this imaginary cylinder are the slave nodes for top RBE.
BTM_RBE_SCALE An imaginary cylinder coaxial to the bolt hole is assumed. Diameter of this imaginary cylinder = "BTM_RBE_SCALE" x diameter of bolt hole. Nodes on contact faces and inside this imaginary cylinder are the slave nodes for bottom RBE.
UNIFORM_TOP_RBE_DIA Instead of defining the scale factor for top RBE, an uniform diameter can be defined for all bolt holes. If this keyword is defined, an imaginary cylinder of this diameter will be assumed for all bolt holes.
UNIFORM_BTM_RBE_DIA Similarly an uniform diameter can be defined for bottom RBE.
BOLT_HEAD_DIA An imaginary cylinder of this diameter and coaxial to the bolt hole is assumed to find the other end of the bolt hole.
INCLUDE_SOLID_NODES YES/NO Option to include solid nodes.

YES - Include solid nodes.

NO - Will not consider solid nodes.
DIA_FOR_SOLID_NODES Diameter to identify solid nodes.
TOP_RBE_SLAVE_NODE_TYPE EDGE_NODE/FACE_OVERLAP_NODE/DEFAULT Option for slave nodes for top RBE.

EDGE_NODE - Nodes on edges of bolt hole are slave nodes for RBE.

FACE_OVERLAP_NODE - Overlapping nodes on contact faces are slave nodes for RBE.

DEFAULT - Nodes inside the imaginary cylinder based on the scale/diameter.
BTM_RBE_SLAVE_NODE_TYPE EDGE_NODE/FACE_OVERLAP_NODE/DEFAULT Option for slave nodes for bottom RBE.
PLANARITY_TOL Planarity tolerance to identify nodes on contact faces and bolt-head sitting faces (Angle in degrees).
BAR_DIA Diameter of bar.
BAR_MATERIAL Material for bar.

Keywords NAME, TYPE are mandatory. If anyone on this keyword is missing or not defined correctly, then that definition< will be invalid. If other keywords are not defined/missed default value will be assumed. The default value for each keyword is

TOP_RBE_SCALE = 1.5

BTM_RBE_SCALE = 1.5

INCLUDE_SOLID_NODES = NO

TOP_RBE_SLAVE_NODE_TYPE = DEFAULT

BTM_RBE_SLAVE_NODE_TYPE = DEFAULT

PLANARITY_TOL = 20.0

BAR_DIA = 1.0

BAR_MATERIAL = Default material

Thread definition

THREAD_DEF - Keyword to define thread

Keyword Value Description
NAME Name of thread definition.
TYPE 1/2/3/4/5/6/7 Type.
  1. Top and bottom RBE with bar
  2. Top and bottom RBE without bar
  3. Bottom RBE with bar
  4. Bottom RBE
  5. Top RBE
  6. Bottom RBE with zero depth
  7. Top and bottom RBE with zero depth
TOP_RBE_SCALE An imaginary cylinder coaxial to the bolt hole is assumed. Diameter of this imaginary cylinder = "TOP_RBE_SCALE" x diameter of bolt hole. Nodes on contact faces and inside this imaginary cylinder are the slave nodes for top RBE.
UNIFORM_TOP_RBE_DIA Instead of defining the scale factor for top RBE, an uniform diameter can be defined for all bolt holes. If this keyword is defined, an imaginary cylinder of this diameter will be assumed for all bolt holes.
NUT_DIA An imaginary cylinder of this diameter and coaxial to the bolt hole is assumed to find the other end of the bolt hole.
SHAPE UP/DOWN/BOTH Shape of bottom RBE.

UP - Nodes on threaded faces above the point based on the depth and pitch.

DOWN - Nodes on threaded faces below the point based on the depth and pitch.

BOTH - Nodes on threaded faces both above and below the point based on the depth and pitch.
PITCH Pitch to identify nodes for bottom RBE.
DEPTH Depth from the contact face to create bottom RBE.
INCLUDE_SOLID_NODES YES/NO Option to include solid nodes.

YES - Include solid nodes.

NO - Will not consider solid nodes.
DIA_FOR_SOLID_NODES Diameter to identify solid nodes.
TOP_RBE_SLAVE_NODE_TYPE EDGE_NODE/FACE_OVERLAP_NODE/DEFAULT Option for slave nodes for top RBE.

EDGE_NODE - Nodes on edges of bolt hole are slave nodes for RBE.

FACE_OVERLAP_NODE - Overlapping nodes on contact faces are slave nodes for RBE.

DEFAULT - Nodes inside the imaginary cylinder based on the scale/diameter.
PLANARITY_TOL Planarity tolerance to identify nodes on contact and bolt-head sitting faces (Angle in degrees).
BAR_DIA Diameter of bar.
BAR_MATERIAL Material for bar.

Keywords NAME, TYPE, PITCH and DEPTH are mandatory. If anyone on this keyword is missing or not defined correctly, then that definition will be invalid. If other keywords are not defined/missed, default value will be assumed. The default value for each keyword is

TOP_RBE_SCALE = 1.5

SHAPE = DOWN

INCLUDE_SOLID_NODES = NO

TOP_RBE_SLAVE_NODE_TYPE = DEFAULT

PLANARITY_TOL = 20.0

BAR_DIA = 1.0

BAR_MATERIAL = Default material