Issue #6 - September 5th, 2007
Software Suite for Durability, Damage Tolerance, and Life Prediction
Augments FEA Solvers MSC Nastran*, ABAQUS, ANSYS & LS-DYNA
* Best Performance and Verified Solutions with MSC Nastran
This Week's Feature Composite Example
Impacted Composite Sandwich Panels
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Simulation of impacted foam core composite panels and calculation of residual strength after impact is a complex and challenging computational process. Accurate prediction requires the integration of material modeling capability with finite element dynamic explicit solution and damage tracking and fracture algorithms. A new computational methodology for assessing impact related damage and determination of residual strength after impact is presented. The analytical procedure relies on both implicit and explicit computational schemes. The degraded damaged properties are progressively updated at every time step of the analysis process.
| Table 1: Comparison between Test and Simulation Results for Impact and Post-Impact Compression Analysis of a Foam Core Composite Sandwich Panel |
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A rigid body impacting a composite sandwich panel with a foam core with high velocity in the center of the panel was simulated. The simulation results indicated local delamination in the panel. The local damage due to impact was then included in the compression analysis. The numerical results obtained from the analytical approach predicted residual strength that is 6% higher than the one from the tests. In all, the analysis predicted that the strength of the sandwich panel in compression was reduced by a factor of 2.25 due to impact.
| Figure 1: Damage Accumulation at the End of Impact Simulation (Left) Damaged Foam (Right) Isolated Ply Damage View of the Foam, Adhesive, and the Face-sheets. Note that both figures show that the adhesive and the face sheets did not accumulate any damage |
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| Figure 2: Comparison of Tests and Simulation Results (Left) Load versus Time and (Right) Impact Energy versus Time |
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| Figure 3: Failure of the Composite Sandwich Panel during the Post-Impact Compression Simulation (Left) Damaged Panel after Impact Analysis (Right) Failure of the Composite Panel due to In-plane Compression at 24.78 kips |
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| Figure 4: Load versus Displacement Curve obtained from Post-Impact Compression Analysis to Assess the Residual Strength |
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The results validated that the novel progressive failure dynamic approach in GENOA can be reliably used to assess damage growth and residual strength of impacted composite panels.
References:
Garg, M. and Abumeri, G., 2007. Assessment of Residual Strength in Impacted Composite Panels. JEC Composites Magazine (Pending Paper)
Did You Know?
Faster and Smaller Native .GEN File Format
Did you know that GENOA introduced a new native binary file format as of version 4.2? This format is identified with the file extension of ".gen" and supports a highly compressed binary format to allow fast reading and writing of project and data files. On average, the file size is usually less than 1/10th the size of the previous text format. For more information on trying out GENOA through our demos, please contact our sales atsales@ascgenoa.com.
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