Sensing of dispersion and adhesion of PU type aircraft topcoat layer for LSP (Lightning Strike Protection) was evaluated by 2 dimensional (2D) electrical resistance (ER) mapping with different treatment times and multi-wall carbon nanotube (MWCNT) weight fractions. Conductive MWCNT was treated using hydrogen peroxide to improve dispersion in polyurethane (PU) type paint for several days. After treatment processing, MWCNT was dispersed in PU type coating solution using sonication dispersion method. CNT/PU coating solution was applied on the aircraft surface of carbon fiber reinforced epoxy composite (CFRC) using spray method. Static contact angle was performed using 4 types of solvents to calculate the work of adhesion between CNT/PU coating layer and CFRC surface. Surface ER of MWCNT added PU coating layer was measured to determine MWCNT dispersion. Visualization of MWCNT dispersion exhibited using 2-D ER mapping, whereas adhesion between MWCNT/PU coating layer and CFRC was evaluated via cross hatched cut test. The optimized condition of MWCNT treatment time and MWCNT weight fraction was found intensively.
The pencil lead drawing paper sensor (PLDPS) is a flexible and wearable sensing device, a new concept sensor that offers a tremendous potential feasibility for a variety of applications. Highly responsive, sensitive, low cost, easy-tohandle pencil lead graphite and paper made from cellulose pulp fibers extracted from wood, rags or grass, which are inexpensive, nature-friendly materials were used. The sensing effect on 3 different papers (Plane, Hwasun, and Han papers) based on the properties of PLDPS was compared via FT-IR, tensile test, optical observation and initial electrical resistance (ER). The interfacial and mechanical properties of epoxy and GF/epoxy composites were evaluated by damage sensing and ER mapping using PLDPS with impact, flexural, and interlaminar shear strength (ILSS) tests. The optimum type of paper used as the adherend for the pencil sensor was chosen as the plane paper. As glass fiber (GF)/epoxy composites were severely damaged, the large change in ER of PLDPS was observed distinctly.
Interfacial and mechanical properties of thermal aged carbon fiber reinforced epoxy composites (CFRP) were evaluated using acoustic emission (AE), electrical resistance (ER), contact angle (CA) and thermogram measurements. Unidirectional (UD)-composites were aged at 200, 300, and 400 °C to produce different interfacial conditions. The interfacial degradation was identified by Fourier transform infrared (FT-IR) spectroscopy after different thermal aging. AE and ER of UD composites were measured along 0, 30, 60 and 90 °. Changes in wavespeed, with thermal aging, were calculated using wave travel time from AE source to AE sensor and the changes in ER were measured. For a thermogram evaluation, the composites were laid upon on a hotplate and the increase in the surface temperature was measured. Static contact angle were measured after different thermal aging and elapsed times to evaluate wettability. Interlaminar shear Strength (ILSS) and tensile strength at transverse direction tests were also performed to explore the effects of thermal aging on mechanical and interfacial properties. While thermal aging of CFRPs was found to affect all these properties, the changes were particularly evident at 400 °C.
Evaluation of sensing for electrical conductive composites has been implemented using electrical conductive nano
materials such as graphene, CNT and carbon fiber. Electrical resistance (ER) measurement for nondestructive evaluation
(NDE) was developed using self-sensing composites because method of damage sensing and crack prediction of
composites under external load is possible to use at aerospace, heavy industry, and automobile. In this research, diverse
damage sensing from mechanical impact and thermal aging for electrical conductive composites was investigated by
using ER method. To have the test, electrical conductive materials such as graphene, CNT and carbon fiber and matrixes
such as epoxy and vinyl ester were used for damage sensing and finding optimum materials for improving the bonding
force. Two and three dimensional ER mapping was used to sense and predict damages from tensile, compressive, impact
and drilling force. The differences in ER from different force were compared to explore their usage for real time
monitoring and sensing of damages. Enhance optimum materials and conditions from diverse force were confirmed by
ER method.
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