mass Module

All mass elements are defined in this file. This includes:

• CMASS1
• CMASS2
• CMASS3
• CMASS4
• CONM1
• CONM2

All mass elements are PointMassElement and Element objects.

class pyNastran.bdf.cards.elements.mass.CMASS1(eid, pid, nids, c1=0, c2=0, comment='')

Bases: pyNastran.bdf.cards.elements.mass.PointMassElement

Defines a scalar mass element.

1	2	3	4	5	6	7
CMASS1	EID	PID	G1	C1	G2	C2

Creates a CMASS1 card

Parameters:

eid : int

element id

pid : int

property id (PMASS)

nids : List[int, int]

node ids

c1 / c2 : int; default=0

DOF for nid1 / nid2

comment : str; default=’‘

a comment for the card

Centroid(self)

Centroid is assumed to be c=(g1+g2)/2. If g2 is blank, then the centroid is the location of g1.

G1(self)

G2(self)

Mass(self)

Pid(self)

Gets the Property ID of an element

Returns:

pid : int

the Property ID

classmethod _init_from_empty()

_properties = ['node_ids']

classmethod add_card(card, comment='')

Adds a CMASS1 card from BDF.add_card(...)

Parameters:

card : BDFCard()

a BDFCard object

comment : str; default=’‘

a comment for the card

center_of_mass(self)

cross_reference(self, model)

Cross links the card so referenced cards can be extracted directly

Parameters:

model : BDF()

the BDF object

node_ids

raw_fields(self)

safe_cross_reference(self, model, xref_errors)

Cross links the card so referenced cards can be extracted directly

Parameters:

model : BDF()

the BDF object

type = 'CMASS1'

uncross_reference(self)

Removes cross-reference links

write_card(self, size=8, is_double=False)

Writes the card with the specified width and precision

Parameters:

size : int (default=8)

size of the field; {8, 16}

is_double : bool (default=False)

is this card double precision

Returns:

msg : str

the string representation of the card

class pyNastran.bdf.cards.elements.mass.CMASS2(eid, mass, nids, c1, c2, comment='')

Bases: pyNastran.bdf.cards.elements.mass.PointMassElement

Defines a scalar mass element without reference to a property entry.

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CMASS2	EID	M	G1	C1	G2	C2

Creates a CMASS2 card

Parameters:

eid : int

element id

mass : float

mass

nids : List[int, int]

node ids

c1 / c2 : int; default=None

DOF for nid1 / nid2

comment : str; default=’‘

a comment for the card

Centroid(self)

Centroid is assumed to be c=(g1+g2)/2. If g2 is blank, then the centroid is the location of g1.

G1(self)

G2(self)

Mass(self)

classmethod _init_from_empty()

_properties = ['node_ids']

classmethod add_card(card, comment='')

Adds a CMASS2 card from BDF.add_card(...)

Parameters:

card : BDFCard()

a BDFCard object

comment : str; default=’‘

a comment for the card

center_of_mass(self)

cp_name_map = {'M': 'mass'}

cross_reference(self, model)

Cross links the card so referenced cards can be extracted directly

Parameters:

model : BDF()

the BDF object

classmethod export_to_hdf5(h5_file, model, eids)

exports the masses in a vectorized way

node_ids

raw_fields(self)

repr_fields(self)

Gets the fields in their simplified form

Returns:

fields : List[varies]

the fields that define the card

safe_cross_reference(self, model, xref_errors)

Cross links the card so referenced cards can be extracted directly

Parameters:

model : BDF()

the BDF object

type = 'CMASS2'

uncross_reference(self)

Removes cross-reference links

validate(self)

card checking method that should be overwritten

write_card(self, size=8, is_double=False)

Writes the card with the specified width and precision

Parameters:

size : int (default=8)

size of the field; {8, 16}

is_double : bool (default=False)

is this card double precision

Returns:

msg : str

the string representation of the card

class pyNastran.bdf.cards.elements.mass.CMASS3(eid, pid, nids, comment='')

Bases: pyNastran.bdf.cards.elements.mass.PointMassElement

Defines a scalar mass element that is connected only to scalar points.

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CMASS3	EID	PID	S1	S2

Creates a CMASS3 card

Parameters:

eid : int

element id

pid : int

property id (PMASS)

nids : List[int, int]

SPOINT ids

comment : str; default=’‘

a comment for the card

Centroid(self)

Mass(self)

S1(self)

S2(self)

classmethod _init_from_empty()

_properties = ['node_ids']

classmethod add_card(card, comment='')

Adds a CMASS3 card from BDF.add_card(...)

Parameters:

card : BDFCard()

a BDFCard object

comment : str; default=’‘

a comment for the card

center_of_mass(self)

cross_reference(self, model)

Cross links the card so referenced cards can be extracted directly

Parameters:

model : BDF()

the BDF object

node_ids

raw_fields(self)

type = 'CMASS3'

uncross_reference(self)

Removes cross-reference links

write_card(self, size=8, is_double=False)

Writes the card with the specified width and precision

Parameters:

size : int (default=8)

size of the field; {8, 16}

is_double : bool (default=False)

is this card double precision

Returns:

msg : str

the string representation of the card

class pyNastran.bdf.cards.elements.mass.CMASS4(eid, mass, nids, comment='')

Bases: pyNastran.bdf.cards.elements.mass.PointMassElement

Defines a scalar mass element that is connected only to scalar points, without reference to a property entry

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CMASS4	EID	M	S1	S2

Creates a CMASS4 card

Parameters:

eid : int

element id

mass : float

SPOINT mass

nids : List[int, int]

SPOINT ids

comment : str; default=’‘

a comment for the card

Centroid(self)

Mass(self)

S1(self)

S2(self)

classmethod _init_from_empty()

_properties = ['node_ids']

classmethod add_card(card, icard=0, comment='')

center_of_mass(self)

cp_name_map = {'M': 'mass'}

cross_reference(self, model)

Cross links the card so referenced cards can be extracted directly

Parameters:

model : BDF()

the BDF object

node_ids

raw_fields(self)

safe_cross_reference(self, model, xref_errors)

type = 'CMASS4'

uncross_reference(self)

Removes cross-reference links

write_card(self, size=8, is_double=False)

Writes the card with the specified width and precision

Parameters:

size : int (default=8)

size of the field; {8, 16}

is_double : bool (default=False)

is this card double precision

Returns:

msg : str

the string representation of the card

class pyNastran.bdf.cards.elements.mass.CONM1(eid, nid, mass_matrix, cid=0, comment='')

Bases: pyNastran.bdf.cards.elements.mass.PointMassElement

Concentrated Mass Element Connection, General Form Defines a 6 x 6 symmetric mass matrix at a geometric grid point

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CONM1	EID	G	CID	M11	M21	M22	M31	M32
	M33	M41	M42	M43	M44	M51	M52	M53
	M54	M55	M61	M62	M63	M64	M65	M66

Creates a CONM1 card

Parameters:

eid : int

element id

nid : int

the node to put the mass matrix

mass_matrix : (6, 6) float ndarray

the 6x6 mass matrix, M

cid : int; default=0

the coordinate system for the mass matrix

comment : str; default=’‘

a comment for the card

::

[M] = [M11 M21 M31 M41 M51 M61]

[ M22 M32 M42 M52 M62] [ M33 M43 M53 M63] [ M44 M54 M64] [ Sym M55 M65] [ M66]

static Centroid()

Cid(self)

static Mass()

MassMatrix(self)

Nid(self)

_finalize_hdf5(self, encoding)

hdf5 helper function

classmethod _init_from_empty()

_properties = ['node_ids']

classmethod add_card(card, comment='')

Adds a CONM2 card from BDF.add_card(...)

Parameters:

card : BDFCard()

a BDFCard object

comment : str; default=’‘

a comment for the card

center_of_mass(self)

cross_reference(self, model)

Cross links the card so referenced cards can be extracted directly

Parameters:

model : BDF()

the BDF object

node_ids

raw_fields(self)

repr_fields(self)

Gets the fields in their simplified form

Returns:

fields : List[varies]

the fields that define the card

safe_cross_reference(self, model, xref_errors)

Cross links the card so referenced cards can be extracted directly

Parameters:

model : BDF()

the BDF object

type = 'CONM1'

uncross_reference(self)

Removes cross-reference links

update_by_cp_name(self, name, value)

write_card(self, size=8, is_double=False)

Writes the card with the specified width and precision

Parameters:

size : int (default=8)

size of the field; {8, 16}

is_double : bool (default=False)

is this card double precision

Returns:

msg : str

the string representation of the card

class pyNastran.bdf.cards.elements.mass.CONM2(eid, nid, mass, cid=0, X=None, I=None, comment='')

Bases: pyNastran.bdf.cards.elements.mass.PointMassElement

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CONM2	EID	NID	CID	MASS	X1	X2	X3
	I11	I21	I22	I31	I32	I33
CONM2	501274	11064		132.274

Creates a CONM2 card

Parameters:

eid : int

element id

nid : int

node id

mass : float

the mass of the CONM2

cid : int; default=0

coordinate frame of the offset (-1=absolute coordinates)

X : (3, ) List[float]; default=None -> [0., 0., 0.]

xyz offset vector relative to nid

I : (6, ) List[float]; default=None -> [0., 0., 0., 0., 0., 0.]

mass moment of inertia matrix about the CG I11, I21, I22, I31, I32, I33 = I

comment : str; default=’‘

a comment for the card

Centroid(self)

This method seems way more complicated than it needs to be thanks to all these little caveats that don’t seem to be supported.

Centroid_no_xref(self, model)

This method seems way more complicated than it needs to be thanks to all these little caveats that don’t seem to be supported.

Cid(self)

I = None

Mass moments of inertia measured at the mass center of gravity in the coordinate system defined by field 4. If CID = -1, the basic coordinate system is implied. (Real) I11, I21, I22, I31, I32, I33 = I

Inertia(self)

Returns the 3x3 inertia matrix .. warning:: doesnt handle offsets or coordinate systems

Mass(self)

Nid(self)

X = None

Offset distances from the grid point to the center of gravity of the mass in the coordinate system defined in field 4, unless CID = -1, in which case X1, X2, X3 are the coordinates, not offsets, of the center of gravity of the mass in the basic coordinate system. (Real)

classmethod add_card(card, comment='')

Adds a CONM2 card from BDF.add_card(...)

Parameters:

card : BDFCard()

a BDFCard object

comment : str; default=’‘

a comment for the card

center_of_mass(self)

cid = None

Coordinate system identification number. For CID of -1; see X1, X2, X3 below. (Integer > -1; Default = 0)

cross_reference(self, model)

Cross links the card so referenced cards can be extracted directly

Parameters:

model : BDF()

the BDF object

eid = None

Element identification number. (0 < Integer < 100,000,000)

classmethod export_to_hdf5(h5_file, model, eids)

exports the elements in a vectorized way

mass = None

Mass value. (Real)

nid = None

Grid point identification number. (Integer > 0)

node_ids

offset(self, xyz_nid)

raw_fields(self)

repr_fields(self)

Gets the fields in their simplified form

Returns:

fields : List[varies]

the fields that define the card

safe_cross_reference(self, model, xref_errors)

Cross links the card so referenced cards can be extracted directly

Parameters:

model : BDF()

the BDF object

type = 'CONM2'

uncross_reference(self)

Removes cross-reference links

update_by_cp_name(self, name, value)

validate(self)

card checking method that should be overwritten

write_card(self, size=8, is_double=False)

Writes the card with the specified width and precision

Parameters:

size : int (default=8)

size of the field; {8, 16}

is_double : bool (default=False)

is this card double precision

Returns:

msg : str

the string representation of the card

write_card_16(self, is_double=False)

class pyNastran.bdf.cards.elements.mass.PointMassElement

Bases: pyNastran.bdf.cards.base_card.Element

repr_fields(self)

Gets the fields in their simplified form

Returns:

fields : List[varies]

the fields that define the card

write_card(self, size=8, is_double=False)

Writes the card with the specified width and precision

Parameters:

size : int (default=8)

size of the field; {8, 16}

is_double : bool (default=False)

is this card double precision

Returns:

msg : str

the string representation of the card

write_card_16(self, is_double=False)

pyNastran.bdf.cards.elements.mass.is_positive_semi_definite(A, tol=1e-08)

is the 3x3 matrix positive within tolerance