Schematic diagram of an HDD without a base.

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... of disk-suspension-slider air-bearing systems was proposed [3]. More recently, an FE model of an HDD was developed [4] to investigate its response to a linear shock and a rotary shock. Comparison of the simulation results obtained under the two types of conditions led to the development of a correlation between the linear and rotary shock tests. Fig. 1 shows a schematic diagram of an HDD without a base, with major components annotated. The disk is mounted onto a spindle. A special electromagnetic reading/writing device called a magnetic head is fabricated on a slider. The slider is mounted onto a suspension and an actuator arm, which is in turn fixed to a base plate via a pivot. The ...

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... acceleration) and different pulse durations (pulse widths) from 0.04 to 4 ms were inputted into the numerical model. The acceleration level of 600g is close to the design shock limit of HDDs. Fig. 9 shows three cases of the input acceleration pulse loadings in which the pulse widths are 0.5 1 and 2 ms, respectively, shown as the abscissae. Fig. 10 shows time history of the relative displacement for the three different pulse widths of a single halfsine acceleration pulse loading with a 600g amplitude, corresponding to Fig. 9. From Fig. 10, it can be seen that the maximum relative displacement occurs at different times for different pulse widths with the same amplitude. Depending ...

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... limit of HDDs. Fig. 9 shows three cases of the input acceleration pulse loadings in which the pulse widths are 0.5 1 and 2 ms, respectively, shown as the abscissae. Fig. 10 shows time history of the relative displacement for the three different pulse widths of a single halfsine acceleration pulse loading with a 600g amplitude, corresponding to Fig. 9. From Fig. 10, it can be seen that the maximum relative displacement occurs at different times for different pulse widths with the same amplitude. Depending on the pulse width, the maximum relative displacement can occur at the first, second, or third oscillation of ...

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... variation of the maximum relative displacement (y max ) with different pulse widths for 600g pulses is shown in Fig. 11. It can be noted that, as the pulse width increases, the maximum relative displacement increases sharply for pulse widths less than 0.5 ms, reaches a peak value at a pulse width of 0.6 ms, decreases quickly to 0.2 mm at a pulse width of 1 ms, and, then, decreases slowly and seems to approach a constant value after about a 2 ms pulse ...

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... further investigate the pseudo-resonance phenomenon, three types of acceleration shocks different in shape (the half-sine, triangular and dual-quadratic waveforms) with an amplitude of 600g and with different pulse widths from 0.1 to 1.0 ms were applied (0.1 ms case shown in Fig. 12). Note that the dual-quadratic waveform consists of a rising portion in the form of bt 2 , where t is time and b a constant, and a falling portion as a mirror image of the foregoing. Fig. 13 shows the variation of the maximum relative displacements (y max ) of the actuator arm subjected to these three types of acceleration shocks with ...

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... triangular and dual-quadratic waveforms) with an amplitude of 600g and with different pulse widths from 0.1 to 1.0 ms were applied (0.1 ms case shown in Fig. 12). Note that the dual-quadratic waveform consists of a rising portion in the form of bt 2 , where t is time and b a constant, and a falling portion as a mirror image of the foregoing. Fig. 13 shows the variation of the maximum relative displacements (y max ) of the actuator arm subjected to these three types of acceleration shocks with different pulse widths of 0.1, 0.2, 0.4, 0.6, 0.8, and 1.0 ms. It can be noticed that, the maximum relative displacement experiences a peak value with an increase of pulse width, i.e., a ...

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... explain the phenomena observed above, a power spectrum analysis was conducted for the different acceleration shocks. Fig. 14 shows the acceleration power spectrum curves of these acceleration shocks different in shape with a pulse width of 0.1 ms. It can be found that, at the resonant frequency of 1.3 kHz of the actuator arm, the acceleration power magnitude of the half-sine acceleration waveform is the largest, followed by those of triangular and ...

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... different in shape with a pulse width of 0.1 ms. It can be found that, at the resonant frequency of 1.3 kHz of the actuator arm, the acceleration power magnitude of the half-sine acceleration waveform is the largest, followed by those of triangular and dual-quadratic waveforms. This relative relation of the acceleration powers is also shown in Fig. 15 and is consistent with that of the corresponding maximum relative displacements as shown in Fig. 13 for the case of 0.1-ms pulse ...

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... of 1.3 kHz of the actuator arm, the acceleration power magnitude of the half-sine acceleration waveform is the largest, followed by those of triangular and dual-quadratic waveforms. This relative relation of the acceleration powers is also shown in Fig. 15 and is consistent with that of the corresponding maximum relative displacements as shown in Fig. 13 for the case of 0.1-ms pulse ...

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... is also noticed, from Fig. 14, that there is a cross-over point (or small interval) for the three different power spectrum curves at a frequency value (location) of 1/T, where T is the pulse width. To prove the ...

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... When the characteristic frequencies of a group of acceleration shocks with different pulse shapes are very close to the resonant frequency of the dynamic system, these acceleration shocks will have nearly equal acceleration powers at the resonant frequency; consequently, they will produce nearly equal shock responses. Fig. 15 shows the variations of acceleration power at the resonant frequency of 1.3 kHz for these three types of acceleration shocks with pulse widths of 0.1, 0.2, 0.4, 0.6, 0.8, and 1 ms. It can be found that, for the 1-ms pulse width and a resonant frequency of 1.3 kHz, the acceleration power magnitude of the dual-quadratic acceleration ...

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... dual-quadratic acceleration waveform is the largest, followed by those of triangular and half-sine waveforms. This relative relation of the acceleration powers for the 1-ms pulse width is in a reverse sequence of that for the case of 0.1-ms pulse width, but it is consistent with that of the corresponding maximum relative displacements as shown in Fig. 13 for the case of 1-ms pulse ...

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... can also be noticed from Fig. 15 that, for both the half-sine and the triangular acceleration shocks, the maximum acceleration powers, for a resonant frequency of 1.3 kHz, are reached at the approximately same pulse width of about 0.6-ms. However, for the dual-quadratic acceleration shock, it is reached at about 0.8-ms pulse width. This observation of the acceleration ...

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... maximum acceleration powers, for a resonant frequency of 1.3 kHz, are reached at the approximately same pulse width of about 0.6-ms. However, for the dual-quadratic acceleration shock, it is reached at about 0.8-ms pulse width. This observation of the acceleration powers gives a reasonable explanation to the pseudoresonance phenomena observed in Fig. ...

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... it can also be found that there is a narrow cross-over interval for the three curves in Fig. 15 around a pulse width of 0.8 ms, and a similar narrow cross-over interval also exists in Fig. 13 around the same pulse width. This is because when the pulse width is approximately equal to 0.8 ms, the characteristic frequencies (1=0:8 ¼ 1:25 kHz) of these acceleration shocks are very close to the resonant frequency (1.3 kHz) of the ...

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... it can also be found that there is a narrow cross-over interval for the three curves in Fig. 15 around a pulse width of 0.8 ms, and a similar narrow cross-over interval also exists in Fig. 13 around the same pulse width. This is because when the pulse width is approximately equal to 0.8 ms, the characteristic frequencies (1=0:8 ¼ 1:25 kHz) of these acceleration shocks are very close to the resonant frequency (1.3 kHz) of the actuator arm. These observations confirm the prediction of the corollary stated above. ...