Manual for LS-DYNA Wood Material Model 143
2. USER’S MANUAL
This section is intended to be a brief user’s manual for those users who want to run the model with a cursory, rather than indepth, understanding of the underlying theory and equations. This section includes a description of the LS-DYNA wood model input, a brief parameter description, and methods of fitting the parameters to data. This section concludes with a brief description of the wood model theory and an example output file.
2.1 LS-DYNA INPUT
*MAT_WOOD_{OPTION}
This is material type 143. This is a transversely isotropic material and is available for solid elements in LS-DYNA. The user has the option of inputting his or her own material properties (<BLANK> option) or requesting default material properties for southern yellow pine (PINE) or Douglas fir (FIR).
Options include: |
|
PINE |
|
FIR |
|
<BLANK> |
such that the keyword cards appear: |
|
*MAT_WOOD_PINE |
|
*MAT_WOOD_FIR |
|
*MAT_WOOD |
Define the following card for all options:
Card Format
Card 1 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
Variable |
MID |
RO |
NPLOT |
ITERS |
IRATE |
GHARD |
IFAIL |
|
Type |
I |
F |
I |
I |
I |
F |
I |
|
Define the following cards for the PINE and FIR options:
Card 2 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
Variable |
MC |
TEMP |
QT |
QC |
UNITS |
IQUAL |
|
|
Type |
F |
F |
F |
F |
I |
I |
|
|
Define the following cards for the <BLANK> option (do not define for PINE or FIR):
Card 3 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
Variable |
EL |
ET |
GLT |
GTR |
nLT |
|
|
|
Type |
F |
F |
F |
F |
F |
|
|
|
Card 4 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
Variable |
XT |
XC |
YT |
YC |
S|| |
S^ |
|
|
Type |
F |
F |
F |
F |
F |
F |
|
|
Card 5 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
Variable |
Gf I^ |
Gf II || |
B |
dmax|| |
Gf I^ |
Gf II^ |
D |
dmax^ |
Type |
F |
F |
F |
F |
F |
F |
F |
F |
Card 6 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
Variable |
h|| |
hC|| |
n|| |
h^ |
hC^ |
n^ |
|
|
Type |
F |
F |
F |
F |
F |
F |
|
|
Card 7 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
Variable |
N|| |
c|| |
N^ |
c^ |
|
|
|
|
Type |
F |
F |
F |
F |
|
|
|
|
Define for all options:
Card 8 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
Variable |
AOPT |
|
|
|
|
|
|
|
Type |
I |
|
|
|
|
|
|
|
Card 9 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
Variable |
XP |
YP |
ZP |
A1 |
A2 |
A3 |
|
|
Type |
F |
F |
F |
F |
F |
F |
|
|
Card 10 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
Variable |
D1 |
D2 |
D3 |
|
|
|
|
|
Type |
F |
F |
F |
|
|
|
|
|
Variable |
Description |
MID |
Material identification (a unique number has to be chosen) |
RO |
Mass density |
NPLOT |
Plotting options: EQ. 1: Maximum of parallel and perpendicular damage (default) EQ. 2: Perpendicular damage |
ITERS |
Number of plasticity algorithm iterations (default is one iteration; values greater than 1 are not recommended) |
IRATE |
Rate-effect options: EQ. 0: Rate-effect model turned off (default) EQ. 1: Rate-effect model turned on |
GHARD |
Perfect plasticity override (values greater than or equal to zero are allowed). Positive values model late-time hardening in compression (an increase in strength with increasing strain). A zero value models perfect plasticity (no increase in strength with increasing strain). The default is zero. |
IFAIL |
Erosion perpendicular to the grain: EQ. 0: No (default) EQ. 1: Yes (not recommended except for debugging) |
Define for PINE and FIR options:
Variable |
Description |
|
|
|
|
MC |
Percent moisture content (if left blank, moisture content defaults to saturated at 30 percent) |
TEMP |
Temperature in °C (if left blank, temperature defaults to room temperature at 20 °C) |
QT |
Quality factor options (these quality factors reduce the clear wood tension/shear and compression strengths as a function of grade): EQ. 0: Grades 1, 1D, 2, 2D |
|
Predefined strength-reduction factors are: |
Pine: |
QT = 0.47 in tension/shear QC = 0.63 in compression |
Fir: |
QT = 0.40 in tension/shear QC = 0.70 in compression |
EQ. -1:DS-65 or SEL STR |
|
Predefined strength-reduction factors are:
QT = 0.80 in tension/shear
QC = 0.93 in compression |
EQ. -2:Clear wood |
|
QT = 1.0 in tension/shear
QC = 1.0 in compression |
GT. 0: |
User-defined quality factor in tension (values greater than 0 and less than or equal to 1 are expected; values greater than 1 are allowed, but may not be realistic. |
QC |
User-defined quality factor in compression (This input value is used if QT > 0. Values greater than 0 and less than or equal to 1 are expected. Values greater than 1 are allowed, but may not be realistic. If left blank when QT > 0, a default value of QC = QT is used.) |
UNITS |
Unit options: EQ. 0: gigapascals (GPa), mm, milliseconds (ms), kilograms per cubic millimeter (kg/mm3), kilonewtons (kN) EQ. 1: MPa, ms, grams per cubic millimeter (g/mm3), newtons (N) EQ. 2: MPa, mm, s, megagrams per cubic millimeter (Mg/mm3), N EQ. 3: lbf/inch2, inch, s, pound second squared per inch to the fourth power (lb-s2/inch4), pounds force (lbf) |
IQUAL |
Apply quality factors perpendicular to the grain: EQ. 0: Yes (default) EQ. 1: No |
Remarks: Material property data are for clear wood (small samples without defects such as knots), whereas real structures are composed of graded wood. Clear wood is stronger than graded wood. Quality factors (strength-reduction factors) are applied to the clear wood strengths to account for reductions in strength as a function of grade. One quality factor (QT) is applied to the tensile and shear strengths. A second quality factor (QC) is applied to the compressive strengths. As an option, predefined quality factors are provided based on correlations between LS-DYNA calculations and test data for pine and fir posts impacted by bogie vehicles. By default, quality factors are applied to the parallel strengths and to the perpendicular strengths. An option is available (IQUAL) to eliminate application perpendicular to the grain.
Define for <BLANK> option only:
Variable |
Description |
EL |
Parallel normal modulus |
ET |
Perpendicular normal modulus |
GLT |
Parallel shear modulus (GLR = GLT) |
GTR |
Perpendicular shear modulus |
nLT |
Parallel major Poisson’s ratio |
XT |
Parallel tensile strength |
XC |
Parallel compressive strength |
YT |
Perpendicular tensile strength |
YC |
Perpendicular compressive strength |
S|| |
Parallel shear strength |
S^ |
Perpendicular shear strength |
Gf I || |
Parallel fracture energy in tension |
Gf II || |
Parallel fracture energy in shear |
B |
Parallel softening parameter |
dmax|| |
Parallel maximum damage |
Gf I ^ |
Perpendicular fracture energy in tension |
Gf II ^ |
Perpendicular fracture energy in shear |
D |
Perpendicular softening parameter |
dmax^ |
Perpendicular maximum damage |
h|| |
Parallel fluidity parameter in tension/shear |
hc|| |
Parallel fluidity parameter in compression |
n|| |
Parallel power |
h^ |
Perpendicular fluidity parameter in tension/shear |
hc^ |
Perpendicular fluidity parameter in compression |
n^ |
Perpendicular power |
N|| |
Parallel hardening initiation |
c|| |
Parallel hardening rate |
N^ |
Perpendicular hardening initiation |
c^ |
Perpendicular hardening rate |
Define for all options:
AOPT material axes option (see MAT_OPTIONTROPIC_ELASTIC for a more complete description):
|
EQ. 0: Locally orthotropic with material axes determined by element |
|
EQ. 1: Locally orthotropic with material axes determined by a point in space and the global location of the element center; this is the a-direction |
|
EQ. 2: Globally orthotropic with material axes determined by vectors defined below, as with *DEFINE_COORDINATE_VECTOR |
XP, YP, ZP Coordinates of point p for AOPT = 1
A1, A2, A3 Coordinates of vector a for AOPT = 2
D1, D2, D3 Components of vector d for AOPT = 2
Remarks: One common option is AOPT = 2. The user defines vectors a and d. Typically, a is the parallel-to-the-grain direction and d is one of the perpendicular-to-the-grain directions. Then, a x d = c and c x a = b, where a, b, and c are the principal material axes.
FHWA-HRT-04-097
|