Optical Solution for Forming Analysis
This content was originally written and published by the GOM team on their website. Reproduced here from https://www.gom.com/metrology-systems/argus.html
Evaluation of Forming Processes and Simulation Validation
The optimization of the sheet metal forming process, taking into account the correct material selection and optimization of tools, is a decisive factor for competitiveness, particularly in the automotive industry during the development process of sheet metal parts, for tool try-out, and in production troubleshooting. The forming analysis system ARGUS supports such optimization processes particularly by convincing and precise results of the surface strain on the components. The full-field results with high local image resolution provided by ARGUS enable the measurement of small and large components.
Applications
- Tool try-out
- Validation and optimization of numerical simulations
- Series production ramp-up
- Material acceptance test (material batches)
- Research and development
- Detection of critical deformation areas
- Solving complex forming problems
Forming Analysis
Forming analysis is a process to evaluate the forming states and surface strain levels of sheet metal parts after forming. GOM’s ARGUS system can be used to capture 3D coordinates of the surface presented in a fine resolution mesh. The forming results are subsequently compared with the Forming Limit Curve (FLC), a material parameter dataset describing the maximum formability, by means of a Forming Limit Diagram (FLD) that is created in the ARGUS software. This diagram clearly indicates whether the areas are over-deformed or still within a certain safety margin, providing decisive information for optimizing forming processes and validating simulations.
ARGUS Professional Software
Based on the measuring data acquired by the ARGUS photogrammetry camera, the ARGUS software provides a fast and efficient evaluation workflow for forming analysis.
FLD/ FLC
The Forming Limit Diagram (FLD) is a proven tool to evaluate the forming process and determine the trend towards cracking. In the ARGUS Professional software, the FLD can be easily created with one click in I-Inspect. Besides the Forming Limit Curve, additional curves such as the Security Curve, Thickness Reduction Curve, Isotropic Tension Curve, can all be visualized in the software. Furthermore, multiple Forming Limit Curves (FLC) can be created by simply importing the ARAMIS material file or calculated directly in the ARGUS Professional software by Keeler for further analysis
Formability
Formability analysis takes one step further. Like in many simulation programs, such as AutoForm, this formability diagram can also be created by one click in the GOM software. The user can define different classification areas and visualize them directly in the Formability Diagram and on the specimen for further inspections.
Simulation
Scalar values and geometries from simulation programs such as ABAQUS, LS-DYNA, or ANSYS, for example, can be imported into the GOM software for a direct comparison to the 3D measuring data. The 3D measuring data can be transformed into the coordinate system of the simulation model by various alignment functions. Thus, the geometry of the simulation model can be compared with the measured 3D surface in the first step. Further analyses, such as the direct comparison of displacements, deformations, and strain, can be carried out for each stage.
Parametric project templates
The GOM software is based on a parametric concept. This approach ensures that all process steps are traceable, thus guaranteeing process reliability for measuring results and reports. In the evaluation process, all steps, including the creation of alignments (for example by CAD), inspection elements, and the complete user-defined reports are documented and can be saved as project templates. Further projects of the same type can be easily repeated by simply changing the measuring data and recalculating the project. This project template can be stored and exchanged between colleagues, departments, or even plants worldwide, which guarantees uniform evaluation standards for your projects.
Guided data acquisition
A successful evaluation requires high-quality measuring data. The active guidance of the GOM software provides direct feedback on the image quality during the image capturing process. Images are automatically considered usable or unusable and displayed clearly in the software. Users can react to the messages shown by those unusable images to adjust the position, change the luminous intensity, for example, or just give a second try. With the new image mapping functionality, the measuring positions are displayed around the object, which makes the missing measuring positions directly visible
Automated mesh generation
Fewer user interactions are now needed to obtain results. The automated starting point allows automatic identification and computation of 3D meshes of single or multiple measuring areas. These meshes can be created independently of the user, which increases the repeatability of the measuring results.
GOM Correlate Software
The measuring data taken from the ARGUS system can be easily viewed and evaluated using the free GOM Correlate software. Besides that, the software supports the free exchange of measuring results between colleagues, across departments and plants worldwide for further analysis.
ARGUS Technology
The certified handheld ARGUS camera is used to record deformed sheet metal parts from different viewing angles. In all acquired high-resolution images, 2D coordinates of all dots are mathematically derived and recalculated to 3D coordinates using photogrammetry principles, taking into account ray intersections, camera positions, and lens distortion. The main result is a fine 3D point cloud, consisting of thousands of points, which represent the 3D surface of the sheet metal part. By evaluating the relative distance between the points in combination with a local plane strain tensor computation, the strains over the entire surface are holistically determined.
Easy and Fast Measurement
Different from conventional methods for forming analysis, the ARGUS system provides an easy and fast measuring process as well as accurate forming results. Even complex and large parts can be measured within a short period of time.
Measurement Planning
Before preparing the part, the measuring areas need to be defined depending on the evaluation purpose, which may be the complete part or specific critical areas known from the production process or numerical simulation.
Preparing
Before forming, raw sheet metal blanks are marked using electro-chemical etching or laser marking with a hexagonal dot pattern.
Measuring
After forming, the sheet metal part is recorded from different viewing angles by using the handheld ARGUS system. Small and large parts can be measured very fast with the same hardware.
Evaluation
Measuring results provide full-field information of the forming distributions on the parts, like major and minor strain, thickness reduction, forming limits, formability, etc.
To know more, please check GOM.
