Command-line interface

PyFlange includes a command-line tool that performs deterministic and Monte Carlo bolt fatigue analyses of flange cases described in the PyFlange JSON format. After installing PyFlange, it can be invoked either as pyflange or as python -m pyflange:

pyflange --help
pyflange COMMAND --help

A complete example case file is available here: fatigue-case.json.

Commands

determ

Performs a deterministic fatigue analysis and writes a detailed report of the case and its results to a JSON file (see Result files).

pyflange determ case.json                    # writes case-res.json
pyflange determ case.json --xlsx             # also writes case-res.xlsx
pyflange determ case.json --gap-angle 45 --gap-height 1.5 --tilt-angle 0.2 --smf 1.1

Option	Description
--gap-angle	Override of the gap angle, in degrees. The shell stiffness is re-interpolated for the new angle.
--gap-height	Override of the gap height, in mm.
--tilt-angle	Override of the tilt angle, in degrees.
--smf	Stress multiplication factor. Defaults to the case SMF, or 1.0.
--odir	Output folder. Defaults to the current folder.
--oname	Output file name. Defaults to <case>-res[<overrides>].json.
--xlsx	Also write the report to an Excel file, as a key/value table with a named cell per value.

sample

Runs a Monte Carlo simulation, based on the Stats section of the case, and writes one row per realization to a CSV file.

pyflange sample case.json                     # 100000 realizations, case-sample.csv
pyflange sample case.json --size 5000 --seed 1 --xlsx

Option	Description
--size	Number of realizations. Defaults to 100000.
--seed	Seed of the random number generator. With the same seed and case, the same sample is generated. If omitted, every run is different.
--odir	Output folder. Defaults to the current folder.
--oname	Output file name. Defaults to <case>-sample.csv.
--xlsx	Also write the sample to an Excel file.

The CSV columns are:

Column	Unit	Description
BoltPreload	N	Bolt preload after losses.
GapShapeFactor	-	Gap shape factor.
TiltAngle	rad	Flange tilt angle.
GapAngle	rad	Gap angle.
GapHeight	m	Gap height.
FatigueClass	Pa	Knee-point stress range of the random bolt S-N curve (size effect included).
MomentRangeCoefficient	-	Factor applied to the Markov matrix ranges.
Damage	-	Fatigue damage.
AllowableDamage	-	Allowable damage.
FatigueLife	as Markov matrix duration	Fatigue life.
SMF	-	Stress multiplication factor.
Utilization	-	Damage / AllowableDamage.

inspect

Rebuilds a single realization of a sample and writes its detailed report, like determ does for the deterministic case. This is useful to investigate outliers.

pyflange inspect case.json 1234               # reads case-sample.csv, writes case-realization-1234.json
pyflange inspect case.json 1234 --spath other-sample.csv --xlsx

Option	Description
--spath	Path of the sample CSV file. Defaults to <case>-sample.csv, in the folder of the case.
--odir, --oname, --xlsx	As for determ.

stats

Prints minimum, 5% quantile, average, 95% quantile, maximum, standard deviation and coefficient of variation of each column of a sample.

pyflange stats case-sample.csv

Migrating from Forrester

The PyFlange command-line interface replaces the Forrester tool of the Bolt & Beautiful project:

• forrester determ, sample, inspect and stats become pyflange determ, sample, inspect and stats, with the same options. sample adds the --seed option and writes the same CSV columns.
• Forrester case files (format version 0.1.0) can be used as they are.
• forrester hist has been removed: plot the sample CSV with your tool of choice.
• forrester export-sgre-case is not part of PyFlange: the conversion of company-specific file formats to the PyFlange JSON format is left to dedicated tools.