Due to poor metallurgical weldability of magnesium alloy,laser welding crack is still one of the main defects.The generations of welding crack seriously affected the weld quality and reduce the mechanical properties o...Due to poor metallurgical weldability of magnesium alloy,laser welding crack is still one of the main defects.The generations of welding crack seriously affected the weld quality and reduce the mechanical properties of welded joints which have become a bottleneck of the magnesium alloy products widely used in the structure materials.In this paper,AZ31B magnesium alloy sheet with 2mm thickness was used for this investigation.The forming reason and extending characteristics of the welding cracks were investigated during the Nd:YAG pulsed laser welding.The results show that welding cracks are mainly solidification crack which were always present in the weld centers.Few welding hot cracks appear multiple furcation phenomenons,and main and branch cracks were intercrystalline crack.The partial branch crack was mixed intercrystalline and transgranular extension.In addition,few cracks in the weld were caused due to irregular shape porosity and inclusion.The delayed crack weren't observed in the weld after deposited 48 hours.In the pre-process on the basis,the characteristics and generation mechanism of YAG pulsed laser welding cracks of magnesium alloy were analyzed further.展开更多
The pathology of patellar tendinopathy and the mechanisms of pain are poorly understood. The most popular treatment modality is the Eccentric overload Exercise. However, there is insufficient evidence to recommend a s...The pathology of patellar tendinopathy and the mechanisms of pain are poorly understood. The most popular treatment modality is the Eccentric overload Exercise. However, there is insufficient evidence to recommend a specific protocol and yet it is the most commonly used treatment modality. The aim of this case study is to present the possible mechanisms of pain and a treatment approach on a patient who was diagnosed as having patellar tendinopathy. It is suggested that hyper extension of the knee might be the source of patellar tendon pain in this patient. Following a course of pulsed short wave diathermy the patient was symptom free and remained so at 6 month review. Further studies to evaluate effectiveness of pulsed short wave diathermy is suggested.展开更多
文摘Due to poor metallurgical weldability of magnesium alloy,laser welding crack is still one of the main defects.The generations of welding crack seriously affected the weld quality and reduce the mechanical properties of welded joints which have become a bottleneck of the magnesium alloy products widely used in the structure materials.In this paper,AZ31B magnesium alloy sheet with 2mm thickness was used for this investigation.The forming reason and extending characteristics of the welding cracks were investigated during the Nd:YAG pulsed laser welding.The results show that welding cracks are mainly solidification crack which were always present in the weld centers.Few welding hot cracks appear multiple furcation phenomenons,and main and branch cracks were intercrystalline crack.The partial branch crack was mixed intercrystalline and transgranular extension.In addition,few cracks in the weld were caused due to irregular shape porosity and inclusion.The delayed crack weren't observed in the weld after deposited 48 hours.In the pre-process on the basis,the characteristics and generation mechanism of YAG pulsed laser welding cracks of magnesium alloy were analyzed further.
文摘The pathology of patellar tendinopathy and the mechanisms of pain are poorly understood. The most popular treatment modality is the Eccentric overload Exercise. However, there is insufficient evidence to recommend a specific protocol and yet it is the most commonly used treatment modality. The aim of this case study is to present the possible mechanisms of pain and a treatment approach on a patient who was diagnosed as having patellar tendinopathy. It is suggested that hyper extension of the knee might be the source of patellar tendon pain in this patient. Following a course of pulsed short wave diathermy the patient was symptom free and remained so at 6 month review. Further studies to evaluate effectiveness of pulsed short wave diathermy is suggested.
