16.16. Honeycomb Model

BEGIN PARAMETERS FOR MODEL HONEYCOMB
  #
  # Elastic constants
  #
  YOUNGS MODULUS = <real>
  POISSONS RATIO = <real>
  SHEAR MODULUS  = <real>
  BULK MODULUS   = <real>
  LAMBDA         = <real>
  TWO MU         = <real>
  #
  # Orthotropic response
  #
  MODULUS_TTTT = <real>
  MODULUS_LLLL = <real>
  MODULUS_WWWW = <real>
  MODULUS_TTLL = <real>
  MODULUS_TTWW = <real>
  MODULUS_LLWW = <real>
  MODULUS_TLTL = <real>
  MODULUS_LWLW = <real>
  MODULUS_WTWT = <real>
  #
  # Material orientation
  #
  TX = <real>
  TY = <real>
  TZ = <real>
  LX = <real>
  LY = <real>
  LZ = <real>
  #
  # Yield behavior
  #
  YIELD_STRESS = <real>
  A1           = <real>
  B1           = <real>
  C1           = <real>
  A2           = <real>
  B2           = <real>
  C2           = <real>
  A3           = <real>
  B3           = <real>
  C3           = <real>

  TS  = <real>
  LS  = <real>
  WS  = <real>
  TLS = <real>
  LWS = <real>
  WTS = <real>

  ESTL = <real>
  ESTW = <real>
  ESLW = <real>
  ESLT = <real>
  ESWT = <real>
  ESWL = <real>

  MODULUS_FUNCTION = <string>
  RATE_FUNCTION    = <string>
  T_FUNCTION       = <string>
  L_FUNCTION       = <string>
  W_FUNCTION       = <string>
  TL_FUNCTION      = <string>
  LW_FUNCTION      = <string>
  WT_FUNCTION      = <string>
  TTP_FUNCTION     = <string>
  LLP_FUNCTION     = <string>
  WWP_FUNCTION     = <string>
  TLTLP_FUNCTION   = <string>
  LWLWP_FUNCTION   = <string>
  WTWTP_FUNCTION   = <string>
  TTLP_FUNCTION    = <string>
  TTWP_FUNCTION    = <string>
END [PARAMETERS FOR MODEL HONEYCOMB]

The honeycomb constitutive model is used to model the energy absorbing capabilities of aluminum honeycomb. There are three orthogonal material directions for the model: \(T\), \(L\), and \(W\). The \(t\)-direction is generally considered as the “strong” direction, the \(W\)-direction is the “weak” direction, and the \(L\)-direction has an intermediate strength. This convention, however, does not necessarily need to be followed when defining material inputs.

\[\begin{split}\begin{Bmatrix} \dot{\sigma}_{TT} \\ \dot{\sigma}_{LL} \\ \dot{\sigma}_{WW} \\ \dot{\sigma}_{TL} \\ \dot{\sigma}_{LW} \\ \dot{\sigma}_{WT} \\ \end{Bmatrix} = \begin{bmatrix} E_{TTTT} & E_{TTLL} & E_{TTWW} & 0 & 0 & 0 \\ E_{TTLL} & E_{LLLL} & E_{LLWW} & 0 & 0 & 0 \\ E_{TTWW} & E_{LLWW} & E_{WWWW} & 0 & 0 & 0 \\ 0 & 0 & 0 & E_{TLTL} & 0 & 0 \\ 0 & 0 & 0 & 0 & E_{LWLW} & 0 \\ 0 & 0 & 0 & 0 & 0 & E_{WTWT} \end{bmatrix} \begin{Bmatrix} \dot{d}_{TT} \\ \dot{d}_{LL} \\ \dot{d}_{WW} \\ \dot{d}_{TL} \\ \dot{d}_{LW} \\ \dot{d}_{WT} \end{Bmatrix}\end{split}\]

Output variables available for this model are listed in Table 16.5.

Table 16.5 State Variables for HONEYCOMB Model

Index	Name	Description
1	CRUSH	minimum volume ratio
2	EQDOT	effective strain rate
3	RMULT	rate multiplier
5	ITER	iterations
6	EVOL	volumetric strain