Recently, flexible pressure sensors featuring enhanced sensitivity and durability through nano/micro additive manufacturing have been employed in various fields, including medical monitoring, E-skin technology, and soft robotics. This study focuses on the fabrication and verification of an interdigitated electrode (IDE) based flexible pressure sensor that incorporates microstructures, utilizing a direct patterning-based additive process. The IDE-patterned sample was designed with a total size of 7.95 × 10 mm2, a line width of 150 µm, a spacing of 200 µm, and a probe pad measuring 1.25 × 2 mm2. It was fabricated using AgNP ink on a primed 100 µm thick polyethylene naphthalate (PEN) substrate. The electrode layer was subsequently covered with a sensing layer made of a MWCNT/Ecoflex composite material, resulting in the final pressure sensor sample. Measurements indicated that the sensor exhibited good sensitivity and response speed, and it was confirmed that further improvements in sensitivity could be achieved by optimizing the size, spacing, and height of the microstructures. Building on the flexible pressure sensor structure developed in this study, we plan to pursue future research aimed at fabricating array sensors with integrated circuits and exploring their applicability in wearable devices for pressure sensing and control functions.
This paper extensively explores and analyzes the latest research trends in Ionic Polymer-Metal Composites (IPMC) sensors. IPMC sensors are known for their flexibility, lightness, and high responsiveness. They show great promise across different fields. They can respond sensitively to various stimuli such as mechanical deformation, humidity, and pressure, making them ideal for bio-responsive detection, health monitoring, and energy harvesting. This paper introduces actuation and sensing mechanisms of IPMCs, discusses their manufacturing processes, and explores how these processes can influence the responsiveness and stability of sensors. Moreover, through case studies of IPMC-based research that can perform self-sensing functions, it presents possibilities brought by the integration of sensors and actuators. This paper emphasizes the potential for research and development of IPMC sensors to expand into various industrial fields and explores ways to continuously improve the accuracy and reliability of sensors. IPMC-based sensors are expected to play a significant role in advancing medical devices and wearable technologies, thereby facilitating innovation in the field.
With the advancement of microstructure manufacturing technology, an array of functional surfaces based on micro/nano structures have been developed. Recently, there has been active research in the development of functional surfaces using composite materials that combine the properties of two different materials. One notable area of research is the creation of functional surfaces that utilize magnetic force to actuate microstructures. Typically, these surfaces are produced using a composite material that blends a flexible, easily deformable material with iron particles that respond to magnetic force. However, the inclusion of iron particles in the flexible material can increase its Young’s modulus, making it more challenging to effectively actuate the microstructures. To address this issue, our paper presents a fabrication method that allows for the effective actuation of microstructures by removing the residual layer of the composite material. This method enables the arrangement of iron particles at the end of the microstructure, maximizing the bending of the microstructure when magnetic force is applied. Furthermore, we conducted experiments to actuate microstructures with varying ratios of iron particles, confirming the effectiveness of this fabrication method.
Recently, with the expansion of application of polymer composite materials, high levels of deformation compensation actions have been developed. However, there is a problem of high-temperature viscoelasticity that occurs over time after completing the injection molding process. In this study, changes of mechanical properties of the Moldflow program for injection molding were analyzed to verify the viscoelasticity phenomenon through deformation analysis. In addition, deformation analysis of plastic injection molded products according to arrangement of three ribs was conducted and two products with different geometric shapes of the same function were compared. As a result, it was possible to reflect the viscoelastic effect by reducing the elastic modulus and shear modulus of the material. It was confirmed that the geometric shape with thick ribs formed in multiple longitudinal directions was mainly responsible. On the surface of the product where the rib arrangement was parallel and perpendicular to the flow direction, the orientation was orthogonal to the linear direction and the maximum residual stress was 81.17 MPa, which showed the largest value. It was judged that viscoelastic phenomena could be predicted and that an arrangement of parallel and perpendicular ribs that might intersect should be avoided.
Fabrication of a durable and strong nanopatterned mold insert using metal sheet and plate is important for molding of thermoplastic materials. Conventionally, the nickel stamper replicating a master pattern by electroforming process has been used for injection molding of nanotextured products such as Blu-ray media. However, a more facile and cheaper mold fabrication process is highly required for manufacturing of functional products based on nanostructured surface. In this study, zirconia nanoparticles were blended with UV curing polymer to fabricate a polymer nanocompositebased nanopattern mold. Compared to the cured pure Ormostamp, the modulus of elasticity of the nanocomposite filled with approximately 54 vol% of zirconia nanoparticles increased by 160 times. Additionally, the modulus of elasticity reached 197 ㎬ by thermal decomposition of the UV-Cured polymer and post-annealing at 800°C of the nanoparticle layer. The nanopatterns were formed on stainless steel sheet and block, and applied to hot embossing of the PMMA films and injection molding of the COC materials, respectively. No deterioration of the mold occurred during the hot embossing 30 times and the injection molding 600 shots. Nanoparticle-enhanced UV curing nanocomposites or post-heat treatment methods are cost-efficient and easy, because many molds can be manufactured from one master pattern.
A fixing frame applied with Foam Cored CFRP Sandwich Composite (FCCSC) that replaces SAPH440 steel used in the fixing frame for hydrogen storage was designed, and its structural safety was evaluated. In the design of the fixing frame, FCCSC was implemented by PMI foam core, a Bakelite mount, and Carbon Fiber Reinforced Plastics (CFRP) using woven carbon fiber prepreg. Unlike the steel fixing frame, the FCCSC-applied fixing frame had a cross-section of hollow-rectangular, and its validity was confirmed through finite element analysis. Structural analysis of the designed FCCSCapplied fixing frame and steel fixing frame was performed. Under the extreme load condition of 9G acceleration, the steel fixing frame showed the lowest safety factor of 1.14 based on the yield strength in the opposite direction of gravity. On the other hand, the FCCSC-applied fixing frame showed a safety factor of 7.6 at the maximum principal stress and 3.15 at the shear stress. Through this result of structural analysis, it was verified that the FCCSC-applied fixing frame, which was 25.8% lighter than the steel fixing frame, was 1.8 times safer.
Recently, large-scale accidents caused by minor damage from fatigue failure and impact on structures have been frequently reported. Therefore, a real-time damage monitoring system of structures is considered to be one of the most important technologies to ensure safety in various types of research. The piezoelectric sensor, which has an advantage of converting deformation of a structure into an electrical signal without using an additional power source, has been reported as one of the most suitable methods for real-time monitoring systems. This review aims to describe the structural monitoring system utilizing piezoelectric paint sensors. First, we present the concept of a piezoelectric paint sensor with the advantages of flexibility and piezoelectric performance. Then, factors affecting the performance of the piezoelectric paint sensor are introduced. Finally, an overview of piezoelectric paint sensors for structural monitoring, such as vibration detection and impact monitoring, are provided. The state-of-the-art of the application of the piezoelectric sensor is also introduced, providing feasibility in industrial fields.
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In this study, the structural integrity of a 6.8 L composite pressure vessel manufactured using H2550 carbon fiber was evaluated by the finite element analysis method, and the reliability of the analysis method was verified by comparing the hydrostatic test and analysis results. The pressure vessel was manufactured using the filament winding method and a hydrostatic test was performed to evaluate the failure mode and burst pressure of the manufactured composite pressure vessel. To construct the finite element model, a cyclic symmetric model, which only considers 1° of the front part, was used to reduce the analysis time and increase the modeling efficiency. As the carbon fiber was wound along the curved surface of the dome part, the winding angle and lamination thickness were modeled to change according to the dome radius. Comparison of the analysis and test results confirmed similar behavior in the axial and hoop strain diagrams due to internal pressure. In addition, it was found that the maximum fiber direction stress of the hoop layer showed an error of 3%, verifying the reliability of the finite element analysis method.
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The munitions industry uses high-strength carbon fiber composites imported from other countries because of the lack of the information about the properties that should be satisfied by the domestic high-strength carbon fiber composites. Verification of the applicability of domestic high-strength carbon fiber composites to the munitions industry requires comparison of the fiber strength transition rate between the carbon fiber composites imported from other countries and domestically. A strand test was performed to evaluate in the unit of a fiber the mechanical properties of the imported high-strength carbon fiber composites and domestically. Additionally, a composite pressure vessel was prepared using the filament winding method to perform a hydrostatic pressure test and calculate the fiber strength in the unit of a structure. Comparison of the fiber strength results showed that the fiber strength transition rates of the domestic carbon fiber composites H2550 and H3055, were 86.35 and 74.19%, respectively. Domestic carbon fiber composite material H2550 is expected to be replaceable in the munitions industry.
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Major aerospace developers continue to push for new structural composite applications to reduce the environmental impact of greenhouse gas emissions, improve both aircraft performance and costs. In this study, the parts that carry the load in the regions where mechanical joints are applied, require whole processing to tighten and identify stress concentration points. In addition, failure modes caused by bearing and by-pass loads were set as the main design factors. Optimum sizing was performed through the application of factors taken into account in the buckling failure mode and production using the preliminary design analysis model of the composite wing structure. In the area where the fuselage is joined with the fuselage, bearing and bypass load were considered important design factors.
The demand for inspection of high-speed systems for machined Carbon Fiber Reinforced Plastics parts for automobileindustry and aviation industry is constantly rising. One of the factors that degrade the performance of an inspection system is micro-vibration from the ground or structure where is placed. Various isolation systems that suppress the vibration have been studied classified as either passive or active system. The passive system is composed of a spring and a damper while the active system suppresses the vibration through an electronic control system using sensors and actuators. In this study, a voice coil motor (force constant 55N/A) acting as the actuator is optimally designed using permeance method and sequential quadratic programming algorithm to suppress the vibration and reaction force by a specimen moving stage. The two optimized voice coil motors are attached to a pneumatic mount that has an advantage in design based on the force and size constraints required by the user for an active vibration isolator with velocity sensors (GS-11d). The active vibration isolation system with the four active vibration isolators -23 dB and -20 dB at resonance frequencies in horizontal and vertical transmissibility performs better than a passive vibration isolation system.
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Since becoming highly functional, complex and flexible, the machining system of CFRP(Carbon Fiber Reinforced Plastic) has recently become highly functional, complex and flexible, its has its controllers are changing into open and distributed structures. These, and need controlling to be controlled to maintain good quality of for a quality of machined parts. In particularSpecifically, an open controller is required urgently needed to apply the optimal processing program for each material and development of embedded SW, which enables after-production of CFRP, CFRP-metal stack material, waterjet processing, inspection, and modification. As theThe characteristics of CFRP materials may create processing defects such as stratified material stripping and un-cut., a A process monitoring module that can minimize or prevent the defects this technology needs to should be applied to hence reducinge tool wear causedthrough by high hardness carbon fiber. Since CFRP is mostly made from additive forming, there are many drilling processes, that require precision measurement techniques and process signal monitoring technology, exist. Tsince the cutting force load and various signals generated during processing are weaker than those during metal processing. An open controller for process control and monitoring of a CFRP processing system was therefore developed. The system will then It is going to develop open controller SW structural design and open platform, multi-channel signal processing algorithm and sensor system, process specific functions (CFRP process control, boundary detection, etc.) and mount drilling tool parent monitoring algorithm on open platform.
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Comparative Analysis and Monitoring of Tool Wear in Carbon Fiber Reinforced Plastics Drilling Kyeong Bin Kim, Jang Hoon Seo, Tae-Gon Kim, Byung-Guk Jun, Young Hun Jeong Journal of the Korean Society for Precision Engineering.2020; 37(11): 813. CrossRef
Transportation industries, such as aerospace and automotive demand high efficiency using lightweight parts. Carbon Fiber Reinforced Plastics (CFRP) present promising materials for transportation industry parts due to their lightweight and highstrength properties. Forming and machining processes are required to manufacture parts from carbon fiber composite materials. The near-net shaping process forms the parts, and the final accurate shape and hole are accomplished using the machining process. However, high-strength carbon fiber chips and dust from the machining process cause cutting tool wear and low productivity. The hybrid CRD (Cutting, Routing and Drilling)/water-jet machine improves tool life and productivity because its water-jet process, employed before the mechanical machining process cuts roughly without chips and dust. In this study, the hybrid CRD/water-jet machine we developed was introduced and its machining performance was evaluated using a drilling process. The delamination factor and surface roughness of drilled holes were compared with the results from a conventional machine tool.
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A chemical ablation analysis of hypersonic missile for thermal protection design was performed using SAMCEF AMARYLLIS V.17, the specific ablation module of commercial software based on a finite element code. The pyrolysis and surface recession models based on the effects of mass loss, pore gas diffusion, and endothermic reaction energy were applied for non-linearity of material and boundary. The numerical studies were carried out to confirm the tendency of the pyrolysis and chemical ablation of theoretical ablative composite for open testing (TACOT) with a chemical composition similar to charring carbon/phenolic composites. The frequency of variation in surface recession, temperature, density and gas mass flux was reviewed to determine the characteristics of multiple decomposition reactions and oxidation via pyrolysis of gas species.
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The objective of this study was to investigate wear characteristics of Fe-TiB₂ composites prepared by pressureless sintering (PLS) and spark plasma sintering (SPS) using nanocomposite mixtures. Prior to wear test, micro-structures and mechanical properties of specimens were examined. Wear characteristics of these specimens slid against SiC were assessed using ball-on-disk tribo-tester. Results showed that PLS specimen had significantly large TiB₂ particles in the Fe matrix than SPS specimen. The relatively large TiB₂ particles in PLS specimen might be due to grain growth and coarsening during sintering process. Hardness of SPS specimen was substantially larger than that of PLS specimen. Furthermore, SPS specimen exhibited significantly larger wear resistance than PLS specimen. These differences in hardness and wear resistance between specimens might be associated with differences in their micro-structures. Results of this study provide better understanding of wear characteristics of Fe-TiB₂ composites.
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