• Title/Summary/Keyword: 저속충격특성

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Low Velocity Impact Characteristics of Glass/phenol Composite Laminates (Glass/phenol 복합적층판의 저속충격 특성)

  • Kim, Jae-Hoon;Kim, Hu-Shik;Park, Byoung-Joon;An, Byoung-Wook
    • Proceedings of the KSME Conference
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    • 2001.11a
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    • pp.228-233
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    • 2001
  • It is well known that composite laminates are easily damaged by low velocity impact. The damage of composite laminates subjected to impact loading are occurred matrix cracking, delamination, and fiber breakage. The damage of matrix cracking and delamination are reduced suddenly the compressive strength after impact. This study is to evaluate impact characteristics and the relationship between impact force and inside damage of composite laminates by low velocity impact loading. UT C-scan is used to determine impact damage areas by impact loading.

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low Velocity Impact Behavior Analysis of 3D Woven Composite Plate Considering its Micro-structure (미시구조를 고려한 3차원 직교직물 복합재료 평판의 저속충격 거동해석)

  • Ji, Kuk-Hyun;Kim, Seung-Jo
    • Composites Research
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    • v.18 no.4
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    • pp.44-51
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    • 2005
  • In this paper, we developed the direct numerical simulation(DNS) model considering the geometry of yams which consist of 3D orthogonal woven composite materials, and using this model, the dynamic behavior of under transverse low-velocity impact has been studied. To build up the micromechanical model considering tow spacing and waviness, an accurate unit structure is presented and used in building structural plate model based on DNS. For comparison, DNS results are compared with those of the micromechanical approach which is based on the global equivalent material properties obtained by DNS static numerical tests. The effects with yarn geometrical irregularities which are difficult to consider in a macroscopic approach are also investigated by the DNS model. Finally, the multiscale model based on the DNS concepts is developed to enhance efficiency of analysis with real sized numerical specimen and macro/micro characteristics are presented.

Fracture Mechanism and Characterization of Falling Weight Impact in CF/Epoxy Composite Plates Under Law-Velocity Impact (저속충격 하에서 CFRP 복합적층판의 낙추 충격특성과 파괴기구)

  • 임광희;박노식;김영남;김선규;심재기;양인영
    • Composites Research
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    • v.17 no.4
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    • pp.53-60
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    • 2004
  • This paper describes a method for a falling weight impact test to estimate the impact energy absorbing characteristics and impact strength of CFRP laminate plates based on considerations of stress wave propagation theory. The absorbed energy of T300 orthotropic composites is higher than that of quasi-isotropic specimen over impact energy 6.8J, but in case of using T700 fiber, much difference does not show. Also, absorbed energy of T300 orthotropic composites, which are composed of the same stacking number and orientation became more than that of T700 fiber specimen; however there was no big difference in case of quasi-isotropic specimens. The delamination areas of the impacted specimen were measured with the ultrasonic C-scanner to find correlation between impact energy and delamination area. The fracture surfaces were observed by using the SEM (scanning electron microscope) through a low-velocity impact test in order to confirm the fracture mechanism.

Low Velocity Impact Property of CF/Epoxy Laminate according to Interleaved Structure of Amorphous Halloysite Nanotubes (비정질 할로이사이트 나노입자의 교차적층 구조에 따른 탄소섬유/에폭시 라미네이트의 저속 충격 특성)

  • Ye-Rim Park;Sanjay Kumar;Yun-Hae Kim
    • Composites Research
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    • v.36 no.4
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    • pp.270-274
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    • 2023
  • The stacking configuration of fiber-reinforced polymer (FRP) composites, achieved via the filament winding process, exhibits distinct variations compared to conventional FRP composite stacking arrangements. Consequently, it becomes challenging to ascertain the influence of mechanical properties based on the typical stacking structures. Thus, it becomes imperative to enhance the mechanical behavior and optimize the interleaved structures to improve overall performance. Therefore, this study aims to investigate the impact of incorporating amorphous halloysite nanotubes (A-HNTs) within different layers of five unique layer arrangements on the low-velocity impact properties of interleaved carbon fiber-reinforced polymer (CFRP) structures. The low-velocity impact characteristics of the laminate were validated using a drop weight impact test, wherein the resulting impact damage modes and extent of damage were compared and evaluated under microscopic analysis. Each interleaved structure laminate according to whether nanoparticles are added was compared at impact energies of 10 J and 15 J. In the case of 10 J, the absorption energy showed a similar tendency in each structure. However, at 15 J, the absorption energy varies from structure to structure. Among them, a structure in which nanoparticles are not added exhibits the highest absorption energy. Additionally, various impact fracture modes were observed in each structure through optical microscopy.

Reconstruction of Damage-Induced Impact Force of Gr/Ep Composite Laminates Using Piezoelectric Thin Film Sensor Signals (고분자 압전센서 신호를 이용한 Gr/Ep 복합재 적층판의 손상유발 충격하중의 복원)

  • 박찬익;김인걸;이영신
    • Composites Research
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    • v.15 no.5
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    • pp.7-13
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    • 2002
  • The piezoelectric thin film sensor has good characteristics to observe the impact responses of composite structures. The capabilities for monitoring impact behavior of Gr/Ep laminates subjected to damage-induced impact using the PVDF(polyvinylidene fluoride) film sensor were examined. For a series of low-velocity impact tests from low energy to damage-induced energy, simulated sensor signals were compared with measured signals and the PVDF film sensor. Local impact damages(matrix cracking and delamination) were found at three impact tests, but the measured signals agreed well with the simulated sensor signals based on the linear relationship between the impact forces and the PVDF film sensor signals. And the inverse technique was applied to reconstruct the impact forces using the PVDF film sensor signals. Most of reconstructed impact forces had good agreement with the measured forces. The comparison results showed that the local damage due. to low-velocity impact didn't disturb the global impact responses of composite laminates and the reconstruction of impact forces from PVDF sensor signals wasn't affected by the local damage.

Dynamic Behaviors of Metal Matrix Composites in Low Velocity Impact (저속 충격하에서의 금속복합재료의 동적 특성)

  • ;Gamal A. Aggag;K.Takahashi
    • Composites Research
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    • v.12 no.1
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    • pp.68-75
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    • 1999
  • This study has observed that the dynamic behavior of Metal Matrix Composites (MMCs) in low velocity impact varies with impact velocity. MMCs with 15 fiber volume percent were fabricated by using the squeeze casting method. The AC8A was used as the matrix, and the alumina and the carbon were used as reinforcements. The tensile and vibration tests conducted yielded the yielded the tensile stress and elastic modulus of MMCs The low pass filter and instrumented impact test machine was adopted to study dynamic behaviors of MMCs corresponding to impact velocity. Stable impact signals were obtained by using the low pass filter. Impact corresponding to impact velocity. Stable impact signals were obtained by using the low pass filter. Impact energy of unreinforced alloy and MM s increased as the impact velocity increased. The increase of crack propagation energy was especially prominent, but the dynamic toughness of each material did not change much. To show the relation between crack initiation energy and dynamic fracture toughness, a simple model was proposed by using the strain energy and stress distribution at notch. The model revealed that crack initiation energy is proportional to the square of dynamic fracture toughness and inversely proportional to elastic modulus.

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A Study on the Low Speed Impact Response and Frictional Characteristics of Shear Thickening Fluid Impregnated Kevlar Fabrics (전단농화유체를 함침한 케블라 직물의 저속충격 거동 및 마찰특성 연구)

  • Lee, Bok-Won;Lee, Song-Hyun;Kim, Chun-Gon;Yoon, Byung-Il;Paik, Jong-Gyu
    • Composites Research
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    • v.21 no.2
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    • pp.15-24
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    • 2008
  • In this study, shear thickening fluid (STF) filled with rigid nano silica particles was impregnated in plain woven Kevlar fabrics to improve the impact resistance performance. The nano silica particles with an average diameter of 100nm, 300nm, and 500nm were used to make shear thickening fluid to estimate the effect of particle size on the impact behavior of STF impregnated Kevlar fabrics. The yam pull-out and frictional tests were conducted to estimate the effect of impregnated STF on the frictional characteristics. The test results showed that the friction forces were dramatically increased at the STF onset shear strain rates that were measured in preliminary rheology tests. The low speed impact tests were performed using the drop test machine. The results showed that the impregnated STF improved the impact resistance performance of the Kevlar fabrics in terms of the impact energy absorption and the deformation. It has been shown through tests that the impregnated STF affects the interfacial friction which contributes to improve the energy absorption in the Kevlar fabrics. Especially, the impregnation of the STF with the smaller particle size into the Kevlar fabrics showed the better performance in impact energy absorption.

A Study on the Stress Wave Propagation of Composite Laminate Subjected to Low-Velocity Impact (저속 충격을 받는 적층 복합재의 응력파 전파에 관한 연구)

  • 안국찬;김문생;김규남
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.13 no.1
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    • pp.9-19
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    • 1989
  • The impact stress and wave propagation of graphite/epoxy and glass/epoxy laminates subjected to the transverse low-velocity impact of steel balls are investigated theoretically. A plate finite element model based on Whitney and Pagano's theory for the analysis of heterogeneous and anisotropic plates taking into account of the transverse shear deformation is used for the theoretical investigation. This model is in conjuction with static contact laws. The basic element is a four-node quadrilateral with the five degrees-of-freedom per node. The reduced integration technique is used for shear locking associated with low-order function in application to thin plates. These two materials are composed of [0.deg./45.deg./0.deg./-45.deg./0.deg.]$_{2S}$ and [90.deg./45.deg./90.deg./-45.deg./90.deg.]$_{2S}$ stacking sequences and have clamped-clamped boundary conditions. Finally, the present results are compared with an existing solution and wave propagation theory and then impact stress and wave propagation phenomena are investigated.gated.

A Study on the Impact Characteristics of the Composite Materials for Low Velocity to Be Applied a Rail Vehicle (철도차량에 적용될 복합재료의 저속충격특성에 관한 연구)

  • 류충현;이영신;김재훈;나재연;조정미;박병준
    • Proceedings of the KSR Conference
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    • 2002.10b
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    • pp.851-856
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    • 2002
  • In this study, the property against low velocity of the compesite material, which will be applied a rail vehicle, is shown using experiment and a finite element code. The property can be denoted the resistance of impact force, which is defined by maximum impact force over damage area. A damage propagation model is necessary to estimate accurately the impact property of a composite material through FEM code.

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