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Behavior of 3D printed carbon fiber reinforced polymers

The most recent research in Materials examined the thermomechanical performance of carbon fiber reinforced polymer (CFRP) additively manufactured with incorporated fiber Bragg grating (FBG) sensors and their suitability for use under thermal stress.

To study: Model of the influence of temperature on samples of carbon fiber reinforced polymers additively fabricated with integrated fiber Bragg grating sensors. Materials, 15 (1). 222. Available at: https://www.mdpi.com/1996-1944/15/1/222 (DOI recording) Image Credit: asharkyu / Shutterstock.com

Introduction to additive manufacturing

Additive manufacturing (AM), also known as 3D printing, is a layer-by-layer manufacturing technique in which successive sheets of material are built up on top of each other to achieve the complete item at the using computer aided design.

Due to recent technological advancements and the recent trend towards a greener lifestyle, it has been widely used in industrial implementations such as aerospace, automotive, orthodontics, structural and healthcare industries. for manufacturing functional designs, especially with complicated geometric topologies, as it offers exceptional design freedom compared to traditional manufacturing techniques.

Image Credit: Shafighfard, T. & Mieloszyk, M., Materials

As a result, additive manufacturing (AM) is expected to be the 3rd industrial transformation, completing the assembly line that dominated manufacturing from the previous century.

Composites improvements

The advancement of technology has not been limited to production processes. In connection with manufacturing methods, one of the main objectives of scientific innovation has been to make materials more productive, for example intelligent materials.

Due to their high proportion of stiffness, as well as their corrosion protection, decorative character and heat resistance, polymer nanocomposites have experienced a tremendous increase over the past decade. Their inherent sensing capabilities, on the other hand, make them excellent for structural health monitoring (SHM) in aeronautical and industrial engineering disciplines.

Benefits of Fiber Bragg Grating (FBG) Sensor

Surface mounted photodetectors have received a great deal of importance in the study of stress analysis and condition monitoring of composites. Fiber Bragg Grating (FBG) sensors have been preferred over other types of sensors for integration into composite constructions due to their compact size and lightness, corrosion resistance, combinatorial capabilities and their prompt response.

An FBG sensor is a kind of scattered Bragg reflection embedded in a short section of optical fiber that reflects specific wavelengths while transmitting all others. The lack of reliable and reliable in-situ monitoring to attempt to control the construction process and the quality of the final product has stifled the development of AM innovation, so the integration of FBG detectors into laminate composites is necessary for monitoring. legitimate temperature variations and techniques for measuring induced effects. residual stresses.

Integration techniques for FMG sensors

During the production process, conventional techniques can be used to implant FBG detectors into composite samples. FBG sensors can be added to pure polymer samples additively created using processes such as multi-jet printing or fusion deposition modeling (FDM). It has been shown that by fusing pure polymers with short and / or continuous fibers during 3D printing with the FDM process, the structural capacity of polymer materials can be significantly improved.

Limits of FMG sensor integration

Despite the advantages of the FDM technique for manufacturing composite structures, it is not without its flaws. The potential defects associated with the FDM process negatively impact the quality and durability of actual applications. Temperature variations are the most common type of defect that generates errors in the sample throughout the production process, as it undergoes consecutive phases of melting and rapid cooling of the substrate material. It can provide harmful stress distribution, which can lead to breakage of the peel. Accordingly, the thermal recording of the created object should be investigated using the FDM process.

search results

There were discrepancies in the characteristics of the PLA material and the previously described M3 crystal, which was also made using a 3D printer. Instead of a linear model, a quadratic polynomial was used to represent the connection between strain and temperature in the M3 crystal. The observed disparities between materials can be attributed not only to the attributes of the materials, but also to the production process used. M3 crystal samples were created using multi-jet printing technology (MJP), while PLA was created using FDM.

The behavior of the material corresponding to the effect of temperature on the CFRP samples was modeled using the Finite Element Method (FEM).

The average strain fluctuation measured for all detectors was 5 × 10-6, but the interrogator’s measurements were 2 × 10-6. All strain gauge graphs have the same shape as the temperature curve.

Total deformation: (a) integrated sensors, (b) sensors on surfaces, (c) free sensor and (d) temperature;  S1, S2, S3 — CFRP Samples Study Name: Model of the influence of temperature on samples of carbon fiber reinforced polymers additively fabricated with integrated fiber Bragg grating sensors

Total deformation: (a) integrated sensors, (b) sensors on surfaces, (c) free sensor and (d) temperature; S1, S2, S3 — CFRP Samples. Image Credit: Shafighfard, T. & Mieloszyk, M., Materials

The quadratic link was obvious. The error for a 3D printed CFRP sample used in this survey was determined to be 2%. This inaccuracy can be considered statistically insignificant and therefore removed from the statistical analysis.

In short, 4-layer omnidirectional composite laminate was created using AM, FDM process. Numerical results were compared to the average strain rates of three samples taken twice. The results of this work could be used to motivate further research on AM methods for composite constructions with integrated FBG sensors.

Further reading

Shafighfard, T. & Mieloszyk, M., 2022. Model of the influence of temperature on samples of carbon fiber reinforced polymers additively fabricated with integrated fiber Bragg grating sensors. Materials, 15 (1). 222. Available at: https://www.mdpi.com/1996-1944/15/1/222

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