• Title, Summary, Keyword: Falling Weight Test

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A STUDY ON IMPACT CHARACTERISTICS OF THE STACKING SEQUENCES IN CFRP COMPOSITES SUBJECTED TO FALLING-WEIGHT IMPACT LOADING

  • Im, K.H.;Park, N.S.;Kim, Y.N.;Yang, I.Y.
    • International Journal of Automotive Technology
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    • v.4 no.4
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    • pp.203-211
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    • 2003
  • This paper describes a method for a falling weight impact test to estimate the impact energy absorbing characteristics and impact strength of CFRP (Carbon-fiber reinforced plastics) laminate plates based on considerations of stress wave propagation theory, which were converted to measurements of load and displacement verses time. The delamination area of impacted specimens for the different ply orientations was measured with an ultrasonic C-scanner to determine the correlation between impact energy and delamination area. The energy absorbed by a quasi-isotropic specimen having four interfaces was higher than that of orthotropic laminates with two interfaces. The more interfaces, the greater the energy absorbed. The absorbed energy of a hybrid specimen embedding GFRP (Glass-fiber reinforced plastics) layer was higher than that of normal specimens. Also, a falling weight impact tester was built to evaluate the characteristics and impact strength of CFRPs.

Characteristics of Sedimentation and Self-weight Consolidation of Dredged clay Focusing on Fines Content and Falling Height (세립분 함유량 및 투기고에 따른 준설토의 자중압밀 특성)

  • Kim, Jin-Young;Kim, Hye-Rin;Jang, Jung-Min;Lee, Sung-Yeol;Jeong, Wun-Gie;Jin, Young-Sik;Jeong, Hyo-Jin;Baek, Won-Jin;Kang, Kwon-Soo;Goh, Nam-Young
    • Journal of The Korean Society of Agricultural Engineers
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    • v.58 no.6
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    • pp.39-45
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    • 2016
  • In this paper, analyzes the characteristics of self-weight consolidation on the dredged clay according to the fines content and falling height. Research was performed with the dredged clay sampled by Sae-mangeum field site. Classification of fines content was performed by sieve analysis test. After adjusting the fine content, self-weight consolidation tests were carried out focussing on the variation of fines content and falling heights. From the test results of the self-weight consolidation test, samples with high fines content had reached sedimentation completion more later than ones with less fine content samples. In other words, the start of self-weight consolidation was slowing down with increasing of fines content. Also, from the test results of calculating the coefficient of sedimentation consolidation, the coefficient value were increased with the fines content increases. In addition, the change of sedimentation ratio and volume ratio showed more higher changed value as the fine content increases. Thus, it is important to consider the fines content when estimate the settlement time of dredged soil in field dredge work.

A Development on the Non-Destructive Testing Equipment for the Compaction Control and the Evaluation of Pavements Properties (지반물성추정 및 다짐관리를 위한 비파괴시험장비의 개발)

  • 최준성;김인수;유지형;김수일
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.385-390
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    • 2000
  • In this study, the Non-Destructive Testing Equipment was introduced for the compaction control and the evaluation of pavements properties and the developing process was showed. Falling Weight Deflectometer(FWD) is a system for performing non-destructive testing of pavement and the other foundation structures. The system develops forces from the acceleration caused by the arrest of a falling weight and these forces are transmitted onto the surface of a structure causing it to deflect much as it would due to the weight of a passing wheel load. The structure will bend downward and exhibit a deflection basin. FWD uses a set of velocity sensors to determine the amplitude and shape of the deflection basin. The deflection response, when related to the applied loading, can provide information about the strength and condition of the various elements of the test structure. In this study, a computer program was developed that can be used to evaluate pavement and foundation structures from the data produced by FWD. The Falling Weight Deflectometer, non-destructive testing equipment, is increasing used at the whole world.

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Influence of Fiber Strength and Stacking Sequences on Impact Damages of CFRP Composites (섬유강도와 적층구성이 CFRP적층판의 충격손상에 미치는 영향)

  • 임광희;박노식;양인영
    • Transactions of the Korean Society of Automotive Engineers
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    • v.9 no.3
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    • pp.210-220
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    • 2001
  • This paper aims at the evaluation on the characterization of CFRP laminate plates using falling weight impact tester. The experimentation was conducted on several laminates of different fiber and ply orientation. A system was built for the impact strength of CFRP laminates in consideration of stress wave propagation with using drop-weight impact tester as one of impact test. Absorbed energy of orthotropic composites with using T300 fiber, which are composed of the same fiber and stacking number is higher than that or quasi-isotropic specimen over impact energy 7J, but in case or using T700 fiber, much difference does not show. Also, absorbed energy of orthotropic composites with using T300 fiber, which are composed or stacking number and orientation became more than that of T700 fiber specimen; however great change doesn't show in case of quasi-isotropic specimens. It is found that influence was confirmed between impact energy and absorbed energy as the impact energy is increased with adding the falling weight.

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Weight Drop Impact Tests of Earthquake-Proof Table (내진테이블의 중량물 낙하 충격실험)

  • Eom, Tae Sung;Huh, Seok Jae;Park, Tae Won;Lee, Sang Hyun
    • Journal of the Earthquake Engineering Society of Korea
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    • v.22 no.7
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    • pp.369-378
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    • 2018
  • Full-scale seismic retrofit of old and deteriorated masonry buildings requires a lot of cost and time. In such buildings, installing an emergency evacuation space can be considered as an alternative. In this study, requirements of the earthquake-proof table used as an emergency evacuation space for buildings hit by earthquake are investigated. Load conditions required for the table, including the impact effects due to building debris drop, are explained. To investigate the impact effects in more detail, weight drop test is performed for an prototype earthquake-proof table. In the test, the weight of the falling object and free fall height were considered as the main test parameters. The results showed that the duration of impact is very short (0.0226~0.0779sec), and thus the impact forces increase to 15.8~45.2 times the weight of the falling object. Based on these results, design considerations and performance verification criteria of the earthquake-proof table as an emergency evacuation space are given.

Development and Performance Evaluation of Falling-type Dried-Persimmon Weight Sorting System Utilizing Load Cell

  • Lim, Jongguk;Kim, Giyoung;Mo, Changyeun;Choi, Inchul
    • Journal of Biosystems Engineering
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    • v.40 no.4
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    • pp.327-334
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    • 2015
  • Purpose: A falling-type weight sorter equipped with a load cell was developed to sort lightweight dried persimmons. The performance of the sorter was also evaluated. Methods: The electronic weight sorter for dried persimmon comprises a feeder part, a weight-measurement part, an indicator part, a carrier cup, a discharging part, and a driving part. The weight setting and zero-point adjustment are performed digitally for the convenience of users. For the experimental trials, 228 rubber-clay specimens (representative of dried persimmons) in the weight range of 24.73~99.56 g were manufactured for use in experiments to evaluate the performance of the sorter. Results: The average error of the weight measurements from three experimental trials was 1.655%, with a bias of -0.492 g, a root-mean-square error (RMSE) of ${\pm}0.808g$, and a coefficient of determination ($R^2$ ) of 0.997. Conclusions: The load-cell-based electronic dried-persimmon weight sorter developed in this study facilitates effective, precise, and convenient sorting of dried persimmons.

Development of the Structural Condition Evaluation Technique for Asphalt Pavements Using Falling Weight Deflectometer Deflections (Falling Weight Deflectometer 처짐값을 이욤한 아스팔트 포장체의 구조적 상태 평가기법 개발)

  • Son, Jong-Chul;Rhee, Suk-Keun;An, Deok-Soon;Park, Hee-Mun
    • International Journal of Highway Engineering
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    • v.8 no.4
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    • pp.115-124
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    • 2006
  • The objectives of this paper are to develop the structural condition evaluation technique using Falling Weight Deflectometer deflections and propose the structural condition criteria for asphalt pavements. To figure out correlation between surface deflections and critical pavement responses, the synthetic database has been established using the finite element pavement structural analysis program. A regression approach was adopted to develop the pavement response model that can be used to compute the stresses and strains within pavement structure using the FWD deflections. Based on the pavement response model, the procedure for assessing the structural condition of pavement layers was proposed in this study. To validate the condition evaluation procedure for asphalt pavements, the FWD test, dynamic cone penetrometer test, and repeated triaxial compression test were conducted on 11 sections of national highway and 8 sections of local road. Test results indicate that the tensile strain at the bottom of AC layer and AC elastic modulus were good indicators for estimating the stiffness characteristics of AC layer. For subbase layer, the BDI value and compressive strain on top of the subbase layer were appropriate to predict the structural capacity of subbase layer. The BCI value and compressive strain on top of the subgrade were found to be good indicators for evaluating the structural condition of the subgrade. The evaluation criteria for structural condition in asphalt pavements was also proposed in this paper.

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A Study on the Influence of Stacking Sequences using CFRP Laminate Plates by Falling Weight Impact (탄소섬유복합평판에 낙추충격을 가할 때 적층구성에 미치는 영향에 관한 연구)

  • 임광희;박노식;양인영
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.106-109
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    • 2000
  • Impact tester was build up to evaluate the characterization of CFRP laminate plates under the low velocity impact. The tests were conducted on several laminates of different ply orientation A system was budded for the impact strength of CFRP laminates in consideration of stress wave propagation theory using drop-weight impact tester as one of impact test. Results indicate that absorbed energy of quasi-isotropic specimen having four interfaces is higher than that of orthotropic laminates with two interfaces. Also the damage area was measured with ultrasonic C-scanner on some samples. In the specimens the relationship was linear between damaged area and absorbed energy to some degree. Absorbed energy in the specimen that ply number, interface number and fiber stacking sequences is same but having hybrid is higher than that of orthotropic laminates without hybrid.

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Characteristics of Low Velocity Impact Responses due to Interface Number and Stacking Sequences of CFRP Composite Plates (CFRP 복합적층판의 적층배향.계면수에 따른 저속충격특성)

  • Im, Kwang-Hee;Park, No-Sick;Ra, Seung-Woo;Kim, Young-Nam;Lee, Hyun;Sim, Jae-Ki;Yang, In-Young
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.10 no.6
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    • pp.48-56
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    • 2001
  • In this paper, this study aims at the evaluation on the characteristics of CFRP laminate plates using a falling weight impact tester. The experiment was conducted on several laminates of different orientation. A system was built far measur- ing the impact strength of CFRP laminates in consideration of stress wave propagation theory using a falling weight impact tester. Delamination areas of impacted specimens for the different ply orientation were measured with ultrasonic C- scanner to find correlation between impact energy and delamination area. Absorbed energy of quasi-isotropic specimen having flour interfaces was higher than that of orthotropic laminates with two interfaces. The more interfaces, the greater the energy absorbed. The absorbed energy oft hybrid specimen containing a GFRP layer was higher than that of normal specimens.

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A Comparison of Static and Dynamic Deformation Modulus by Dynamic Plate Test (동평판 재하시험을 이용한 정적 및 동적 변형계수 비교)

  • 박용부;정형식
    • Journal of the Korean Geotechnical Society
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    • v.19 no.5
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    • pp.335-342
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    • 2003
  • The method of measuring ground deformation modulus, in situ-testing has the disadvantage where the exam number is limited because it needs counter weight and a lot of measurement times. Recently, it has supplemented this problem and the equipments by which measurement can be made quickly are developed and applied in field., That is Falling Weight Deflectometer(FWD), Light Drop Weight Tester(LDWT), Geogauge. Light Drop Weight Teste.(LDWT) is introduced firstly in the name of ‘a lightweight fall circuit tester for a railroad public corporation’ by KTX. Since KTX introduced LDWT, a number of research organizations have used LDWT to find out domestic standard for quality management of base ground. In this study we used ZFG 02 which was manufactured by Stendal in Germany and measured the dynamic deformation modulus in soil box and in-situ. And we analyzed the correlation of the dynamic deformation modulus with static deformation modulus based on plate test in the same ground.