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Young-jin Yum - One of the best experts on this subject based on the ideXlab platform.

  • mechanical properties of the interface of Gelcoat resin composite materials and improvements via surface treatment methods
    Advanced Composite Materials, 2016
    Co-Authors: Thanh Nhut Pham, Young-jin Yum
    Abstract:

    A Gelcoat resin was applied to improve the surface properties of composite materials. Combinations of a Gelcoat with a glass/epoxy or carbon/epoxy result in a prime composite structure. Prior to application, however, the mechanical properties of these bonds should be studied. Three material pairs, glass/epoxy-Gelcoat (GEG), carbon/epoxy-Gelcoat (CEG), and glass/polyester-Gelcoat (GPG), were studied to experimentally determine the interfacial properties. Then, four surface treatment methods were applied to the GEG and CEG composite, and the resulting materials were investigated to assess potential improvements to the interfacial properties. Three tests, single-leg bending, peel, and single lap joint, were carried out, and experimental results were combined with equations to obtain the strength or energy. It was observed that the strength or energy of the GPG material was higher than that of the GEG and CEG. After the surface treatment, the energy and strength of the interfaces had increased over that of th...

  • Evaluation of cavitation erosion of a propeller blade surface made of composite materials
    Journal of Mechanical Science and Technology, 2015
    Co-Authors: Nhut Pham-thanh, Hoang Van Tho, Young-jin Yum
    Abstract:

    Cavitation erosion strongly impacts the efficiency and strength of marine propellers. This is more important for propellers made from different types of composite materials. Thus, an investigation of cavitation erosion on the blade surface of composite ship propellers is necessary. A small three-blade propeller was made from fiberglass combined with epoxy, polyester and Gelcoat resin. This propeller was tested in a circulating water channel and revolution speed and depth were determined by conditions of cavitation number. Cavitation erosion was observed and evaluated by images, weight loss and cavitation area. The results indicated that the cavitation erosion occurred at regions 0.4 R (Radius) and 0.7 R from the center, and cavitation also occurred randomly on pressure or suction surfaces and leading or trailing edges. Most damaged regions propagated along the circumferential direction of the propeller. Among the blade materials, the Ge-GF blade had the best property. This material had the smallest cavitation area and the most stable cavitation area rate. The Po-GF blade had the worst property with strong progression of the cavitation area, and the Ep-GF blade was of medium quality with a small reduction of the damage area rate. Besides, the depth of the damaged area of the Ge-GF blade was also lower than that of the Ep-GF and Po-GF blade.

  • Mechanical properties of the interface of Gelcoat resin–composite materials and improvements via surface treatment methods
    Advanced Composite Materials, 2015
    Co-Authors: Thanh Nhut Pham, Young-jin Yum
    Abstract:

    A Gelcoat resin was applied to improve the surface properties of composite materials. Combinations of a Gelcoat with a glass/epoxy or carbon/epoxy result in a prime composite structure. Prior to application, however, the mechanical properties of these bonds should be studied. Three material pairs, glass/epoxy-Gelcoat (GEG), carbon/epoxy-Gelcoat (CEG), and glass/polyester-Gelcoat (GPG), were studied to experimentally determine the interfacial properties. Then, four surface treatment methods were applied to the GEG and CEG composite, and the resulting materials were investigated to assess potential improvements to the interfacial properties. Three tests, single-leg bending, peel, and single lap joint, were carried out, and experimental results were combined with equations to obtain the strength or energy. It was observed that the strength or energy of the GPG material was higher than that of the GEG and CEG. After the surface treatment, the energy and strength of the interfaces had increased over that of th...

  • study on improved methods for interfacial properties of Gelcoat composites
    대한기계학회 춘추학술대회, 2013
    Co-Authors: Pham Thanh Nhut, Tae Hyoung Kim, Young-jin Yum
    Abstract:

    Gelcoat resin is applied to improve the surface properties of composite materials. Combinations of Gelcoat and glass/epoxy or carbon/epoxy will make a perfect composite structure. However, mechanical properties of these bonds need to study before application. Two pairs of material (glass/epoxy-Gelcoat, carbon /epoxy-Gelcoat) were studied to improve the interfacial properties by experiment with four treatment methods on the surfaces of outer and inner adherends. Three different tests (single-leg bending, peel and single lap-joint) were carried out for above works. Experiment results were combined with equations to obtain the strength or energy. From the results, it was observed that the strength or energy of of GEG and CEG material were almost the same. After using the treatment methods of surfaces, the energy and strength of four methods were higher than the values of initial surfaces. The P-method has the lowest and GAP-method has the highest strength or energy. G-method and GA-method were better than P-method but negligible.

M.o.w. Richardson - One of the best experts on this subject based on the ideXlab platform.

  • A study of water absorption characteristics of a novel nano-Gelcoat for marine application
    Progress in Organic Coatings, 2009
    Co-Authors: S.c. See, Zhongyi Zhang, M.o.w. Richardson
    Abstract:

    Abstract One of the major factors affecting the acceptability of novel coating in engineering applications is the degradation of the coating by the moistures that will affect the physical and mechanical performances and causing it to fail. Nanoscale reinforcement provides opportunities for enhancing the polymer system with unique properties and increases the performance. These advantages not only lead to an improvement in the mechanical properties but also act as a barrier to slow the water permeation. In this study, an organically modified montmorillonite (MMT) nanoclay and a further modified “X-treated supernanoclay” were used to reinforce an isophthalic unsaturated polyester Gelcoat. Five Gelcoat systems were prepared and characterised by using a boiling water absorption test (with a saturation time of 12 h) to characterise and quantify the degree of water absorption. All nanocomposite samples show a very convincing result in terms of the coefficient of moisture absorption and reduction in water ingress as a function of weight fraction of nanoclays. The “X-treated supernanoclay” reinforced systems show the greatest improvement compared to conventional nanoclay system.

  • Characterisation and evaluation of nano Gelcoat degradations in marine environment
    Journal of Nanoscience and Nanotechnology, 2009
    Co-Authors: Zhongyi Zhang, S.c. See, M.o.w. Richardson
    Abstract:

    Nanotechnology has been extensively explored and exploited for developing functional and smart coating systems with significant performance enhancement. In this context, a development of novel characterisation methodology for surface quality evaluation of diverse coating systems at nano and micro scales has great importance and significance. In this study, nano particles were introduced into conventional Gelcoat system in an attempt to achieve improved coating quality and enhanced anti-blistering performance. Accelerated Gelcoat ageing in a marine environment was carried out by maintaining constant contact with water using a purpose built jig at 65 degrees C. The progressive ageing of samples has been monitored and evaluated by visual observation, nano-indention test, surface roughness and profile measurement. It was observed that the addition of nano-clays led to an increase in hardness. Although the ageing of various coating systems resulted in a reduction in hardness, the degree of hardness change due to ageing for all nano-coating was significantly less than for coating system without nano-clays. The coating degradations were further characterised by reduced surface homogeneity in terms of standard deviations of hardness. The accelerated ageing induced coating degradations were also quantified by surface profile and roughness measurement in which a stylus profilometer was employed to scan different locations of the coatings. It showed significant differences in surface roughness of different coatings systems and incremental degradations as a function of ageing durations. It has demonstrated that anti-blistering Gelcoat systems can be developed by introducing chemically modified nano-clays into conventional Gelcoat systems for marine applications.

  • Nanomechanical behaviour and thermal degradation of nanoclays and supernanoclays enhanced marine Gelcoat system
    International Journal of Materials Engineering Innovation, 2009
    Co-Authors: Seng Chai See, Zhongyi Zhang, Hom Nath Dhakal, M.o.w. Richardson
    Abstract:

    Novel nanoclay reinforced unsaturated polyester Gelcoats for marine vessels are evaluated in terms of their thermal and mechanical performance. In this study, mechanical and thermal tests have been employed to characterise different Gelcoat systems with various loading levels of nanoclays with and without X-treatment. Differences in mechanical properties were determined by using nano-indentation testing which shown an increase in hardness compared to the control system. Thermal degradation characteristics were determined using a thermogravimetric analyser (TGA). An increase in thermal stability was observed for all nanocomposites compared to the control system. Additionally, differential scanning calorimetry (DSC) showed that the effect of inclusion of nanoclays is to hinder the structure of unsaturated polyester Gelcoats and hence increase glass transition temperatures. Furthermore, X-treated supernanoclay is shown to be significantly more effective than untreated nanoclay. Enhancement of mechanical property and thermal degradation could be attributed to the grafting of hydroxyl groups (?OH) in the nanoclays with polymer chains.

Arash Afshar - One of the best experts on this subject based on the ideXlab platform.

Ali Keskin - One of the best experts on this subject based on the ideXlab platform.

  • Tensile and Fatigue Behavior of Glass Fiber-Reinforced (MAT-8)/Polyester Automotive Composite
    Arabian Journal for Science and Engineering, 2014
    Co-Authors: Abdulkadir Yasar, İlyas Kacar, Ali Keskin
    Abstract:

    In this study, tensile and fatigue behavior of glass fiber-reinforced (MAT-8)/polyester automotive composite was investigated experimentally. The composite used in this study consists of polyester, fiber and Gelcoats. The fiber contents were kept constant at 37 wt% during the tests. But, polyester and Gelcoat contents were changed. The tests were conducted at five different MAT-8 thicknesses. It is clearly shown that polyester content is the only determinative factor for fatigue strength, while both polyester and Gelcoat contents are effective for tensile strength. According to the results, optimum tensile strength was achieved, while fiber ratio was constant in the specific mixing of polyester and Gelcoats. It is thought that the combination of 52.14 wt% polyester and 9.75 wt% Gelcoats can be a preferableway for designs requiring the best tensile and fatigue strength properties at the same time.

Keskin A. - One of the best experts on this subject based on the ideXlab platform.

  • Tensile and Fatigue Behavior of Glass Fiber-Reinforced (MAT-8)/Polyester Automotive Composite
    'Springer Science and Business Media LLC', 2014
    Co-Authors: Yasar A., Keskin A.
    Abstract:

    In this study, tensile and fatigue behavior of glass fiber-reinforced (MAT-8)/polyester automotive composite was investigated experimentally. The composite used in this study consists of polyester, fiber and Gelcoats. The fiber contents were kept constant at 37 wt% during the tests. But, polyester and Gelcoat contents were changed. The tests were conducted at five different MAT-8 thicknesses. It is clearly shown that polyester content is the only determinative factor for fatigue strength, while both polyester and Gelcoat contents are effective for tensile strength. According to the results, optimum tensile strength was achieved, while fiber ratio was constant in the specific mixing of polyester and Gelcoats. It is thought that the combination of 52.14 wt% polyester and 9.75 wt% Gelcoats can be a preferableway for designs requiring the best tensile and fatigue strength properties at the same time. © 2013 King Fahd University of Petroleum and Minerals