Material Modeling of Metals in Abaqus

Perhaps the most common and yet important engineering materials are the metal alloys. Metal alloys are used in objects from skyscrapers to miniature electronic devices. Engineers are often asked to evaluate, through simulation, the strength and durability of these structures. Material models are key components in these simulations. Therefore, engineers need to understand what material models are used for metals and how these material models are defined.

Interested in learning more about Material Modeling of Metals? Join our eSeminar on June 23rd.

The Abaqus Unified FEA product has powerful material modeling capabilities. It has material models for metal plasticity, creep, damage, etc. Of course, Abaqus contains material models for other types of materials like rubber, concrete, soils, and so on, but these are topics for another day.

The users of Abaqus should be aware of which models are most appropriate for their applications. Plasticity definitions that are appropriate for simple monotonic loading scenarios may be of little use for more complicated cyclic loading scenarios. The material model may change if the application changes even though the material itself is the same.

Most Abaqus users have encountered the simpler material models like linear elasticity and isotropic-hardening plasticity. They may be unaware that even the basic models have advanced features like temperature-dependence and rate-dependence. The material models for advanced materials behaviors seen in cyclic loading or under extreme loading will be less familiar. Abaqus contains material models capable of predicting realistic behavior for repeated application of strain. Abaqus has damage modeling to simulate material separation under extreme conditions.

Finding out what material models are available for an application is just a beginning. Material models are parametric and the simulation engineers will be faced with the task of defining the parameters so that the material model is specific to their needs. They need to know how the parameters are defined and they need to know the pitfalls of using incorrect parameter values. Noisy test data for a plastic hardening curve needs to be processed and smoothed. A hardening curve which is non-monotonic will be problematic.

The task of defining even the most basic of metal material models can be complicated by a lack of information. The yield stress for a metal alloy may be given as a 2% offset value in references. Is this the appropriate value for the yield stress in an Abaqus plasticity definition? If not, why not and how can a proper material model be defined without the correct yield stress? Uniaxial test data is commonly used to define metal plasticity but plastic strain in simulations often exceeds the plastic strain at the onset of necking. How can plasticity definitions be extended beyond the range of the available data?

A comprehensive description of material modeling for metal alloys will not fit into the framework of an e-seminar. Neither can every question be answered completely. Fortunately, there are many resources available to the SIMULIA software users. The SIMULIA community is a good starting point for those who seek additional information on material modeling and SIMULIA in general. The Dassault Systèmes Knowledge Base contains many helpful entries, and training courses are available as well.

Interested in this topic? Join us on June 23rd for the eSeminar, Material Modeling of Metals in Abaqus. Register, here.

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