Material Insights by CAE Type

Abaqus

A Framework for the Calibration and Validation of Multiscale Material Models

Multiscale material models are being increasingly applied for high-level simulation of complex materials, such as continuous reinforced material products (unidirectional and woven product forms). These multiscale material models require input data from a minimum of experimental tests, which are then used to characterize a multiscale material model that can be used in structural simulations within a variety of commercial finite element solvers, including OptiStruct, RADIOSS, Abaqus, and LS-Dyna. Using these models, it is possible is to predict the performance of layups from single layer properties, as well as performance of these composites under complex loadings. We present a framework where the required experimental data are collected, including a process for maintaining traceability and consistency of the experimental data using the Matereality software. Experimental test data are transmitted to the HyperWorks Multiscale Designer software for development of an appropriate multiscale material model. The resulting multiscale material model data is stored within Matereality linked to the source experimental data. Different manufactured layups are tested and compared to simulation in a validation step which provides a measure of the solution accuracy.

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Determination and Use of Material Properties for Finite Element Analysis: Book Review

This book is intended to be a companion to the NAFEMS book, "An Introduction to the Use of Material Models in FE". It informs Finite Element Analysis users of the manner and methodologies by which materials are tested in order to calibrate material models currently implemented in various FEA programs. While the authors seek first to satisfy the basic material models outlined in the companion book, they make important extensions to FEA used in currently active areas including explicit simulation.

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The Role of Material Data in the Simulation of Injection Molded Parts

The modeling of material behavior for injection molded plastics is a vital step for good simulation results. We detail the types of material data needed by various injection-molding simulation programs, factors that can affect simulation quality including test techniques and process variables such as moisture content. The case of fiber filled plastics is covered along with the extension to structural analysis applications.

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Using an Intermediate Validation Step to Increase CAE Confidence

Simulations contain assumptions and uncertainties that a designer must evaluate to obtain a measure of accuracy. The assumptions of the product design can be differentiated from the ones for the solver and material model through the use of a mid-stage validation. An open loop validation uses a controlled test on a standardized part to compare results from a simulation to the physical experiment. From the validation, confidence in the material model and solver is gained. In this study, the material properties of a polypropylene are tested to characterize for an *ELASTIC *PLASTIC model in ABAQUS. A validation of a quasi-static three-point bending experiment of a parallel ribbed plate is then performed and simulated. A comparison of the strain fields resulting from the complex stress state on the face of the ribs obtained by digital image correlation (DIC) vs. simulation is used to quantify the simulation's fidelity.

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Challenges in the Modeling of Plastics in Computer Simulation

Finite-element analysis and injection-molding simulation are two technologies that are seeing widespread use today in the design of plastic components. Limitations exist in our ability to mathematically describe the complexity of polymer behavior to these software packages. Material models commonly used in finite-element analysis were not designed for plastics, making it difficult to correctly describe non-linear behavior and plasticity of these complex materials. Time-based viscoelastic phenomena further complicate analysis. Dealing with fiber fillers brings yet another layer of complexity. It is vital to the plastics engineer to comprehend these gaps in order to make good design decisions. Approaches to understanding and dealing with these challenges, including practical strategies for everyday use, will be discussed.

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