Preprocessing data for Lagamine program.
This page contains a description of the data to be indicated in the *.lag file for the Prepro.

The control data is defined in 4 lines (in exponent, column on which the variable must be fit in with).

→ for mono-block loading:

→ for multi-block loading:

In general, a node has 3 DOF displacements and 1 DOF temperature. In the case of 3D shell elements, it has 3 DOF displacements and 3 DOF rotations. The variable NTANA allows the program to decide which is the maximum number of nodal DOF potentially useful for a given type of analysis (dimension NDOFN, classed as NSPAC, space dimension). It also allows to define the active DOF (i.e. those which can produce an equation) and the passive ones (which do not produce equations).

A negative value of NTANA is used for dynamic analysis.

• The last node is a special one; it always has 3 DOF, $\alpha_0$, $\alpha_1$ et $\alpha_2$, such that the thickness (in z direction) of a slice of slid varies according to: $b = \alpha_0 + \alpha_1 X + \alpha_2 Y$
• To be consistent with these 3 DOF of the last node, it is necessary to specify NTANA such that there exists at least 3 active DOF per node but may perhaps fix the non-significant ones.
  For example, for the mechanical generalized plane state, NTANA = 7, IANA = 5 and fix the 3rd DOF for all the nodes (except for the last one eventually).
• Initial values of $\alpha_0$, $\alpha_1$ et $\alpha_2$ can be introduced: they are the “coordinates” of the last node.
  2 remarkable particular cases are worth noting :
  1. Plane strain state : $\alpha_0$ = 1, $\alpha_1$ = $\alpha_2$ = 0 (and $\alpha_i$ all fixed)
  2. Axisymmetric state : $\alpha_0$ = 0, $\alpha_1$ = 1, $\alpha_2$ = 0 (and $\alpha_i$ all fixed).
• The last node appears in all the elements; therefore, the bandwidth is maximum → use the skyline system solver.

These variables are used in dynamic allocation of memory. In case of thermal analysis, the properties can be described at different temperatures, the default allocations could be insufficient and one must calculate MPARA.

Sub-tree algorithm for contact searching, developed by OCAS, has been implemented both for solid (CFI3D) and shell element (COQJ4). It is activated by option ITREE≥1 in PREPRO. Details of algorithm can be found in “OCAS Technical Report Hgr/9501, 1995” by H. Bruneel and I. De Rycke.
Currently sub-tree contact searching algorithm only works with tools which are driven by a displacement pilot node. No rotation of tools is allowed. Even if the foundation is fixed, a (fixed) pilot node must be defined. Also the algorithm works with tools described by triangular segments (ICODE=5). (Note by Y. Kim, Jan. 97). Note that the sub-tree method only works with foundations containing more than one triangular segment.

Remark : convention
The plane or axisymmetric state axis system is direct (right-handed). Conventionally the Y axis is directed toward the top. In the axisymmetric state, the Y axis is the same as the symmetry axis. All the nodes, elements, and local axis lists definitions must be given in the same axis system, implicit in the whole of this handbook.

This section only exists if IGRAV=1.

This section only exists if IRENU=1.
The renumbering does not change the nodes numbers. It only changes the equations number corresponding to the DOF of these nodes.
File DFIXED.F in Prepro

KZONE and BDFAC are factors which have an effect on the new numbering search as the computer time.

This section only exists if NDUPL>0.

This section only exists if IDMAT = 0 or 2. One must define in this section all the stays without structure displacements.

For the thermal and flow problems, only the DOF nr 3 (2D, axisym) or 4 (3D) can be fixed.

This section only exists if IDMAT = 1.

This section only exists if NDISP ≠ 0. After a sub-title card, the program reads the cards 9.2 until it founds NDISP imposed displacements to non zero values.

This section only exists if INCFO = 1.
… To be completed …

This section only exists if NVELO ≠ 0 and NTANA < 0.
After a sub-title card, the program reads the cards 10.2. until it founds NVELO initial speeds different from zero.
File VELACC.F in Prepro

This section only exists if NACC0 ≠ 0 and NTANA < 0.
After a sub-title card, the program reads the cards 11.2 until it founds NACC0 initial accelerations different from zero.

This section always appears

Remark : In thermal and flow problems, the forces are heat flux or flow, positive when they go in the system. On the other hand, the reactions are the heat flux or flow, positive when they go out the system.

This section only exists if NTANA < 0 (dynamic analysis) and NMASC > 0.
After a sub-title card, the program reads the cards 13.2 until it founds NMASC imposed masses different from zero.

This section only exists if NTANA < 0 (dynamic analysis) and NDAMC > 0.
After a sub-title card, the program reads the cards 14.2. until it founds NDAMC imposed masses different from zero.

File LAWPRE.F in Prepro

→ See Laws

This section only exists if NFOUN > 0 and ICECN = 0. The foundations and the tools can be rigid (then the nodes must be fixed) or deformable (and must be FE facets).

This section must be repeated NFOUN times.

Fig. 1: An example of contact zone for ICAS≤1, IDIR=1 Fig. 2: An example of contact zone for ICAS=2, IDIR=1

The definition direction is important. In 2D (ICODE = 1 to 4), when the segment is examined in the described direction, the foundation or the tool must be placed on the right.
In 3D (ICODE=5 or ICODE=11), the normal to the triangular facet is given by the vectors product $\vec{12} \vec{13}$ built on the facet's nodes $n=\vec{12} \wedge \vec{13}$ . This normal (marked by red face in DESFIN) must get inside the foundation, i.e., be directed from the contact element to the foundation.

• For ICODE = 6, the first node represents the circle center, the second node has the (R, φ) coordinates where φ represents the circle rotation (initially φ = 0).
  
• For ICODE = 7, the first two nodes represent the cylinder axis limits. The last one has the (R, φ, 0) coordinates where φ represent the cylinder rotation (initially φ = 0).
  
• For ICODE = 8, the first two nodes represent the cone frustrum axis limits. The last one has the (R₁, R₂, φ) coordinates where R₁ and R₂ are the radius at nodes 1 and 2, and φ represents the cone frustum rotation (initially φ = 0).
• For ICODE = ±9, the first two nodes represent the cone frustum axis limits (N1 and N2). The third node represents the middle of the arc in the plane perpendicular to the cone frustum axis, coming from N1. The fourth node has the (R1, R2, θ) coordinates where R1 and R2 are the radius at the nodes 1 and 2, and θ is the angle (in radian) of the cone frustum (see figure 3) – only one case has been tested presently: the cone frustum axis is parallel to the z axis.

Fig. 3

• For ICODE = 10, the first node represents the sphere center, the second node has the (R, F) coordinates where F allows to see only one part of the sphere.
  F=0.abcdef
  a=1 : positive X part visible
  b=1 : negative X part visible
  c=1 : positive Y part visible
  d=1 : negative Y part visible
  e=1 : positive Z part visible
  f=0 : negative Z part visible.
  Example: F=0.101010 draws the X, Y, Z positive parts.
• For ICODE = 98 and 99, this segment is composed by only one node which DOF pilot the supposed rigid foundation.
  This segment type is unique for a given foundation and MUST be placed in the first position. The pilot node DOF can be free or fixed (fixed or imposed displacement), but all the other foundation nodes must be fixed. The pilot node DOF must be consistent with the analysis type. In case of rotations, it means finite rotations. The foundation follows its pilot, its displacement can be defined by DMULT or *.DEP. In the case ICODE = 98, the foundation can have rotations.
• Case ICODE = 98, for the 2D case, the DOF 1 represents the rotation around the perpendicular to the plan (2), on the other hand for the 3D case, the DOF 1 represents the rotation around x, the DOF 2 represents the rotation around y and the DOF 3 the rotation around z. All these rotations are given in radian.

→ See Elements