Mechanical amplification for sensitivity enhancement of a FBG-based sensor

Mechanical amplification for sensitivity enhancement of a FBG-based sensor

Iedema, Menno (TU Delft Mechanical, Maritime and Materials Engineering)

Goosen, J.F.L. (mentor)
van der Veen, G.J. (graduation committee)
Hassan HosseinNia, S. (graduation committee)

Delft University of Technology

Mechanical Engineering | Precision and Microsystems Engineering

Engineered functional material structures for advanced sensing in high-tech instruments.

2023-08-18

High-tech machines are being improved by extend- ing product quality inspections through implementing better sensors. The resolution of an integrated optical sensor can be optimized through mechanical amplification. In this work mechanical sensitivity enhancement of a Fiber Bragg Grating based sensor is realized, through optimizing output displacement and force (strain) with limited input force and displacement. A compliant mechanical force amplifier is designed with key parameters, through which the amplification of the structure and its stiffness versus efficiency are adjustable. Input compression is converted to output tension and its two flexible hinges are loaded axially in tension. The simple one DOF lever mechanism can be used as a building block for compound mechanisms. Through a Matlab model based on beam theory a parametric analysis is performed. A functional load test is performed to experimentally verify the design function. A finite element analysis in COMSOL is used to validate optimal designs and compared to the model and experiment. Through topology optimization a rhombus design is generated, which is compared with the lever designs. The initial strain of a 2 mm steel rod at 1 N input force is 0.38 με. By integrating the in-line amplifier/transducer that gets compressed by 41.9 μm and amplifies the force by a factor 1.64 with an efficiency η of 65.6 %, the output strain is improved to 2 mε, by a factor of 5300. The number of resolution steps with an interrogator resolution of 1 pm/bit and a fiber transduction of 1.21 pm/με is ε · T /R = 2435. The force per resolution step is 0.41 mN . An integrated FBG-based sensor combined with the mechani- cal amplifier/transducer is a viable option to measure input force with a high resolution. The next step is to realise implementation with the sensor and a 1:1 scale prototype fabricated with milling and wire-EDM.

Compliant Mechanism
Fiber Bragg Grating
Sensitivity enhancement
Force Amplification

http://resolver.tudelft.nl/uuid:16fe9ace-63f1-48c2-8b41-20655c2d7991

Student theses

master thesis

© 2023 Menno Iedema