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Abaqus User Subroutines Reference Manual

1.2.2 VDLOAD User subroutine to specify nonuniform distributed loads.

Product: Abaqus/Explicit

References ? ? ? ? ?

“Applying loads: overview,” Section 33.4.1 of the Abaqus Analysis User's Manual “Distributed loads,” Section 33.4.3 of the Abaqus Analysis User's Manual *DLOAD *DSLOAD “Deformation of a sandwich plate under CONWEP blast loading,” Section 9.1.8 of the Abaqus Example Problems Manual

Overview

User subroutine VDLOAD:

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can be used to define the variation of the distributed load magnitude as a function of position, time, velocity, etc. for a group of points, each of which appears in an element-based or surface-based nonuniform load definition; will be called for load integration points associated with each nonuniform load definition including PENU and PINU loads applicable for pipe elements; does not make available the current value of the nonuniform distributed loads for file output purposes; and recognizes an amplitude reference (“Amplitude curves,” Section 33.1.2 of the Abaqus Analysis User's Manual) if it appears with the associated nonuniform load definition.

User subroutine interface

subroutine vdload ( C Read only (unmodifiable)variables 1 nblock, ndim, stepTime, totalTime, 2 amplitude, curCoords, velocity, dirCos, jltyp, sname, C Write only (modifiable) variable 1 value ) C include 'vaba_param.inc' C dimension curCoords(nblock,ndim), velocity(nblock,ndim), 1 dirCos(nblock,ndim,ndim), value(nblock) character*80 sname C do 100 km = 1, nblock

user coding to define value

100 continue return end

Variable to be defined

value (nblock) Magnitude of the distributed load. Units are FL–2 for surface loads, FL–3 for body forces.

Variables passed in for information

nblock Number of points to be processed in this call to VDLOAD. ndim Number of coordinate directions: 2 for two-dimensional models, 3 for three-dimensional models. The model will be considered three-dimensional if any three-dimensional elements are defined (including SPRINGA elements).

stepTime Value of time since the step began. totalTime Value of total time. The time at the beginning of the step is given by totalTime – stepTime. amplitude Current value of the amplitude referenced for this load (set to unity if no amplitude is referenced). You must multiply the load by the current amplitude value within the user subroutine if the amplitude is required. curCoords (nblock, ndim) Current coordinates of each point for which the load is to be calculated. velocity (nblock, ndim) Current velocity of each point for which the load is to be calculated. dirCos (nblock, ndim, ndim) Current orientation of the face, edge, pipe, or beam for pressure type loads (not applicable for body force type loads). The second dimension indicates the vector, and the third dimension indicates the components of that vector. For faces (pressures on three-dimensional continuum, shell, and membrane elements), the first and second vectors are the local directions in the plane of the surface and the third vector is the normal to the face, as defined in “Conventions,” Section 1.2.2 of the Abaqus Analysis User's Manual. For solid elements the normal points inward, which is the opposite of what is defined in the conventions; for shell elements the normal definition is consistent with the defined conventions. For edges (pressures on two-dimensional continuum elements and two-dimensional beams and pipes), the first vector is the normal to the edge, the second vector is the tangent to the edge, and, if ndim=3, the third vector will be a unit normal in the out-of-plane direction. For three-dimensional beam and pipe elements, the first and second vectors are the local axes ( , ) and the third vector is the tangent vector ( ), as defined in “Beam element cross-section orientation,” Section 29.3.4 of the Abaqus Analysis User's Manual. jltyp

Key that identifies the distributed load type. The load type may be a body force, a surface-based load, or an element-based surface load. For element-based surface loads, this variable identifies the element face for which this call to VDLOAD is being made. See Part VI, “Elements,” of the Abaqus Analysis User's Manual for element load type identification. This information is useful when several different nonuniform distributed loads are being imposed on an element at the same time. The key is as follows: Jltype Load type 0 1 2 3 20 21 22 23 24 25 26 27 28 41 42 43 Surface-based load BXNU BYNU BZNU PNU P1NU P2NU P3NU P4NU P5NU P6NU PINU PENU PXNU PYNU PZNU

sname Surface name for a surface-based load definition (JLTYP=0). For a body force or an element-based load the surface name is passed in as a blank.

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