In order to improve the output power and increase the lifetime of laser diodes,expansion-matched submounts were investigated by finite element analysis.The submount was designed as sandwiched structure.By varying the ...In order to improve the output power and increase the lifetime of laser diodes,expansion-matched submounts were investigated by finite element analysis.The submount was designed as sandwiched structure.By varying the vertical structure and material of the middle layer,the thermal expansion behavior on the mounting surface was simulated to obtain the expansion-matched design.In addition,the thermal performance of laser diodes packaged by different submounts was compared.The numerical results showed that,changing the thickness ratio of surface copper to middle layer will lead the stress and junction temperature to the opposite direction.Thus compromise needs to be made in the design of the vertical structure.In addition,the silicon carbide（SiC） is the most promising material candidate for the middle layer among the materials discussed in this paper.The simulated results were aimed at providing guidance for the optimal design of sandwich-structure submounts.展开更多
Material properties are obvious different between aluminum matrix composites and iron and steel materials. After the brake disk braked at the same speed, the average temperature of the aluminum brake disk is 1.5 times...Material properties are obvious different between aluminum matrix composites and iron and steel materials. After the brake disk braked at the same speed, the average temperature of the aluminum brake disk is 1.5 times as high as one of iron and steel brake disk, the thermal expansion value of the aluminum brake disk is 2 times as big as one of iron and steel brake disk. Mechanical property of the material decreases with the temperature increasing generally during braking, on the other hand, the big thermal stress in the brake disk happens because the material expansion is constrained. Firstly, the reasons of the thermal stress generation and the fracture failure of brake disks during braking are analyzed qualitatively by virtue of three-bar stress frame and sandwich deformation principles in physic, and then the five constraints which cause the thermal stress are summarized. On the base of the experimental results on the 1：1 emergency brake test, the thermal stress and temperature fields are simulated; The behavior of the fracture failure is interpreted semi-quantitatively by finite element analysis, There is the coincident forecast for the fraction position in term of the two methods. In the end, in the light of the analysis and calculation results, it is the general principles observed by the structure design and assembly of the brake disk that are summarized.展开更多
文摘In order to improve the output power and increase the lifetime of laser diodes,expansion-matched submounts were investigated by finite element analysis.The submount was designed as sandwiched structure.By varying the vertical structure and material of the middle layer,the thermal expansion behavior on the mounting surface was simulated to obtain the expansion-matched design.In addition,the thermal performance of laser diodes packaged by different submounts was compared.The numerical results showed that,changing the thickness ratio of surface copper to middle layer will lead the stress and junction temperature to the opposite direction.Thus compromise needs to be made in the design of the vertical structure.In addition,the silicon carbide（SiC） is the most promising material candidate for the middle layer among the materials discussed in this paper.The simulated results were aimed at providing guidance for the optimal design of sandwich-structure submounts.
基金This project is supported by National Hi-tech Research and Development Program of China(863 Program,No.2003AA331190).
文摘Material properties are obvious different between aluminum matrix composites and iron and steel materials. After the brake disk braked at the same speed, the average temperature of the aluminum brake disk is 1.5 times as high as one of iron and steel brake disk, the thermal expansion value of the aluminum brake disk is 2 times as big as one of iron and steel brake disk. Mechanical property of the material decreases with the temperature increasing generally during braking, on the other hand, the big thermal stress in the brake disk happens because the material expansion is constrained. Firstly, the reasons of the thermal stress generation and the fracture failure of brake disks during braking are analyzed qualitatively by virtue of three-bar stress frame and sandwich deformation principles in physic, and then the five constraints which cause the thermal stress are summarized. On the base of the experimental results on the 1：1 emergency brake test, the thermal stress and temperature fields are simulated; The behavior of the fracture failure is interpreted semi-quantitatively by finite element analysis, There is the coincident forecast for the fraction position in term of the two methods. In the end, in the light of the analysis and calculation results, it is the general principles observed by the structure design and assembly of the brake disk that are summarized.
