Description of the phenomenon #

In AXISVM, various error messages can alert the user to minimize inaccuracies and associated risks during modeling. The next article will showcase the reasons of the “Load Calculation Error” witch can occur during the analysis.

This error message warns that the total value of loads placed on finite elements differs from the total value of defined loads. Additionally, the error message indicates the magnitude of the resultant deviation in each direction.

The error message must not be ignored under any circumstances, as it alerts us that not all defined loads are being transferred to the structure!

In this article, we will first present the most common causes of errors and how to identify and resolve them.

Typical Causes #

Inaccurately defined loads or load panels. #

This is most often the cause of the error. In such cases, due to some modeling inaccuracies, the load lies outside the finite element, preventing its transfer. Here are a few examples of common scenarios:

• Line loads do not properly align with a load panel edge. This causes an error when the level of inaccuracy exceeds the set editing tolerance.
• In the case of line loads on domain edges, it may happen that due to editing inaccuracies along the domain’s boundary is not a perfectly straight line. However, the edge load is defined between the first and last points of the boundary, which can thus deviate from the actual boundary at certain sections due to editing inaccuracies. If the load is outside of the finite element, it can no longer be transferred.
• For surface loads, if the planes of the finite elements deviate from each other more than the set flatness tolerance value, it also leads to errors.
• The load panel may have been inaccurately defined. If we didn’t used one of the automatic load panel creation method but manually drew the contour of the panel, inaccuracies can occur. If these inaccuracies exceed the set editing precision, they result in errors.

Incorrect load transfer settings for load panels #

It’s possible for a load panel to carry load, but this load won’t be reduced to any finite elements. This typically occurs due to incorrect load panel settings. The most common setting mistake is defining a load panel bounded by edges of domains with the setting “Loads will be distributed over domains and line elements under load panel”. In this case, the panel cannot transfer loads to any elements.

Parallel line elements or edges under a load panel #

A less common scenario is when multiple parallel line elements or parallel edges are covered by a larger contiguous load panel. For various reasons, in such cases, we may encounter this error message, which is caused by anomalies in load distribution. In such situations, the entire load panel becomes ineffective, and its loads are not transferred. The figure bellow illustrates such a scenario, where nearly parallel cantilever beams are covered by a large contiguous load panel.

Finding the error #

To resolve the error, the cause must first be identified. When the “Load Calculation Error” message appears during the analysis, the calculation should be interrupted by selecting the “No” option.

Each listed load, load panel, or domain must be examined individually to determine if any of the common causes outlined in the “Typical Causes” section are recognizable.

To identify modeling inaccuracies, the “Check Geometry” command under the “Geometry” tab can be utilized.

For load panels, enabling the “Load distribution scheme” and “Surface load distributed to trusses/beams/ribs” switches can be helpful for identifying malfunctioning load panels. These switches can be found in the “Load display on/off” section of the lower ribbon menu.

Once the cause of the problem has been identified, proceed as detailed in the following section.

Resolving the error #

In the case of inaccurately defined load or load panels #

If the cause of the error is a “floating,” inaccurately defined load, then the load must be deleted and redefined with sufficient precision.

If the error is caused by an imperfect domain edge or a line element, it needs to be either redefined or the editing tolerance needs to be increased.

If surface load is not being transferred, it’s possible that the domain intended for load reduction isn’t perfectly flat due to editing errors. In such cases, it’s advisable to correct the editing error and then redefine the load. However, if there is intentionally a small angle between the planes of domain elements, then the flatness tolerance value should be adjusted.

For inaccurately defined load panels, the faulty load panel should be deleted and redefined with sufficient precision.

In case of incorrectly set load panels #

If a load panel bounded by domain edges fails to distribute its loads onto the domain edges, its settings in the load panel properties need to be modified. After opening the Load Panel Definition window, select the Properties command, highlight the incorrectly set load panel, and check the “Also distribute loads over domain edges on the perimeter of the load panel” option.

For load panels defined on parallel line elements #

If a load panel is defined over multiple parallel line elements or edges and results in a load calculation error, it’s advisable to divide the panel into several smaller parts.