Under Simulation Stopping Criterion define the Tolerance, the Maximal Iterations, and Maximal Run Time to control the iterative process of the solver. Only the tolerance must be set, the other two parameters are optional.

For each iteration step, the relative error of the current solution is computed. If this relative error is smaller than the given tolerance for ten subsequent steps, the computation is finished. When there is doubt about the quality of the solution, decrease the tolerance value by a factor of ten for that solver. In general, it is recommended to keep the default setting for tolerance.

When the solver stops because the Maximal Iterations or the Maximal Run Time are reached, the quality of the solution might be doubtful since the requested accuracy is not reached. Therefore, those two options are disabled by default and should only be selected if there are strong constraints on the allowed runtime.

For the FeelMath-Deformations solver, three different iterative methods are available: Fast (Conjugate Gradient), Intermediate (Memory Efficient Conjugate Gradient), and Memory Efficient (Neumann Series).

The Fast method converges faster, especially for strongly varying material parameters and nonlinear material laws (as e.g. plasticity or damage), but needs about four times as much memory as the Memory Efficient method.

The Intermediate Method needs approximately 40 % less memory than the Fast method but is slower. The Estimate Memory button in the ElastoDict section, can be used to decide which method is applicable for the current structure on the available computer, as described in the ElastoDict chapter.

In general, it is recommended to use the default (Memory Efficient Conjugate Gradient) or the Conjugate Gradient method. The Neumann Series method should only be used if the memory is not sufficient for the other methods.

The degradation simulation, like the charging simulation, can be accelerated by running the computation on multiple CPU cores, as explained here.

For information on how to set up and use BatteryDict-Degradation in a Cluster configuration, contact support@math2market.de.

BatteryDict-Degradation can handle non-isotropic constituent materials. For these materials, an orientation must be additionally specified. If the analyzed structure consists of analytical objects (gad data), the orientation of these objects is used when Use Orientation from Analytic Objects (gad) is selected.

Alternatively, with Load Orientation Information from File (*.gof), orientation information can be loaded from a file. Such a file can be generated for example with GrainFind for granular structures. The third option, Use the Global XYZ-Coordinate System, allows to use anisotropic materials even if no orientation information for the structure is available. This makes sense only if the grains are all oriented directly according to the coordinate axis, which is usually not the case.

For the computation of the deformed structures, intermediate data is computed which describes the displacement for each voxel. Before this computation, it is not clear how large this data will be, since a voxel in the original structure might be partially moved in multiple voxels in the deformed structure. Therefore, this data might not fit in the main memory of the computer. Due to this, it is possible to write the deformation data to a file on the hard disk by checking Write Deformation Data to File.

But note that writing and loading data from the hard drive is many times slower than writing and loading data in the main memory (even if the drive is an SSD). This causes a bottleneck, which can slow down the simulation.

Therefore, the default is to keep the deformation data in memory. In most cases, the data fits into the main memory, and this option is many times faster. We recommend keeping this setting, and to select Write Deformation Data to File only if the simulation fails because the data does not fit into the RAM.