Structural Health Monitoring of Additively Manufactured Parts Using Fiber Bragg Gratings

Abstract

Many industries are moving toward the opportunities afforded by additive manufacturing (AM) techniques as a primary manufacturing method for components. Additionally, AM continues to be an effective option for rapid prototyping in many applications. Some advantages AM processes have over traditional manufacturing include the ability to create highly complex and multi-material parts with little or no restriction on the geometry of the object at a relatively low price point. However, one of the main challenges that from AM techniques is the relatively high variation, in both material properties and exact geometry, from part to part. This variation calls for structural health monitoring of each individual part. In this paper, fiber Bragg gratings (FBGs) -- chosen because they can be embedded with minimal effect on the desired structure -- are inserted into AM geometries between layers, allowing for strain readings to be taken in situ. These measurements provide empirical data of incipient failure as AM parts tend to fail between layers. Fused deposition modeling (FDM) is used, as it is relatively common and inexpensive, to create parts into which the FBGs are embedded. Measurements taken under a variety of tests are compared to analogous finite element as well as analytical models allowing for model accuracy evaluation for AM parts. This work provides experimental data to validate models, in addition to forming a better understanding of the validity and procedure of embedding FBGs into FDM parts. Additionally, this work serves as a proof of concept and calls for more work to be done in the field.