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RISS 인기검색어
- 검색키워드
- 저자 : S.A.C. Abdullah (검색결과 5 건)
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Neuro-fuzzy fatigue life assessment using the wavelet-based multifractality parameters
C. H. Chin,S. ABDULLAH,S.S.K. Singh,A. K. ARIFFIN,D. Schramm 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.2
This study aims to establish a fatigue life predictive model based on multifractality of road excitations using neuro-fuzzy method to assess the durability of suspension spring. Traditional durability analysis in time domain is complicated and time-consuming due to the needs of large data amount. Thus, it is an idea to adopt an adaptive neuro-fuzzy inference system (ANFIS) for relating the performance of coil spring to the multifractal properties of road excitations, giving a meaningful fatigue life prediction. Different membership function numbers were tested to obtain the optimum membership function number. During the data training process, the checking data was used to test the trained model each Epoch of training for overfitting detection. As a result, the Morrow-based fatigue life prediction model was found to give the most suitable result with three membership functions. The SWT-based model needed five membership functions due to nonlinear properties in the SWT-based fatigue life data. Training process of Morrow-based-ANFIS was stopped at Epoch 8 given its lowest checking root-meansquare-error of 0.6953. SWT-based model recorded a higher error of 0.7940. The neuro-fuzzy models gave accurate fatigue life predictions with 96 % of the data distributed within the acceptance boundary, hence, contributing to an acceptable assessment of coil spring fatigue life based on load multifractality. This study had shown a nonlinear relationship between road multifractality and durability performance of coil spring. Multifractality had been proven an important feature to characterise various road excitations for durability prediction.
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C. H. Chin,S. ABDULLAH,S.S.K. Singh,A. K. ARIFFIN,D. Schramm 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.1
This paper aims to assess the fatigue reliability of random loading signals of a suspension coil spring using probabilistic approaches. Strain time histories were acquired while the car was travelling on different road conditions (i.e., in a rural area, in an industrial area, on a university campus, on a highway and on a newly constructed road). Fatigue lives were predicted from the strain histories and fitted into probability density functions. Lognormal distribution was found to be an appropriate way to represent fatigue data. Next, the reliability function and mean-cycles-to-failure (MCTF) were determined. The results indicated that fatigue reliability rapidly deteriorated under rural road conditions, which resulted in a short MCTF of 10 4 cycles. Meanwhile, the new road signals had the longest MCTF of about 10 8 cycles. Accordingly, this is due to the rural road having the most surface irregularities, which caused more severe fatigue damage to the coil spring. This study contributed to a greater in-depth understanding of the effect of loading signals on fatigue reliability. This is essential in determining the appropriate service life of the coil spring during its production to ensure vehicle safety and reduce maintenance costs.
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Vibration fatigue analysis through frequency response function of variable amplitude loading
C. H. Chin,S. ABDULLAH,A. G. Yin,A. K. ARIFFIN 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.1
This paper aims to evaluate the modal frequency responses of suspension lower arm subjected to random road excitations for fatigue life prediction. Traditional timedomain approaches for durability prediction require long signals and computationally heavier. Hence, frequency domain method was utilised to assess the fatigue life of suspension lower arm. Road tests were conducted under various road conditions to acquire the road excitation signals. Modal frequency response analysis was performed to obtain the frequency response function of the spring. In addition, fatigue life of the component was calculated using frequency domain approach with different power spectral density cycle counters, namely, Lalanne, Dirlik and narrow band. Results showed that the rural road had the lowest fatigue lives of 1.1-3.3×10 3blocks to failure. It is confirmed that the Dirlik gave the most accurate prediction of fatigue life with a difference of 51 % with the time domain approaches. This study contributed to the determination of appropriate frequency domain approach for fatigue life prediction of suspension lower arm without the need of long signals.
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Suhaila M Sanip,A. F. ISMAIL,P. S. GOH,B. C. NG,M. S. ABDULLAH,T. SOGA,M. TANEMURA,H. YASUHIKO 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2010 NANO Vol.5 No.4
The functionalization of multiwalled carbon nanotubes (MWNTs) with β cyclodextrin (β-CD) is described. The functionalization using β-CD treatment is an environmentally friendly and nondestructive method to modify carbon nanotubes. It was observed that the degree of functionalization increases with increasing ratios of β-CD as seen from the Raman analysis. The Raman spectra also indicated that the nanotubes walls were not damaged. The presence of functional groups associated with β-CD on the functionalized MWNTs indicated that the cyclodextrin groups were found to be adsorbed at the surface of the nanotubes walls. Mixed matrix membrane (MMM) was prepared by a phase inversion process. Enhanced selectivity and permeability for CO2 over CH4 was observed for MMM prepared using functionalized MWNTs.
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Performance Evaluation of the RTK-GNSS Navigating under Different Landscape
K.M. Ng,J. Johari,S.A.C. Abdullah,A. Ahmad,B. N. Laja 제어로봇시스템학회 2018 제어로봇시스템학회 국제학술대회 논문집 Vol.2018 No.10
The navigation of autonomous vehicles depends on various sensors. One of the technologies that assist in the vehicles position localization and navigation is the Global Positioning System (GPS). Enhancement of the GPS technology reveals the application of Real Time Kinematics (RTK)-GPS to achieve higher accuracy based on corrections sent from a base station to the receiver. However, there is limited evaluation of the performance of the RTK-GPS when the vehicle is travelling in land area that is obstructed by buildings and also in uneven landscape. Hence, the purpose of this work is to conduct an experimental and comparative study to evaluate the performance of the RTK-GPS in flat-unobstructed, uneven-unobstructed and uneven-obstructed situations respectively. Three locations that possess the respective landscape characteristics in the state of Selangor, Malaysia were chosen to conduct the experiments. Results of logged RTK coordinates were compared with coordinates of the actual path travelled by the vehicle using statistical methods. In addition, the quality indicators of the coordinates logged were also evaluated. The results show that navigation on flat-unobstructed and uneven-unobstructed landscape has similar performances with floating coordinates range of errors.
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