In order to prolong the service life of aircraft skin made from AA2524, the effects of laser shock peening(LSP) on fatigue crack growth(FCG) rate and fracture toughness(K_(c)) of AA2524 were investigated. Multiple LSP...In order to prolong the service life of aircraft skin made from AA2524, the effects of laser shock peening(LSP) on fatigue crack growth(FCG) rate and fracture toughness(K_(c)) of AA2524 were investigated. Multiple LSP treatment was performed on compact tension(CT) specimen from single side and double sides. The surface integrity was measured with Vickers hardness tester, X-ray diffractometer and confocal laser scanning microscope, respectively. FCG rate test and fracture toughness test under plane stress were carried out after LSP treatment. The microstructure features of cross-sections were observed with scanning electron microscope. The results showed that the micro-hardness and residual stress of CT specimens were increased dramatically after LSP treatment. Compared to the base metal(BM), the fatigue life was prolonged by 2.4 times and fracture toughness was increased by 22% after multiple LSP.展开更多
Laser shock peening is a new type of metal surface modification technology.Compared to the traditional strengthening method,its enhancement effect and applicability are better.The applications of laser shock peening t...Laser shock peening is a new type of metal surface modification technology.Compared to the traditional strengthening method,its enhancement effect and applicability are better.The applications of laser shock peening technology are closely related to the equipment development technology.At present,foreign countries have developed a series of laser shock enhancement equipments,but there is a big gap between domestic and foreign countries be-cause of the late start and foreign related technology blockade,mainly for the performance of equipment instability,poor environmental adaptability and low degree of automation control.It is difficult to achieve industrial production applications.In view of the above problems,a fixed optical system structure and modular design method are used to develop a laser shock peening equipment.It can complete the processing of aero enginq blade with once clamping,and has a high degree of automation and high precision characteristics.Laser shock peening equipment is mainly com-posed of the control system,high-energy pulse laser,optical shaping system,trajectory robot,water supply robot,monitoring system and other modules.Under the coordination of the control system,the laser outputs short pulse high energy,and laser beam forms a different mode of laser through the optical path shaping system.Meanwhile,the track robot and waterjet robot in accordance with the pre-programmed program movement,and equipment equipped with monitoring system can monitor the operation of each sub-module system and read the running data and fault alarm in real time,and the formation of closed-loop control system feedback control each sub module system.When the room temperature stable at(22±2)C and 20 minutes after the device is switched on,the technical parameters such as the maximum output single pulse energy up to 25 J,energy instability<3%,pulse width which can be contin-uously adjusted between 16 ns and 20 ns,pulse width instability within-1 ns~1 ns,beam divergence<2.5 mrad,beam points instability<50 urad,the repetition frequency of 0.5 Hz~5 Hz are achieved,the transmission efficiency of the optical system is about 92%,the thickness of the constraint layer is uniform and the flow rate is continuously con-trolled.The test results show that the performance of the laser shock peening equipment is good.展开更多
基金Project(52075552) supported by the National Natural Science Foundation of ChinaProject(kq2007085) supported by Changsha Municipal Natural Science Foundation,China。
文摘In order to prolong the service life of aircraft skin made from AA2524, the effects of laser shock peening(LSP) on fatigue crack growth(FCG) rate and fracture toughness(K_(c)) of AA2524 were investigated. Multiple LSP treatment was performed on compact tension(CT) specimen from single side and double sides. The surface integrity was measured with Vickers hardness tester, X-ray diffractometer and confocal laser scanning microscope, respectively. FCG rate test and fracture toughness test under plane stress were carried out after LSP treatment. The microstructure features of cross-sections were observed with scanning electron microscope. The results showed that the micro-hardness and residual stress of CT specimens were increased dramatically after LSP treatment. Compared to the base metal(BM), the fatigue life was prolonged by 2.4 times and fracture toughness was increased by 22% after multiple LSP.
文摘Laser shock peening is a new type of metal surface modification technology.Compared to the traditional strengthening method,its enhancement effect and applicability are better.The applications of laser shock peening technology are closely related to the equipment development technology.At present,foreign countries have developed a series of laser shock enhancement equipments,but there is a big gap between domestic and foreign countries be-cause of the late start and foreign related technology blockade,mainly for the performance of equipment instability,poor environmental adaptability and low degree of automation control.It is difficult to achieve industrial production applications.In view of the above problems,a fixed optical system structure and modular design method are used to develop a laser shock peening equipment.It can complete the processing of aero enginq blade with once clamping,and has a high degree of automation and high precision characteristics.Laser shock peening equipment is mainly com-posed of the control system,high-energy pulse laser,optical shaping system,trajectory robot,water supply robot,monitoring system and other modules.Under the coordination of the control system,the laser outputs short pulse high energy,and laser beam forms a different mode of laser through the optical path shaping system.Meanwhile,the track robot and waterjet robot in accordance with the pre-programmed program movement,and equipment equipped with monitoring system can monitor the operation of each sub-module system and read the running data and fault alarm in real time,and the formation of closed-loop control system feedback control each sub module system.When the room temperature stable at(22±2)C and 20 minutes after the device is switched on,the technical parameters such as the maximum output single pulse energy up to 25 J,energy instability<3%,pulse width which can be contin-uously adjusted between 16 ns and 20 ns,pulse width instability within-1 ns~1 ns,beam divergence<2.5 mrad,beam points instability<50 urad,the repetition frequency of 0.5 Hz~5 Hz are achieved,the transmission efficiency of the optical system is about 92%,the thickness of the constraint layer is uniform and the flow rate is continuously con-trolled.The test results show that the performance of the laser shock peening equipment is good.
