Design and analysis of head expander of electrodynamic shaker for vibration testing

2021 ◽  
Author(s):  
Vinod Kumar Bandu ◽  
Venkata Narayana Yenugula ◽  
B. Shirish
Keyword(s):  
Vibration Testing ◽  
Electrodynamic Shaker

Method for increasing the speed of an electrodynamic shaker for vibration test of rolling stock equipment

2021 ◽  
pp. 107754632110466
Author(s):  
Peng Wang ◽  
Hua Deng ◽  
Yue Liu ◽  
Yi-ming Wang ◽  
Yi Zhang ◽  
...  
Keyword(s):  
Input Impedance ◽  
Vertical Direction ◽  
Maximum Velocity ◽  
Rolling Stock ◽  
Vibration Test ◽  
Vibration Testing ◽  
High Frequencies ◽  
Electrodynamic Shaker ◽  
Long Life ◽  
The Impact

The velocity required in IEC 61373 for long-life random vibration testing of Category-3 rolling stock equipment in the vertical direction is 2.7821 m/s, but the maximum velocity of existing electrodynamic shakers falls in the range of 2–2.5 m/s. In this study, an electrodynamic shaker with a velocity satisfying the requirements for vibration testing of Category-3 rolling stock equipment was developed. First, mechanical and equivalent circuit models of an electrodynamic shaker were developed. On this basis, reducing the impedance of the armature coil was identified as the best option for increasing the velocity of the shaker. However, owing to the impact of the back electromotive force of the armature coil, a decrease in the input impedance of the armature coil at low frequencies leads to an increase in its input impedance at high frequencies. To reduce the input impedance at high frequencies, a shading coil was incorporated into the circuit. The shading coil-incorporated new design was modeled using equivalent circuits and simulated numerically. The results showed that the improvement measures—incorporating a shading coil, increasing the cross-sectional area, and reducing the number of turns of the armature coil—effectively reduced the input impedance of the armature coil, thereby increasing the armature coil current and the velocity of the shaker. Finally, a shaker with a maximum velocity of 3.2 m/s was fabricated based on the new design and was validated to satisfy the high-velocity requirement for the long-life vibration test of Category-3 equipment in the vertical direction as specified in IEC 61373.

Upgrading of Tubular Heat Exchangers by the Helical Spacer Method and Evaluation

2002 ◽  
Author(s):  
F. L. Eisinger ◽  
R. E. Sullivan
Keyword(s):  
Theoretical Analysis ◽  
Acoustic Wave ◽  
Heat Exchangers ◽  
Test Results ◽  
Vibration Testing ◽  
Safe Operation ◽  
Shell Side ◽  
Full Load ◽  
Post Modification ◽  
Side Flow

The tubular heat exchangers described exhibited a sensitivity to flow-induced tube vibration at about 50% of their design shell-side flow. Following a detailed theoretical analysis, the heat exchangers were modified by the helical spacer method providing additional tube supports in-between the existing support plates and in the U-bend. This modification aimed at allowing the heat exchangers to operate safely and reliably at full load, including a 25% overload. Post modification sound and vibration testing was performed which confirmed the adequacy of the modification. The test results showed however, that at the overload condition, an unusual acoustic wave inside the shell was developing. It was determined that this wave would not be harmful to the safe operation of the heat exchangers. The paper will discuss the findings in more detail.

An Investigation of the Vibration Testing Method for Small Diameter Endmills

2014 ◽  
Vol 625 ◽  
pp. 134-139
Author(s):  
Takenori Ono
Keyword(s):  
Small Diameter ◽  
Milling Process ◽  
Modal Parameters ◽  
Vibration Testing ◽  
Function Generator ◽  
Testing Method ◽  
Milling Tool ◽  
Compliance Curve ◽  
Vibration Tests ◽  
The Impact

This paper introduced about the in-process vibration testing method for small diameter endmill. By this method, the natural frequency and modal parameters such as mass, damping, and stiffness of the milling tool can be determined in the milling process. An oscillation of the vibrator is controlled by the function generator to apply the impact force at the appropriate cutting period. The measurement setup can determine the compliance curve by the measurement signals of the exiting force and tool deformation. To evaluate the feasibility of the new method, vibration tests were performed on a square endmill which has the diameter of 4 mm in the milling on brass material. Results of vibration tests show that modal parameters of the specific vibration mode can be determined by the new developed method.

Vibration testing for anomaly detection

2009 ◽  
Vol 32 (7) ◽  
pp. 863-874 ◽  
Author(s):  
Habib Ammari ◽  
Hyeonbae Kang ◽  
Eunjoo Kim ◽  
Hyundae Lee
Keyword(s):  
Anomaly Detection ◽  
Vibration Testing
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