CALCS BAS005
FATIGUE LIFE, HSE OFFSHORE INSTALLATIONS, SECTION A21.2

NOTATION

CASEcase title
CCcycle class id
fustress, unit load (MPa)
frstress, range (MPa)
gcgroup cycles (x10^6)
JCjoint classification id
lfatigue endurance, for a particular stress range, l=n/N
Lnon-dimensional life, sum(l), fatigue life for specified duty, >1.00 life exceeded
LGload group id
lrload ranges
nstress cycles thru design life
Nstress cycles from S-N Curve
Ncasno.cases
Nccno.cycle classes
Nfuno.unit load stresses per cycle class
Nlgno.load groups per cycle class
REMremark lines may be inserted anywhere for clarification
SRPstress recovery point id

APPLICATION

Structures subject to cyclic loading which may cause fatigue damage.
Maximum numbers: Nlg 10, Nfu 10, JC 10.

OUTPUT

fatigue life

SEE ALSO

BAS021, PROC050, PROC052

THEORY

as title

GUIDANCE

Definitions:
Load Group: External loading event causing a set of stress ranges fr to be developed at the selected points in the structure. A single stress range is associated with each load group at each point.
Cycle Classes: An operating duty may be composed of a number of components. For example, a deck crane is subject to crane operating and ship motion inertial fatigue loading.
Cases: These may differentiate between similar structures in different locations, subject to position specific loading.
Unit load sets: May be for example predominately roll, pitch and combined acceleration sets, composed of longitudinal, transverse and vertical accelerations.
Load Ranges: Load Ranges may be obtained from BAS021. The program calculates load ranges from a combination of unit load sets defined for each load group.
Stress Ranges: Determined for each load group by summing unit load stress products with the appropriate load ranges.
Usage instructions: Only the LOAD RANGE data is repeated for more than one CASE. DATA statements are used for data input. S-N curves for joint types D E F F2 G & W are presently available. Others may be added as required.

INPUT FORMAT

DAT005title
REM remark lines may be inserted anywhere for clarification
NccNcc
NsrpNsrp
NcasNcas
Nlg< FOR A=1 TO Ncc > Nlg < NEXT > :REM no.load groups per cycle class
Nfu< FOR A=1 TO Ncc > Nfu < NEXT > :REM no.unit load stresses per cycle class
< FOR A=1 TO Ncc >
gc< FOR B=1 TO Nlg > gc < NEXT > :REM stress cycles per group per class
< NEXT >
JC< FOR A=1 TO Nsrp > JC < NEXT >:REM joint classification
< FOR A=1 TO Ncc:FOR B=1 TO Nfu >
fu< FOR C=1 TO Nsrp > DATA fu < NEXT > :REM unit load stresses
< NEXT:NEXT >
< FOR A=1 TO Ncas >
CASEcasetitle
< FORB=1 TO Ncc:FOR C=1 TO Nfu >
lr< FOR D=1 TO Nlg > lr < NEXT >:REM load ranges
< NEXT:NEXT:NEXT >
ENDDAT

EXAMPLE

Input

DAT005example
Ncc2
Nsrp7
Ncas1
REMCC1CC2
Nlg101
Nfu31
REM gc1 for CC1 10 ship motion groups
REM gc2 for CC2 1 crane operating group
REMLG1LG2LG3LG4LG5LG6LG7LG8LG9LG10
gc140.319.023.036.3356.067317.278.1511.301.1438.0288
gc2.073
REMSRP1SRP2SRP3SRP4SRP5SRP6SRP7
JCDDDF2F2GG
REM fu (for 3 unit accels & 1 crane op case)
REMSRP1SRP2SRP3SRP4SRP5SRP6SRP7
fu194.266.6044.4036.20
fu2066.694.2071.0036.2
fu34.24.24.24.26.700
fu4123.4123.4123.461.398.036.736.7
REM load ranges
CASE1AFT CRANE FATIGUE LIFE
REMLG1LG2LG3LG4LG5LG6LG7LG8LG9LG10
lr16.3744E-33.3077E-26.364E-20.120240.178937.4335E-34.3288E-20.112330.135790.19049
lr21.0632E-34.6161E-31.3726E-23.3871E-25.8129E-26.3744E-32.7465E-20.134930.244990.41558
lr39.9968E-34.857E-28.008E-29.7079E-20.15421.2722E-26.3397E-20.123290.137220.21345
lr42
ENDDAT

Output

OUTPUTexample, output shown for stress recovery point1 only
DAT005 FATIGUE LIFE, HSE OFFSHORE INSTALLATIONS, SECTION A21.2
AFT CRANE FATIGUE LIFE, STRESS POINT1,JOINT CLASS D
fr= +94.2*6.374E-3+0*1.063E-3+4.2*9.997E-3= 0.642
l= 4.03E7/1E9=4.0E-2
fr= +94.2*3.308E-2+0*4.616E-3+4.2*4.857E-2= 3.32
l= 1.902E7/1E9=1.9E-2
fr= +94.2*6.364E-2+0*1.373E-2+4.2*8.008E-2= 6.33
l= 3.036E6/1E9=3.0E-3
fr= +94.2*0.1202+0*3.387E-2+4.2*9.708E-2= 11.73
l= 3.356E5/1.515E10=2.2E-5
fr= +94.2*0.1789+0*5.813E-2+4.2*0.1542= 17.5
l= 6.73E4/2.171E9=3.1E-5
fr= +94.2*7.434E-3+0*6.374E-3+4.2*1.272E-2= 0.753
l= 1.727E7/1E9=1.7E-2
fr= +94.2*4.329E-2+0*2.747E-2+4.2*6.34E-2= 4.34
l= 8.151E6/1E9=8.1E-3
fr= +94.2*0.1123+0*0.1349+4.2*0.1233= 11.1
l= 1.301E6/1.986E10=6.5E-5
fr= +94.2*0.1358+0*0.245+4.2*0.1372= 13.37
l= 1.438E5/8.044E9=1.7E-5
fr= +94.2*0.1905+0*0.4156+4.2*0.2135= 18.84
l= 2.88E4/1.518E9 = 1.897E-5 135= 18.84
l= 2.88E4/1.518E9=1.8E-5
fr= +123.4*2= 246.8
l= 7.3E4/1.011E5= 0.722
L= SUM(l)= 0.810
END005