pyflange.bolts

Bolt, washer, and nut fastener components.

This module contains classes and factory functions representing bolt, washer, and nut fastener components. In particular it provides:

  • A MetricBolt class that models generic bolts with metric screw threads and a StandardMetricBolt factory function that generates MetricBolt objects with standard properties.
  • A FlatWasher class that models generic flat washers and an ISOFlatWasher factory function that returns a FlatWasher with ISO 7089 standard dimensions.
  • A HexNut class that models generic hexagonal nuts, an ISOHexNut factory function that generates a HexNut with ISO 4032 dimensions, and a RoundNut factory function that generates a standard flanged nut.

Bolt

Base class for bolt representations.

BoltCrossSection dataclass

Circular cross-section of a bolt.

Attributes:
  • diameter (float) –

    Cross-section diameter.

area cached property

float: Cross-sectional area.

elastic_section_modulus cached property

float: Elastic section modulus of the circular cross-section.

second_moment_of_area cached property

float: Second moment of area of the circular cross-section.

FlatWasher dataclass

Bases: Washer

Generic flat washer.

The parameters must be expressed in a consistent system of units. For example, if you choose to input distances in meters (m) and forces in newtons (N), then stresses must be expressed in pascals (N/m²). All attributes and methods return values consistent with the input units of measurement.

All input parameters are also available as attributes of the generated instance (e.g. washer.thickness, washer.poissons_ratio, etc.).

Instances of this class are designed to be immutable; changing attributes after instantiation is not recommended. If a washer with different attributes is needed, instantiate a new one.

Attributes:
  • outer_diameter (float) –

    Outer diameter of the washer.

  • inner_diameter (float) –

    Inner (hole) diameter of the washer.

  • thickness (float) –

    Thickness of the washer.

  • elastic_modulus (float) –

    Young's modulus of the washer material. Defaults to 210 GPa (210e9 N/m²).

  • poissons_ratio (float) –

    Poisson's ratio of the washer material. Defaults to 0.3.

area cached property

float: Surface area of the flat annular face.

axial_stiffness cached property

float: Compressive axial stiffness of the washer (EA / t).

HexNut dataclass

Bases: Nut

Generic hexagonal nut.

The parameters must be expressed in a consistent system of units. For example, if you choose to input distances in meters (m) and forces in newtons (N), then stresses must be expressed in pascals (N/m²). All attributes and methods return values consistent with the input units of measurement.

All input parameters are also available as attributes of the generated instance (e.g. nut.thickness, nut.bearing_diameter, etc.).

Instances of this class are designed to be immutable; changing attributes after instantiation is not recommended. If a nut with different attributes is needed, instantiate a new one.

Attributes:
  • nominal_diameter (float) –

    Nominal diameter of the inner thread.

  • thickness (float) –

    Height/thickness of the nut.

  • inscribed_diameter (float) –

    Diameter of the circle inscribed in the hexagon (distance between opposite flats).

  • circumscribed_diameter (float) –

    Diameter of the circle circumscribed around the hexagon (distance between opposite vertices).

  • bearing_diameter (float) –

    Outer diameter of the circular contact surface between nut and washer or flange.

  • elastic_modulus (float) –

    Young's modulus of the nut material. Defaults to 210 GPa (210e9 N/m²).

  • poissons_ratio (float) –

    Poisson's ratio of the nut material. Defaults to 0.3.

MetricBolt dataclass

Bases: Bolt

Generic bolt with ISO 68-1 metric screw thread.

The parameters must be expressed in a consistent system of units. For example, if you choose to input distances in meters (m) and forces in newtons (N), then stresses must be expressed in pascals (N/m²). All bolt attributes and methods return values consistent with the input units of measurement.

All input parameters are also available as attributes of the generated instance (e.g. bolt.shank_length, bolt.yield_stress, etc.).

Instances of this class are designed to be immutable; changing attributes after instantiation is not recommended. If a bolt with different parameters is needed, instantiate a new one.

Attributes:
  • nominal_diameter (float) –

    Outermost (nominal) diameter of the screw thread.

  • thread_pitch (float) –

    Pitch of the metric thread.

  • yield_stress (float) –

    Nominal yield stress (0.2% strain limit) of the bolt material.

  • ultimate_tensile_stress (float) –

    Nominal ultimate tensile stress of the bolt material.

  • elastic_modulus (float) –

    Young's modulus of the bolt material. Defaults to 210 GPa (210e9 N/m²).

  • poissons_ratio (float) –

    Poisson's ratio of the bolt material. Defaults to 0.3.

  • shank_length (float) –

    Length of the unthreaded shank. Defaults to 0.0.

  • shank_diameter_ratio (float) –

    Ratio between the shank diameter and the nominal diameter. Defaults to 1.0 (shank has nominal diameter).

  • stud (bool) –

    True if this is a stud bolt, False otherwise. Defaults to False.

designation cached property

str: Bolt designation string (e.g. 'M16' for a bolt with 16 mm diameter).

nominal_cross_section cached property

BoltCrossSection: Bolt cross-section with nominal diameter.

nominal_cross_section_area cached property

float: Area of a circle with nominal diameter.

Deprecated

Use MetricBolt.nominal_cross_section.area instead.

shank_cross_section cached property

BoltCrossSection: Bolt shank cross-section.

shank_cross_section_area cached property

float: Area of the shank transversal cross-section.

Deprecated

Use MetricBolt.shank_cross_section.area instead.

shank_diameter cached property

float: Diameter of the unthreaded shank.

shear_modulus cached property

float: Shear modulus G, under the assumption of isotropic linear elastic material.

tensile_cross_section_area cached property

float: Tensile stress area, according to ISO 898-1:2013, section 9.1.6.1.

Deprecated

Use MetricBolt.thread_cross_section.area instead.

tensile_moment_of_resistance cached property

float: Tensile moment of resistance, according to ISO 898-1:2013, section 9.1.6.1.

Deprecated

Use MetricBolt.thread_cross_section.elastic_section_modulus instead.

thread_basic_minor_diameter cached property

float: Basic minor diameter (d1), per ISO 68-1:1998.

thread_basic_pitch_diameter cached property

float: Basic pitch diameter (d2), per ISO 68-1:1998.

thread_cross_section cached property

BoltCrossSection: Bolt cross-section used for tensile calculations (ISO 898-1:2013, sec. 9.1.6.1).

thread_height cached property

float: Height of the metric thread fundamental triangle (H), per ISO 68-1:1998.

thread_minor_diameter cached property

float: Minor diameter (d3), per ISO 898-1:2013.

axial_stiffness(length)

Evaluate the axial stiffness of the clamped bolt.

Calculates the axial stiffness according to VDI 2230 Part 1, Section 5.1.1.1.

Parameters:
  • length (float) –

    Clamped length.
Returns:
  • float –

    Axial stiffness of the bolt.
Raises:
  • AssertionError –

    If length is less than shank_length.

bending_stiffness(length)

Evaluate the bending stiffness of the clamped bolt.

Calculates the bending stiffness according to VDI 2230 Part 1, Section 5.1.1.2.

Parameters:
  • length (float) –

    Clamped length.
Returns:
  • float –

    Bending stiffness of the bolt.
Raises:
  • AssertionError –

    If length is less than shank_length.

ultimate_tensile_capacity(standard='Eurocode')

Evaluate the ultimate tensile force that the bolt can sustain.

Parameters:
  • standard (str, default: 'Eurocode' ) –

    Standard according to which the ultimate tensile force should be calculated. Currently supported: "Eurocode" (EN 1993-1-8:2005). Defaults to "Eurocode".
Returns:
  • float –

    The bolt ultimate tensile force according to the specified standard.
Raises:
  • ValueError –

    If the requested standard is not supported.

Nut

Base class for nut representations.

Washer

Base class for washer representations.

ISOFlatWasher(designation)

Generate a standard flat washer according to ISO 7089.

Parameters:
  • designation (str) –

    Metric screw thread designation. Allowed values: 'M4', 'M5', 'M6', 'M8', 'M10', 'M12', 'M14', 'M16', 'M18', 'M20', 'M22', 'M24', 'M27', 'M30', 'M33', 'M36', 'M39', 'M42', 'M45', 'M48', 'M52', 'M56', 'M60', 'M64', 'M72', 'M80', 'M90', 'M100'.
Returns:
  • FlatWasher –

    A FlatWasher instance having standard dimensions defined in ISO 7089 (e.g., for "M16", outer diameter 30 mm, hole diameter 17 mm, thickness 3 mm).

ISOHexNut(designation)

Generate a standard hexagonal nut according to ISO 4032.

Parameters:
  • designation (str) –

    Metric screw thread designation. Allowed values: 'M4', 'M5', 'M6', 'M8', 'M10', 'M12', 'M14', 'M16', 'M18', 'M20', 'M22', 'M24', 'M27', 'M30', 'M33', 'M36', 'M39', 'M42', 'M45', 'M48', 'M52', 'M56', 'M60', 'M64', 'M72', 'M80', 'M90', 'M100'.
Returns:
  • HexNut –

    A HexNut instance with dimensions according to ISO 4032.

RoundNut(designation)

Generate a standard flanged round nut.

Parameters:
  • designation (str) –

    Metric screw thread designation. Allowed values: 'M4', 'M5', 'M6', 'M8', 'M10', 'M12', 'M14', 'M16', 'M18', 'M20', 'M22', 'M24', 'M27', 'M30', 'M33', 'M36', 'M39', 'M42', 'M45', 'M48', 'M52', 'M56', 'M60', 'M64', 'M72', 'M80', 'M90', 'M100'.
Returns:
  • HexNut –

    A HexNut instance configured with dimensions of a standard flanged round nut.

StandardMetricBolt(designation, material_grade, shank_length=0.0, shank_diameter_ratio=1.0, stud=False)

Create a metric bolt with standard dimensions and material properties.

This function provides a convenient way of creating a MetricBolt object, given the standard geometry designation (e.g. "M20") and the standard material grade designation (e.g. "8.8").

Parameters:
  • designation (str) –

    Metric screw thread designation. Allowed values: 'M4', 'M5', 'M6', 'M8', 'M10', 'M12', 'M14', 'M16', 'M18', 'M20', 'M22', 'M24', 'M27', 'M30', 'M33', 'M36', 'M39', 'M42', 'M45', 'M48', 'M52', 'M56', 'M60', 'M64', 'M72', 'M80', 'M90', 'M100'.

  • material_grade (str) –

    Material grade designation. Allowed values: - Carbon-steel: '4.6', '4.8', '5.6', '5.8', '6.8', '8.8', '9.8', '10.9', '12.9' - Austenitic stainless: 'A50', 'A70', 'A80', 'A100' - Duplex stainless: 'D70', 'D80', 'D100' - Martensitic stainless: 'C50', 'C70', 'C80', 'C110' - Ferritic stainless: 'F45', 'F60'

  • shank_length (float, default: 0.0 ) –

    Length of the unthreaded shank. Defaults to 0.0.

  • shank_diameter_ratio (float, default: 1.0 ) –

    Ratio between the shank diameter and the bolt nominal diameter. Defaults to 1.0.

  • stud (bool, default: False ) –

    True if this is a stud bolt, False otherwise. Defaults to False.
Returns:
  • MetricBolt –

    A MetricBolt instance with standard properties.