Large Deflections of Buckled Bars

With this post, we start a new category of application scope examples for Ple4Win. The emphasis of these examples is using the program ‘beyond the box’. That includes showing applications that are not actual pipeline projects, but “weird” or humorous, or showing examples that illustrate the internal working of the program. The first example of this series falls into the latter category, more can be found here.

Large Deflections of Buckled Bars

Consider a slender rod, as shown in figure 1. It is fixed at the base, free at the upper end.

Figure 1: Vertical bar, fixed at the base.

If a load P is applied that is somewhat larger than the critical value described by Euler’s Column Formula:


with

then a large deflection of the bar is produced. As described in Timoshenko & Gere’s “Theory of elastic stability” (chapter 2.7 “Large deflections of buckled bars (The Elastica)”) the relation between applied load and deflection can be described using the formula:


with

With Ple4Win, it is possible to calculate this beam deflection behaviour. Figure 2 shows the calculated bar deflections at different ratio’s P / Pcr

Figure 2: Deflections of a vertical bar at different ratio’s P / Pcr,

Note that the “non-linear geometry model” option must be used as well as the “linear material model” option. As the theory does not take compression effects or the influence of shear force into account, the material parameters in Ple4Win must be adapted to minimise their influence (these effects can not be switched off in Ple4Win).

Figure 3 shows a comparison between vertical and horizontal deflections as calculated by the program and as mentioned in the book by Timoshenko & Gere. The deviations are less than 2% for an angle  of 20° (compression effects) and between 0.1% and 0.5% for angles of 40° and higher.

Figure 3: Comparison between theoretical calculations and results obtained from Ple4Win.

 

PleEdu4Win 4.4.2 released

The educational PleEdu4Win version 4.4.2 has been released. This version contains all improvements, modifications and adaptations of the professional Ple4Win version 4.4.2, where applicable. As with previous educational versions, this program can be downloaded and used freely to gain a good insight into what the Ple4Win program can do.

Download Ple4Win Educational 4.4.2.

The main highlights of the new release are:

3D data visualisation

  • Changing data in the 3D visualisation while keeping the same viewport;
  • Show the pipeline’s centreline instead of the actual diameter, this improves the visibility for very long pipelines;
  • Show a settlements line;
  • Show distance labels;
  • View of circumferential data of last calculated element.

Data entry

  • Reference identifiers now possible with input table SUPPORTS;
  • Increased flexibility to define additional identifiers.

Other

  • Underlying calculation methodology modernised.

Ple4Win 4.4.2 updated

After releasing version 4.4.2 a critical (older) bug in the calculation core has been discovered.

We updated (patched) the program to correct it.

At the same time a couple of other bugs have also been fixed, see the change log for more details.

We encourage all users to un-install the original version 4.4.2 and install the updated version afterwards.

Ple4Win 4.4.2 released

Ple4Win version 4.4.2 has been released. This version focuses on improvements of data entry and data visualisation. It also contains a number of other improvements, modifications and adaptations. For a detailed description of the changes, please see the change log.

As always, we advise customers to upgrade to the latest version, even if no issues have been encountered using version 4.4.1.
Download Ple4Win Professional 4.4.2.

The main highlights of the new release are:

3D data visualisation

  • Changing data in the 3D visualisation while keeping the same viewport;
  • Show the pipeline’s centreline instead of the actual diameter, this improves the visibility for very long pipelines;
  • Show a settlements line;
  • Show distance labels.

Data entry

  • Reference identifiers now possible with input tables PIPES, SUPPORTS and SISPRC;
  • Increased flexibility to define additional identifiers.

Other

  • Latest NEN 3650-1+C1:2017 confirms the calculation method of the upward vertical soil stiffness for deeply situated pipelines as applied by the Soil Model Wizard of Ple4Win;
  • Underlying calculation methodology modernised.

Courses for Ple4Win users

The performance, accuracy and speed of a project calculated using Ple4Win depends for not a small part on how the project is modeled. More often than not, a good pipeline model has greater benefits than e.g. a faster computer and may prevent lots of calculations on model variations. We are planning to provide for a course on the art of making a good functional pipeline model. This half-day course is primarily intended for experienced users.

For more detailed information, call +31 (0)70 390 2386 or mail to info@eds-ple.nl.

We also offer dedicated training for individuals or small groups, focused on specified wishes of the attendees and/or going into details of specific problems the attendees have encountered. Again, contact us for more information.

Ple4Win forum

For support or advice, please visit the Ple4Win forum. There you can also read the FAQs, tips & tricks, report your findings or tell us your views.

50 years Ple4Win anniversary

On October 1, 2015, we celebrated the 50th anniversary of Ple4Win, more specifically that 50 years ago the necessity arose to calculate the behaviour of buried pipelines in soft soils.

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Meeting at the historical fortress Wierickerschans, a presentation was given about the difficulties the Dutch Gasunie encountered when they wanted to cross the nearby Dubbele Wiericke with a 36″ high-pressure gas pipeline in 1965.

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The construction finally used was too conservative (and too expensive!) for all practical purposes, but almost nothing was known about pipe-soil interaction then. So the necessity to explore the behaviour of buried pipelines was pressing, and this was the starting point for developments that finally led to the Ple4Win program of today.