The parametric analysis of the centrifugal insurance mechanism in MEMS safety and arming device
In this paper, a MEMS S&A device has been proposed. The size of the device is φ 12×0.3mm. The role of the centrifugal insurance mechanism is to ensure the safety in handling transportation and storage, and reliable firing with the launch overload. Through establishing the three-dimensional model of the centrifugal insurance mechanism, establishing the force and the parameters of the centrifugal insurance mechanism, deriving the mathematical model according to the rigid dynamic mechanics theory and establishing the finite element model by using ANSYS/LS-DYNA, appropriate centrifugal insurance mechanism is designed to meet two items, one item is deformation of elastic beam can reliably release slider when the speed is more than 30000r/min and the centrifugal insurance mechanism can restrict the slider again when the speed is reduced; the other item is the centrifugal insurance mechanism can effectively restrict the slider to ensure the safety of the device when primary insurance accident arming in handling transportation.
Design of an H-shaped linear piezoelectric motor for safety and arming device
Abstract In this contribution, an H-shaped piezoelectric motor based safety and arming device that is driven by the hybrid of symmetrical first longitudinal mode and second bending mode is proposed, designed and experimental investigated. The proposed system operates based on the concept of self-moving and show potential infield of fuse system with different calibers. The actuating mechanism is that the four driving feet contact with the guides alternately and push the motor to move continuously. Modal and harmonic analysis are conducted to determine the dimension of the structure, confirm the working principle and analyze the motion trajectories of driving feet with finite element method. It is shown that trajectories of the driving feet are oblique ellipses with different angles because of the asymmetry of structure. In addition, a prototype is fabricated and experimented. The results show that the average speeds of the prototype in two directions are 120.6 mm/s and 130.1 mm/s respectively under the driving voltage of 120 V0-p and working frequency of 88.5 kHz. The H-shaped piezoelectric motor based safety and arming device can change its state from safety to arming or reversely in 25 ms with the fixed stroke of 3 mm.
A study of the local tissue reactions in man to cortisone and compound F. VI. Histopathological studies of the local effect of compound F in normal and pathologic skin of man.
After our previous negative studies (1) of the local effect of cortisone acetate in the skin of man, a year ago, a parallel study of 17-hydroxycorticosterone-21-acetate, Compound F, was outlined. Theoretically, Compound F should be the active steroid. It was so suggested by Rothman (2), that in all probability Compound F and not cortisone would be active locally in the skin of man.