FEA History: Lower Structure Table 1: Early results (from ANSYS Worbench 8.0)

Model 4 1 st mode = 93Hz 2 nd mode = 100Hz Model 5 2 nd mode = 96Hz  Bracing added in locations that mimic approach the approach used by Tim in November Model 6 1 st mode = 92Hz  Addition of bracing as circled above (as was used in model 4)  1 st mode (longitudinal) increased by 30Hz  2 nd mode (transverse) of 100Hz Model 7 1 st mode = 94Hz  Quick addition of bracing as circled above  1 st mode now in transverse direction Graphical accompaniment to Table 1

FEA continued…. Table 2: further results from ANSYS

Model 8 1 st mode = 90Hz  Change in BC’s in model – constraining all nodes round edge of top surface  1 st mode goes down Model 9 2 nd mode = 126Hz  Quick change - lengthening of braces to support further down the structure  1 st mode still in transverse (88Hz)  2 nd, 3 rd, and 4 th modes all in the lengthened braces as shown above Model 10  Addition of bracing to increase the Transverse mode  The following two models involved using the same geometry, changing the combinations of displacement constraints used at the top of the lower structure 1 st mode = 120Hz Model 13  Shortening of overall length of lower structure used in model, following assessment of overall structural dimension in SoildWorks (Reduced height in location shown above! Initial numbers had stemmed from limitations set by ) 1 st mode = 140Hz Graphical accompaniment to Table 2

*Most recent Model of Lower Structure* Boundary Conditions: Uppermost surface of implementation ring fixed in all DOF Mesh: (in Workbench 8.0) Default setting: Global Control – basic, Relevance: -100 nodes: , elements:

*Results: Most recent model of Lower Structure* (nodes: , elements: ) 1 st Mode: 128 Hz (transverse - see pic below) 2 nd Mode: 140 Hz (longitudinal) 3 rd Mode: 166 Hz (1 st Torsional) 4 th Mode: 214 Hz (2 nd Transverse)

Model Geometry: Lower Structure….General comments/assumptions/ Limitation: Model Geometry creates a ‘uniform transition’ between the basic structure and stiffening members at all joins (as highlighted opposite) consciously left in additional material in locations where further detailing is ongoing all bracing member as solid bars so far (for speed)

Planned change/improvements: Lower structure Widening of footprint to improve improve access (in progress) Fcomplete the detail at all connection locations (I.e. with clamps/stiffeners etc) to mass