Some problems for dynamic computation of closed cylindrical shell due to axial impact load

AbstractIn this paper, the dynamic buckling of an elastic cylindrical shell subjected to an axial impact load is analyzed in Hamiltonian system. By employing a symplectic method, the traditional governing equations are transformed into Hamiltonian canonical equations in dual variables. In this system, the critical load and buckling mode are reduced to solving symplectic eigenvalues and eigensolutions respectively. The result shows that the critical load relates with boundary conditions, thickness of the shell and radial inertia force. And the corresponding buckling modes present some local shapes. Besides, the process of dynamic buckling is related to the stress wave, the critical load and buckling mode depend upon the impacted time. This paper gives analytically and numerically some new rules of the buckling problem, which is useful for designing shell structures.

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On the elastic buckling of cross-ply composite closed cylindrical shell under hydrostatic pressure

Ocean Engineering ◽

10.1016/j.oceaneng.2021.108633 ◽

2021 ◽

Vol 227 ◽

pp. 108633

Author(s):

Muhammad Imran ◽

Dongyan Shi ◽

Lili Tong ◽

Ahsan Elahi ◽

Muqeem Uddin

Keyword(s):

Cylindrical Shell ◽

Hydrostatic Pressure ◽

Elastic Buckling ◽

Closed Cylindrical Shell

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Experimental Study on Axial Impact Mitigating Stick-Slip Vibration with a PDC Bit

Shock and Vibration ◽

10.1155/2021/8897283 ◽

2021 ◽

Vol 2021 ◽

pp. 1-8

Author(s):

Yong Wang ◽

Hongjian Ni ◽

Yiliu (Paul) Tu ◽

Ruihe Wang ◽

Xueying Wang ◽

...

Keyword(s):

Impact Force ◽

Impact Load ◽

Similarity Theory ◽

Impact Frequency ◽

Stick Slip ◽

Axial Impact ◽

Pdc Bit ◽

Fluctuation Amplitude ◽

Rotary Speed ◽

The Impact

Stick-slip vibration reduces the drilling rate of penetration, causes early wear of bits, and threatens the safety of downhole tools. Therefore, it is necessary to study suppression methods of stick-slip vibration to achieve efficient and safe drilling. Field tests show that the use of downhole axial impactors is helpful to mitigate stick-slip vibration and improve rock-breaking efficiency. However, there are many deficiencies in the study of how axial impact load affects stick-slip vibration of a PDC bit. In this paper, based on the two-degrees-of-freedom spring-mass-damper model and similarity theory, a laboratory experiment device for suppressing stick-slip vibration of a PDC bit under axial impact load has been developed, and systematic experimental research has been carried out. The results show that the axial impact force can suppress the stick-slip vibration by reducing the amplitude of weight on bit and torque fluctuations and by increasing the main frequency of torque. The amplitude of impact force affects the choice of the optimal back-rake angle. The impact frequency is negatively correlated with the fluctuation amplitude of the rotary speed. When the impact frequency is greater than 100 Hz, the fluctuation amplitude of the rotary speed will not decrease.

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Dynamic Buckling of Cylindrical Shells under Axial Impact in Hamiltonian System

International Journal of Nonlinear Sciences and Numerical Simulation ◽

10.1515/ijnsns-2011-0105 ◽

2012 ◽

Vol 13 (1) ◽

Author(s):

Jia-Bin Sun ◽

Xin-Sheng Xu ◽

Chee-Wah Lim

Keyword(s):

Hamiltonian System ◽

Critical Load ◽

Impact Load ◽

Dynamic Buckling ◽

Inertia Force ◽

Elastic Cylindrical Shell ◽

Symplectic Method ◽

Buckling Mode ◽

Axial Impact ◽

Dual Variables

AbstractIn this paper, the dynamic buckling of an elastic cylindrical shell subjected to an axial impact load is analyzed in Hamiltonian system. By employing a symplectic method, the traditional governing equations are transformed into Hamiltonian canonical equations in dual variables. In this system, the critical load and buckling mode are reduced to solving symplectic eigenvalues and eigensolutions respectively. The result shows that the critical load relates with boundary conditions, thickness of the shell and radial inertia force. And the corresponding buckling modes present some local shapes. Besides, the process of dynamic buckling is related to the stress wave, the critical load and buckling mode depend upon the impacted time. This paper gives analytically and numerically some new rules of the buckling problem, which is useful for designing shell structures.

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Axial Impact Load of a Concrete-Filled Steel Tubular Member with Axial Compression Considering the Creep Effect

Materials ◽

10.3390/ma12193134 ◽

2019 ◽

Vol 12 (19) ◽

pp. 3134 ◽

Cited By ~ 2

Author(s):

Tao Lan ◽

Guangchong Qin ◽

Jinzhao Zhuang ◽

Youdi Wang ◽

Qian Zheng ◽

...

Keyword(s):

Impact Load ◽

Slenderness Ratio ◽

Concrete Strength ◽

Pressure Ratio ◽

Impact Resistance ◽

Axial Pressure ◽

Axial Impact ◽

Creep Effect ◽

The Impact ◽

Peak Value

The dynamic loads acting on concrete-filled steel tubular members under axial impacts by rigid bodies were studied herein by FEM. The whole impact process was simulated and the time history of the impact load was obtained. The effects of eight factors on the axial impact load were studied; these factors were the impact speed, mass ratio, axial pressure ratio, steel ratio, slenderness ratio, concrete strength, impact position, and boundary conditions. Besides this, the effects of concrete creep on the impact load were also considered by changing the material parameters of the concrete. The results show that axial impact load changes with time as a triangle. The peak value of impact load increases and the impact resistance improves with the growth of the axial pressure ratio, steel ratio, slenderness ratio, and concrete strength after creep occurs. As the eccentricity of the axial impact acting on a concrete-filled steel tubular member increases, the peak value of the impact load decreases. The enhancement of constraints at both ends of the member can improve the impact resistance. The creep reduction coefficients for the peak axial impact load of a concrete-filled steel tubular member under axial compression and considering the creep effect over 6 months and 30 years are 0.60 and 0.55, respectively. A calculation formula for the peak value of impact load was suggested based on the existing formula, and its accuracy was proved by finite element calculation in this study.

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