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Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A novel small-caliber safety and arming (S&A) device is proposed to improve the fuze performance of modern small caliber projectile within a limited space, for which the “locking” and “unlocking” properties of magnetorheological (MR) grease with/without the presence of magnetic field are used. Based on the principle of MR grease flow through an abrupt contraction-expansion under squeezed pressure, the delay time for arming the firing section was obtained. The delay time mathematical model of reflecting the factors, such as structure size and fluid elasto-viscosity characteristics, is further derived by analyzing the fluid dynamic and magnetic fields. Simulated and experimental results show that the modified local damping coefficient favors to reduce the maximum model error to 6.7%. A delay time range of 9-84 ms was successfully achieved by adjusting the physical parameters, including orifice diameter, spinning rate and particle concentration, etc. Owning to a wide temperature operation range and reliable working mechanism, the proposed MR grease S&A device is expected to have extensive application prospects in small and medium caliber fuze systems. [ABSTRACT FROM AUTHOR]

A novel multi-coil magnetorheological (MR) absorber, which has the capability of being applied with input currents individually, is proposed for the impact mitigation of a gun. The dynamic response characteristics of the proposed MR absorber working in three different modes, namely, uniform loading, combined control and open-loop cascade, are discussed according to ideal profile of recoil resis- tance at 45-degree angle. Impact experimental results show that, in the non-controllable region, a gas compression stage exists in single-stroke damping process, resulting in a significant hysteresis between the damping force and recoil speed; in the controllable region, given a total 2 A input current, the maximum Coulomb damping force generated by the mode of combined control of more than two working coils behaves better than that generated by equivalent loading; and the mode of open-loop cascade control can effectively reduce the peak force and delay its occurrence moment for approaching the ideal buffer effect. However, this requires additional effective stroke for the recoil buffer. It can be seen through analysis that the MR absorber can be used to achieve flexible and variable damping output based on the temporal and spatial two-dimensional current loading sequence, which shows a certain controllability in the application of gun recoil systems with large firing angles. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Vibration Engineering is the property of Nanjing University of Aeronautics & Astronautics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)