• Title, Summary, Keyword: low velocity impact

Search Result 277, Processing Time 0.048 seconds

Damage of Composite Laminates by Low-Velocity Impact (저속충격에 의한 복합재료 적층판의 손상)

  • Nam, Ki-Woo;Ahn, Seok-Hwan
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
    • /
    • /
    • pp.284-288
    • /
    • 2003
  • This study was investigated the nondestructive characteristics of the damage caused by low-velocity impact on symmetric cross-ply laminates. These laminates were $[0^{\circ}/90^{\circ}]{_{16s,}}\;{_{24s,}}\;{_{32s,}}\;{_{48s}}$, that is, the thickness was 2, 3, 4 and 6 mm. The impact machine, model 8250 Dynatup Instron, was used a drop-weight type with gravity. The impact velocities used in experiment were 0.75, 0.90, 1.05, 1.20 and 1.35 m/sec. The load and deformation were increased as impact velocity increase. Even if the load increased with laminates thickness in same impact velocity, the deformation decreased. The extensional velocity was a quick as laminate thickness increase in same impact velocity and as impact velocity increase in same laminate thickness. In ultrasonic scans, damaged area was represented an dimmed zone. This is due to the fact that the wave, after having been partially reflected by the defects, has not enough energy to tough the oposite side or to come back from it. The damaged laminate areas were different according to the laminate thickness and the impact velocity. The extensional velocities became lower in if direction and higher in $0^{\circ}$ direction when the size of the defects increases. But, it was difficult to draw any conclusion for the extensional velocities in $45^{\circ}$ direction.

  • PDF

Design and analysis of low velocity impact on thermoplastic hat section with curvilinear profile

  • Gaur, Kumresh K;Dwivedi, Mayank;Bhatnagar, Naresh
    • Advances in materials Research
    • /
    • v.6 no.1
    • /
    • pp.65-78
    • /
    • 2017
  • A hat section was designed and developed for maximum impact energy absorption and/or transmission under low velocity impact. Towards this, different hat sections, having material properties of thermoplastic, were modeled and investigated numerically using finite element analysis (FEA) in the range of 20-50 J impact energy. In the study it was experienced that the design configuration of hat section with curvilinear profile (HSCP) was excellent in energy attenuation capacity and for even distribution of maximum impact force around and along the hat section under low velocity impact loading. To validate the numerical findings, polypropylene copolymer (Co-PP) HSCP and low density polyethylene (LDPE) HSCP were developed and evaluated experimentally in the said impact energy range. A correlation was established between FEA and experimental test results, thereby, validating a numerical model to predict results for other thermoplastic materials under given range of impact energy. The LDPE HSCP exhibited better performance as compared to Co-PP HSCP in the said range of impact energy. The findings of this study will enable the engineers and technologists to design and develop low velocity impact resistance devices for various applications including devices to protect bone joints.

Low-Velocity Impact Damage Detection for Gr/Ep Laminates Using PVDF Sensor Signals (PVDF 센서신호를 이용한 Gr/Ep 적층판의 저속충격 손상탐지)

  • 박찬익;김인걸;이영신
    • Proceedings of the Korean Society For Composite Materials Conference
    • /
    • /
    • pp.158-162
    • /
    • 2003
  • The PVDF(polyvinylidene fluoride) film sensor as one of smart sensors has good characteristics to detect the impact damages of composite structures. The capabilities of the PVDF film sensor for evaluating impact behaviors and damages of Gr/Ep laminates subjected to low-velocity impact were examined. From sensor signals, the specific wave-forms implying the damage were detected. The wavelet transform(WT) and Short Time Fourier Transform(STFT) were used to decompose the piezoelectric sensor signals in this study. The impact behaviors of Gr/Ep laminates were simulated and the impact forces were reconstructed using the sensor signals. Finally, the impact damages were predicted by finite element analysis with the reconstructed forces. For experimental verification, a series of low-velocity impact tests from low energy to damage-induced energy were carried-out. The extent of damage in each case was examined by means of ultrasonic C-scan and the measured damage areas were agreed well with the predicted areas by the F.E.A.

  • PDF

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
    • /
    • /
    • pp.228-233
    • /
    • 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.

  • PDF

Experimental Investigation of Low Velocity Impact Characteristics of Composites Laminate Used in the Light Rail Transit (경전철용 복합적층재에 대한 저속충격특성의 실험적 연구)

  • 김재훈;김후식;박병준;조정미;주정수
    • Proceedings of the KSR Conference
    • /
    • /
    • pp.211-216
    • /
    • 2001
  • It is well known that composite laminates are easily damaged by low velocity impact. Low velocity impact damage characteristics and residual compressive strength of composite laminates used in light rail transit are investigated. 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. The objectives of 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.

  • PDF

Low-Velocity Impact Response Analysis of Composite Laminates Considering Higher Order Shear Deformation and Large Deflection (고차전단변형과 대처짐을 고려한 복합적층판의 저속충격거동 해석)

  • 최익현;홍창선
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.17 no.12
    • /
    • pp.2982-2994
    • /
    • 1993
  • Low-velocity impact responses of composite laminates are investigated using the finite element method based on various theories. In two-dimensional nonlinear analysis, a displacement field considering higher order shear deformation and large deflection of the laminate is assumed and a finite element formulation is developed using a C$^{o}$-continuous 9-node plate element. Also, three-dimensional linear analysis based on the infinitesimal strain-displacement assumptions is performed using 8-node brick elements with incompatible modes. A modified Hertzian contact law is incorporated into the finite element program to evaluate the impact force. In the time integration, the Newmark constant acceleration algorithm is used in conjuction with successive iterations within each time step. Numerical results from static analysis as well as the impact response analysis are presented including impact force histories, deflections, strains in the laminate. Impact responses according to two typical low-velocity impact conditions are compared each other.

Probability Analysis for Impact Behavior of Composite Laminates Subjected to Low-Velocity Impact (저속충격을 받는 복합적층판의 충격거동에 대한 확률분포 특성)

  • Ha, Seung-Chul;Kim, In-Gul;Lee, Seok-Je;Cho, Sang-Gyu;Jang, Moon-Ho;Choi, Ik-Hyeon
    • Composites Research
    • /
    • v.22 no.6
    • /
    • pp.18-22
    • /
    • 2009
  • In this paper, we examined impact force and impact behavior through low velocity impact tests of composite laminates. And through c-scan as nondestructive inspection, explored the damaged area being difficult to examine with the visual inspection. Through CAI tests, we also measured the compression strength of composite laminates subjected to low velocity impact. To examine the characteristics of impact behavior measured from low velocity impact test, nondestructive inspection, and CAI test, the simulated data are generated from the test data using Monte-Carlo simulation, then represented it by probability distribution. The testing results using visible stochastic distribution were examined and compared.

Stundy on Simulation Characteristics of Low Velocity Impact Test of Carbon/Epoxy Composite Plates Manufactured by Filament Winding Method (필라멘트 와인딩 공법으로 제작한 탄소섬유/에폭시 복합소재 평판의 저속 낙하 충격시험 시뮬레이션에 관한 연구)

  • BYUN, JONGIK;KIM, JONGLYUL;HEO, SEOKBONG;KIM, HANSANG
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.29 no.2
    • /
    • pp.190-196
    • /
    • 2018
  • Carbon fiber/epoxy composites are typical brittle materials and have low impact properties. Recently, it is important to investigate impact characteristics of carbon fiber composites because of increasing use as automobile parts and high pressure hydrogen vessels of fuel cell electric vehicles for light weight. In this study, the low velocity impact properties of carbon fiber/epoxy composites fabricated by a filament winding method are studied. The low velocity impact properties were measured by performing tests according to ASTM D7136. The low velocity impact simulations were carried out using commercial structural analysis software, Abaqus. The absorbed energy and the delamination shapes were compared between the experimental and simulation results. The numerical analysis method showed that the absorbed energy decreased with the reduced number of cohesive elements in the composite models.

A Study on Low-Velocity Impact Characterization of Various Sandwich Panels for the Korean Low Floor Bus Application (초저상 버스 차체 적용을 위한 샌드위치 패널들의 저속충격 특성 연구)

  • Lee, Jae-Youl;Lee, Sang-Jin;Shin, Kwang-Bok
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.31 no.4
    • /
    • pp.506-516
    • /
    • 2007
  • In this paper, a study on low-velocity impact response of four different sandwich panels for the hybrid bodyshell and floor structure application of the Korean low floor bus vehicle was done. Square samples of 100mm sides were subjected low-velocity impact loading using an instrumented testing machine at six energy levels. Impact parameters like maximum force, time to maximum force, deflection at maximum force and absorbed energy were evaluated and compared for four different types of sandwich panels. The impact damage size and depth of the permanent indentation were measured by 3-Dimensional Scanner. Failure modes were studied by sectioning the specimens and observed under optical microscope. The impact test results show that sandwich panel with composite laminate facesheet could not observe damage mode of a permanent visible indentation after impact and has a good impact damage resistance in comparison with sandwich panel with metal aluminum facesheet.

Damage of scarf-repaired composite laminates subjected to low-velocity impacts

  • Cheng, Xiaoquan;Zhao, Wenyi;Liu, Shufeng;Xu, Yunyan;Bao, Jianwen
    • Steel and Composite Structures
    • /
    • v.17 no.2
    • /
    • pp.199-213
    • /
    • 2014
  • The damage characters of scarf repaired composite laminates subjected to low-velocity impact with various energy levels at different locations are studied experimentally. The results are compared with those of the original laminates which have no initial damage and don't need repair. The impact load-time history of the specimens, the velocity-time curves of the impactor, the post impact compressive strength of the specimens and the C-scan photographs of the damaged regions are obtained. The delamination threshold load and damage character of the specimen section at impact point are also studied. The results have shown that the impact response of a repaired composite laminate is sensitive to the location of the impact. The impact load and the delamination threshold load have shown different characters for specimens with different impact locations. The debonding characters of the adhesive and compressive strength after impact of the specimens are also influenced by impact locations.