Mechanical Fault Diagnosis Using Numerical Hilbert Analysis

2002 ◽  
Author(s):  
Baozhong Yang ◽  
C. Steve Suh
Keyword(s):  
Failure Modes ◽  
Dynamic Instability ◽  
Negative Impact ◽  
System Response ◽  
Short Time Scale ◽  
Time Frequency ◽  
Long Time ◽  
Mechanical Faults ◽  
Temporal Events ◽  
Instantaneous Frequencies

Dynamic instability induced by the initiation and development of mechanical faults in a rotary element is known to have a large negative impact on the reliability and operation safety of an entire system. This type of nonlinear system response is generally perturbed by shock impulses of extremely short time scale and amplitude. Thus difficulty presents itself in identifying and isolating features indicative of the presence and progression of faults possibly leading to mechanical deterioration. The perturbed and deteriorated states of a bearing-shaft system subjected to the actions of various types of commonly seen mechanical faults are investigated using the Numerical Hilbert Transform. The presented approach characterizes and realizes temporal events of both short and long time scales as instantaneous frequencies in the joint time-frequency domain. Examples are given to demonstrate the feasibility of applying the approach to the characterization of various deteriorating bearing states and the identification of parameters associated with several failure modes.

Characterization of Dynamical Instability Using Instantaneous Frequency

2002 ◽  
Author(s):  
Baozhong Yang ◽  
James Fisher ◽  
C. Steve Suh
Keyword(s):  
Instantaneous Frequency ◽  
Dynamical Instability ◽  
Time Frequency ◽  
Shaft System ◽  
Long Time ◽  
Mechanical Faults ◽  
Harmonic Components ◽  
Temporal Events ◽  
Instantaneous Frequencies

Dynamical instability induced by the initiation and advancement of mechanical faults in rotary elements is detrimental to the reliability and operation safety of the entire system. The inherent nonlinearity associated with bifurcation presents itself as difficulties in identifying and isolating features indicative of the presence and progression of faults that could lead to eventual mechanical deterioration. The perturbed and deteriorated states of a bearing-shaft system subjected to the actions of two types of commonly seen mechanical faults, namely, rotor speed and imbalance, are investigated using the basic notion of instantaneous frequency. The presented approach realizes temporal events of both short and long time scales as instantaneous frequencies in the joint time-frequency domain and thus effectively uncouples the harmonic components resulted from the coupling of multitude faults. Examples are given to demonstrate the feasibility of applying the approach to the characterization of various deteriorating bearing states and the identification of parameters associated with various modes of instability and chaotic response.

On Failure Mechanisms in Flip Chip Assembly—Part 2: Optimal Underfill and Interconnecting Materials

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Yoonchan Oh ◽  
C. Steve Suh ◽  
Hung-Jue Sue
Keyword(s):  
Time Scale ◽  
Flip Chip ◽  
Thermal Stresses ◽  
Failure Modes ◽  
Scale Effects ◽  
Short Time Scale ◽  
Long Time ◽  
Solder Joint Fatigue ◽  
Scale Properties ◽  
Short Time

The physics explored in this investigation enables short-time scale dynamic phenomenon to be correlated with package failure modes such as solder ball cracking and interlayer debond. It is found that although epoxy-based underfills with nanofillers are shown to be effective in alleviating thermal stresses and improving solder joint fatigue performance in thermal cycling tests of long-time scale, underfill material viscoelasticity is ineffective in attenuating short-time scale propagating shock waves. In addition, the inclusion of Cu interconnecting layers in flip chip area arrays is found to perform significantly better than Al layers in suppressing short-time scale effects. Results reported herein suggest that, if improved flip chip reliability is to be achieved, the compositions of all packaging constituent materials need be formulated to have well-defined short-time scale and long-time scale properties. Chip level circuit design layout also needs be optimized to either discourage or negate short-time wave propagation. The knowledge base established is generally applicable to high performance package configurations of small footprint and high clock speed. The approach along with the numerical procedures developed for the investigation can be a practical tool for realizing better device reliability and thus high manufacturing yield.

Characterization and Detection of Crack-induced Rotary Instability

2001 ◽  
Vol 124 (1) ◽  
pp. 40-48 ◽  
Author(s):  
B. Yang ◽  
C. S. Suh ◽  
A. K. Chan
Keyword(s):  
High Speed ◽  
Failure Modes ◽  
Dynamic Instability ◽  
Chaotic Motions ◽  
Nonlinear Dynamical ◽  
Chaotic Response ◽  
System A ◽  
Common Causes ◽  
Mechanical Faults ◽  
Rotary Instability

System instability and chaotic response are the failure modes that could significantly impact the reliability and operating safety of high-speed rotor-dynamical machines. Initiation and propagation of surface cracks in rotary shafts are common causes for such failure modes. To be able to detect the onset and progression of these faults will considerably extend the lifetime and improve the reliability of the mechanical system. A wavelet-based algorithm effective in identifying mechanical chaotic response has been applied to determine the nonlinear dynamical characteristics of a model-based, cracked rotor. This investigation confirms reported correlation of surface crack breathing with rotor chaotic motions. The effectiveness of the algorithm in detecting rotor-dynamic instability induced by mechanical faults as contrast to algorithms that are based on nonlinear dynamics is discussed. The results show not just the feasibility of the algorithm in mechanical fault diagnosis but also suggest its applicability to in-line, real-time condition monitoring at both the system and component levels.

On Failure Mechanisms in Flip Chip Assembly—Part 1: Short-Time Scale Wave Motion

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Yoonchan Oh ◽  
C. Steve Suh ◽  
Hung-Jue Sue
Keyword(s):  
Time Scale ◽  
Wave Motion ◽  
Flip Chip ◽  
Thermal Stresses ◽  
Failure Modes ◽  
Coefficient Of Thermal Expansion ◽  
Short Time Scale ◽  
Time Frequency ◽  
Thermal Transients ◽  
Short Time

The demand for higher clock speed and larger current magnitude in high-performance flip chip packaging configurations of small footprint has raised the concern over rapid thermal transients and large thermal spatial gradients that could severely compromise package performance. This paper explores coupled electrical-thermal-mechanical multiphysics to evaluate the concern and to establish the knowledge base necessary for improving flip chip reliability. It is found that within the first few hundreds of nanoseconds after power-on, there are fast-attenuating, dispersive stress waves of extremely high frequency propagating in the package. The concepts of high cycle fatigue, power density, and joint time-frequency analysis are employed to characterize the waves along with the various damage modes resulting from the propagation of these short-lived dynamical disturbances in bulk materials and along bimaterial interfaces. A qualitative measure for failure is developed to evaluate the extent of damage inflicted by short-time wave motion. Damages identified in this study are in agreement with physical failure modes commonly seen in industry, thus implying that micron scale cracks or interfacial adhesion flaws initiated at the short-time scale would be further propagated by the coefficient of thermal expansion induced thermal stresses at the long-time scale and result in eventual electrical disruptions.

Comparison of wavelet continuous transform and signal averaged ECG for high frequency content and late potential detection in healthy individuals

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
D Garcia Iglesias ◽  
J.M Rubin Lopez ◽  
D Perez Diez ◽  
C Moris De La Tassa ◽  
F.J De Cos Juez ◽  
...  
Keyword(s):  
High Frequency ◽  
Classical Method ◽  
Total Power ◽  
Frequency Content ◽  
Healthy Individuals ◽  
Time Frequency ◽  
Qt Intervals ◽  
Long Time ◽  
Power Content ◽  
High Frequency Content

Abstract Introduction The Signal Averaged ECG (SAECG) is a classical method forSudden Cardiac Death (SCD) risk assessment, by means of Late Potentials (LP) in the filtered QRS (fQRS)[1]. But it is highly dependent on noise and require long time records, which make it tedious to use. Wavelet Continuous Transform (WCT) meanwhile is easier to use, and may let us to measure the High Frequency Content (HFC) of the QRS and QT intervals, which also correlates with the risk of SCD [2,3]. Whether the HFC of the QRS and QT measured with the WCT is a possible subrogate of LP, has never been demonstrated. Objective To demonstrate if there is any relationship between the HFC measured with the WCT and the LP analyzed with the SAECG. Methods Data from 50 consecutive healthy individuals. The standard ECG was digitally collected for 3 consecutive minutes. For the WCT Analysis 8 consecutive QT complexes were used and for the SAECG Analysis all available QRS were used. The time-frequency data of each QT complex were collected using the WCT as previously described [3] and the Total, QRS and QT power were obtained from each patient. For the SAECG, bipolar X, Y and Z leads were used with a bidirectional filter at 40 to 250 Hz [1]. LP were defined as less than 0.05 z in the terminal part of the filtered QRS and the duration (SAECG LP duration) and root mean square (SAECG LP Content) of this LP were calculated. Pearson's test was used to correlate the Power content with WCT analysis and the LP in the SAECG. Results There is a strong correlation between Total Power and the SAECG LP content (r=0.621, p<0.001). Both ST Power (r=0.567, p<0.001) and QRS Power (r=0.404, p=0.004) are related with the SAECG LP content. No correlation were found between the Power content (Total, QRS or ST Power) and the SAECG LP duration. Also no correlation was found between de SAECG LP content and duration. Conclusions Total, QRS and ST Power measured with the WCT are good surrogates of SAECG LP content. No correlation were found between WCT analysis and the SAECG LP duration. Also no correlation was found between the SAECG LP content and duration. This can be of high interest, since WCT is an easier technique, not needing long recordings and being less affected by noise. Funding Acknowledgement Type of funding source: None

scholarly journals Nonlinearities of heart rate variability in animal models of impaired cardiac control: contribution of different time scales

2017 ◽  
Vol 123 (2) ◽  
pp. 344-351 ◽  
Author(s):  
Luiz Eduardo Virgilio Silva ◽  
Renata Maria Lataro ◽  
Jaci Airton Castania ◽  
Carlos Alberto Aguiar Silva ◽  
Helio Cesar Salgado ◽  
...  
Keyword(s):  
Nonlinear Dynamics ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Time Scales ◽  
Multiscale Entropy ◽  
Time Frequency ◽  
Cardiac Control ◽  
Long Time ◽  
Nonlinear Features ◽  
Short Time

Heart rate variability (HRV) has been extensively explored by traditional linear approaches (e.g., spectral analysis); however, several studies have pointed to the presence of nonlinear features in HRV, suggesting that linear tools might fail to account for the complexity of the HRV dynamics. Even though the prevalent notion is that HRV is nonlinear, the actual presence of nonlinear features is rarely verified. In this study, the presence of nonlinear dynamics was checked as a function of time scales in three experimental models of rats with different impairment of the cardiac control: namely, rats with heart failure (HF), spontaneously hypertensive rats (SHRs), and sinoaortic denervated (SAD) rats. Multiscale entropy (MSE) and refined MSE (RMSE) were chosen as the discriminating statistic for the surrogate test utilized to detect nonlinearity. Nonlinear dynamics is less present in HF animals at both short and long time scales compared with controls. A similar finding was found in SHR only at short time scales. SAD increased the presence of nonlinear dynamics exclusively at short time scales. Those findings suggest that a working baroreflex contributes to linearize HRV and to reduce the likelihood to observe nonlinear components of the cardiac control at short time scales. In addition, an increased sympathetic modulation seems to be a source of nonlinear dynamics at long time scales. Testing nonlinear dynamics as a function of the time scales can provide a characterization of the cardiac control complementary to more traditional markers in time, frequency, and information domains. NEW & NOTEWORTHY Although heart rate variability (HRV) dynamics is widely assumed to be nonlinear, nonlinearity tests are rarely used to check this hypothesis. By adopting multiscale entropy (MSE) and refined MSE (RMSE) as the discriminating statistic for the nonlinearity test, we show that nonlinear dynamics varies with time scale and the type of cardiac dysfunction. Moreover, as complexity metrics and nonlinearities provide complementary information, we strongly recommend using the test for nonlinearity as an additional index to characterize HRV.

Appearance FMEA: A Method for Appearance Quality Evaluation of Early Design Concepts

2009 ◽  
Author(s):  
Karin Forslund ◽  
Timo Kero ◽  
Rikard So¨derberg
Keyword(s):  
Industrial Design ◽  
Failure Modes ◽  
Negative Impact ◽  
Consumer Products ◽  
Product Development Process ◽  
Early Design ◽  
Product Experience ◽  
Design Concepts ◽  
Quality Aspects ◽  
Noise Factors

For consumer products, early design stages are often concerned with the product’s industrial design, with primary focus on the consumer’s product experience. At this stage, aspects such as manufacturability and robustness are often not thoroughly taken into account. Industrial design concepts not properly suited for manufacture, assembly and process variability can result in final products in which the appearance intent is not satisfactorily realized. This can have a negative impact on the customer’s product quality perception. If such problems are discovered late in the product development process, late design changes and increased project costs may follow. The main difficulty in evaluating perceived quality aspects during industrial design is that the product is still under development. It is not mature enough to enable prediction of the prerequisites for achieving high manufacturing quality. In this paper, we suggest that concepts instead could be evaluated as far as the intrinsic tendency of the product appearance to support manufacturing variation and other noise factors. This is addressed through the concept of visual robustness: the ability of a product’s visual appearance to stimulate the same product experience despite variety in its visual design properties. Here, a method is suggested based on the Failure Modes and Effects Analysis (FMEA). The method follows a structured procedure for addressing appearance issues.

The Optimization of Time-Frequency Control: Using Non-Autonomous Time-Delay Feedback Systems as Example

2016 ◽  
Author(s):  
Chi-Wei Kuo ◽  
C. Steve Suh
Keyword(s):  
Time Delay ◽  
Dynamic Instability ◽  
Frequency Control ◽  
Frequency Resolution ◽  
Control Technique ◽  
Time Step ◽  
Time Frequency ◽  
Control Scheme ◽  
Fxlms Algorithm ◽  
On Line

A novel time-frequency nonlinear scheme demonstrated to be feasible for the control of dynamic instability including bifurcation, non-autonomous time-delay feedback oscillators, and route-to-chaos in many nonlinear systems is applied to the control of a time-delayed system. The control scheme features wavelet adaptive filters for simultaneous time-frequency resolution. Specifically Discrete Wavelet transform (DWT) is used to address the nonstationary nature of a chaotic system. The concept of active noise control is also adopted. The scheme applied the filter-x least mean square (FXLMS) algorithm which promotes convergence speed and increases performance. In the time-frequency control scheme, the FXLMS algorithm is modified by adding an adaptive filter to identify the system in real-time in order to construct a wavelet-based time-frequency controller capable of parallel on-line modeling. The scheme of such a construct, which possesses joint time-frequency resolution and embodies on-line FXLMS, is able to control non-autonomous, nonstationary system responses. Although the controller design is shown to successfully moderate the dynamic instability of the time-delay feedback oscillator and unconditionally warrant a limit cycle, parameters are required to be optimized. In this paper, the setting of the control parameters such as control time step, sampling rate, wavelet filter vector, and step size are studied and optimized to control a time-delay feedback oscillators of a nonautonomous type. The time-delayed oscillators have been applied in a broad set of fields including sensor design, manufacturing, and machine dynamics, but they can be easily perturbed to exhibit complex dynamical responses even with a small perturbation from the time-delay feedback. These responses for the system have a very negative impact on the stability, and thus output quality. Through employingfrequency-time control technique, the time responses of the time-delay feedback system to external disturbances are properly mitigated and the frequency responses are also suppressed, thus rendering the controlled responses quasi-periodic.

scholarly journals The Application of Mahagony Bark (Swietenia Mahagony L.) for Natural Dyeing

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Immas Lutfi ◽  
Rois Fatoni ◽  
Siti Fatimah
Keyword(s):  
Calcium Oxide ◽  
Negative Impact ◽  
Ferrous Sulphate ◽  
Optimal Concentration ◽  
Natural Dyes ◽  
Synthetic Dyes ◽  
Color Fastness ◽  
Natural Dyeing ◽  
Long Time

Recently many batik industries owner have switched to using natural dyes because synthetic dyes in the long time have a negative impact on the environment. Natural dyes that are widely used are mahogany (Swietenia Mahagony L.) bark dyes. In the process of coloring batik fabric, there is stage of fixation. Fixation is the stage of binding the color with the fixator. There are three types of fixators used, namely alum (Al2(SO4)3.12H2O), calcium oxide (CaO) and ferrous sulphate (FeSO4) with certain concentrations. The owner of batik industries don't know yet the concentration of a strong and optimal fixator for binding natural dyes in batik fabric. The purpose of this study is to determine the type of strong fixator and optimal concentration of fixator for binding natural mahogany dyes on batik fabric. The owner of batik industries usually use an estimated concentration of 30 g / L to 100 g / L. In this study, the variables are 30 g / L, 60 g / L and 90 g / L in each type of fixator to test the color aging value. and color fastness to rub wet and dry. Judging from the value of R% (color aging) and color fastness test against wet and dry rubbing, it can be concluded that alum and calcium oxide are strong fixators that used with mahogany dyes and the most optimal concentration of alum and calcium oxide is 60 g / L. 

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