• Title/Summary/Keyword: Vibration Correlation Technique

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Study on the Prediction Technique of Vehicle Performance Using Parameter Analysis (파라미터 해석을 통한 차량 성능 예측 기법 연구)

  • Kim, Ki-Chang;Kim, Chan-Mook;Kim, Jin-Taek
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.20 no.11
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    • pp.995-1000
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    • 2010
  • With the development of the auto industry, the automobile manufacturers demand to shorten development period and reduce the cost. Compared with the traditional method, applying the virtual prototype is more economical. This paper presents a method for parameters sensitivity analysis and optimizing the performance of vehicle noise and vibration. The existing design processes were repeatedly analyzed with a focus on vehicle performance to decide the design parameters of dimension, thickness, mounting type of body and chassis systems in the vehicle development period. This paper describes the prediction technique of vehicle performance using L18 orthogonal array layout, quality deviation analysis and parameter sensitivity analysis for robust design. This paper analyzed the performance correlation equation through the frequency and sensitivity database according to a design factor change. The new concept is that the performance prediction is possible without repeated activities of test and analysis. This paper described the parameter analysis applications such as bush dynamic stiffness and bush void direction of rear suspension. Design engineer could efficiently decide the design variable using parameter analysis database in early design stage. These improvements can reduce man hour and test development period as well as to achieve stable NVH performance.

The Estimation of Buckling Load of Pressurized Unstiffened Cylindrical Shell Using the Hybrid Vibration Correlation Technique Based on the Experimental and Numerical Approach (실험적/수치적 방법이 혼합된 VCT를 활용한 내부 압력을 받는 원통형 쉘의 좌굴 하중 예측)

  • Lee, Mi-Yeon;Jeon, Min-Hyeok;Cho, Hyun-Jun;Kim, Yeon-Ju;Kim, In-Gul;Park, Jae-Sang
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.50 no.10
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    • pp.701-708
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    • 2022
  • Since the propellant tank structure of the projectile is mainly subjected to a compressive force, there is a high risk of damage due to buckling. Large and lightweight structures such as propellant tank have a complex manufacturing process. So it requires a non-destructive test method to predict buckling load to use the structure after testing. Many studies have been conducted on Vibration Correlation Technique(VCT), which predicts buckling load using the relationship between compressive load and natural frequency, but it requires a large compressive load to predict the buckling load accurately, and it tends to decrease prediction accuracy with increasing internal pressure in structure. In this paper, we analyzed the causes of the decrease in prediction accuracy when internal pressure increases and proposed a method increasing prediction accuracy under the low compressive load for being usable after testing, through VCT combined testing and FEA result. The prediction value by the proposed method was very consistent with the measured actual buckling load.

Estimation of bridge displacement responses using FBG sensors and theoretical mode shapes

  • Shin, Soobong;Lee, Sun-Ung;Kim, Yuhee;Kim, Nam-Sik
    • Structural Engineering and Mechanics
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    • v.42 no.2
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    • pp.229-245
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    • 2012
  • Bridge vibration displacements have been directly measured by LVDTs (Linear Variable Differential Transformers) or laser equipment and have also been indirectly estimated by an algorithm of integrating measured acceleration. However, LVDT measurement cannot be applied for a bridge crossing over a river or channel and the laser technique cannot be applied when the weather condition is poor. Also, double integration of accelerations may cause serious numerical deviation if the initial condition or a regression process is not carefully controlled. This paper presents an algorithm of estimating bridge vibration displacements using vibration strains measured by FBG (Fiber Bragg Grating) sensors and theoretical mode shapes of a simply supported beam. Since theoretically defined mode shapes are applied, even high modes can be used regardless of the quality of the measured data. In the proposed algorithm, the number of theoretical modes is limited by the number of sensors used for a field test to prevent a mathematical rank deficiency from occurring in computing vibration displacements.89The proposed algorithm has been applied to various types of bridges and its efficacy has been verified. The closeness of the estimated vibration displacements to measured ones has been evaluated by computing the correlation coefficient and by comparing FRFs (Frequency Response Functions) and the maximum displacements.

Ground Vibration Test for Korean Utility Helicopter (한국형 기동헬기 전기체 지상진동시험)

  • Kim, Se-Hee;Kwak, Dong-Il;Jung, Se-Un;Choi, Jong-Ho;Kim, Joung-Hun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.41 no.6
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    • pp.495-501
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    • 2013
  • Korean Utility Helicopter (KUH) has been designed to avoid the blade passing frequency and any instability due to a coupling of dynamic characteristics between the main rotor and the airframe in ground operation. For these design objectives, the vibration analysis and the ground resonance analysis were performed to analyze the dynamic characteristics of the airframe and the main rotor. Then, the whirl-tower test was conducted to identify the dynamic characteristics of the main rotor and the ground vibration test (GVT) was conducted to identify the dynamic characteristics of the airframe. The GVT for KUH was conducted with the test conditions and test articles established in consideration of each flight and ground condition. This paper shows the method and technique for performing the GVT for KUH and presents the correlation technique and the results for the correlated analysis model.

Application of ALE for detection of rolling ball bearing defects in noisy environment (잡음환경에서 구름 볼 베어링의 결함검출을 위한 ALE의 적용)

  • 김영태;최만용;김기복;박해원;박정학;김종억;류준
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2004.10a
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    • pp.86-91
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    • 2004
  • It is very important to detect the bearing defects in rotating machinery since the critical failure of bearing cause a machinery shutdown. However it is difficult to detect the vibration signal resulting from the initial defects of bearing because of the high level of broadband noise. A signal processing technique, called the adaptive line enhancer(ALE) as one of adaptive filter, is studied in this work. This technique is to eliminate broadband noise without a prior knowledge of the noise and signal characteristics. Also we propose the optimal methods for selecting the three main ALE parameters such as correlation length, filter order and adaptation constant used in the adaptative process. Vibration signals for three abnormal bearings, including inner and outer raceways and ball defects, were acquired from Anderon(angular derivative of radius on)meter. The experimental results showed that the proposed technique can reliably detect the bearing defective signals masked by broadband noise.

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Comparative Study on the Measures of Similarity for the Location Template Matching(LTM) Method (Location Template Matching(LTM) 방법에 사용되는 유사성 척도들의 비교 연구)

  • Shin, Kihong
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.24 no.4
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    • pp.310-316
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    • 2014
  • The location template matching(LTM) method is a technique of identifying an impact location on a structure, and requires a certain measure of similarity between two time signals. In general, the correlation coefficient is widely used as the measure of similarity, while the group delay based method is recently proposed to improve the accuracy of the impact localization. Another possible measure is the frequency response assurance criterion(FRAC), though this has not been applied yet. In this paper, these three different measures of similarity are examined comparatively by using experimental data in order to understand the properties of these measures of similarity. The comparative study shows that the correlation coefficient and the FRAC give almost the same information while the group delay based method gives the shape oriented information that is best suitable for the location template matching method.

Comparative Study on the Measures of Similarity for the Location Template Matching (LTM) Method (Location Template Matching(LTM) 방법에 사용되는 유사성 척도들의 비교 연구)

  • Shin, Kihong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2014.04a
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    • pp.506-511
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    • 2014
  • The location template matching (LTM) method is a technique of identifying an impact location on a structure, and requires a certain measure of similarity between two time signals. In general, the correlation coefficient is widely used as the measure of similarity, while the group delay based method is recently proposed to improve the accuracy of the impact localization. Another possible measure is the frequency response assurance criterion (FRAC), though this has not been applied yet. In this paper, these three different measures of similarity are examined comparatively by using experimental data in order to understand the properties of these measures of similarity. The comparative study shows that the correlation coefficient and the FRAC give almost the same information while the group delay based method gives the shape oriented information that is best suitable for the location template matching method.

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Parameter Identification and Nonlinear Seismic Analysis of Soil-Structure Interaction System (지반-구조물 상호작용계의 계수추정 및 비선형 지진응답해석)

  • 윤정방
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 1997.04a
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    • pp.265-272
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    • 1997
  • This paper presents the result of an international cooperative research on the post-correlation analysis of forced vibration tests and the prediction of earthquake responses of a large-scale seismic test structure. Through the post-correlation analysis, the properties of the soil layers are revised so that the best correlation in the responses may be obtained compared with the measured force vibration test data. Utilizing the revised soil properties as the initial linear values, the seismic responses are predicted for an earthquake using the equivalent linearlization technique based on the specified strain dependent characteristics of the shear moduli and damping ratios. It has been found that the predicted responses by the equivalent nonlinear procedure are in excellent agreement with the observed responses, which those using the initial properties are fairly off from the measured results.

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Noise and Vibration Characteristics by Heavy-weight Floor Impact (중량바닥충격에 의한 소음 및 진동 특성)

  • 서상호;송희수;전진용
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.11a
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    • pp.919-922
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    • 2003
  • The correlation between noise and vibration by a heavy-weight floor impact was studied. The triggering technique was used for increasing the reliability and stability to measure the level of sound pressure, sound intensity and vibration acceleration. The simple finite element and rigid body analysis method were suggested to calculate the natural frequencies of the multi-layer floor system. The result show that the isolation material adapted to reduce the light-weight floor impact noise, causing the natural frequency lower, make resonance with dominant driving frequency, and increase the noise level very sharply. Therefore the noise level Peak in the region of low frequency, below 63Hz, would be related with the natural frequencies of the floor system.

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Vibration Source Signal Identification of Structures Using ICA (ICA 기법을 이용한 구조물의 진동원 신호 규명)

  • Kim, Kookhyun;Kwon, Hyuk-Min;Cho, Dae-Seung;Kim, Jae-Ho;Jun, Jae-Jin
    • Journal of the Society of Naval Architects of Korea
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    • v.49 no.6
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    • pp.498-503
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    • 2012
  • Independent component analysis (ICA) technique based on statistical independency of the signals is known as suitable to identify the source signals by measuring and separating mixed signals through transfer paths and has successfully applied in the field of medical care, communications and so forth. In this study, the ICA technique is introduced for the identification of excitation sources from measured vibration signals of structures, which can be done by evaluating negentropy of centered and whitened vibration signals and correlation of separated signals. To validate the method, numerical analyses are carried out for a plate and a cylinder structure. The results show that the method can be applied efficiently to source identification of complex structures. Nevertheless, additional studies would be required to complement problems of occasional inaccuracy.