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Download LINKpipe 3.2.3 [21.6 MB] (2014-03-11)

LINKpipe Release Notes

Version 3.2.3 (2014-03-11)

Improvements:

  • BS7910 ECA calculation: The user can now select which crack length range the ECA curve should be plotted for.

Fixes:

  • The BS7910 report generation has been made more robust.
  • The BS7910 calculations (FAD window and/or ECA window) could crash if no BS7910 geometry (cylinder/curved shell) was selected.

Version 3.2.2 (2014-02-19)

Fixes:

  • Earlier LINKpipe versions occasionally failed to read the input files in the beginning of a calculation. Very often this was not reproducible and the next time the calculation was started, it would run successfully. Fixed.
  • When running calculations on clad pipes, the calculation would occasionally fail to start the calculation. Fixed.

Version 3.2.1 (2013-12-13)

Fixes:

  • Version 3.2.0 had problems allocating large amount of memory. Fixed; version 3.2.1 will now allocate memory the same way as older LINKpipe versions.
  • Generation of the calculation report crashed if the model contained the combined misalignment model. Fixed.
  • Fixed a crash during generation of BS7910 report.

Version 3.2.0 (2013-11-11)

Improvements:

  • The concept for the J calculation has been improved. See the theory manual for details.
  • Other minor improvements.

Fixes:

  • For cracks positioned at the fusion line ("split lines-spring"): The J values written to result.res was based on results from only one side of the split-linespring. Depending on the mismatch (overmatch/undermatch), this would give too low values or too high values for J.

Version 3.1.4 (2014-02-19)

Fixes:

  • Earlier LINKpipe versions occasionally failed to read the input files in the beginning of a calculation. Very often this was not reproducible and the next time the calculation was started, it would run successfully. Fixed.

Version 3.1.3 (2014-02-12)

Fixes:

  • When running calculations on clad pipes, the calculation would occasionally fail to start the calculation. Fixed.

Version 3.1.2 (2013-12-13)

Fixes:

  • Generation of the calculation report crashed if the model contained the combined misalignment model. Fixed.
  • Fixed a crash during generation of BS7910 report.

Version 3.1.1 (2013-07-01)

Fixes:

  • In LINKpipe 3.1.0, the selection of crack position was fixed to "Middle of weld" and it was therefore not possible to select "At fusion line". Fixed.

Version 3.1.0 (2013-06-28)

New features:

  • It is now possible to position the crack at the weld fusion line. This is done by introducing asymmetric conditions to the linespring elements. The asymmetric linespring is called "split-linespring". The asymmetry is currently limited to having different materials on each side of the split-linespring element.
  • A new misalignment option is available: A combination of thickness misalignment and eccentricity misalignment.

Improvements:

  • The support for shallow surface cracks has been improved and validated. The validation tests indicates that LINKpipe is valid down to at least a/t =4%.
  • Improved numerical stability: Due to the fact that the yield surface for the linespring elements are point-wise, there have been some issues with numerical noise because the solution have a tendency to "snap" to the points. This have been improved by introducing more points to make the yield surfaces smoother.
  • Modeling of thickness misalignment has been improved.
  • A plot with all materials has been added to the html report.
  • Other minor improvements

Fixes:

  • ECA analysis: When running with embedded defects, the ligament was not updated correctly if the user specified the distance to the inner surface.
  • If a negative eccentric misalignment was saved to an lpp file, it would be interpreted as no misalignment when the user read the file into the preprocessor again.
  • Wrong values for the mesh parameters was written to the html report.
  • The plot window in the preprocessor: If the user viewed results along the crack tip, the bottom "Copy" did not copy the data for the shown curve.
  • The BS7910 calculations contains some minor bugfixes.
  • Other minor bug fixes

Version 3.0.3

Improvements:

  • It is now possible to specify weld geometry for embedded cracks. This will activate the new mismatch approach (introduced in LINKpipe 3.0) which was available only for surface cracks in the previous versions. The mismatch approach will take into account that some of the ligament yielding can occour outside the weld material (see chapter 2.4.5 in the user manual and chapter 2.1.11 in the theory manual for details).
  • In the previous LINKpipe versions, the new mismatch approach was used only when the weld geometry was specified. The mismatch approach takes into account that some of the ligament yielding can occur outside the weld material. It is implemented by using an artificial material for the line-spring elements. In LINKpipe 3.0.3, the mismatch approach will also be used when modelling a pipe with clad layer but no weld. The artificial material used for the line-spring element will be a weighted combination of the base material and the clad material. The weights are calculated from how much of the yielding will occur in the base material and in the clad material. See chapter 2.4.5 in the user manual and chapter 2.1.11 in the theory manual for details.

Fixes:

  • Fixed an error in the ECA analysis when having an embedded crack: An embedded crack can be specified with a distance to the outer surface or to the inner surface. It would be reasonable to expect that all the calculations in the ECA analysis should start with this specified distance to the given surface. But instead, the ECA analysis started the calculations with the same distance to the outer surface when positioning the crack before running the next calculation.
  • The html calculation report contained incorrect values for the mesh parameters DX2 and DY2. Fixed.

Version 3.0.2

Improvements:

  • Improved feedback to user if no valid license is found
  • Other minor improvements

Fixes:

  • Wrong ligament in certain circumstances for fatigue calculations. For a special combination of 1) a calculation having a fatigue load as the first load station 2) an embedded crack 3) the crack is closer to the inside than to the outside of the pipe wall 4) no misalignment, the fatigue calculation will run the fatigue calculation with a ligament that is too large. This will have two effects: 1) It will normally give a crack growth that is too small, 2) the crack will use longer time to grow to the surface.
  • Fixed broken bibliography references in the documentation
  • Some example files gave warnings about backward compatibility problems when opened

Version 3.0.1

Improvements:

  • Digitally signed installation program
  • More flexible placement of the license file
  • Support for running calculations on larger models

Fixes:

  • The "Save as" will now ask if the user wants to overwrite existing files

Version 3.0.0

LINKpipe 3.0.0 is a major release that contains a lot of new features, improvements and small fixes. The list below contains the largest and most important changes in this release.

New features:

  • New module with plain BS7910 calculations that runs separately from the finite element analyses
  • Support for calculation on pipes with a clad layer
  • New material model with kinematic hardening for cyclic loading
  • Option for relaxation of residual stresses
  • Support for embedded cracks
  • Added advanced options for the fatigue calculations
  • Support for longitudinally oriented cracks

Improvements:

  • Multi-slope Paris curve
  • Select Paris curve from predefined sets of BS7910 recommendations
  • Improved support for weld mismatch and weld geometry

Version 2.4.2

New features:

  • The Theory manual and the Validation manual are now included in the release

Improvements:

  • The user now has better control with the number of line-spring elements in the model. This can be used to reduce the calculation time for the ECA analysis. In the previous versions, one had to choose an element size that gave accurate results for the shortest cracks. This often lead to an unnecessary high number of line-spring elements for the longest cracks.
  • The convergence for rotation controlled load stations is improved. This makes it possible to bend the pipe to larger rotations and the calculations will also run faster.
  • The validation function in the preprocessor has been improved and can now be switched on and off. When it is switched on, it will validate the input data while the user is entering input data.
  • The progress bar showing the calculation progress now offers the user to set the priority of the calculation process.

Fixes:

  • Fatigue calculations: if the fatigue calculations was run with 0 cycles, the crack length and depth was set to 0 instead of keeping the crack size unchanged. Fixed.
  • The validation function in the preprocessor will now also validate the data in the load stations.
  • The progress bar showing the calculation progress was sometimes reset to 0%. Fixed. 

Version 2.4.1

Fixes:

  • Fixed a problem when calculating Irwin correction during elastic unloading. The calculation exited with an error message from the beam elements and the texts "*** CONTACT ***", "*** ERROR IN Mk_CoRo_T ***" and "*** ERROR FROM ROUTINE SSH_BEAM ***" in the file result.out.

Version 2.4.0

New features:

  • High cycle fatigue calculations are now available in LINKpipe. The calculations consists of an integration of Paris' law. In this first version the stress intensity ranges ΔK are calculated from the equations in BS 7910. To add fatigue calculations to the analysis, just add a load station of type "High Cycle Fatigue". It is possible to combine the high cycle fatigue station with other load stations to simulate both the installation phase and operational phase in one single calculation.

Improvements:

  • Improved the accuracy of calculations for shallow cracks (a/t < 0.15).
  • More linespring results and global results are available in the post processor
  • Calculation of the Irwin correction to account for local plasticity ahead of the crack tip has been improved.
  • ECA analysis can be run with multiple acceptance criteria. CTOD can now be used as acceptance criterion even if ductile tearing is active.

Fixes:

  • Results were stored to result files for every increment even if user specified another store frequency.
  • Semi-elliptical cracks at the inside of the pipe were meshed incorrectly.

Version 2.3.0

New features:

  • Support for semi-elliptical surface cracks
  • New load station type for reeling
  • Simple plotting of results directly from the preprocessor
  • List of most recent input files makes it easier to open previously opened input files
  • List of most recent results makes it easier to open old analysis results
  • Calculation of end cap effect from the pressure inside/outside the pipe

Improvements:

  • More flexible specification of load stations
  • Stress-strain curve for user defined materials can contain more than 25 points
  • The preprocessor is simplified to make it easier to enter input data
  • Global displacement, rotation, force (absolute value) and bending moment (absolute value) is available in new plotting feature in preprocessor

Fixes:

  • Calculations with ductile crack growth (tearing) was too conservative because a reduction of the effective ligament (necking) was also calculated. Now the necking will be calculated if there is no tearing going on. From the point where the tearing starts, the necking will not increase during the rest of the analysis. 

Breaking changes (non-backward-compatible changes):

  • LINKpipe 2.3 can generally read input files from version 2.1 and 2.2. But there are a few breaking changes concerning reading of old input files. The user will be warned if LINKpipe reads a file that is not compatible with the current version. The breaking changes are:
    • Reading old input files with ECA analysis: In previous versions, a target strain level had to be entered together with the ECA data. From version 2.3, the ECA analysis does not contain any strain level. The ECA will run all the load stations as they would be run in a normal analysis.
    • Reading old input files containing displacement/rotation controlled load stations: The boundary conditions will always be applied at the end of the pipe. But in previous versions, the user could specify a position where the resulting displacement/rotation should be measured. This could easily be misunderstood and would rarely be used. In version 2.3 the resulting displacements/rotations will always be measured at the point where the boundary conditions are applied (at the end of the pipe).

Version 2.2.2

Improvements:

  • The user material can now be specified both with comma and punctuation as decimal separator. This is convenient when pasting data from other programs.

Fixes:

  • If user defined materials were used, it was not possible to have a weld material different from the base material.
  • The quit confirmation dialog did not remember that the user selected "Don't show this dialog again" when exiting the preprocessor.

Version 2.2.1

Fixes:

  • Version 2.2.0 could read input files from version 2.1.1 but not from version 2.1.0. Fixed; version 2.2.1 can now read input files from all version back to version 2.1.0.

Version 2.2.0

New features:

  • ECA analysis can be run with ctod as a stop criterion (without ductile crack growth)
  • Added possibility to save user settings like startup directory and result directory
  • Added possibility to specify result directory in a flexible way
  • Added a progress bar with a cancel button that is shown during the analysis
  • Added possibility to specify a comment that will be saved together with the data in the input file
  • Added possibility to specify regions with reduced wall thickness
  • Added possibility to calculate displacement or rotation from global strain. Also added possibility to calculate rotation from a curvature radius or a midpoint deflection for a pipe that is being bent.
  • The user can now specify a startup directory
  • Saves the input data in a input file together with the results when running an analysis

Improvements:

  • Some simplifications of input data specification
  • Multi analysis: Added possibility to specify which parameters that should be a part of the multi analysis.
  • Multi analysis: Can now be run also with user defined material and a weld material that differ from the base material
  • Other minor improvements

Fixes:

  • Improved mapping of the crack length onto the shell elements for inside surface cracks. This gives slightly longer inside cracks compared to the previous versions.
  • ECA analysis with eccentric crack often failed to find the critical defect depth