At CSA Engineering, we use finite element modeling as a tool to aid in the design and optimization of our isolation products. Isolators and dampers for vibration mitigation are common components for finite element modeling. Engineers begin by drafting a three-dimensional part using I-Deas Simulation software or our 3-D modeling package SolidWorks. The solid geometry is then meshed using I-Deas. These finite element (FE) models are then exported in a MSC/Nastran bulk data format for analysis. The necessary static or dynamic analyses are performed on the design. The engineer can then revise the design, if necessary, if the part has not met the requirements of stress, stiffness, isolation ability, or weight.

Solid Geometry of a Whole-Spacecraft Isolator

Mesh of Solid Geometry

MSC/Nastran is the industry-wide trusted and benchmarked finite element analysis software used at CSA. This software is used in whole or in part for all static and dynamic analyses. Matlab is also a significant analysis tool used for data interpretation, plotting, and automating analyses. The combination of MSC/Nastran and Matlab allows for rapid turnaround in going from a preliminary design to an optimized part.

Some of the static analyses performed include stress analysis of an isolator given a maximum loading condition. This is critical since parts have to be designed for strength and knowledge of maximum stress distribution is necessary for the part not to yield or fail in typical use. Static or dynamic analysis can be used to optimize an isolator's damping characteristics through the recovery of strain energy distribution.

Stress Contours Under Load

Finished Part

Dynamic analysis includes normal modes, transient, and frequency response analyses. Tuned mass dampers (TMDs) and absorbers can be optimally sized and located by analyzing a structure's mode shapes from a normal modes analysis. Typical transient analyses include the recovery of acceleration, displacement, or force responses due to an input dynamic force in a system-level FE model. The vibration mitigation system characteristics can be iterated upon in that system to arrive at the necessary requirements (i.e. stiffness and damping properties) for the final system. Frequency-domain analyses include random vibration responses (such as power spectral density (PSD) inputs) and frequency response functions (FRF). These analyses are also used to gauge the attenuation abilities of an isolator or damper in a system model.