RESUMO
The ultrasonic welding (UW) technique is a fast-joining process; it is very suitable for the carbon fiber reinforced thermoplastic (CFRTP) composite. For improving the consistency of the welded joint quality, a new pre-pressing ring clamp (PPRC) was designed for ultrasonic welding carbon fiber reinforced nylon composites in this paper. The effects of the PPRC on the weld quality of the ultrasonic welding welded 4.0 mm thick 30% mass short carbon fiber reinforced Nylon 6 composite was investigated and compared with that of normal clamp weld joint. The weld strength, microstructure, and temperature evolution of the joint were analyzed by tensile test, scanning electron microscope, and temperature measurement. The results showed that the PPCR UW joints had larger central weld nugget size (478 mm2 vs. 300 mm2), thicker stable fusion region thickness (1.10 mm vs. 0.96 mm), resulting in a higher joint strength (6.86 kN vs. 6.21 kN) compared with the normal clamp UW joints under the same welding parameters. The real-time monitor curve of the horn displacement and temperature at the faying interface showed that the PPRC increased the heat rating at the faying interface during instable melting stage. The PPRC could improve the contact condition between workpieces and the utilization efficiency of ultrasonic energy, which boosted the melting rate of materials at faying interface and consequently the formation of a sound joint with enough weld size (i.e., 433 mm2) in a shorter welding time (i.e., 1.3 s). Therefore, the flexibility of component assembly would be increased by the use of this sort of clamps.
RESUMO
Brain cyst formation of temporal lobe induced by radionecrosis in ear carcinoma is rare. A 73-year-old man with basosquamous carcinoma of the left external ear canal received excision of tumor and postoperative radiation therapy in 1992. For osteonecrosis of the left temporal bone, a series treatment including oral and intravenous antibiotics and hyperbaric oxygen therapy was given in following years. Encephalomalasia of the left temporal lobe on brain computed tomography (CT) was noted in 1997. The patient suffered from headache, poor concentration, memory impairment, depressed mood, bad temper, and one 8 x 5 x 3.5 cm cystic lesion of the left temporal lobe with tempomandibular joint defect revealed by brain CT in 2001. Symptoms relieved after stereotactic aspiration of cystic fluid and external drainage (Omaya reservoir) insertion under magnetic resonance image by neurosurgeon. We report the progressive radionecrosis of temporal lobe and cyst formation, which caused the neuropsychological symptoms 10 years after radiotherapy.
