Table of Content

20 January 2002, Volume 30 Issue 1

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Application of PVF 2 Film Sensor on Dynamic Measurement System of a Model Pile#br#



Su Wei guo

2002, 30(1):  1-5. 

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 In this paper a highly accurate system for dynamic measurement of model pile was installed．
A new type of force transducer—piezoelectric polyvinylidence fluoride （PVF 2 ） film and a grating dis-
placement sensor were used to measure the force and displacement at the pile toe respectively for the
first time．The system can be used to synchronously measure 4signalsi．e．the force and displace-
ment at the pile toe as well as the force and acceleration at the head of pile when the pile is subjected to
an axial impact load．It is verified that the signals from the transducers is well coincident with the cal -
culated solutions．The system would be an ideal one to study mult- i parameter dynamic measurement of
model pile by stress wave theory and the resistance model of the pile toe．


The Investigation of the Mechanism of High Frequency Short Pulse Electrochemical Machining

Wang Jian-ye

2002, 30(1):  6-11. 

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In this paper the mechanism of high frequency short pulse electrochemical machining （HSPECM） is investigated．The results show that the intensive pulse effects by HSPECM improve the behaviour of the inter-electrode gap of electrochemical machining （ECM）．The intensive pressure wave the large inverse current in pulse interval and microsparks all result in intensive depolarisation so the current efficiency feature is improved and the cut-off gap is shortened．These lead to intensive anodic dissolution localisation ability and micro inter-electrode gap machining．It has been proved by technology experiments that the above alternations result in high machining accuracy better surface quality and good profit．For example in die-sinking samples by HSPECM ellipticity attains to0．02mm  repeatability to0．05mm‚surface roughness to Ra0．60μm．It improves ECM from sem-i rough ma chining to precision machining．