SHELL61


Axisymmetric-Harmonic Structural Shell

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SHELL61 Element Description

SHELL61 has four degrees of freedom at each node: translations in the nodal x, y, and z directions and a rotation about the nodal z-axis. The loading may be axisymmetric or nonaxisymmetric. Various loading cases are described in Harmonic Axisymmetric Elements with Nonaxisymmetric Loads.

Extreme orientations of the conical shell element result in a cylindrical shell element or an annular disc element. The shell element may have a linearly varying thickness. See SHELL61 in the Mechanical APDL Theory Reference for more details about this element.

Figure 61.1: SHELL61 Geometry

SHELL61 Geometry

SHELL61 Input Data

The geometry, node locations, and the coordinate system for this element are shown in Figure 61.1: SHELL61 Geometry. The element is defined by two nodes, two end thicknesses, the number of harmonic waves (MODE on the MODE command), a symmetry condition (ISYM on the MODE command), and the orthotropic material properties. The element coordinate system is shown in Figure 61.2: SHELL61 Stress Output. θ is in the tangential (hoop) direction. The MODE or ISYM parameters are discussed in detail in Harmonic Axisymmetric Elements with Nonaxisymmetric Loads.

The material may be orthotropic, with nine elastic constants required for its description. The element loading may be input as any combination of harmonically varying temperatures and pressures. Harmonically varying nodal forces, if any, should be input on a full 360° basis.

The element may have variable thickness. The thickness is assumed to vary linearly between the nodes. If the element has a constant thickness, only TK(I) is required. Real constant ADMSUA is used to define an added mass per unit area.

Element loads are described in Element Loading. Harmonically varying pressures may be input as surface loads on the element faces as shown by the circled numbers on Figure 61.1: SHELL61 Geometry. Positive pressures act into the element. The pressures are applied at the surface of the element rather than at the centroidal plane so that some thickness effects can be considered. These include the increase or decrease in size of surface area the load is acting on and (in the case of a nonzero Poisson's ratio) an interaction effect causing the element to grow longer or shorter under equal pressures on both surfaces. Material properties EY, PRXY, and PRYZ (or EY, NUXY, and NUYZ) are required for this effect.

Harmonically varying temperatures may be input as element body loads at the four corner locations shown in Figure 61.1: SHELL61 Geometry. The first corner temperature T1 defaults to TUNIF. If all other temperatures are unspecified, they default to T1. If only T1 and T2 are input, T3 defaults to T2 and T4 defaults to T1. For any other input pattern, unspecified temperatures default to TUNIF.

KEYOPT(1) is used for temperature loading with MODE greater than zero and temperature-dependent material properties. Material properties may only be evaluated at a constant (nonharmonically varying) temperature. If MODE equals zero, the material properties are always evaluated at the average element temperature. KEYOPT(3) is used to include or suppress the extra displacement shapes.

A summary of the element input is given in "SHELL61 Input Summary". A general description of element input is given in Element Input.

SHELL61 Input Summary

Nodes

I, J

Degrees of Freedom

UX, UY, UZ, ROTZ

Real Constants
TK(I) - Shell thickness at node I
TK(J) - Shell thickness at node J (TK(J) defaults to TK(I))
ADMSUA - Added mass/unit area
Material Properties

MP command: EX, EY, EZ, PRXY, PRYZ, PRXZ (or NUXY, NUYZ, NUXZ), ALPX, ALPZ (or CTEX, CTEY, CTEZ or THSX, THSY, THSZ), DENS, GXZ, ALPD, BETD. (X is meridional, Y is through-the-thickness, and Z is circumferential), DMPR, DMPS

Surface Loads
Pressures -- 
face 1 (I-J) (top, in -Y direction)
face 2 (I-J) (bottom, in +Y direction)
Body Loads
Temperatures -- 

T1, T2, T3, T4

Mode Number

Number of harmonic waves around the circumference (MODE)

Loading Condition

Symmetry condition (MODE)

Special Features

Stress stiffening

KEYOPT(1)

If MODE is greater than zero, use temperatures for:

0 -- 

Use temperatures only for thermal bending (evaluate material properties at TREF)

1 -- 

Use temperatures only for material property evaluation (thermal strains are not computed)

KEYOPT(3)

Extra displacement shapes:

0 -- 

Include extra displacement shapes

1 -- 

Suppress extra displacement shapes

KEYOPT(4)

Member force and moment output:

0 -- 

No printout of member forces and moments

1 -- 

Print out member forces and moments in the element coordinate system

KEYOPT(6)

Location of element solution output:

0 -- 

Output solution at mid-length only

N -- 

Output solution at N equally spaced interior points and at end points (where N = 1, 3, 5, 7 or 9)

SHELL61 Output Data

The solution output associated with the element is in two forms:

Several items are illustrated in Figure 61.2: SHELL61 Stress Output. The printout may be displayed at the centroid, at the end points and at N equally spaced interior points, where N is the KEYOPT(6) value. For example, if N = 3, printout will be produced at end I, 1/4 length, mid-length (centroid), 3/4 length, and at end J. Printout location number 1 is always at end I. Stress components which are inherently zero are printed for clarity.

In the displacement printout, the UZ components are out-of-phase with the UX and UY components. For example, in the MODE = 1, ISYM = 1 loading case, UX and UY are the peak values at θ = 0° and UZ is the peak value at  θ = 90°. We recommend that you always use the angle field on the SET command when postprocessing the results. For more information about harmonic elements, see Harmonic Axisymmetric Elements with Nonaxisymmetric Loads

A general description of solution output is given in Solution Output. See the Basic Analysis Guide for ways to view results.

Figure 61.2: SHELL61 Stress Output

SHELL61 Stress Output

The Element Output Definitions table uses the following notation:

A colon (:) in the Name column indicates that the item can be accessed by the Component Name method (ETABLE, ESOL). The O column indicates the availability of the items in the file jobname.out. The R column indicates the availability of the items in the results file.

In either the O or R columns, “Y” indicates that the item is always available, a letter or number refers to a table footnote that describes when the item is conditionally available, and “-” indicates that the item is not available.

Table 61.1: SHELL61 Element Output Definitions

NameDefinitionOR
ELElement NumberYY
NODESNodes - I, JYY
MATMaterial numberYY
LENGTHDistance between node I and node JYY
XC, YCLocation where results are reportedY2
TEMPTemperatures T1, T2, T3, T4YY
PRESPressures P1 (top) at nodes I,J; P2 (bottom) at nodes I,JYY
MODENumber of waves in loadingYY
ISYMLoading key: 1 = symmetric, -1 = antisymmetricYY
T(X, Z, XZ)In-plane element X, Z, and XZ forces at KEYOPT(6) location(s)YY
M(X, Z, XZ)Out-of-plane element X, Z, and XZ moments at KEYOPT(6) location(s)YY
MFOR(X, Y, Z), MMOMZMember forces and member moment for each node in the element coordinate system1Y
PK ANGAngle where stresses have peak values: 0 and 90/MODE°. Blank if MODE = 0.YY
S(M, THK, H, MH)Stresses (meridional, through-thickness, hoop, meridional-hoop) at PK ANG locations, repeated for top, middle, and bottom of shellYY
EPEL(M, THK, H, MH)Elastic strains (meridional, through-thickness, hoop, meridional-hoop) at PK ANG locations, repeated for top, middle, and bottom of shellYY
EPTH(M, THK, H, MH)Thermal strains (meridional, through-thickness, hoop, meridional-hoop) at PK ANG locations, repeated for top, middle, and bottom of shellYY

  1. These items are printed only if KEYOPT(4) = 1.

  2. Available only at centroid as a *GET item.

Table 61.2: SHELL61 Item and Sequence Numbers (KEYOPT(6) = 0 or 1) lists output available through the ETABLE command using the Sequence Number method. See The General Postprocessor (POST1) in the Basic Analysis Guide and The Item and Sequence Number Table in this reference for more information. The following notation is used in Table 61.2: SHELL61 Item and Sequence Numbers (KEYOPT(6) = 0 or 1):

Name

output quantity as defined in the Table 61.1: SHELL61 Element Output Definitions

Item

predetermined Item label for ETABLE command

I,J

sequence number for data at nodes I and J

ILn

sequence number for data at Intermediate Location n

Table 61.2: SHELL61 Item and Sequence Numbers (KEYOPT(6) = 0 or 1)

Output Quantity NameETABLE and ESOL Command Input
ItemIIL1J
Top
SMLS11325
STHKLS21426
SHLS31527
SMHLS41628
EPELMLEPEL11325
EPELTHKLEPEL21426
EPELHLEPEL31527
EPELMHLEPEL41628
EPTHMLEPTH11325
EPTHTHKLEPTH21426
EPTHHLEPTH31527
EPTHMHLEPTH41628
Mid
SMLS51729
STHKLS61830
SHLS71931
SMHLS82032
EPELMLEPEL51729
EPELTHKLEPEL61830
EPELHLEPEL71931
EPELMHLEPEL82032
EPTHMLEPTH51729
EPTHTHKLEPTH61830
EPTHHLEPTH71931
EPTHMHLEPTH82032
Bot
SMLS92133
STHKLS102234
SHLS112335
SMHLS122436
EPELMLEPEL92133
EPELTHKLEPEL102234
EPELHLEPEL112335
EPELMHLEPEL122436
EPTHMLEPTH92133
EPTHTHKLEPTH102234
EPTHHLEPTH112335
EPTHMHLEPTH122436
Element
MFORXSMISC1-7
MFORYSMISC2-8
MFORZSMISC3-9
MMOMZSMISC6-12
TXSMISC131925
TZSMISC142026
TXZSMISC152127
MXSMISC162228
MZSMISC172329
MXZSMISC182430
P1SMISC31-32
P2SMISC35-36

 Corner Location
 1234
TEMPLBFE1234

Table 61.3: SHELL61 Item and Sequence Numbers (KEYOPT(6) = 3)

Output Quantity NameETABLE and ESOL Command Input
ItemIIL1IL2IL3J
Top
SMLS113253749
STHKLS214263850
SHLS315273951
SMHLS416284052
EPELMLEPEL113253749
EPELTHKLEPEL214263850
EPELHLEPEL315273951
EPELMHLEPEL416284052
EPTHMLEPTH113253749
EPTHTHKLEPTH214263850
EPTHHLEPTH315273951
EPTHMHLEPTH416284052
Mid
SMLS517294153
STHKLS618304254
SHLS719314355
SMHLS820324456
EPELMLEPEL517294153
EPELTHKLEPEL618304254
EPELHLEPEL719314355
EPELMHLEPEL820324456
EPTHMLEPTH517294153
EPTHTHKLEPTH618304254
EPTHHLEPTH719314355
EPTHMHLEPTH820324456
Bot
SMLS921334557
STHKLS1022344658
SHLS1123354759
SMHLS1224364860
EPELMLEPEL921334557
EPELTHKLEPEL1022344658
EPELHLEPEL1123354759
EPELMHLEPEL1224364860
EPTHMLEPTH921334557
EPTHTHKLEPTH1022344658
EPTHHLEPTH1123354759
EPTHMHLEPTH1224364860
Element
MFORXSMISC1---7
MFORYSMISC2---8
MFORZSMISC3---9
MMOMZSMISC6---12
TXSMISC1319253137
TZSMISC1420263238
TXZSMISC1521273339
MXSMISC1622283440
MZSMISC1723293541
MXZSMISC1824303642
P1SMISC43---44
P2SMISC47---48

 Corner Location
 1234
TEMPLBFE1234

Table 61.4: SHELL61 Item and Sequence Numbers (KEYOPT(6) = 5)

Output Quantity NameETABLE and ESOL Command Input
ItemIIL1IL2IL3IL4IL5J
Top
SMLS1132537496173
STHKLS2142638506274
SHLS3152739516375
SMHLS4162840526476
EPELMLEPEL1132537496173
EPELTHKLEPEL2142638506274
EPELHLEPEL3152739516375
EPELMHLEPEL4162840526476
EPTHMLEPTH1132537496173
EPTHTHKLEPTH2142638506274
EPTHHLEPTH3152739516375
EPTHMHLEPTH4162840526476
Mid
SMLS5172941536577
STHKLS6183042546678
SHLS7193143556779
SMHLS8203244566880
EPELMLEPEL5172941536577
EPELTHKLEPEL6183042546678
EPELHLEPEL7193143556779
EPELMHLEPEL8203244566880
EPTHMLEPTH5172941536577
EPTHTHKLEPTH6183042546678
EPTHHLEPTH7193143556779
EPTHMHLEPTH8203244566880
Bot
SMLS9213345576981
STHKLS10223446587082
SHLS11233547597183
SMHLS12243648607284
EPELMLEPEL9213345576981
EPELTHKLEPEL10223446587082
EPELHLEPEL11233547597183
EPELMHLEPEL12243648607284
EPTHMLEPTH9213345576981
EPTHTHKLEPTH10223446587082
EPTHHLEPTH11233547597183
EPTHMHLEPTH12243648607284
Element
MFORXSMISC1-----7
MFORYSMISC2-----8
MFORZSMISC3-----9
MMOMZSMISC6-----12
TXSMISC13192531374349
TZSMISC14202632384450
TXZSMISC15212733394551
MXSMISC16222834404652
MZSMISC17232935414753
MXZSMISC18243036424854
P1SMISC55-----56
P2SMISC59-----60

 Corner Location
 1234
TEMPLBFE1234

Table 61.5: SHELL61 Item and Sequence Numbers (KEYOPT(6) = 7)

Output Quantity NameETABLE and ESOL Command Input
ItemIIL1IL2IL3IL4IL5IL6IL7J
Top
SMLS11325374961738597
STHKLS21426385062748698
SHLS31527395163758799
SMHLS416284052647688100
EPELMLEPEL11325374961738597
EPELTHKLEPEL21426385062748698
EPELHLEPEL31527395163758799
EPELMHLEPEL416284052647688100
EPTHMLEPTH11325374961738597
EPTHTHKLEPTH21426385062748698
EPTHHLEPTH31527395163758799
EPTHMHLEPTH416284052647688100
Mid
SMLS517294153657789101
STHKLS618304254667890102
SHLS719314355677991103
SMHLS820324456688092104
EPELMLEPEL517294153657789101
EPELTHKLEPEL618304254667890102
EPELHLEPEL719314355677991103
EPELMHLEPEL820324456688092104
EPTHMLEPTH517294153657789101
EPTHTHKLEPTH618304254667890102
EPTHHLEPTH719314355677991103
EPTHMHLEPTH820324456688092104
Bot
SMLS921334557698193105
STHKLS1022344658708294106
SHLS1123354759718395107
SMHLS1224364860728496108
EPELMLEPEL921334557698193105
EPELTHKLEPEL1022344658708294106
EPELHLEPEL1123354759718395107
EPELMHLEPEL1224364860728496108
EPTHMLEPTH921334557698193105
EPTHTHKLEPTH1022344658708294106
EPTHHLEPTH1123354759718395107
EPTHMHLEPTH1224364860728496108
Element
MFORXSMISC1-------7
MFORYSMISC2-------8
MFORZSMISC3-------9
MMOMZSMISC6-------12
TXSMISC131925313743495561
TZSMISC142026323844505662
TXZSMISC152127333945515763
MXSMISC162228344046525864
MZSMISC172329354147535965
MXZSMISC182430364248546066
P1SMISC67-------68
P2SMISC71-------72

 Corner Location
 1234
TEMPLBFE1234

Table 61.6: SHELL61 Item and Sequence Numbers (KEYOPT(6) = 9)

Output Quantity LabelETABLE and ESOL Command Input
ItemIIL1IL2IL3IL4IL5IL6IL7IL8IL9J
Top
SMLS11325374961738597109121
STHKLS21426385062748698110122
SHLS31527395163758799111123
SMHLS416284052647688100112124
EPELMLEPEL11325374961738597109121
EPELTHKLEPEL21426385062748698110122
EPELHLEPEL31527395163758799111123
EPELMHLEPEL416284052647688100112124
EPTHMLEPTH11325374961738597109121
EPTHTHKLEPTH21426385062748698110122
EPTHHLEPTH31527395163758799111123
EPTHMHLEPTH416284052647688100112124
Mid
SMLS517294153657789101113125
STHKLS618304254667890102114126
SHLS719314355677991103115127
SMHLS820324456688092104116128
EPELMLEPEL517294153657789101113125
EPELTHKLEPEL618304254667890102114126
EPELHLEPEL719314355677991103115127
EPELMHLEPEL820324456688092104116128
EPTHMLEPTH517294153657789101113125
EPTHTHKLEPTH618304254667890102114126
EPTHHLEPTH719314355677991103115127
EPTHMHLEPTH820324456688092104116128
Bot
SMLS921334557698193105117129
STHKLS1022344658708294106118130
SHLS1123354759718395107119131
SMHLS1224364860728496108120132
EPELMLEPEL921334557698193105117129
EPELTHKLEPEL1022344658708294106118130
EPELHLEPEL1123354759718395107119131
EPELMHLEPEL1224364860728496108120132
EPTHMLEPTH921334557698193105117129
EPTHTHKLEPTH1022344658708294106118130
EPTHHLEPTH1123354759718395107119131
EPTHMHLEPTH1224364860728496108120132
Element
MFORXSMISC1---------7
MFORYSMISC2---------8
MFORZSMISC3---------9
MMOMZSMISC6---------12
TXSMISC1319253137434955616773
TZSMISC1420263238445056626874
TXZSMISC1521273339455157636975
MXSMISC1622283440465258647076
MZSMISC1723293541475359657177
MXZSMISC1824303642485460667278
P1SMISC79---------80
P2SMISC83---------84

 Corner Location
 1234
TEMPLBFE1234

SHELL61 Assumptions and Restrictions

  • The axisymmetric shell element must be defined in the global X-Y plane and must not have a zero length. Both ends must have nonnegative X coordinate values and the element must not lie along the global Y-axis.

  • If the element has a constant thickness, only TK(I) need be defined. TK(I) must not be zero.

  • The element thickness is assumed to vary linearly from node I to node J.

  • The element assumes a linear elastic material.

  • Post analysis superposition of results is valid only with other linear elastic solutions.

  • Strain energy does not consider thermal effects.

  • The element should not be used with the large deflection option.

  • The element may not be deactivated with the EKILL command.

  • You can use only axisymmetric (MODE,0) loads without significant torsional stresses to generate the stress state used for stress stiffened modal analyses using this element.

SHELL61 Product Restrictions

There are no product-specific restrictions for this element.