Liquid Resin Infusion Process Validation through Fiber Optic Sensor Technology

In the proposed work, a fiber-optic-based sensor network was employed for the monitoring of the liquid resin infusion process. The item under test was a panel composed by a skin and four stringers, sensorized in such a way that both the temperature and the resin arrival could be monitored. The network was arranged with 18 Fiber Bragg Gratings (FBGs) working as temperature sensors and 22 fiber optic probes with a modified front-end in order to detect the resin presence. After an in-depth study to find a better solution to install the sensors without affecting the measurements, the system was investigated using a commercial Micron Optics at 0.5 Hz, with a passive split-box connected in order to be able to sense all the sensors simultaneously. The obtained results in terms of resin arrival detection at different locations and the relative temperature trend allowed us to validate an infusion process numerical model, giving us better understanding of what the actual resin flow was and the time needed to dry preform filling during the infusion process.

A Study on Tensile Behavior According to the Design Method for the CFRP/GFRP Grid for Reinforced Concrete

In the present study, fiber-reinforced plastics (FRP) grid-reinforced concrete with very rapid hardening polymer (VRHP) mortar composites were fabricated using three types of design methods for the FRP grid (hand lay-up method, resin infusion method, and prepreg oven vacuum bagging method), along with two types of fibers (carbon fiber and glass fiber) and two types of sheets (fabric and prepreg). The FRP grid was prepared by cutting the FRP laminates into a 10 mm thick, 50 mm × 50 mm grid. The tensile behavior of the FRP grid embedded in composites was systematically analyzed in terms of the load extension, fracture mode, partial tensile strain, and load-bearing rate. The CFRP grid manufactured by the prepreg OVB method showed the best tensile behavior compared to the CFRP grid manufactured by the hand lay-up and resin infusion methods. The load-bearing of each grid point was proportional to the height from the load-bearing part when reaching the maximum tensile load. In addition, finite element analysis was conducted to compare the experimental and analysis results.

INVESTIGASI KARAKTERISTIK GETARAN KOMPOSIT SANDWICH BERBAHAN SERAT KARBON UNI-DIRECTIONAL BERPENGUAT CRESTAPOL

Material Komposit Sandwich adalah jenis komposit yang terdiri dari susunan komposit laminate dengan core didalamnya. Pemanfaatan komposit sandwich saat ini sangat luas termasuk salah satunya sebagai struktur sekunder dalam pesawat mengingat masa komposit jenis ini lebih ringan dibandingkan komposit dengan full laminate. Salah satu pemanfaatanya adalah dalam pembuatan kompartemen float. Penggunaan komposit sebagai bahan kompartemen float perlu diketahui karakteristik dinamisnya. Dalam penelitian ini sampel yang digunakan dibuat dengan metode Vacuum Assisted Resin Infusion (VARI). Variasi sampel komposit akan diambil data karakteristik dinamik nya berupa damping factor dan natural frekuensinya sebagai acuan awal pemilihan komposisi material. Sampel uji yang digunakan berukuran 50x230mm dengan metode pengujian menggunakan metode Oberst. Profil getaran yang digunakan untuk pengujian adalah jenis sapuan sinus dari 10Hz sampai 2000Hz. Hasil pengujian menunjukkan bahwa sampel 3C3 memiliki Frekuensi natural yang lebih tinggi dibandingkan dengan sampel 2C2 namun memiliki nilai Damping properties yang lebih rendah. Hasil ini menunjukkan bahwa sampel 3C3 memiliki nilai kekakuan yang lebih tinggi dibandingkan 2C2. Dari hasil juga memperlihatkan bahwa sampel 2C2 memiliki kemampuan redaman yang lebih baik dibanding sampel 3C3. Pemilihan material berdasarkan hasil pengujian menunjukkan bahwa 2C2 memiliki keunggulan damping ratio dibandingkan 3C3 namun masih diperlukan lebih banyak variasi lagi untuk mendapatkan komposisi material terbaiknya.

3D Permeability of Thick-Section Glass Fabric Reinforced Polymer Composite by Vacuum-Assisted Resin Infusion Molding

Determination of permeability of thick-section glass fabric preforms with fabric layers of different architectures is critical for manufacturing large, thick composite structures with complex geometry, such as wind turbine blades. The thick-section reinforcement permeability is inherently three-dimensional and needs to be obtained for accurate composite processing modeling and analysis. Numerical simulation of the liquid stage of vacuum-assisted resin infusion molding (VARIM) is important to advance the composite manufacturing process and reduce processing-induced defects. In this research, the 3D permeability of thick-section E-glass fabric reinforcement preforms is determined and the results are validated by a comparison between flow front progressions from experiments and from numerical simulations using ANSYS Fluent software. The orientation of the principal permeability axes were unknown prior to experiments. The approach used in this research differs from those in literature in that the through-thickness permeability is determined as a function of flow front positions along the principal axes and the in-plane permeabilities and is not dependent on the inlet radius. The approach was tested on reinforcements with fabric architectures which vary through-the-thickness direction, such as those in a spar cap of a wind turbine blade. The computational simulations of the flow-front progression through-the-thickness were consistent with experimental observations.

Design, Development, and Characterization of Advanced Textile Structural Hollow Composites

The research is focused on the design and development of woven textile-based structural hollow composites. E-Glass and high tenacity polyester multifilament yarns were used to produce various woven constructions. Yarn produced from cotton shoddy (fibers extracted from waste textiles) was used to develop hybrid preforms. In this study, unidirectional (UD), two-dimensional (2D), and three-dimensional (3D) fabric preforms were designed and developed. Further, 3D woven spacer fabric preforms with single-layer woven cross-links having four different geometrical shapes were produced. The performance of the woven cross-linked spacer structure was compared with the sandwich structure connected with the core pile yarns (SPY). Furthermore, three different types of cotton shoddy yarn-based fabric structures were developed. The first is unidirectional (UD), the second is 2D all-waste cotton fabric, and the third is a 2D hybrid fabric with waste cotton yarn in the warp and glass multifilament yarn in the weft. The UD, 2D, and 3D woven fabric-reinforced composites were produced using the vacuum-assisted resin infusion technique. The spacer woven structures were converted to composites by inserting wooden blocks with an appropriate size and wrapped with a Teflon sheet into the hollow space before resin application. A vacuum-assisted resin infusion technique was used to produce spacer woven composites. While changing the reinforcement from chopped fibers to 3D fabric, its modulus and ductility increase substantially. It was established that the number of crossover points in the weave structures offered excellent association with the impact energy absorption and formability behavior, which are important for many applications including automobiles, wind energy, marine and aerospace. Mechanical characterization of honeycomb composites with different cell sizes, opening angles and wall lengths revealed that the specific compression energy is higher for regular honeycomb structures with smaller cell sizes and a higher number of layers, keeping constant thickness.