Novel in-situ residual strain measurements in additive manufacturing specimens by using the Optical Backscatter Reflectometry

Wang, Shaoquan; Lasn, Kaspar; Elverum, Christer W.; Wan, Di; Echtermeyer, Andreas T.

doi:10.1016/j.addma.2020.101040

Cited by 17 publications

(12 citation statements)

References 19 publications

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“…The residual strains of in situ ‘Embedding’ ( Figure 10 e) originate from the shrinkage of cooling from the deposited PA6 filament during the 3-D printing process [ 15 ]. Printing parameters, such as the temperature, extrusion speed, and printing speed, are automatically well controlled, resulting in a high but very uniform residual strain distribution along the attached OF.…”

Section: Discussionmentioning

confidence: 99%

“…However, the integration of OF sensors inside the component, or attaching them on the component surface, is still a challenge for many practical applications [ 1 ]. A limited scope literature review identifies basic types of attachment methods [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ] for fixing the optical fibers, as shown in Table 1 . Structural engineering applications (concrete, timber, and steel) tend to adhere the OF directly on the surface by a rigid glue [ 2 ], pre-embed the OF in a package filled with rigid glue or soft rubber [ 5 , 6 , 7 ], or attach specialized optical cables to the component [ 8 ].…”

Section: Introductionmentioning

confidence: 99%

“…Similar methods are adopted for polymers and polymer composites [ 9 , 10 ]. In addition, the OF can be embedded directly inside the polymer or composite components during the manufacturing process [ 11 , 12 , 13 , 14 , 15 ]. Polymer matrix surrounding the OF enables the strain transfer and protects the sensor.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of DOFS Attachment Methods for Time-Dependent Strain Sensing

Wang

Sæter

Lasn

2021

Sensors

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Structural health monitoring (SHM) is a challenge for many industries. Over the last decade, novel strain monitoring methods using optical fibers have been implemented for SHM in aerospace, energy storage, marine, and civil engineering structures. However, the practical attachment of optical fibers (OFs) to the component is still problematic. While monitoring, the amount of substrate strain lost by the OF attachment is often unclear, and difficult to predict under long-term loads. This investigation clarifies how different attachment methods perform under time-dependent loading. Optical fibers are attached on metal, thermoset composite, and thermoplastic substrates for distributed strain sensing. Strains along distributed optical fiber sensors (DOFS) are measured by optical backscatter reflectometry (OBR) and compared to contact extensometer strains under tensile creep loading. The quality of the bondline and its influence on the strain transfer is analyzed. Residual strains and strain fluctuations along the sensor fiber are correlated to the fiber attachment method. Results show that a machine-controlled attachment process (such as in situ 3-D printing) holds great promise for the future as it achieves a highly uniform bondline and provides accurate strain measurements.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Comparison of DOFS Attachment Methods for Time-Dependent Strain Sensing

Wang

Sæter

Lasn

2021

Sensors

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“…However, for accurate strain measurements, the fiber must have adequate mechanical coupling with the component. Ideally the fiber-optic sensors could be directly embedded and bonded within the surrounding metal matrix [12][13][14][15][16][17], thus eliminating concerns related to the degradation of adhesives at high temperatures or under irradiation. Typically, 316L and 304 stainless steels (SSs) are chosen for the core block materials because of their relatively high strength, corrosion resistance, and high commercial availability [18,19].…”

Section: Introductionmentioning

confidence: 99%

Characterization of Embedded Sensors in Stainless Steel Test Articles and Design/Planning for MAGNET Testing

Hyer

Sweeney

Petrie

2021

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“…Since polyimide is the sensor's jacket, the adhesion between the polyimide and 3D-printed materials is particularly important for the performance of these products. There are several investigations in the literature [11,12] which have reported the successful integration of the above-mentioned sensors into additively manufactured polymeric structures. The reported deviation in readings between the FBG sensor and different strain recording devices is less than three percent [11].…”

Section: Introductionmentioning

confidence: 99%

Adhesion Optimization between Incompatible Polymers through Interfacial Engineering

et al. 2021

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Additive manufacturing technologies such as fused filament fabrication (FFF) open many possibilities in terms of product functionality, including the possibility to integrate a sensor in FFF parts to perform structural health monitoring. In this context, embedding fiber Bragg grating (FBG) sensors into 3D-printed polymeric structures for strain or temperature measurements has attracted increasing attention in recent years. Indeed, offering structural health monitoring functionality can optimize the maintenance cost and increase security compared with conventional materials. However, the transmission of strain and temperature between the polymeric matrix and the FBG polymer jacket requires optimal bonding between them. In this work, the two polymers of interest are polyimide (PI) and poly(lactic acid) (PLA) for the FBG jacket and printed polymer, respectively. The current study investigates the influence of different surface treatment methods on the adhesion between a PI film and a plate of PLA, with PLA and PI being incompatible polymers. The adhesion promotion applied to the PI surface relies on cleaning, plasma activation, roughness modification, or the use of adhesive nanocoating. Bilayer samples of PI-PLA are processed by welding PLA against the treated PI by heating, whereas the adhesion between PI and PLA is measured by peel testing. It is observed that the highest adhesion between PI and PLA is achieved by a combination of mechanical abrasion increasing roughness and the use of polydopamine as an adhesive. This finding is discussed based on a synergetic effect between mechanical interlocking and chemical interaction between the two counterfaces.

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Novel in-situ residual strain measurements in additive manufacturing specimens by using the Optical Backscatter Reflectometry

Cited by 17 publications

References 19 publications

Comparison of DOFS Attachment Methods for Time-Dependent Strain Sensing

Comparison of DOFS Attachment Methods for Time-Dependent Strain Sensing

Characterization of Embedded Sensors in Stainless Steel Test Articles and Design/Planning for MAGNET Testing

Adhesion Optimization between Incompatible Polymers through Interfacial Engineering

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