UGENS

This problem contains basic test cases for one or more Abaqus elements and features.

This page discusses:

ProductsAbaqus/Standard

Elements tested

S8R

SAX2

SAXA22

Features tested

User subroutine to define a shell section stiffness and right-hand side vector for various shell element types. The subroutine argument list is stored in an array reserved for solution-dependent state variables. This array is then written to the results file for verification.

Problem description

To verify user subroutine UGENS, the data line input option is used to specify the shell section stiffness and thickness of the shell elements (passed into UGENS via array PROPS). The general shell section stiffness is determined from a prior analysis along with a material reference from which Abaqus determines equivalent section properties.

ugensbvr.inp

This problem is discussed in detail in The barrel vault roof problem. A 4 × 4 mesh of S8R elements is used to model a deeply arched roof supported only by diaphragms at its curved edges. The first and second steps verify the response to thermal loading as perturbation and general steps, respectively. The coefficient of thermal expansion is taken as 1.0 × 10−6 at a reference temperature of 70°. The structure is heated to 120° from an initial temperature of 70°. The thermal properties, the section force, and the moment vectors, as well as the thermal loading, are all specified in user subroutine UGENS. In the third step a frequency extraction is performed to determine the eigenmodes of the structure. In the fourth step the structure is subjected to a body force in the vertical direction while the previously applied thermal loading is removed. The buckling loads are then determined in the fifth step.

ugenscan.inp

SAXA22 elements are used to model a cantilevered pipe loaded at its tip. This problem is discussed in detail in Cantilever beam analyzed with CAXA and SAXA elements.

ugenspsx.inp

A mesh of five SAX2 elements is used to model one-half of a hollow sphere subject to a point load applied in the radial direction. This problem is discussed in detail in The pinched sphere problem.

Results and discussion

The verification consists of comparing results from the above models to those in a general shell section without user subroutine UGENS. In each case the results were identical. The values of the subroutine arguments are verified via the results file.