brittleness and hardness of metals

momidormomidor Member Posts: 29

Good morning, 

I wonder how can I present in Engineering Data a brittleness and hardness of metal.

1. For example grey casting. I know that I can take it from the library but I can not see a Vikers hardenss. 

2. How to present very hard and thin a nitrided metal surface ?

3. How to present a rebars which is soft and plastic in inside and very hard on the surface?  

 

 

Thanks in advance 

Comments

  • peteroznewmanpeteroznewman Posts: 12,548Member
    edited February 2020

    Hardness is not a material property that is used in any material model I know of.

    Hardness is correlated with yield strength. Plasticity is the material model that uses yield strength.

    You can have two materials in Engineering Data both with Plasticity material models. One with a low yield strength to represent the soft inner material and another with high yield strength to represent the hard outer layer.

    There are two approaches, depending on how thick the hard outer layer is.

    You can have two solid bodies using shared topology, and assign each body the appropriate material and have many layers of elements in the mesh through the thickness of the outer layer.

    Or you can use a surface coating on a solid body. This feature enables you to apply a surface coating (shell layer) of a specified material and thickness over one or more faces of your model. This feature is beneficial when you want to include the ability to accurately evaluate surface stresses or to overlay your structure with thin parts, such as modelling Thermal Barrier Coatings or sheet metal over support structures. To accurately model this type of application, Mechanical enables you to specify the thickness, stiffness behavior, coordinate system, and material.

  • momidormomidor Posts: 104Member
    edited February 2020

    Thanks Peter, 

    By the way: is the any way to implement a impact test results in [ J ] or [ J/cm2 ] which is being function of temperature,  to Engineering Data materials?  

    Thanks in advance

    Jerzy 

  • peteroznewmanpeteroznewman Posts: 12,548Member
    edited February 2020

    Rate-Dependent Plasticity is what you might use to create a material model that can simulate impact tests.

    Read the following section of the ANSYS Help system.

    4.3.2. Rate-Dependent Plasticity

    The rate-dependent plasticity model includes four options. The options are defined via the TB,RATE command TBOPT = PERZYNA, PEIRCE, EVH, and ANAND, respectively, and are available with most current-technology elements.

    The material hardening behavior is assumed to be isotropic. The integration of the material constitutive equations are based a return mapping procedure to enforce both stress and material tangential stiffness matrix are consistent at the end of time step. A typical application of this material model is the simulation of material deformation at high strain rate, such as impact.

    The following topics describe each rate-dependent plasticity option:

    • Perzyna Option
    • Peirce Option
    • Exponential Visco-Hardening (EVH) Option
    • Anand Viscoplasticity Option
  • momidormomidor Posts: 104Member
    edited February 2020

    Hi Peter, 

    Thanks but where I can write: TBOPT = PERZYNA ? In commands line or menu parts ? If menu parts so where I could fint it ? 

     

     

  • peteroznewmanpeteroznewman Posts: 12,548Member
    edited February 2020

    It's a material property, so open Engineering Data and look under Plasticity, I can see Anand Viscoplasticity.

    To access other material models inside Workbench/Mechanical, you may need a Command Object.

    I am not an expert at APDL, so some other member or ANSYS staff will have to help you now.

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