Fiber Bragg Sensors Embedded in Cast Aluminum Parts: Axial Strain and Temperature Response

Abstract

In this study, the response of fiber Bragg gratings (FBGs) embedded in cast aluminum parts under thermal and mechanical load were investigated. Several types of FBGs in different types of fibers were used in order to verify general applicability. To monitor a temperature-induced strain, an embedded regenerated FBG (RFBG) in a cast part was placed in a climatic chamber and heated up to 120∘C within several cycles. The results show good agreement with a theoretical model, which consists of a shrink-fit model and temperature-dependent material parameters. Several cast parts with different types of FBGs were machined into tensile test specimens and tensile tests were executed. For the tensile tests, a cyclic procedure was chosen, which allowed us to distinguish between the elastic and plastic deformation of the specimen. An analytical model, which described the elastic part of the tensile test, was introduced and showed good agreement with the measurements. Embedded FBGs - integrated during the casting process - showed under all mechanical and thermal load conditions no hysteresis, a reproducible sensor response, and a high reliable operation, which is very important to create metallic smart structures and packaged fiber optic sensors for harsh environments.

High temperature measurements using femtosecond written FBGs of a titanium substrate under intense heat flow

“…In the Figure 6, we shows the evolution of the temperature and the strain measured by the FBGs. This highlights the ability of the FBG sensors to perform strain measurements [9][10] at high temperature thanks to their thermal stability and to their efficient anchoring procedure. Further strain analysis will be presented during the conference.…”

Preisach Elasto-Plastic Model for Mild Steel Hysteretic Behavior-Experimental and Theoretical Considerations

“…To measure strains and temperature in real structures in civil and mechanical engineering and aeronautics, embedded sensors can be used, as explained in [8]. The purpose of this paper is to establish stress-strain relations and construction of cyclic stress-strain loops for arbitrary elements in structures.…”

“…Also, temperature rises due to plastic deformation can be calculated using the algorithm given in this paper. This temperature can be measured with embedded elements as shown in [8]. As stated in [8]: "For the tensile tests, a cyclic procedure was chosen, which allowed us to distinguish between the elastic and plastic deformation of the specimen.…”

“…This temperature can be measured with embedded elements as shown in [8]. As stated in [8]: "For the tensile tests, a cyclic procedure was chosen, which allowed us to distinguish between the elastic and plastic deformation of the specimen. An analytical model, which described the elastic part of the tensile test, was introduced and showed good agreement with the measurements."…”

“…An analytical model, which described the elastic part of the tensile test, was introduced and showed good agreement with the measurements." Readers of the paper are invited to see the explanation how to measure strains (elastic and plastic) given in reference [8] (Sections 2.2 and 3). It is in detail explained theoretically in Section 2.2 as an application of FBG embedded in cast aluminum during a tensile test.…”