Welding of Copper to Aluminium With Laser Beam Wavelength of 515 nm

In laser joining of copper (Cu) and aluminum (Al) sheets, the Al sheet is widely chosen as the top surface for laser irradiation because of increased absorption of laser beam and lower melting temperature of Al in contrast to Cu. This research focus on welding from Cu side to Al sheet. The main objective of irradiating the laser beam from the copper side (Cu on top) is to exploit higher solubility of Al in Cu. A significantly lower laser power can be used with 515 nm laser in comparison to 1030 nm. In addition to low laser power, a stable welding is obtained with 515 nm. Because of this advantage, 515 nm is selected for the current research. By fusion of Cu and Al the two sheet metals are welded, with presence of beneficial Cu solid solution phase and Al+Al2Cu in the joint with the brittle phases intermixed between the ductile phase. Therefore the mixed composition strengthens the joint. However excessive mixing leads to formation of more detrimental phases and less ductile phases. Therefore optimum mixing must be maintained. Energy dispersive X-ray spectroscopy (EDS) analysis indicate that large amount of beneficial Cu solid solution and Al rich phases is formed in the strong joint. From the tensile shear test for a strong joint, fracture is obtained on the heat-affected zone (HAZ) of Al. Therefore the key for welding from copper side is to have optimum melt with beneficial phases like Cu and Al+ Al2Cu and the detrimental phases intermixed between the ductile phases

Morphologic Variations of end Trunks of M1 Segment of Middle Cerebral Artery

Introduction: The middle cerebral artery is divided into four segments: proximal M1, insular M2, opercular M3 and cortical M4. M1 extends from the bifurcation point of ACI at ACA and ACM to the insula threshold, laterally from chiasma opticum, laterally from tractus opticus and caudally from trigonum olfactorium, directed laterally, dorsally and rostrally. Early division of the M1 segment into the final trunk is possible at any of the first points of the limb insulae. Material and methods: The study of the micromorphological and morphometric characteristics of the M1 segment was performed in 25 brain (50 ACM preparations) obtained from autopsy of both sexes of different ages without pathological changes. For the removal of the brain from the skull we used the usual technique of obduction. Results: This segment was arch-shaped, in 32 (64%) arteries, rarely S-shaped, in 12 (24%) arteries, much less straight alignment, in 6 (12%) arteries. The average length of the M1 segment of the S shape was 20.6 ± 3.31mm, with a 19.8 mm 4.41mm arch shape, while the straight shape was 16.9 ± 3.62mm. The average S-shaped diameter was 2.7 ± 0.51 mm, arched 2.6 ± 0.47 mm, straight form 2.6 ± 0.36 mm. Variations of M1 branching were: common in 38 cases, early branching in 12 cases, joint trunk with cortical branch in 9 cases, lateral cortical branch in 21 cases, final bifurcation in 24 cases, final trifurcation in 13 cases, duplication in 1 case and M1 accessory in just 1 case. Conclusion: True bifurcation refers to the division of the M1 segment into two final trunks. In cases where the strong joint cortical branch trunk divides from segment M1, while dividing into two terminal trunk immediately after ACM knee formation, it is described as false branching of M1 segment into three terminal branches.

Mechanical Behavior of Concrete Filled Steel Tubular out Stiffener Ring Connections with Reduced Beam Section

The past study indicates that, when the space joint of concentric annular-stiffer is loaded, stress concentration may generate at corner. The destruction usually concentrates in the joint region, and then cannot generate “strong joint”. To change this unfavorable characteristic, the reduced beam section connection is adopted. Through oriented reducing beam section, the plastic region is formed, which can achieve the aim of “weak beam, strong joint”. After the simulation and analysis to space joints on outer concentric annular-stiffer which are processed by reduced beam section, the loading conditions of the joints are obviously improved in the following aspects: (1) the stress distribution on annular plate is smoothed obviously, the degree of stress concentration on corner is significantly decreased; (2) to assure plastic hinge firstly appear on the beam end but not the ring surface, we can change the size of ring plate, length of beam and the flange weaken degree; (3)the joint stiffness does not decrease during the stage of elastic loading; (4)under repeated loading, the joint region has little change and the plastic expansion on the ring surface is not obvious. Above all, reducing beam section can improve the mechanical properties of CFST-steel beam space joints with outer concentric annular-stiffer, thus the “strong joint” requirement could be fulfilled.

III.—On the Discovery of a Quartzose Conglomerate at Caldon Low, Staffs

During a visit to the limestone quarries at Caldon Low last September we had the good fortune to discover an interesting exposure of a quartzose conglomerate containing numerous fossils. The bed was exposed in a strong joint-face running approximately N.N.W. to S.S.E., at the northern extension of the quarry on the north-west flank of the Low, just beyond the mineral line of the North Staffordshire Railway. The altitude is about 900 feet O.D. The conglomerate apparently extended some little distance to the south-west before the opening of the quarry, as we ascertained that some 20 or 30 yards had been removed in gaining access to the limestone behind. It appears to extend for some distance round the flank of the Low towards the north-east.