3.1. Nonlinear Elements Supported in an HBM Analysis

The supported nonlinear elements are listed here, followed by tables detailing supported options for each element. Any combination of these HBM supported nonlinear elements can be used to build the nonlinear part of the model.

Polynomial nonlinearity USER300 (KEYOPT(1) = 2)
- A predefined polynomial user element (USER300) is provided. For information on its inputs and usage, see Example 1: 1-DOF Duffing Oscillator.
Nonlinear spring COMBIN39
Combination COMBIN40
Node-to-node contact CONTA178

Table 3.1: Supported Options for Nonlinear Spring Element COMBIN39

KEYOPTION / Real constant	Details
Real Constants D1, F1, D2, F2, D3, F3, D4, F4, ..., D250, F250	D value for the n^th point on force-deflection curve F value for the n^th point on force-deflection curve
KEYOPT(1) Unloading Path	KEYOPT(1) = 0 - Unload along same loading curve
KEYOPT(2) Element behavior under compressive load	KEYOPT(2) = 0 - Compressive loading follows defined compressive curve (or reflected tensile curve if not defined)
KEYOPT(3) Element degrees of freedom (1D) (KEYOPT(4) overrides KEYOPT(3))	KEYOPT(3) = 0,1 - UX (Displacement along nodal X axes) KEYOPT(3) = 2 - UY (Displacement along nodal Y axes) KEYOPT(3) = 3 - UZ (Displacement along nodal Z axes) KEYOPT(3) = 4 - ROTX (Rotation about nodal X axes) KEYOPT(3) = 5 - ROTY (Rotation about nodal Y axes) KEYOPT(3) = 6 - ROTZ (Rotation about nodal Z axes)
KEYOPT(4) Element degrees of freedom (2D or 3D)	KEYOPT(4) = 0 - Use any KEYOPT(3) option KEYOPT(4) = 1 - 3D longitudinal element (UX, UY and UZ) KEYOPT(4) = 2 - 3D torsional element (ROTX, ROTY and ROTZ) KEYOPT(4) = 3 - 2D longitudinal element. (UX and UY) Element must lie in an X-Y plane

Table 3.2: Supported Options for Combination Element COMBIN40

KEYOPTION / Real constant	Description
Real Constants^[a]	K1 - Spring constant C - Damping coefficient GAP - Gap size
KEYOPT(1) Gap behavior	KEYOPT(1) = 0 - Standard gap capability
KEYOPT(3) Element degrees of freedom	KEYOPT(3) = 0, 1 - UX (Displacement along nodal X axes) KEYOPT(3) = 2 - UY (Displacement along nodal Y axes) KEYOPT(3) = 3 - UZ (Displacement along nodal Z axes)

^[a]The units for real constants depend on the KEYOPT(3) setting. See the COMBIN40 element description for details.

Table 3.3: Supported Options for 3D Node-to-Node Contact Element CONTA178

KEYOPTION / Real constant	Description
Real Constants	FKN - Normal Stiffness GAP - Gap size FKS - Sticking stiffness NX - Defined gap normal - X component NY - Defined gap normal - Y component NZ - Defined gap normal - Z component CV1 - Damping coefficient CV2 - Nonlinear damping coefficient
KEYOPT(1) Gap type	KEYOPT(1) = 0 - Unidirectional gap
KEYOPT(2) Contact algorithm	KEYOPT(2) = 1 - Pure penalty method
KEYOPT(4) Gap size	KEYOPT(4) = 0 - Gap size based on real constant GAP + initial node locations KEYOPT(4) = 1 - Gap size based on real constant GAP (ignore node locations)
KEYOPT(5) Basis for contact normal	KEYOPT(5) = 0 - Node locations or real constants NX, NY, NZ KEYOPT(5) = 1 - X component of nodal coordinate system (average on two contact nodes) KEYOPT(5) = 2 - Y component of nodal coordinate system (averaging on two contact nodes) KEYOPT(5) = 3 - Z component of nodal coordinate system (averaging on two contact nodes) KEYOPT(5) = 4 - X component of defined element coordinate system (ESYS) KEYOPT(5) = 5 - Y component of defined element coordinate system (ESYS) KEYOPT(5) = 6 - Z component of defined element coordinate system (ESYS)
KEYOPT(6) Selects degrees of freedom	KEYOPT(6) = 0 - UX, UY, UZ
KEYOPT(9) Initial gap step size application	KEYOPT(9) = 0 - Initial gap size is step applied
KEYOPT(10) Behavior of contact surface	KEYOPT(10) = 0 - Standard