# Three Ansys Tables

No Frames

The properties of each element are described in three tables of the preprocessor, /PREP7 section:

1. ET, the Element Types
2. R, the Real constants
3. MP, the Material Properties

• The ET (element type) command: One or more element types must be selected from a list of over 100. The ET command has at least two options separated by commas. The first number is the position in the Element-Type table. It starts with 1 and is referenced by the TYPE command. The second option selects the type of element. We will use type 1, 3, 8, 10, 16, 32, 34, 42, 55, 68, 82, and 93. The element-type statements look like this:

ET,1,Link1    ! 2D spar, Lesson 6, trusses
ET,1,Beam3    ! 2D elastic beam
ET,1,Link8    ! 3D spar, Lesson 6, trusses
ET,2,Link10   ! 3D Tension-only spar, Lesson 6, trusses
ET,1,Pipe16   ! Elastic straight pipe, Axial 1
ET,2,Link32   ! 2D thermal conduction bar
ET,1,Plane42  ! 2D, 4-node structural solid, Lesson 4, axisymmetric cylinder
ET,1,Plane55  ! 2D, 4-node thermal solid, Lesson 5, temperature in a 2D plate
ET,1,Plane82  ! 2D, 8-node structural solid, Lesson 9, stressed plate with hole
ET,1,Shell93  ! 8-node structural shell Lesson 3, Ansys graphics mode

• The R (real) command: The real constants specify extensive properties such as area, diameter, wall thickness, moment of inertia, and electrical conductance for each element type. Of course, the appropriate constants change from one element type to another. The R command has at least two options. Like the ET command, the first number is the position in the Real table and is referenced by the REAL command. The remaining options give the extensive properties. The meaning of these options depends on the element type. The real statements look like this:

pi = 4*atan(1)     ! Define pi symbol
dia2 = 0.5         ! Define dia symbol
R,1,(pi/4*dia2**2) ! Cross-sectional area for ET 1
R,1,dia2,(dia2/2)  ! OD and wall thickness for ET 16
R,1,9.1,110,8      ! Area, Iz, height for beam ET 3
R,3,(SQRT(2)/3)    ! Length / resistance for ET 68

Notice that mathematical operations such as (SQRT(2)/3) are allowed. Furthermore, you can also define constants such as pi and dia. Note: there is one R statement for each different property, not one for each element. For example, if R defines cross sectional area, and several elements have the same area, use only one R. Then define those elements after the corresponding REAL statement.

• The MP (material property) command: The material properties statements specify intensive properties such as Young's modulus, shear modulus, poisson's ratio, density, thermal expansion coefficient, thermal conductivity, convection coefficient, and electrical resistivity according to the element type. The MP command has at least three options. The first specifies the type of property and the second is the position in the Material-Property table and is referenced by the MAT command. The third option gives the intensive value. The MP command looks like this:

MP,EX,1,30e6      ! elastic modulus, steel
MP,GXY,1,11.2E6   ! shear modulus, steel
MP,DENS,1,0.284   ! mass density, steel lbs/cu in
MP,HF,1,2         ! convection or film coefficient
MP,KXX,2,0.5      ! thermal conductivity, concrete
MP,ALPX,1,11.7e-6 ! thermal expansion coeff, steel
MP,RSVX,1,1       ! electrical resistivity

MENG 421 | Lectures | Source Program -- Nodes and Elements -- Element-Property Tables -- Ansys index | Class assignments