High definition fiber optic sensing for strain can provide a virtually continuous line of strain measurements versus and is perfect for measuring areas with high strain gradients or sensing strain in areas difficult to instrument with strain gages.
Strain gradients in composite structures
As industry transitions away from metals to advanced lightweight composites engineers will be faced with greater uncertainty given the heterogeneous and anisotropic properties of composites. At left a fiber is routed along the perimeter of a composite bonded joint revealing several areas with sharp strain gradients. A complete characterization of these gradients would be impractical using traditional point sensing methods.
Automotive component lightweighting
The light weighting trend in automotive will extend to small components. At left is an automotive spring instrumented with fiber along it’s entire length. HD-FOS can provide a complete characterization of strain along the entire length of the spring. Read more.
Validation of finite element models
HD-FOS, and it’s ability to provide a measurement along each millimeter of fiber, is ideal for validating finite element (FE) models, particularly in areas of known stress concentration points. The image at left shows predicted strains of a composite airfoil under load. The predicted strains are compared to actual strain measurements using a 3D visualization tool. See related video.
Embedded fiber for structural health monitoring
Fiber, at only 150 microns in diameter, can be embedded in composite structures during their fabrication and used during service to provide valuable data about a structures operational health. At left is a composite overwrapped pressure vessel (COPV) with a fiber sensor embedded. As the tank is pressurized, high definition strain measurements are taken and correlated to the volumetric expansion of the tank. This data can be used to validate the structural health of the tank without having to remove it from service. Read more.
Embedded fiber for process characterization
Fiber can also be embedded in composite or additively manufactured structures during fabrication. Measurements can be taken during fabrication as part of process development or used to determine the residual stress within structures. At left is an additively manufactured block with fiber embedded in nine layers during its fabrication. The strain measurements show an accumulated residual stress concentrated toward the center of the block. Read more.