Experimental dynamic characterizations and modelling of disk vibrations for HDDs

Area of Science:

• Mechanical Engineering
• Materials Science
• Data Storage Technology

Background:

• Increasing spindle motor speeds in Hard-Disk Drives (HDDs) enhances data throughput but also increases disk platter vibrations.
• These vibrations, driven by air-flow and assembly imbalances, lead to Track Mis-Registration (TMR), limiting recording density.
• TMR is a critical challenge for the future development of mobile HDDs.

Purpose of the Study:

• To characterize the natural mode shapes of HDD disk platters.
• To verify vibration analysis using Finite Element Methods (FEM) with Scanning Laser Doppler Vibrometer (SLDV) measurements.
• To model disk Operating Deflection Shapes (ODS) for servo compensation.

Main Methods:

• Finite Element Methods (FEM) analysis was employed to model disk natural mode shapes.
• Scanning Laser Doppler Vibrometer (SLDV) measurements were used to experimentally verify the FEM analysis.
• Disk ODS vibrations were modeled as repeatable disturbance components for HDD servo systems.

Main Results:

• SLDV measurements accurately captured static disk mode shapes without complex air-flow models.
• The identified vibration frequencies and amplitudes of disk ODS correlated well with experimental data.
• FEM analysis and SLDV measurements provide a reliable method for characterizing disk vibrations.

Conclusions:

• The study successfully characterized HDD disk natural mode shapes and ODS.
• SLDV measurements offer an accurate and practical alternative to intricate aero-elastic models.
• The proposed vibration model aids in servo compensation, potentially improving HDD recording density and performance.