Multi-Physics SCAIMapper

Fraunhofer-Institut für Algorithmen und Wissenschaftliches Rechnen SCAI

Technical Description

    Technical Description

Manufacturing History

Simulation process chains need to be completed; simulation results have to be validated by experiments. The SCAIMapper enables the coupling of a wide range of commercially available FEM software products. Codes for metal forming, heat treatment and crash simulations as well as data from forming analysis tools are supported by SCAIMapper and thus can be used in a coupled manufacturing process chain.

The crash behavior of relevant components does not only depend on design geometry and material properties, but is also influenced by manufacturing history. A failure can be caused by local thickness reduction or residual stress peaks which are a result of the stamping process. This failure can limit the functionality of the entire component. In particular the local hardening step can induce gradients in the phase proportions or influence residual stresses – and thus influence the dynamic behavior of the crash part.

Metal Forming Workflows

In most cases it needs just a few steps to map results from manufacturing simulations into prepared input decks of a crash or structural analysis:

  1. Read in source model and results as well as the target model
  2. Choose source parts to map
  3. Mirror source parts (optional)
  4. Adjust position of the meshes for mapping
  5. Choose quantities to be mapped
  6. Map
  7. Validate results (optional)
  8. Save result

SCAIMAPPER WORKFLOWS

SCAIMapper supports most of the relevant CAE file formats and can be applied to typical engineering workflows in metal forming ar

  • Forming Simulation ==> Heat Treatment ==> Machining ==> Crash
  • Forming Simulation ==> Assembly ==> Coating/Painting ==> Crash
  • Forming Simulation ==> Buckling Analysis
  • Forming Simulation <==> Forming Analysis

Mesh Alignment

SCAIMapper offers a semi-automatic method to adjust models with incompatible positions in the coordinate system. In a first “rough alignment” step the meshes will be rotated and moved in a close position to each other. In a second “fine alignment” step least square methods minimize the overall distance between the two models. Manually alignment by mouse or import of a predefined translation matrix is also possible.

Mapping Quantities

Supported quantities are

  • thickness (scalar),
  • stress (tensor),
  • strain(tensor), and
  • effective plastic strain (scalar).
  • History variables, young's modulus and others can be mapped and exported to LSDyna and Sysweld.

Quantities are of type nodal, element wise nodal, or element integration points (reduced and full integration).

Unit Systems

Most FEM file formats miss information about the applied units. To allow mapping between models with different unit systems, the SCAIMapper offers the possibility to add information about unit systems: e.g. unitsystem = mm, ms, g.

Quality Checks

In order to validate the quality of interpolation, a method to visualize inaccuracies of the mapping process is part of the SCAIMapper tool. Large deviations between the element sizes of source and target mesh or non-matching geometry parts easily can be detected

HOW GOOD IS YOUR MAPPING

The concept of validation is to compare the original values from the source mesh with those values which were mapped from source to target mesh and back again onto the source mesh. The local differences can be calculated and visualized. The validation panel allows to check all mapped quantities. Additionally the validation has methods to calculate and visualize the association distance and the nodal distances between the coupled meshes. Thus the validation module provides an outstanding possibility to examine the quality of mappings.

Example for the validation of the interpolation (transmission of plastic strains): The original values (lower left) are compared with values, which are a result of the backmapping (lower right). Large local differences (right top) can be seen, where the meshes (top left) differ locally.

Compare Simulation and Expertiment

Stamping simulation results can be compared with experimental data from forming analysis. SCAIMapper can import files from Argus and Autogrid. Measured geometries and value distributions can the be compared with virtual simulation results - SCAIMapper will show you the local differences.

The figure above shows the comparison between simulation and measurement for the thickness distribution on the blank as well as the forming diagrams. The experimental data originate from a measurement with GOM ARGUS. The behaviour of the blank was computed properly in simulation. Differences are mainly due to potential deviations of the friction coefficient as well as the rigid body modelling of the stamping tool.

Numerical Methods

In most cases the FEM codes do not use compatible discretised models (meshes). Especially for meshes based on shell elements the corresponding areas have to be assigned to each other. If the size of elements of the coupled meshes differs strongly simple interpolation methods may lead to a loss of information and an increasing “blurring”. A modified algorithm (Shephard’s method) has been implemented in the SCAIMapper. The SCAIMapper supports models with different number of shell layers and allows code specific usage of integration points in shell elements.

TENSOR MAPPING FOR SHELL ELEMENTS

The SCAIMapper provides accurate and high performance methods for interpolation of tensor quantities like strains and stresses. These tensor values needed to be transferred in a conservative way. The SCAIMapper considers the tensor nature of these conditions, which is ensured by the separate interpolation of the main components and their directions in space.

File Formats

  • Abaqus (.inp): Reading & writing is supported. S4, S4R, S4RS, S4RS, S3, S3R, S3RS.
  • Autoform (.af):
  • Autogrid (.txt):
  • Argus (.dat):
  • Indeed (.gns): Only reading is supported. Effective plastic strain and thickness are read in. Only reduced shells are supported.
  • LSDyna (.key, .dyn): Reading & writing is supported. Full integrated trians and quads. Arbitrary out of plane integration types up to 10 integration points out of plane. History variables can be mapped.
  • Nastran (.nas): Reading & patching is supported. Only thickness values are supported for reading and patching.
  • Pam (_M00_ M99): Reading & writing is supported. Full integrated trians and quads. Arbitrary out of plane integration number. Suffix must be in the range from _M00 to _M99.
  • Pam (.pc,.ps): Reading is supported. Output is written in _Mxx format. Neither material nor part cards are interpreted currently. All elements are supposed to be reduced shells. ECTRL integration type statement is not considered. The default integration type SIMPSON is considered
  • Radioss (Yxxx): Reading & writing is supported. Fully integrated and reduced integrated triangles and quads are supported.
  • Radioss (D00): Reading is supported. Fully integrated and reduced integrated triangles and quads are supported
  • Sysweld (.asc): Reading, writing and patching is supported. Mechanical and thermal transient files are supported including the reading of proportions of the phases.