OS-C501

Recommendations

Info

Offshore Standard DNV-OS-C501, November 2013 Sec.6 Failure mechanisms and design criteria – Page 106 3.1.8 Regardless of the analysis method used, these laminates should always be analysed with non-degraded matrix dominated elastic constants, i.e., E 2 , G 12 , n 12 . 3.2 Fibre failure at the ply level 3.2.1 For single loads, the maximum strain design criterion is given as: where: ε nk ̂ γ F γ Sd, γ M γ Rd, Characteristic value of the local response of the structure (strain) in the fibre direction n Characteristic value of the axial strain to fibre failure Partial load effect factor Partial load-model factor Partial resistance factor Partial resistance-model factor, given in [3.2.2] (below). 3.2.2 The selection of the resistance model factor γ Rd depends on the choice of structural analysis method: — if a linear analysis with non-degraded properties is chosen according to Sec.9 [2.4], then γ Rd = γ A , as described in Sec.9 [3.2.2] — in all other cases γ Rd = 1.0. 3.2.3 The maximum strain criterion shall be checked in all n directions parallel to the fibres, and for tensile and compressive strains. 3.2.4 εˆ k fibre is the time dependent characteristic strength of the ply in fibre direction. It shall be determined according to Sec.4 [3]. One value for one fibre and weave type. 3.2.5 For N combined loads, with combination j being the worst combination (see Sec.3 [11.2]) the maximum strain design criterion is given by: where, e i nk γ Sd ⎡ j . ⎢γ F . ε ⎣ γ . γ ∧ fiber k Characteristic value of the local response of the structure (strain) in the fibre direction - n - due to load - i - ˆ ε fibre k Characteristic value of the axial strain to fibre failure γ i F Partial load effect factor for load - i - Ψ i Combination factor for load - i - γ j F , Partial load effect and resistance factors for load - j - γ M Partial resistance factor γ Rd Partial resistance-model factor, given in [3.2.2] 3.2.6 The partial resistance factor γ M shall be the largest value for all load strength combinations - j -. Guidance note: In the equation above, it is important to see that the partial resistance factor γ j M , corresponding to the load j alone, is used as the common partial resistance factor. ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 3.3 Fibre failure check using a modified Tsai-Wu criterion j nk F Sd +∑ i≠ j . ε nk i F ε < γ . γ 3.3.1 In many cases the maximum fibre strain criterion is not available in commercial software packages. As an alternative the Tsai-Wu criterion may be used with modified input parameters as described here. This approach was developed by FiReCo AS. 3.3.2 If [3.1.5] is relevant, this criterion may be used to check simultaneously for fibre failure and laminate failure due to high shear in the plies. i nk M γ . ε . Ψ i Rd ∧ fiber k ⎤ ε ⎥ < ⎦ γ M . γ Rd DET NORSKE VERITAS AS
Offshore Standard DNV-OS-C501, November 2013 Sec.6 Failure mechanisms and design criteria – Page 107 3.3.3 The Tsai-Wu criterion is described in 3-D as: in 2-D: with R = γ F · γ Sd · γ m · γ Rd R 2 + R + R R 2 2 2 2 2 2 2 ( F11σ 1 + F22σ 2 + F33σ 3 + F12σ 12 + F13σ 13 + F23σ 23 ) 2 ( 2H12σ 1σ 2 + 2H13σ 1σ 3 + 2H 23σ 2σ 3 ) ( Fσ + F σ + F σ ) < 1 1 1 2 2 3 3 2 2 2 ( F σ + F σ + F σ + H σ σ ) + R ( Fσ + F σ ) < 1 11 1 22 2 12 12 2 12 1 2 1 1 2 2 F 11 = ∧ σ 1t 1 ∧ σ 1c , F 22 = ∧ σ 2t 1 ∧ σ 2c , F 33 = ∧ σ 3t 1 ∧ σ 3c 1 1 F 12 = , F ∧ 13 = , ∧ 2 2 σ 12 σ 13 F 23 = 1 ∧ 2 23 σ F 1 = ∧ σ 1 1t 1 − ∧ σ 1c , F 2 = ∧ σ 1 2t − ∧ σ 1 2c , F 3 = ∧ σ 1 3t − ∧ σ 1 3c * H12 * H13 H 12 = , H 13 = , F F F F 11 22 11 33 H = * 23 H F 22 23 F 33 where, n σ∧ n σ nt ∧ σ nc ∧ the co-ordinate system is the ply co-ordinate system, where n refers to the directions 1, 2, 3, 12, 13 and 23 characteristic value of the local load effect of the structure (stress) in the direction n characteristic tensile strength in the direction n characteristic compressive strength in the direction n σ nk characteristic shear strength in the direction nk γ F partial load effect factor γ Sd, partial load-model factor γ M partial resistance factor γ Rd partial resistance-model factor, for values see [3.3.4]. H 12 H 13 H 23 * * * 3.3.4 The interaction parameters , , should be determined experimentally for each material. In that case γ Rd = 1.0. Alternatively values between 0 and -0.5 may be chosen as a default, in that case γ Rd = 1.15. 3.3.5 Since Tsai-Wu criterion is here only used to check for fracture of the laminate (see [3.1.5]) and small matrix cracks are acceptable, strength properties should be taken as described below. Characteristic strengths as described in Sec.4 [2.4] should always be used. ∧ σ ∧ σ 1t 1c ∧ σ ∧ σ ∧ σ 2t 2c 3t ∧ σ 3c E ∧ 2 = σ E 1 E ∧ 2 = σ E 1 1t 1c tensile ply strength in fibre direction, as defined in Sec.4. compressive ply strength in fibre direction, as defined in Sec.4. modified in-plane tensile ply strength transverse to the fibres. modified in-plane compressive ply strength transverse to the fibres. tensile through thickness ply strength in fibre direction, as defined in Sec.4. compressive through thickness ply strength in fibre direction, as defined in Sec.4. DET NORSKE VERITAS AS
Page 1 and 2:
OFFSHORE STANDARD DNV-OS-C501 Compo
Page 3 and 4:
Offshore Standard DNV-OS-C501, Nove
Page 5 and 6:
Page 7 and 8:
Page 9 and 10:
Page 11 and 12:
Page 13 and 14:
Page 15 and 16:
Page 17 and 18:
Page 19 and 20:
Page 21 and 22:
Page 23 and 24:
Page 25 and 26:
Page 27 and 28:
Page 29 and 30:
Page 31 and 32:
Page 33 and 34:
Page 35 and 36:
Page 37 and 38:
Page 39 and 40:
Page 41 and 42:
Page 43 and 44:
Page 45 and 46:
Page 47 and 48:
Page 49 and 50:
Page 51 and 52:
Page 53 and 54:
Page 55 and 56: Offshore Standard DNV-OS-C501, Nove
Page 105: Offshore Standard DNV-OS-C501, Nove
Page 157 and 158:
Page 159 and 160:
Page 161 and 162:
Page 163 and 164:
Page 165 and 166:
Page 167 and 168:
Page 169 and 170:
Page 171 and 172:
Page 173 and 174:
Page 175 and 176:
Page 177 and 178:
Page 179 and 180:
Page 181 and 182:
Page 183 and 184:
Page 185 and 186:
Page 187 and 188:
Page 189 and 190:
Page 191 and 192:
Page 193 and 194:
Page 195 and 196:
Page 197 and 198:
Page 199 and 200:
Page 201 and 202:
Page 203 and 204:
Page 205 and 206:
Page 207 and 208:
Page 209 and 210:
Page 211 and 212:
Page 213 and 214:
Page 215 and 216:
Page 217 and 218:
Page 219 and 220:
Page 221 and 222:
Page 223 and 224:
Page 225 and 226:
Page 227 and 228:
Page 229 and 230:
Page 231 and 232:
Page 233 and 234:
Page 235 and 236:
Page 237 and 238:
Page 239 and 240:
Page 241 and 242:
Page 243 and 244:
Page 245 and 246:
Page 247 and 248:
Page 249 and 250:
show all

OS-C501

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?