Crashworthiness requirement of fuel tanks is one of the important requirements in helicopter designs. The relations among the protection frame, textile layer and rubber layer of the fuel tank are introduced. Two appro...Crashworthiness requirement of fuel tanks is one of the important requirements in helicopter designs. The relations among the protection frame, textile layer and rubber layer of the fuel tank are introduced. Two appropriate FE models are established, one is for an uncovered helicopter fuel tank without protection frame, and the other is for fuel tank with protection frame. The dynamic responses of the two types of fuel tanks impinging on the ground with velocities of 17.3 m/s are numerically simulated for the purpose of analyzing energy-absorbing capabilities of the textile layer and protection frame. The feasibility of the current crashworthiness design of the fuel tank is examined though comparing the dynamic response behaviors of the two fuel tanks.展开更多
Theoretical analysis and numerical calculations of Love wave propagation in layered graded composites with imperfectly bonded interface are described in this paper. On the basis of WKB method, the approximate analytic...Theoretical analysis and numerical calculations of Love wave propagation in layered graded composites with imperfectly bonded interface are described in this paper. On the basis of WKB method, the approximate analytic solutions for Love waves are obtained. By the interface shear spring model, the dispersion relations for Love waves in layered graded composite structures with rigid, slip, and imperfectly bonded interfaces are given, and the effects of the interface conditions on the phase velocities of Love waves in SiC/Al layered graded composites are discussed. Numerical analysis shows that the phase velocity decreases when the defined flexibility parameter is greater. For the general imperfectly bonded interface, the phase velocity changes in the range of the velocities for the rigid and slip interface conditions.展开更多
A genuinely three-dimensional spacetime conservation element and solution element(CE/SE)scheme is built as simple,consistent and straightforward extensions of an improved high resolution 2D CE/SE scheme.It is applied ...A genuinely three-dimensional spacetime conservation element and solution element(CE/SE)scheme is built as simple,consistent and straightforward extensions of an improved high resolution 2D CE/SE scheme.It is applied to examine the mechanism of three-dimensional detonation process in rectangular ducts.The simulations clearly show detailed three-dimensional detonation modes,namely a rectangular mode and a diagonal mode.Furthermore,the formation of unreacted pockets with high density and low temperature behind the detonation is observed for the two modes.展开更多
A void growth model considering the Bauschinger effect(BE)is proposed for ductile materials sustaining impact loading.Numerical simulations of two high-velocity impact problems are carried out by our newly developed E...A void growth model considering the Bauschinger effect(BE)is proposed for ductile materials sustaining impact loading.Numerical simulations of two high-velocity impact problems are carried out by our newly developed Eulerian programs.The proposed model is tested by a plate impact problem and a qualitative agreement with the experiment is obtained.Then a more complicated problem,a plate impacted by a spherical projectile at a velocity of 6.0 km/s,is simulated.The numerical results are in better accordance with the experimental data when the BE is considered.The proposed model reveals that the BE has an obvious effect on the spall process.展开更多
基金Foundation items: NSFC Key Project (10532020) Engineering Research Institute, Peking University (ERIPKU) (204038)
文摘Crashworthiness requirement of fuel tanks is one of the important requirements in helicopter designs. The relations among the protection frame, textile layer and rubber layer of the fuel tank are introduced. Two appropriate FE models are established, one is for an uncovered helicopter fuel tank without protection frame, and the other is for fuel tank with protection frame. The dynamic responses of the two types of fuel tanks impinging on the ground with velocities of 17.3 m/s are numerically simulated for the purpose of analyzing energy-absorbing capabilities of the textile layer and protection frame. The feasibility of the current crashworthiness design of the fuel tank is examined though comparing the dynamic response behaviors of the two fuel tanks.
基金Engineering Research Institute of Peking University (ERIPKU) Joint Building Project of Beijing Education Committee
文摘Theoretical analysis and numerical calculations of Love wave propagation in layered graded composites with imperfectly bonded interface are described in this paper. On the basis of WKB method, the approximate analytic solutions for Love waves are obtained. By the interface shear spring model, the dispersion relations for Love waves in layered graded composite structures with rigid, slip, and imperfectly bonded interfaces are given, and the effects of the interface conditions on the phase velocities of Love waves in SiC/Al layered graded composites are discussed. Numerical analysis shows that the phase velocity decreases when the defined flexibility parameter is greater. For the general imperfectly bonded interface, the phase velocity changes in the range of the velocities for the rigid and slip interface conditions.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10732010 and 10972010.
文摘A genuinely three-dimensional spacetime conservation element and solution element(CE/SE)scheme is built as simple,consistent and straightforward extensions of an improved high resolution 2D CE/SE scheme.It is applied to examine the mechanism of three-dimensional detonation process in rectangular ducts.The simulations clearly show detailed three-dimensional detonation modes,namely a rectangular mode and a diagonal mode.Furthermore,the formation of unreacted pockets with high density and low temperature behind the detonation is observed for the two modes.
基金by the National Natural Science Foundation of China under Grant Nos 10732010,10972010 and 11028206.
文摘A void growth model considering the Bauschinger effect(BE)is proposed for ductile materials sustaining impact loading.Numerical simulations of two high-velocity impact problems are carried out by our newly developed Eulerian programs.The proposed model is tested by a plate impact problem and a qualitative agreement with the experiment is obtained.Then a more complicated problem,a plate impacted by a spherical projectile at a velocity of 6.0 km/s,is simulated.The numerical results are in better accordance with the experimental data when the BE is considered.The proposed model reveals that the BE has an obvious effect on the spall process.
