Positioning, Tree File

Fig. 21: Cut through model with joints

The ES-2 model is delivered with a tree file for the OASYS Primer pre-processor (may work also for ALTAIR Hypermesh, not verified by DYNAmore). This allows the user to position the dummy and adjust the parts according to their degrees of freedom.

Figure 21 shows the connections of movable parts via tree file. The accompanying local coordinate systems are shown in Figure 5 of the section 'Local Coordinate Systems'.  All revolute joints are visualized by beams.

Two coordinate systems are modeled at the H-point. These coordinate systems are connected to each other by a spherical joint. One coordinate system is connected to global directions which means only translations are possible, rotations are disabled. The other one is connected to the dummy and hence the pelvis angle of the ES-2 during the positioning simulation can be measured quite easily . These coordinate systems are also used to determine the initial pelvis angle with OASYS-Primer.

Movable parts and revolute joints are:

• Foot, left and right about their ankle joints

      (stop angle: -30.0 and 30.0 degrees)

• Lower leg, left and right about their knee joints

      (stop angle: -7.0 and 90.0 degrees)

• Upper leg bone, left and right about x-axis

      (stop angle: -40.0 and 40.0 degrees)

• Upper leg bone, left and right about hip joints in y-,z-axis

      (stop angle y-axis: -5.0 and 5.0 degrees)

      (stop angle z-axis: -1.0E.4 and 5.0 degrees)

• Arm, left and right about their arm joints

      (no stop angle)

If the upper legs are rotated at the hip joints about the given stop angles, initial penetrations will occur. This reaction is based on the hardware. In the hardware, the geometry is deformed if the position of the upper leg is changed with respect to the pelvis. This is the reason why the degrees of freedom for the upper legs are disabled in the OASYS-Primer tree-file. It is better to position the upper legs by a pre-simulation. A special positioning-file <positioning_es-2_v4.1(_re_1.0)_mm_ms_kg.key> is delivered to do this pre-simulation.

The positioning file of ES-2 is very easy to use. At the top of this file you will find a set of parameters to be defined. These parameters are shown in the following table.

Parameter	Description
tmove	time to move parts
trans_x	translation of whole dummy model in x direction
trans_z	translation of whole dummy model in z direction
lfemry	left femur rotation about y
rfemry	right femur rotation about y
lfemrz	left femur rotation about z
rfemrz	right femur rotation about z

If you do not want to translate or rotate an assembly use a very small value like 1.0E-20. Please do not use zero as the value, because zero as scaling factor is default 1 in LS-DYNA . As the second step you have to fill in your include files necessary for positioning the dummy model. Usually only the seat model and the dummy model are used for the positioning procedure. Please define a *CONTACT_AUTOMATIC_SURFACE_TO_SURFACE for contact between dummy and the seat (environment). The ES-2(re) properties for this contact are defined in the part set 1500.

Figure 22 shows the location of the H-Point and Hm-Point. More details are given in the  "User Manual ES-2; 2002, FTSS Inc."

Following nodes are used:

• The H-point is located at the node 10200.
  
• The Hm-Point, determined by the HIII Manikin, is located at node 10201