Study On Precision Forming With Semi-die Based On Big Laser Spot Single Shock

Base on the preliminary study on LSF (Laser Shock Forming) both at home and abroad, a new method and device of big laser spot single shock precision forming with semi-die is proposed. Experiments and finite element simulation were carried out on constant elastic alloy diaphragm laser shock forming with semi-die. The main contents and results in this paper are listed as follows:1. The formation mechanism of laser induced shock wave is analyzed, the formula for calculating the peak pressure of shock wave in constraint model is given, and the material constitutive relationship suitable for high pressure, high strain rate, thermal insulation condition and the main factors affecting accuracy in LSF process are discussed.2. The constant elastic alloy diaphragm laser shock precision forming with semi-die method was first studied by experiments. The contours of the sample were obtained by using of reverse engineering technology and forming accuracy was characterized. Different laser pulse energy influent on forming accuracy was discussed in this paper. The results show that when the laser energy was low, the diaphragm could not touch the concave die closely, while the laser energy was too high, inverse deformation was found in partial area of the metal diaphragm, especially it was more obvious in the centre, which affected the forming accuracy greatly.3. The motion equations and the cause of the reverse plastic deformation of the metal sheet during LSF process as well as the optimal laser pulse energy range are obtained through theoretical analysis. The diagram can have a collision with the concave die but can't produce reverse plastic deformation if energy in this range, so forming accuracy can be improved.4. Based on the experiments, the finite element software ABAQUS was used to simulate the constant elastic alloy metal sheet forming by laser shock waves with semi-die process in this paper. The analysis result agrees with the existed experimental result very well. Different laser pulse energy influence on the circular center node velocity was investigated and the law of velocities in different regions of the sample at the same energy was discussed. This can make up the inadequacy of the existing experimental detection systems.