MAT1

Isotropic Material Property Definition

Description: Defines the material properties for linear, temperature-independent, isotropic materials.

Format:

Example:

Field Definition Type Default
MID Material identification number. Integer > 0 Required
E Young's modulus. Real ≥ 0.0 or blank See Remarks 4, 5, and 6
G Shear modulus. Real ≥ 0.0 or blank
NU Poisson's ratio. -1.0 < Real ≤ 0.5 or blank
RHO Mass density. Real or blank 0.0
A Thermal expansion coefficient. Real or blank 0.0
TREF Reference temperature for the calculation of thermal loads. Real or blank 0.0
GE Structural element damping coefficient. See Remarks 10, 11, and 13. Real or blank 0.0
ST, SC, SS Allowable stresses in tension, compression, and shear, respectively. Required if composite element failure index is desired. Real ≥ 0.0 or blank 0.0
FSM Factor of safety calculation method, selected by one of the following values (see Remark 14).
0 = no calculation
1 = von Mises Stress
2 = Principal Stress
Integer 1
CS Honeycomb sandwich core cell size. Required if material defines the core of a honeycomb sandwich and dimpling stability index is desired (LAM = HCS on the PCOMP entry). Real ≥ 0.0 or blank 0.0
EC Honeycomb sandwich core Young's modulus used for stability index analysis. Real ≥ 0.0 or blank E
GC Honeycomb sandwich core shear modulus used for stability index analysis. Real ≥ 0.0 or blank G
ALPHA0 Fracture angle for uniaxial transverse compression in degrees. Used in the NASA LaRC02 failure theory only (see LARC02 in PCOMP entry). See Remark 15. 0.0 ≤ Real ≤ 90.0 53.0
SB Allowable inter-laminar shear stress of the composite laminate bonding material (allowable interlaminar shear stress). See Remark 16. Real ≥ 0.0 or blank See Remark 16
ERSF Young's modulus reduction scale factor for nonlinear composite Progressive Ply Failure Analysis (PPFA). See Remark 18. 0.0 ≤ Real ≤ 1.0 0.0
GRSF Shear modulus reduction scale factor for nonlinear composite Progressive Ply Failure Analysis (PPFA). See Remark 18. 0.0 ≤ Real ≤ 1.0 0.0
FT Composite failure theory. The following theories are allowed:
HILL for the Hill theory
HOFF for the Hoffman theory
TSAI for the Tsai-Wu theory
STRESS for the maximum stress theory
STRAIN for the maximum strain theory
Character or blank
NB Allowable inter-laminar normal stress of the composite laminate bonding material (allowable interlaminar normal stress). See Remark 17. Real ≥ 0.0 or blank See Remark 17
TERSF Identification number of a TABLES1 or TABLEST entry which defines the extensional stress-strain relationship for nonlinear composite Progressive Ply Failure Analysis (PPFA). Integer ≥ 0 or blank
TGRSF Identification number of a TABLES1 or TABLEST entry which defines the shear stress-strain relationship for nonlinear composite Progressive Ply Failure Analysis (PPFA). Integer ≥ 0 or blank

Remarks:

  1. The material identification number must be unique for all MATi entries.
  2. Either E or G must be specified (i.e. nonblank).
  3. If any one of E, G, or NU is blank, it will be computed to satisfy the identity E = 2(1 + NU)G; otherwise, values supplied by the user will be used.
  4. If E and NU or G and NU are both blank, they will both be given the value 0.0.
  5. Implausible data on one or more MAT1 entries will result in a warning message. Implausible data is defined as any of E < 0.0, or G < 0.0, or NU > 0.5, or NU < 0.0, or |1 – E / [2(1+NU)G]| > 0.01.
  6. It is strongly recommended that only two of the three values E, G, and NU be input. The three values may be input independently on the MAT2 entry.
  7. MAT1 materials may be made temperature-dependent by use of the MATT1 entry. In STATIC solutions, linear elastic material properties will be updated as prescribed under the TEMPERATURE Case Control command.
  8. The mass density, RHO, will be used to automatically compute mass for all structural elements.
  9. Weight density may be used in field 6 if the value 1/g is entered on the PARAM, WTMASS entry, where g is the acceleration of gravity.
  10. To obtain the damping coefficient GE, multiply the critical damping ratio C/C0, by 2.0.
  11. TREF and GE are ignored if the MAT1 entry is referenced by a PCOMP entry.
  12. TREF is used only as the reference temperature for the calculation of thermal loads in linear solutions. If TEMPERATURE(INITIAL) is specified, TREF will be ignored.
  13. If PARAM, W4 is not specified, GE is ignored in transient response analysis. (See Section 5, Parameters, for more information on W4.)
  14. Factor of safety calculations are based on two methods: von Mises stress or principal stress. When FT is set to 1, the factor of safety is calculated using:

    and when FT is set to 2, the factor of safety is calculated using:

    where ST and SC come from fields 2 and 3 of the continuation entry, is the von Mises stress, and and are the maximum and minimum principal stresses.

  15. The default value for ALPHA0 has been found experimentally and is typical for fiber reinforced polymer laminates.
  16. The allowable inter-laminar shear stress value SB corresponds to the top surface of the ply. The default value for SB is defined in the SB field of the PCOMP, PCOMPG, and PCOMPS entries and will be used when this field is blank.
  17. The allowable inter-laminar normal stress value NB corresponds to the top surface of the ply. The default value for NB is defined in the NB field of the PCOMPS entry and will be used when this field is blank.
  18. Recommended values for ERSF and GRSF are shown in the below table.
    Variable Recommended Value
    ERSF 0.04
    GRSF 0.20
Parent topic: Section 4: Bulk Data