Multiscale and Single-scale Material Models

An accurate material model is the key for reliable prediction of composite mechanical behavior through simulation, thus allowing design-optimization as part of the development process and finally verification of the performance of the design without need for extensive physical testing. Multiscale material modeling has proven to be the most promising approach to accurately predict the behavior of fiber-reinforced composites all the way to rupture. The multiscale material models developed with Altair® Multiscale Designer® can be used in widely used finite element solvers.

Multiscale Designer allows development of highly predictive and computationally efficient multiscale material models from brittle and/or ductile homogeneous isotropic to heterogeneous anisotropic material behavior with minimum experimental data. Additionally, single-scale material models can also be developed.

Forward and Inverse Material Model Development Workflows

The forward approach to material model development utilizes known constituent material properties (e.g. fiber and matrix) to forward calculate the homogenized product material properties (e.g. continuous fiber-reinforced unidirectional ply). The forward approach is most often used in material design and concept design phases and produces approximate material models. The inverse approach to material model development utilizes known homogenized material properties (e.g. continuous fiber-reinforced unidirectional ply) to inverse calculate the constituent material properties (e.g. fiber and matrix). The inverse approach is most often used in detailed design phases and produces highly predictive material models.

Deterministic and Stochastic Material Models

Both deterministic (mean value response) and stochastic (probability distribution function response, mean value and standard deviation) material modeling capabilities are available within Multiscale Designer material models to account for real world variation.

Parametric Unit Cell Library and External Unit Cells

A built-in parametric unit cell library can be used to easily create unit cells for continuous, discontinuous, woven, and particle product forms. In addition, the ability to create any unit cell in any pre-processor of choice and import that unit cell into Multiscale Designer is available for OptiStruct (.fem), Abaqus (.inp), and Nastran (.bdf) formats.

Material Database

Multiscale Designer included two material databases, a constituent material database and a multiscale material database. The constituent material database includes "typical" material properties for metals (ferrous and nonferrous), polymers (thermoplastics and thermosets), and fibers (aramid, carbon, glass, and others). All multiscale material models are available in psi and MPa units. The multiscale material database includes multiscale material models validated against NIAR NCAMP/AGATE database for:

• AS4/8552 UNI and PW
• IM7/8552 UNI
• T700/2510 UNI and PW
• T700/E765 UNI

Injection Molding Material Models

Multiscale Designer offers a full methodology for developing material models for reinforced injection molded materials that account for the full anisotropic material behavior using the fiber orientation tensor. Mapping of the fiber orientation tensor from the molding simulation mesh to the structural simulation mesh is easy and intuitive in Altair® HyperMesh®. One material model with the fiber orientation tensor results from a molding simulation for each part is all that is required for highly predictive and computationally efficient injection molding structural simulation.

Virtual Test Lab

Multiscale Designer includes a parametric library of structural models for common ASTM and ISO test specimens. Any multiscale or single-scale material model can be applied to any specimen in the parametric library and a full simulation of the defined test is performed to obtain the load-deflection and/or stress-strain curves as if they were experimentally tested.

Both deterministic and stochastic material models can be utilized to obtain mean value and/or probability distribution function results including A- and B-basis allowables. The following specimens are included in the parametric library:

• Unnotched Tension/Compression (ASTM D3039, D3518, D6641 and ISO 527, 604, 14126, 14129)
• Three- and Four-Point Bending (ASTM D2344, D6272, D7264 and ISO 178, 14125)
• Open-Hole Tension/Compression (ASTM D5766, D6484)
• Rail Shear (ASTM D7078)
• Dogbone (ASTM D638, ASTM D695)

Multiscale Structural Simulation

Multiscale Designer includes plugins to structural simulation solvers that allow any multiscale or single-scale material model to be used on any externally created model and supports both implicit and explicit solutions with full SMP, MPI, and hybrid SMP/MPI parallelization on both Windows and Linux. The following structural simulation solvers are supported:

• Altair® OptiStruct®
• Altair® Radioss®
• Abaqus
• Ansys
• LS-Dyna

Material Model Development as a Service

For those lacking their own resources, Altair offers a multiscale material model development service.

• Review of the material characterization needs with the customer.
• Required tests are defined.
• Test laminates are produced by the customer using their in-house processing parameters.
• Testing at accredited test laboratory of choice or by customer in-house.
• Based on the test results, a multiscale material model is developed by Altair experts and delivered to the customer, ready for use in simulations.