1. CRS8 - Axisymmetric cross section with axial/torsion strain model and hysteresis effects in bending/cuvature relation

1.1. Data group identifier

NEW COMPonent CRS8

1.2. Component type identifier

Identical to input for cross-section type CRS1 , see Component type identifier for CRS1.

1.3. Mass and volume

Identical to input for cross-section type CRS1 , see Mass and volume for CRS1.

1.4. Stiffness properties classification

If the axial-torsion parameter \(\mathrm {\beta}\) is nonzero, the axial force and torsional moment curves must be linear and and must pass through the origin.

The axial force and torque corresponding to a specific axial strain and torsional strain are determined as follows:

\[\begin{bmatrix} F_x \\ M_x \end{bmatrix} = \begin{bmatrix} EA & \beta EA \\ \beta EA & GJ + \beta^2 EA \end{bmatrix} \begin{bmatrix} \epsilon_x \\ \kappa_x \end{bmatrix}\]

where

  • \(\mathrm {F_x,}\) - Axial force

  • \(\mathrm {M_x}\) - Torsional moment

  • \(\mathrm {EA}\) - Axial stiffness

  • \(\mathrm {GJ}\) - Torsional stiffness

  • \(\mathrm {\beta}\) - Axial-torsion coupling parameter

  • \(\mathrm {\epsilon_x}\) - Axial strain

  • \(\mathrm {\kappa_x}\) - Torsional strain

The equation above may be applied to estimate the \(\mathrm {\beta}\)-parameter based on laboratory testing or by using an axi-symmetric load analysis software.

IEAIGT

  • IEAIGT: integer, default: 1: Axial and torsion stiffness code

    • 1 - constant stiffness

The axial and torsion stiffness code must be specified to 1

1.5. Axial stiffness. Case 1, IEAIGT=1

EA

  • EA: real > 0: Axial stiffness \(\mathrm {[F]}\)

1.6. Bending stiffness.

EI MF SF

  • EI: real: Bending stiffness \(\mathrm {[FL^2]}\)

  • MF: real: Internal friction moment, see figure below. \(\mathrm {[FL]}\)

  • SF: real, default: 10.: Internal friction moment stiffness factor. \(\mathrm {[-]}\)

The default value of SF corresponds to the earlier fixed value of 10.0.

um ii fig71
Figure 1. Internal friction moment description

1.7. Torsion stiffness

Constant torsion stiffness. Case 1 IGT=1
GT BETA

  • GT: real > 0: Torsion stiffness \(\mathrm {[FL^2/Radian]}\)

  • BETA: real: Tension/torsion coupling parameter \(\mathrm {[L]}\)

If the tension/torsion coupling parameter BETA is set to zero, coupling effects between axial force and torsional moment will not occur.

1.8. Damping specification

Identical to input for cross-section type CRS1 , see Damping specification for CRS1.

1.9. Hydrodynamic load types

Identical to input for cross-section type CRS1, see Hydrodynamic load type identification for CRS1.

1.10. Aerodynamic force coefficients

Identical to input for cross-section type CRS1, see Aerodynamic load type identification for CRS1.

1.11. Capacity parameter

Identical to input for cross-section type CRS1, see Capacity parameter for CRS1.