In Situ Evaluation of Composite Structural Performance in Presence of High Stress/Strain Gradients using Multiaxis Fiber Grating Strain Sensors

In order to measure multi-axis strain fields and strain field gradients interior to composite materials, it is necessary to be able to measure both transverse axes of strain and axial strain. In addition, these sensors should be capable of measuringstrain gradients. Blue Road Research has developed a multi-axis fiber optic grating sensor that can be used to meet these requirements. This proposal describes how these sensors may be used to monitor transverse strain, transverse strain gradients, axialstrain, and shear strain in the interior of a structure. Blue Road Research in collaboration with the University of Delaware will develop techniques and models to effectively utilize this technology to monitor interior strain changes in textile compositematerials while preserving the structural performance properties of the composite structure being evaluated. Composite materials are widely used by the aerospace industry and on ships. Efforts are underway to increase their usage on autos, trucks, and awide variety of applications where lightweight materials are needed. The system being developed by Blue Road Research and the University of Delaware could be widely applied to improve manufacturing processes and yields for composite materials.