Papers by Keyword: Strain Signal

Abstract: This paper proposes the correlation of absorbed energy with calculated energy using the power spectrum density (PSD) method. The total absorbed energy was obtained using the dial/encoder system may significantly vary depending on the strength and ductility of the material. In addition, according to ASTM E23, over 80% of absorbed energy is inaccurate and approximate. For this reason, we determined the energy collected from the dial/encoder Charpy impact test using the signal processing approach. Strain gauges were connected to the Charpy impact striker and the high frequency data acquisition system in order to capture the dynamic impact strain response. Specimens of an aluminium alloy of 6061-T6 and carbon steel 1050 with different velocities and thicknesses were used in the experiment. The specimens are prepared based on the ASTM E23. A collection of signal was converted from the time domain to the frequency domain by means of PSD method and the area under its plot was used to calculate strain energy. The comparison between energy absorbed during the experiment with PSD peak and the strain energy were performed using different materials, velocities and thicknesses. The total energy absorbed for both material with the PSD peak and the strain energy using the dial/encoder system can be linked by a power law equation with R² 96% and R² 94 %. Thus, the effects of the strain signal pattern and impact duration with different parameters were correlated with the PSD peak and the strain energy. This correlation using PSD can be used as an alternative for the charpy impact test and solve the problem of inaccurate absorbed energy.

Abstract: Fuel injector in automotive engine is a very important component in injecting the correct amount of fuel into the combustion chamber. The injection system need to be in a very safe and optimum condition during the engine operation. The mulfunction of the injection system can be avoided if the current working condition is known and a proper maintenence procedure is implemented. This paper proposes the development of a fuel injector monitoring method using strain signals captured by a single-channel strain gage attached on the fuel injector body. The fuel injector was operated under three main sets of parameters; pulse width (ms), frequency (Hz) and pressure (bar) which were varried from 5 ms to 15 ms, 17 Hz to 25 Hz and 10 bar to 70 bar respectively. The settings produce 27 different engine operations and the strain signal will be captured at each operation. The captured strain signals will be analyzed using I-kaz^TM Multilevel technique and will be correlated with the main parameters. The relationship between the I-kaz^TM Multilevel coefficient and the main parameters indicate good correlations which can be used as the guidance for fuel injector monitoring during actual operation. The I-kaz Multilevel technique was found to be very suitable in this study since it is capable of showing consistence pattern change at every parameter change during the engine operation. This monitoring system has a big potential to be developed and improved for the optimization of fuel injector system performance in the automotive industry.

Abstract: This paper presents a methodology to determine the durability of Quad Flat No-Lead (QFN) package. The QFN package is useful for improving the reliability of the package. A mechanical fatigue test namely three points bending cyclic test and signal analysis were proposed in this paper. The three points bending cyclic test method is a test assembly that supports a specimen on two anvils or rollers, and symmetrically loads the specimen on the opposite surface with an anvil or roller using micro-tester machine. For strain signal collection, a strain gauge was connected to the dynamic data acquisition system, and it was used for each tested QFN package for determining the response of the captured cyclic strain signal. It was found that the sinusoidal amplitude pattern of signal response has been obtained during the constant three points bending cyclic test. The obtained response signals were then analysed using the Power Spectral Density.

Abstract: Wavelet transform of strain signal can be used in the damage relative damage extent identification. The proposed method is validated by trial on a simply supported steel beam. And meanwhile the relative damage extent can be identified by drawing the curve of the maximum modulus of the wavelet coefficient and damage extent.

Abstract: In this paper, a new time-domain method for detecting structural local damage has been developed, which is based on the measured strain signals. The “pseudo strain energy density (PSED)” is defined and used to build two major damage indexes, the “average pseudo strain energy density” (APSED) and the “average pseudo strain energy density changing rate” (APSEDR). A probability and mathematical statistics technique is utilized to derive a standardized damage index. Afterwards, these indexes are used to establish the damage identification strategies for beam structures and plate structures respectively. Furthermore, the wavelet packet transform is used to pre-process the measured dynamic strain signals. Then, the effectivity of the new damage identification method is confirmed by numerical simulations. Finally, a laboratory beam model experiment is conducted to verify this method examine the feasibility and applicability of the new method.