Why is there an option to make a SOLID MODEL in ACP PRE?

We have imported a surface body into ACP PRE, but why would I need to make it a SOLID MODEL? What does making it a solid model mean?

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Best Answers

  • SheldonISheldonI Member
    Accepted Answer

    Hi @Rameez_ul_Haq ,

    The option of creating a solid model based on the layup definition in ACP-Pre is generally to perform a more detailed analysis. Composite shell elements make use of certain assumptions of through-thickness stress (zero) or interlaminar shear stresses. For more detailed stress analyses in local regions, analysts may wish to make use of solid elements. Another situation is when studying delamination (debonding), as solid elements are required for such purposes (along with CZM, for example).

    Regards,

    Sheldon

  • SheldonISheldonI Member
    edited January 12 Accepted Answer

    Hi @Rameez_ul_Haq ,

    Let's take a simple case of a regular (non-composite) shell element. An integration point usually has 6 components of stress (SXX, SYY, SZZ, SXY, SYZ, SXZ), and let's say that the element z-direction is in the 'through-thickness' direction (where x- and y-directions are in the plane of the shell element).

    A shell element is in a state of plane stress, so SZZ is always zero. However, your bending stresses can vary, so SXX will differ at the 'top' of the shell compared with the 'bottom' of the shell. Even though there may be one node along the thickness of the shell, there are many integration points in-plane and through the thickness of the shell. Therefore, we can visualize a variation of stress in the thickness direction, but if we just look at the through-thickness stress SZZ, it will be zero.

    I hope that may clarify my earlier comment.

    Regards,

    Sheldon

Answers

  • SheldonISheldonI Member
    Accepted Answer

    Hi @Rameez_ul_Haq ,

    The option of creating a solid model based on the layup definition in ACP-Pre is generally to perform a more detailed analysis. Composite shell elements make use of certain assumptions of through-thickness stress (zero) or interlaminar shear stresses. For more detailed stress analyses in local regions, analysts may wish to make use of solid elements. Another situation is when studying delamination (debonding), as solid elements are required for such purposes (along with CZM, for example).

    Regards,

    Sheldon

  • @SheldonI, but if I have a surface which I modelled as shell elements, I do see stresses to be changing within the thickness of the surface although there is just a single node along the thickness of shell.

  • SheldonISheldonI Member
    edited January 12 Accepted Answer

    Hi @Rameez_ul_Haq ,

    Let's take a simple case of a regular (non-composite) shell element. An integration point usually has 6 components of stress (SXX, SYY, SZZ, SXY, SYZ, SXZ), and let's say that the element z-direction is in the 'through-thickness' direction (where x- and y-directions are in the plane of the shell element).

    A shell element is in a state of plane stress, so SZZ is always zero. However, your bending stresses can vary, so SXX will differ at the 'top' of the shell compared with the 'bottom' of the shell. Even though there may be one node along the thickness of the shell, there are many integration points in-plane and through the thickness of the shell. Therefore, we can visualize a variation of stress in the thickness direction, but if we just look at the through-thickness stress SZZ, it will be zero.

    I hope that may clarify my earlier comment.

    Regards,

    Sheldon

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