The experiments of CO 2 laser TIG paraxial hybrid welding with 4 mm thick AISI 321 stainless steel sheet have been performed. The arc images and welding characteristics have been investigated with different energy ratios between laser and arc. The experimental results indicate that the hybrid welding is similar to laser welding and has also two welding mechanisms: deep penetration welding and heat conduction welding. Because of the effect of keyhole induced by laser, the arc root can be stabilised and compressed, and the current density and the penetration depth are all increased significantly, which show the characteristics of deep penetration welding. However, when the current is increased to a critical value, the laser induced keyhole disappears and the arc expands obviously, which decreases the penetration depth, so that the welding mechanism has been changed from deep penetration welding to heat conduction welding. Furthermore, the effects of distance between laser beam and electrode, pulsed laser and hybrid manners on hybrid welding characteristics have also been studied.
In order to study the effects of laser induced metal vapour on arc plasma during laser arc double sided welding (LADSW), emission spectroscopy techniques were utilised. The arc plasma in LADSW of 5A06 aluminium alloy was compared with conventional gas tungsten arc welding (GTAW) in this work. The electron temperature and density were estimated by the Saha-Boltzmann equation and the Stark broadening effect. The results indicated that the amount of metal vapour in the arc plasma during LADSW was larger than that of GTAW. Furthermore, the electron temperature of arc plasma in LADSW was lower than that in GTAW, and the electron density of arc plasma in LADSW was higher than that in GTAW near the arc anode. It was shown that the differences in arc properties between LADSW and the conventional GTAW processes were the result of laser induced metal vapour changing the composition of the arc plasma.
An Urgent Rehabilitation Technique Education Program was conducted in response to the needs of the enormous number of the Wenchuan earthquake patients and the shortage of rehabilitation professionals. This program referred to an urgent training program of several rehabilitation techniques that was beneficial to earthquake victims. This short-term program covered the basic clinical technical trainings in physiotherapy, occupational therapy, prosthetics and orthotics, which were included in concentrated technical training, decentralized technical training, and disaster area technical advising. More than 1,500 health-care professionals in Sichuan province took this education program at different locations, which can improve the shortage of rehabilitation professionals, addressing to the clinical need of the earthquake patients, improving local rehabilitation technique, and standardized of the rehabilitation treatments for earthquake patients. This program could be considered as an economical and effective method to help the disaster situation especially there was shortage of health professionals.
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