• Title/Summary/Keyword: Compression-after-Impact(CAI)

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Evaluation of Impact Damage and Residual Compression Strength after Impact of Glass/Epoxy Laminate Composites for Lightweight Bogie Frame induced by Ballast-Flying Phenomena (도상자갈 비산에 의한 경량 대차프레임 적용 유리/에폭시 적층 복합재의 충격손상 및 충격 후 잔류압축강도 평가)

  • Goo, Jun-Sung;Shin, Kwang-Bok;Kim, Jung-Suk
    • Journal of the Korean Society for Railway
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    • v.15 no.2
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    • pp.109-115
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    • 2012
  • In order to evaluate the effect of structural degradation of a GFRP composite bogie frame due to ballast-flying phenomena, the impact test and residual compression test after impact was conducted for glass fiber/epoxy 4-harness satin woven laminate composites applied to skin part of a bogie frame. The impact test was performed using a instrumented impact testing system with energy levels of 5J, 10J, and 20J, and the impactor was designed to have various ballast shapes such as sphere, cube, and cone to consider the ballasted track environments. The residual compression strength was tested to evaluate the degradation of mechanical properties of impact-damaged laminate composites. The results showed that the damage area and the degradation of residual compressive strength after impact for laminate composites was increased with increase of impact energy for all ballast shapes, and was particularly most influenced by ballast shape of cone.

Effect of Temperature on Low Velocity Impact Characteristics of Composite Laminates (복합적층재의 온도에 의한 저속충격특성)

  • 한영욱;김후식;김재훈;이영신;조정미;박병준
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2002.05a
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    • pp.93-96
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    • 2002
  • Instrumented impact tests and compression-after-impact(CAI) tests have been used to evaluate the effect of temperature on the low-velocity impact characteristics of phenolic matrix composites reinforced with various woven glass fabric. Impact characteristics and damage area in laminates are evaluated by C-scan. It is shown that the extent of damage and residual compressive strength of the laminates vary with energy level and impact test temperature. The damage area increases with increasing impact energy and temperature. All these observations indicate reduced impact damage resistance and damage tolerance of the laminates at elevated temperature.

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Fabrication and Characterization of 3D Woven Textile Reinforced Thermoplastic Composites (3차원 직조형 열가소성수지 복합재료 제조 및 특성화)

  • 홍순곤;변준형;이상관
    • Composites Research
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    • v.16 no.2
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    • pp.33-40
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    • 2003
  • In order to overcome one of the most pronounced shortcomings of conventional laminated composites, such as the low damage tolerance due to delamination, the thermoplastic materials and 3D (three-dimensional) preforms have been utilized in the manufacture of composite materials. From the newly developed process termed as the co-braiding, hybrid yarns of the thermoplastic fibers (PEEK) and reinforcing fibers (carbon) have been fabricated. In order to further enhance the delamination suppression, through thickness fibers have been introduced by way of 3D weaving technique in the fabrication of textile preforms. The preforms have been thermoformed to make composite materials. Complete impregnation of the PEEK into the carbon fiber bundles has been confirmed. For the comparison of mechanical performance of 3D woven composites, quasi-isotropic laminates using APC-2/AS4 tapes have been fabricated. Tensile and compressive properties of both the composites have been determined. Furthermore. the open hole, impact and CAI(Compression After Impact) tests were also carried out to assess the applicability of 3D woven textile reinforced thermoplastic composites in aerospace structures.

Impact Performance of 3D Orthogonal Composites by Automated Tape Placement Process (자동적층 공정에 의한 3차원 직교 섬유배열구조 복합재의 충격특성)

  • Song S-W;Lee C-H;Um M-K;Hwang B-S;Byun J-H
    • Composites Research
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    • v.18 no.3
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    • pp.38-46
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    • 2005
  • In order to characterize the outstanding performance of three-dimensional (3D) composites, the low velocity impact test has been carried out. 3D fiber structures have been achieved by using the automated tape placement (ATP) process and a stitching method. Materials for the ATP and the stitching process were carbon/epoxy prepreg tapes and Kevlar fibers, respectively. Two-dimensional composites with the same stacking sequence as 3D counterparts have also been fabricated for the comparison of damage tolerance. For the assessment of damage after the impact loading, specimens were subjected to C-Scan nondestructive inspection. Compression after impact (CAI) tests were conducted to evaluate residual compressive strength. The damage area of 3D composites was greatly reduced $(30-40\%)$ compared with that of 2D composites. Although the CAI strength did not show drastic improvement for 3D composites, the ratio of retained strength was $5-10\%$ higher than 2D samples. The effect of stitching on the impact performance was negligible above the energy level of 35 Joules.