Oasys LS-DYNA Environment 8.1 VOLUME 3 ... - Oasys Software

More documents

Recommendations

Info

Oasys LS-DYNA Environment: User Guide (Version 8.1) Pressure 145 140 135 130 125 120 115 110 105 E-3 100 0 0.02 0.04 0.06 0.08 0.10 Time With Jetting Without Jetting MULTI-CHAMBER AIRBAGS AIRBAG WITH 30 DEGREE JETTING Oasys T/HIS Version 7.0 14-Apr-97 Oasys T/HIS Version 7.0 14-Apr-97 Side-impact airbags frequently contain many separate chambers, with venting occurring between the chambers. These chambers can be modelled as separate airbags in LS-DYNA. Each airbag is given a unique ID at the end of the *AIRBAG keyword. The *AIRBAG_INTERACTION keyword is then used to define the amount of venting between each pair of adjacent chambers. The venting is based on a vent area and a shape factor and increases with the pressure difference between the chambers. The vent area can be defined explicitly as a constant, or via a load curve as a function of time by using a negative value whose absolute value is the load curve ID. Alternatively, a part ID can be given instead; in this case, the total area of all shell elements in this part is used for the vent area. The vent hole can then be meshed with shells made of a null material, and the part ID of these shells used for the vent area. Any change in size of the hole as the bag inflates will thus lead to changes in the mass flow rate between the chambers. *AIRBAG_SIMPLE_AIRBAG MODEL_1 $ SET ID SET TYPE RIGID ID V FACTOR P FACTOR VOLUME DAMPING S FACT 1 1 0 0.000E+00 0.000E+00 0.000E+00 5.000E+01 0.700E+00 8.500E+08 1.100E+09 8.000E+02 1 1.000E+00 50.00000 1.019E-01 1.200E-12 0 *SET_PART_LIST 1 1 3 $ Page 16.8
Oasys LS-DYNA Environment: User Guide (Version 8.1) *AIRBAG_SIMPLE_AIRBAG MODEL_2 $ SET ID SET TYPE RIGID ID V FACTOR P FACTOR VOLUME DAMPING S FACT 2 1 0 0.000E+00 0.000E+00 0.000E+00 5.000E+01 0.700E+00 8.500E+08 1.100E+09 8.000E+02 1 1.000E+00 50.00000 1.019E-01 1.200E-12 0 *SET_PART_LIST 2 2 3 $ $ *AIRBAG_INTERACTION 1 2 500 1.0 0 ERRORS Two common errors in airbag simulations are: (I) Negative energy in control volume. This is usually caused by one of: ! Fabric layers insufficiently widely spaced ! Inconsistent units ! Mass flow curve too high ! Jet focus too close to airbag ! Jet blowing the wrong way (which is visible in D3PLOT) ! Contact errors ! Timestep too big with folded mesh (ii) Negative mass in control volume. This is usually caused by a very large vent area leading to all the gas escaping in a single timestep. If such a large vent area is really required, reduce the timestep. Page 16.9
Page 1:
Oasys LS-DYNA Environment 8.1 VOLUM
Page 4 and 5:
Oasys LS-DYNA Environment: User Gui
Page 6 and 7:
Page 8 and 9:
Page 10 and 11:
Page 12 and 13:
Page 14 and 15:
Page 16 and 17:
Page 18 and 19:
Page 20 and 21:
Page 22 and 23:
Page 24 and 25:
Page 26 and 27:
Page 28 and 29:
Page 30 and 31:
Page 32 and 33:
Page 34 and 35: Oasys LS-DYNA Environment: User Gui
Page 134 and 135:
Page 136 and 137:
Page 138 and 139:
Page 140 and 141:
Page 142 and 143:
Page 144 and 145:
Page 146 and 147:
Page 148 and 149:
Page 150 and 151:
Page 152 and 153:
Page 154 and 155:
Page 156 and 157:
Page 158 and 159:
Page 160 and 161:
Page 162 and 163:
Page 164 and 165:
Page 166 and 167:
Page 168 and 169:
Page 170 and 171:
Page 172 and 173:
Page 174 and 175:
Page 176 and 177:
Page 178 and 179:
Page 180 and 181:
Page 182 and 183:
Page 184 and 185:
Page 186 and 187:
Page 188 and 189:
Page 190 and 191:
Page 192 and 193:
Page 194 and 195:
Page 196 and 197:
Page 198 and 199:
Page 200 and 201:
Page 202 and 203:
Page 204 and 205:
Page 206 and 207:
Page 208 and 209:
Page 210 and 211:
Page 212 and 213:
Page 214 and 215:
Page 216 and 217:
Page 218 and 219:
Page 220 and 221:
Page 222 and 223:
Page 224 and 225:
Page 226 and 227:
Page 228 and 229:
Page 230 and 231:
Page 232 and 233:
Page 234 and 235:
show all

Oasys LS-DYNA Environment 8.1 VOLUME 3 ... - Oasys Software

Create successful ePaper yourself

Delete template?

Save as template?