The Research Of Thermomechanical Field Due To Transient Head/bpm Disk Contacts

Because of the superparamagnetic effect of magnetic recording media, the traditional theory of magnetic recording has reached the limit. In order to increase the storage density to 1Tb/in2, many recording methods are being explored. And BPM (bit patterned media, BPM) storage technology is considered as one of the most promising directions.When the hard disk works, the intermittent contacts between head and disk are inevitable. The contacts can cause large plastic deformation and high temperature rise which will induce demagnetization and instability of the head/disk interface. Due to the fact that the recording layer of BPM is patterned into an array of discrete, nanometer-sized island-like bit cells, the intermittent contact between BPM disk and slider is more serious than normal disk. But there are only few research on head/BPM transient contact. This paper uses the finite element method to analyze the thermomechanical field caused by head/BPM transient contact. The research contents are as follows:Because the geometric style of the island-like bit cell has not been finalized, this paper selected four common geometric styles: cuboid, cylinder, frustum and oblique cuboid. According to the working condition and theoretical model, three-dimensional finite element model has been developed for each geometric style respectively to investigate which is the best style.In order to reveal the discipline of the thermomechanical field caused by transient contact, a three-dimensional finite element model of head/BPM transient contact has been performed. This paper chooses two substrate materials and two BPM materials to form four disk constitutes and analyzed the effect of them on the thermomechanical field respectively to investigate which disk constitute is best. The effect of contact conditions has also been researched.Planarization of BPM is considered to be an effective approach to significantly improve the performance of the BPM. This paper has verified the effectiveness of this approach by comparing the discipline of the thermomechanical field with the case that BPM is not planarized. The effect of filler material properties has also been analyzed. And the correctness of the model used in this paper has been verified with the conclusions in the reference.