Thermal Response Of 7075 Aluminum Alloy With Different Scaling Laws Under High Power Laser

Under realistic conditions,due to the limitations of the experimental equipment,experimental cost and experimental site,many experiments can not be carried out under the original size model,only a small number of experiments can be carried out for qualitative research,and regular research should be based on the accumulation of a large number of experimental data.The equivalent scaling model of the original size model can be scaled down to the appropriate size to carry out experimental research according to actual experimental conditions.Therefore,the study of the thermal response scale law and the relationship between the thermal response of the target structure and the damage ratio of the target structure can not only effectively study the thermal damage mechanism under strong laser irradiation,but also have important practical problems for many engineering problems.significance.In this paper,simulation and experimental research on laser heating effects of different scale laws are carried out,mainly from the following aspects:An equivalent scaling model of laser heating different scale aluminum alloy plates was established.Through the classical Fourier heat conduction equation and similarity theory,the temperature field distribution equations of the prototype and the model are obtained.Comparing the equivalent scaling law of the mechanical problem,it is found that the heat transfer problem is in contradiction with the equivalent scaling law of the time term in the mechanical problem,so it is concluded that the heat transfer and the mechanical structure are different,and the equivalent scaling law is satisfied.The influence law between the thermal response of the material and the scale law is discussed separately here.Combining the prototype and model temperature field differential equations,using the similarity theory to derive the proportional relationship between the physical quantities commonly found in the equivalent scaling model on heat transfer problems.It provides theoretical support for the subsequent establishment of simulation models.The numerical simulation of different scale aluminum alloy plates was carried out by COMSOL Multiphysic finite element simulation software.During the simulation,the physical field selects “solid heat transfer”,and the laser is applied to the surface of the aluminum alloy by means of surface heat source.The boundary conditions are divided into adiabatic conditions and convective heat transfer and thermal radiation.Laser power,spot radius and irradiation The time is set according to the theoretically derived equivalent scaling model parameters,and then the temperature field calculation is performed for each scale model.The temperature distribution of aluminum alloy plates with different scales under adiabatic boundary conditions and convective heat transfer and thermal radiation boundary conditions is obtained by numerical calculation.Then the temperature field is used as the load to solve the stress distribution and displacement field of each model.The results show that under the adiabatic condition,the temperature field distribution of each scale model in the equivalent irradiation time is the same,and the temperature rise rate is the same;the boundary conditions are the heat convection and heat radiation,after the equivalent irradiation time,each The temperature distribution of the scale law model is different.The model with smaller scale law has a faster temperature rise rate and the final temperature value is higher.The stress distribution is proportional to the temperature difference of the model temperature field,and the thermal expansion displacement field is inversely proportional to the scale law.Experiments were carried out on the simulation model,and the temperature rise experiment of laser irradiation on different scales of aluminum alloy plates was carried out.The experimental results have good similarity with the simulation results,which verifies the rationality and correctness of the simulation model.For the temperature difference where the experimental results are less than the simulation results,the error sources are analyzed from three aspects: material parameters,laser absorption rate and experimental environment.