Theoretical And Experimental Study Of Aluminum Alloy Under High Energy Continuous Laser And External Load

Since the laser was found, because it has the advantages that ordinary electromagnetic wave doesn’t have, laser is widely used in industrial processing, medical education, and national defense military field. On the one hand, when the local region of specimen is irradiated by the strong laser, the temperature in the laser irradiation region rises quickly, and the thermal mechanical properties of the materials have changed dramatically, making the material thermal softening and melting and gasification spray; on the other hand, due to the material’s elastic modulus, yield strength decreases gradually with the increasing of the temperature, the laser irradiation area gets into the plastic yield stage and with the increase of the irradiation time, the yield region expands to the specimen interior gradually and causes stress damage to the specimen. When the workpiece is clamped or the aircraft and missiles are flying at high speed, the specimen will be in the condition of external load pre loading, to correspond with the actual application, this paper presents the theoretical and experimental research on the problems of aluminum alloy target which are under the combination effect of high power laser and tension loading.(1) Based on the method of numerical simulation, the two-dimensional physical model is established based on the theory of heat conduction, thermal force coupling and elastic plasticity, the temperature field, stress field and the time of equivalent stress minimum appears of the aluminum alloy sheet subjected to uniaxial tensile loading are studied by using the finite element method. Considering the nonlinear material properties and the phase transformation in the numerical simulation, this paper firstly studies the influence of the existence of external load on the plastic yield time and material failure mechanism. Then, the relationship between the laser power density, the applied tensile force, the thickness of the specimen and the time of plastic yield starts and the equivalent stress minimum appears under the combination effect of high power laser and tension loading are studied.(2) The uniaxial tension experiment is conducted without laser irradiation on 1060 and 6061 aluminum alloy, the effects of thickness and width of the material on the fracture process, fracture displacement, fracture morphology, plastic yield point and maximum fracture load are obtained. After the upper experiment, the 6061 aluminum alloy is chosen to carry out the combined loading test, the change curve of external force loading from external force to laser irradiation until the fracture is recorded. The mechanism of material failure, the temperature rise of laser irradiation center, the laser irradiation time and the fracture location are studied and the influence of laser power density, the change of specimen thickness on the fracture morphology, the time of temperature rise and fracture failure is studied.