Advanced Materials Research Vols. 690-693

Abstract: Test of 5052 Al alloy contact reactive brazing has been conducted in the case of special brazing parameters, using Cu foil-Mg power-Cu foil as reaction layer material, the microstructure were analyzed and discussed primarily. The results show that the brazing seam structure consisted of α-Al solid solution and CuAl₂ intermetallic compound; the organizations of brazed seam include Al (Mg, Cu) solid solution CuAl₂ binary intermetallic compound, complicated ternary intermetallic compound and Al₂MgO₄.

Abstract: Finite element (FE) modeling of laser welds for dynamic analysis is a research issue because of the complexity and uncertainty of the welds and thus formed structures. A Bayesian probabilistic framework incorporating MCMC for updating the parameters of a spot weld structure model was presented, cooperation of finite element program and multiple chains sampling technology was realized, and statistical characteristics of structural parameters were obtained. Distribution ranges of the three frequencies were predicted based on parameter estimation. Numerical simulation indicates that there are little changes in standard deviations of posterior distribution compared to prior distribution, the posterior mean values are in good agreement with the corresponding measured average values. The convergence indicates the techniques feasibility and effectiveness. The present work offers an alternative approach to updating the spot weld structure parameters.

Abstract: Tension tests on T700/EXOPY unidirectional laminates and 3-D and six-directional braided composites single-lap adhesive joints with different adhesive types under uniaxial tensile loading are performed in the presented paper. Failure modes, strengths and load-displacement curves of two kinds of different adhesive joints are compared and analyzed. According to the experimental results, it is found that the strength of the joints of the smaller adhesive shear strength is less, in contrast, the strength of the joints of the bigger adhesive shear strength is greater, Failure shear strength average is grown 27% relatively. And the starting position of the crack is appeared at the overlap ends, and the whole joint is failed with propagation of the crack.

Abstract: The CTOD test was performed on Instron8801 servo hydraulic testing machine according to the GB/T 2358-94 standard at room temperature. Scanning microscopy was used for observation of the fracture surface of the test specimens and compared with general TIG welded joint. The results show that the average CTOD for high frequency TIG welded joints is lower than the average CTOD for TIG welded joints because of the decrease of the plastic portion of CTOD. The fracture characteristic of high frequency TIG welded joints is dendritic crystal fracture.

Abstract: Through analysing the shortcomings of the traditional methods of eliminating residual stress, and aimed at the mechanism of eliminating residual stress, put forward the method of eliminating aluminium alloy welding residual stress by ultrasonic. Explained the superiority of using ultrasonic to eliminate aluminium alloy welding residual stress by the comparison with heat treatment and vibration processing that are the most commonly used methods in practical engineering.

Abstract: Underwater weld technology is urgently needed for the widely development of marine recourses, and weld automation technology is the inevitable choice because of the underwater environment. Because of the influence of the rigorous environment, the weld seam forming of underwater wet welding is very poor. To control the weld seam forming automatically, the model between the weld parameters and the weld seam shape must be built. This paper used arc sensor to monitor the electrical information of underwater wet welding process, and regression method was used to model the process, and the factors that influence the weld seam forming mostly were analyzed.

Abstract: Different numerical simulation methods on forming of tailor-welded blanks has been introduced with details, and the influence of various numerical models on the results of simulation was compared. Forming process of Square box was studied, and the difference between simulation results of two kinds of numerical modeling was discussed. The development direction of tailor-welded blanks CAE has been put forward.

Abstract: The selection of welding parameter has an important effect on weld quality. In this paper, an orthogonal experiment method was used to optimize the resistance microwelding (RMW) parameters for the connection of insulated copper wire and phosphor bronze sheet. An orthogonal array with three factors (welding current, weld time and electrode force) and five levels was used. Joint breaking force (JBF) and surface appearance were selected as the evaluation criterion of the weld quality. The results show that welding current was the most influencing parameter on joint strength, while the electrode force had the most significant effect on the surface appearance. The orthogonal method was proved to be an effective method to obtain the optimum conditions for RMW of insulated copper wire.

Abstract: Failure prediction of adhesively bonded single-lap laminates joints with spew fillets in the overlap ends under uniaxial tensile loading is performed by progressive failure analysis method. A modified form of Hashins failure criterion by Shokrieh and maximum stress criterion are used to detect the laminate failure and adhesive failure, respectively, where a sudden degradation model is proposed to reduce engineering material constants. Five kinds of failure modes are considered. The numerical analysis of composites adhesive joints is implemented in ANSYS Parametric Design Language (APDL) with commercial finite element codes ANSYS. The error of simulation and experimental failure loads is 6.9% and the model has been validated by comparing numerical results with experimental results.

Abstract: Welding experiments were made with δ=14mm, 16MnR steel by three welding methods, manual electric arc welding, automatic submerged arc welding and semi-auto solid-core CO2 shielded arc welding, and weld joint test with samples from every welding specimen. The properties of welding joint were analyzed by three welding methods and in every position of welding, concluded that brittlement problems in heat affected zone arise from the CO2 shielded arc welding, it is because of the heat damage of alloy elements of weld joint metal while using CO2 shielded arc welding, but the strength of the weld joint is high because of its high fusion ratio. So for improving the mechanical properties of weld joints.it had better accelerate the cooling rate of weld bead and decrease the heat input of welding.