• Title, Summary, Keyword: Impact

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A study on the impact pulse analysis with various shapes and materials of impactor (충격자의 형상 및 재질변화에 따른 펄스형성에 관한 연구)

  • Lee, Yeong-Sin;Kim, Dong-Jin;Gang, Geun-Hui;O, Jong-Su
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.22 no.1
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    • pp.52-63
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    • 1998
  • The impact programmer for impact test was designed and the impact analysis was conducted. The effects of the material and geometric parameters on the impact force and pulse shape were investigated. The impact characteristics were examined by experimental and finite element method. The impact test was conducted with free drop impact tester. The ABAQUS/Explicit 5.5 version was used for finite element analysis. The geometric parameters of the conical and dome type impact programmer were analyzed. The polyurethane impact programmers were fabricated and tested. The effects of the hardness and thickness of the impact programmer were studied. The peak acceleration and time duration of impact programmer have close correlation with the hardness, impact energy and thickness of the impactor. The experiment was good agreement with analytical predictions. The impact pulse shape generated with polyurethane impact programmer was half sine shape. The maximum impact force was proportional to impact energy. The impact acceleration was decreased with thickness of impact programmer. The maximum impact time duration level was about 2 msec.

Evaluations on isolation method of floor impact sounds by real impact source (실충격원을 고려한 바닥충격음 저감방안의 평가)

  • Yoo, Seung-Yup;Lee, Pyung-Jik;Jeong, Young;Jeon, Jin-Yong;Ryu, Jong-Kwan
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.366-370
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    • 2006
  • In this study, characteristics of impact force and impact sound of impact source such as bang machine, impact ball, and children's jumping were review. Results of review showed that impact ball has most similar characteristic to real impact sources in terms of objective properties such as impact force and impact sound. The effects of various isolator on floor impact sound were also investigated in apartment building and test facilities building using bang machine an impact ball. From the field measurement, it was found that the difference in reduction sound level between bang machine and impact ball was relatively large and the reduction sound level by impact ball was much larger than bang machine.

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Comparison of the Standard Floor Impact Sound with Living Impact Source by Subjective Evaluation

  • Park, Hyeon Ku;Kim, Kyeong Mo;Kim, Sun-Woo
    • KIEAE Journal
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    • v.14 no.1
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    • pp.39-48
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    • 2014
  • In the previous test, the verification of the standard floor impact source was carried out comparing the physical characteristics with living impact sources. The result was appeared the validation of the standard impact source was very low because of differences of physical characteristics. This study aims to evaluate annoyance and loudness of standard impact source which is used for the measurement of floor impact sound, and to compare the annoyance and loudness of living impact sources which are produced in real life. The impact sources considered are tapping machine, tire and impact ball as standard sources, and nine real sources which were chosen from the existing researches. The result showed differences of annoyance and loudness between standard impact sources and living impact sources, which means the standard impact sources may rate the performance of floor system inappropriately. In the future, the rating method should be examined how the standard impact sources are similar with real sources in the point of rating the performance of floor system.

Analysis and Evaluation of Impact Sound Insulation of Concrete Floor Structures in Response to Characteristics of Heavy-weight Impact Sources (중량충격원에 따른 콘크리트 바닥판의 차음특성 분석 및 평가에 관한 연구)

  • Yoo, Seung-Yup;Yeon, Jun-Oh;Jeon, Jin-Yong
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.10
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    • pp.1062-1068
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    • 2009
  • In this study, the impact force levels of bang machine and impact ball were measured, then the heavy-weight impact sounds generated by the bang machine and impact ball were investigated. It was found that the heavy-weight impact sources generated through modal excitation, and the impact force of the impact ball was similar to that of real impact source. The heavy-weight impact sounds were also measured in the real apartments with different slab thickness and floor structures. The results showed that the floor impact sound levels in terms of $L_{iFmax,AW}$, generated by impact ball sounds were reduced by using the resilient isolators. The frequency characteristics of heavy-weight impact sounds at 125 and 250 Hz were consistent with the characteristics of impact force spectrum. However, the difference between the impact sounds and the impact forces were found at 63 and 500 Hz due to the resonance of the floor structure and flanking noise, respectively.

Comparison of Standard Floor Impact Sources with a Human Impact Source (바닥충격음 측정용 표준충격원과 실충격원의 특성 비교)

  • Lee, Pyoung-Jik;Jeong, Jeong-Ho;Park, Jun-Hong;Jeon, Jin-Yong
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.16 no.8
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    • pp.789-796
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    • 2006
  • The characteristics of the four standard floor impact sources (impact ball, bang machine, tapping machine, modified tapping machine) and a human impact source (jumping children) were investigated. First, the mechanical impedance of each source were evaluated. Then, the impact force exposure level of each source were measured. The results showed that fundamental frequency and impedance produced by the impact ball are the most similar to those of the human impact source. The frequency characteristics of the impact ball were most similar to those of jumping children. Consequently, the impact ball more accurately reproduces human impact compared to the other standard impact sources. Therefore, the impact ball should be considered as the reliable impactor in evaluating floor impact noise.

Improvement of Floor Impact Noise Measurement and Method for Rating Floor Impact Noise Isolation Performance (바닥충격음 측정 및 차음 평가의 방향)

  • Jeong, Jeong-Ho;Jeong, Yeong;Seo, Sang-Ho;Song, Hee-Soo;Jeon, Jin-Yong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.269-274
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    • 2004
  • The aims of this study were to Investigate the floor impact noise isolation performance of floating floor with isolation materials and propose the improvement direction of floor impact noise measurement method and evaluation classes using impact ball. Reduction of light-weight impact sound pressure level can be achieved by the finishing materials, such as vinyl finishing material and wooden flooring with isolation materials. Floor impact noise Isolation material which satisfy the properties of the floor impact noise isolation materials cause resonance in the low frequency band and worsen heavy-weight impact sound pressure level. Heavy-weight impact sound level can be reduced by using noise reduction flooring, ceiling and increase of slab thickness. Strong impact force in low frequency bang below 63Hz of bang machine is not similar to human impact source and causes some problem in evaluating heavy-weight impact noise but heavy-weight impact noise measurement and evolution using impact ball which is very similar to human impact is more reliable than bang machine. Correction value on the background noise and sensitivity of residents should be considered on the floor impact noise evaluation classes.

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The Reduction of Floor Impact Noise and Impact Force Level of PVC Vinyl Floor coverings and Mats for Children (PVC 바닥 마감재와 아이들 매트의 바닥 충격음 및 충격력 저감)

  • Mun, Dae-Ho;Park, Hong-Gun;Song, Guk-Gon;Lee, Cheol-Seung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.425-430
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    • 2014
  • Floor coverings and Mats are for children are economical and has excellent workability, as well as they can reduce floor impact noise effective. "When these floorings contact to impact source, they are deformed and change impact force characteristics that strikes floor structure. It is important to measure the impact force spectrum of floorings in order to evaluate reduction of floor impact noise for floorings. In experimental test of floor impact noise and impact force for 14 PVC vinyl floor coverings and 16 mats for children, we confirmed that the impact force spectrum directly related to the floor impact noise spectrum.

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Impact minimization by impact ellipsoids (임팩트 타원을 이용한 임팩트의 최소화)

  • Lee, Ji-Hong;Lee, Young-Il;Yoo, Jun
    • 제어로봇시스템학회:학술대회논문집
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    • pp.726-729
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    • 1996
  • A weighted impact ellipsoid normalized by maximum allowable angular velocity changes is defined and compared with conventional impact ellipsoids and impact polytopes. The results shows that the conventional impact ellipsoid may give false solution as far as the optimal direction of motion is concerned.

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Effect of Impact Energy on the Impact-Wear Properties of High Manganese Steels in Acidic Corrosive Conditions

  • Wang, Kai;Du, Xiao-Dong;Wu, Kai;Youn, Kuk-Tae;Lee, Chan Gyu;Koo, Bon Heun
    • Corrosion Science and Technology
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    • v.7 no.6
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    • pp.362-369
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    • 2008
  • The impact abrasion behavior of high manganese steel is investigated under three kinds of impact energy in acid hematite ore slurry by using a modified MLD-10 impact abrasion tester. Through the SEM observation of the worn surface and the optical metallographic analysis of the cross-sectional samples, the corrosive impact abrasion mechanisms of the steel under different impact energies are studied. In acid-hematite slurry, the variations of impact energies would result in synchronous transformation of the impact abrasion properties and mechanisms of the high manganese steel in the corrosive condition, as led different corrosive impact abrasion mechanism under different impact energies.

Verification of Effectiveness of the Standard Floor Impact Source by Comparing with Living Impact Sources (실생활 충격소음을 통한 표준 바닥충격원의 실효성 검증)

  • Park, Hyeon Ku;Kim, Kyeong Mo;Kim, Sun-Woo
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.12
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    • pp.1117-1126
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    • 2013
  • The standard impact sources, standardized to rate the sound insulation performance of floor structure, should simulate well the real floor impact sources, which is very important to grade the floor structure then to establish counter plan to improve the performance of floor. Recently the tire, the standard heavyweight impact source, has been discussed that the impact force is too big to represent the real impact force. And researches have been carried on the applicability as a substitute or a supplementary. In addition, tapping machine, the standard lightweight impact source, is also questionable if it is representative of real lightweight impact source. This study aims to examine the similarity of standard impact sources with living impact sources, comparing the physical characteristics such as impact force, frequency contents and sound level. The result showed that the physical characteristics of standard impact sounds were somewhat different with that of living impact sounds, and the standard sources couldn't be verified from this result. Later subjective evaluation should be followed to compare how the physical differences make relationship with the subjective differences.