Two forms of analysis were carried out in order to ensure that the Pathfinder 1B Rocket airframe would withstand the specified loading. The first was hand calculations and the second was by building a model in Patran. Once the hand calculations ensured that the airframe laminate was capable of withstanding the loading criteria, a second opinion was sought from Patran.
To start off, a geometrical model of the rocket was created and 71 different coordinate systems added in order to align the fibres in the appropriate direction. Patran then enveloped the model in an adequate mesh using a total of 4220 nodes to completely encase the structure. Thirdly, the forces acting on the rocket (such as drag, weight, thrust and internal pressure force) were multiplied by a factor of 2 (to ensure an appropriate factor of safety was reached) and added to the model. The properties of carbon fibre/epoxy and fibreglass/epoxy materials (such as transverse and longitudinal modulus) were added into Patran and a three layer composite laminate was designed. A simulation was run and results for deformation and maximum stress emerged.
The simulation successfully calculated that the rocket would not deform extensively or fracture under the given loading. The design of the 1.8mm-thick three ply laminate would be able to withstand the calculated flight path of the rocket.