Due to their simple structure,crooked plates are widely processed into energy absorption structures.There are obvious differences in the final deformation of crooked plates with different materials and dynamic conditi...Due to their simple structure,crooked plates are widely processed into energy absorption structures.There are obvious differences in the final deformation of crooked plates with different materials and dynamic conditions under the impact of constant-input kinetic energy.To better understand this phenomenon,we solved the Zhang-Yu equation with Maple software,obtained the law of generalized coordinates(rotation angle)of the energy absorber changing with time,and compared the energy absorption capacity of a crooked plate energy absorber under different parameters.To better understand how the motion of the energy absorber is affected by the change of parameters,we calculated the phase diagram of the energy absorber dynamics.After many numerical simulations,we found that the four-crooked plate energy absorber should have a mass-sensitive structure.We established the finite element model of dynamic buckling of mild steel and 6061-T6 aluminum alloy,and compared it with the Calladine-English dynamic experiment and Zhang-Yu rigid viscoplastic model.The results show that:(1)the Zhang-Yu rigid viscoplastic model has more guiding significance for mild steel(strain rate-sensitive material),and has greater error for 6061-T6 aluminum alloy(strain rate-insensitive material),and the prediction error further increases with the initial angle;and(2)by modifying the equivalent plastic length A of a plastic hinge according to the finite element model,the prediction accuracy of the Zhang-Yu rigid viscoplastic model can be improved.Our research results certain guiding significance for the design and manufacture of energy-absorbing structures of crooked plates.展开更多
On a late summer morning,the sky was clear and the weather fine.Kids were playing in the open,with laughter and joy in the air.It was Aug 28 when I met with Michael Crook and his mother,Isabel Crook,the recent recipie...On a late summer morning,the sky was clear and the weather fine.Kids were playing in the open,with laughter and joy in the air.It was Aug 28 when I met with Michael Crook and his mother,Isabel Crook,the recent recipient of the Friendship Medal of the People’s Republic of China,on the campus of Beijing Foreign Studies University.展开更多
The complex geological conditions in doubly complex areas tend to result in difficult surface survey operations and poor target layer imaging in the subsurface which has a great impact on seismic data quality. In this...The complex geological conditions in doubly complex areas tend to result in difficult surface survey operations and poor target layer imaging in the subsurface which has a great impact on seismic data quality. In this paper, we propose an optimal crooked line survey method for decreasing the surface survey operational difficulties and improving the sub-layer event continuity. The method concentrates on the surface shooting conditions, first, selecting the proper shot positions based on the specific surface topographic features to reduce the shot difficulties and then optimizing the receiver positioning to meet the prerequisite that the subsurface reflection points remain in a straight line. Using this method cannot only lower the shooting difficulty of rough surface condition areas but also overcome the subsurface reflection point bending problem appearing in the traditional crooked line survey method. On the other hand, we use local infill shooting rather than conventional overall infill shooting to improve sublayer event continuity and uniformity with lower survey operation cost. A model has been calculated and processed with the proposed optimal crooked line survey and local infill shooting design method workflow and the results show that this new method can work for seismic surveys in double complex areas.展开更多
文摘Due to their simple structure,crooked plates are widely processed into energy absorption structures.There are obvious differences in the final deformation of crooked plates with different materials and dynamic conditions under the impact of constant-input kinetic energy.To better understand this phenomenon,we solved the Zhang-Yu equation with Maple software,obtained the law of generalized coordinates(rotation angle)of the energy absorber changing with time,and compared the energy absorption capacity of a crooked plate energy absorber under different parameters.To better understand how the motion of the energy absorber is affected by the change of parameters,we calculated the phase diagram of the energy absorber dynamics.After many numerical simulations,we found that the four-crooked plate energy absorber should have a mass-sensitive structure.We established the finite element model of dynamic buckling of mild steel and 6061-T6 aluminum alloy,and compared it with the Calladine-English dynamic experiment and Zhang-Yu rigid viscoplastic model.The results show that:(1)the Zhang-Yu rigid viscoplastic model has more guiding significance for mild steel(strain rate-sensitive material),and has greater error for 6061-T6 aluminum alloy(strain rate-insensitive material),and the prediction error further increases with the initial angle;and(2)by modifying the equivalent plastic length A of a plastic hinge according to the finite element model,the prediction accuracy of the Zhang-Yu rigid viscoplastic model can be improved.Our research results certain guiding significance for the design and manufacture of energy-absorbing structures of crooked plates.
文摘On a late summer morning,the sky was clear and the weather fine.Kids were playing in the open,with laughter and joy in the air.It was Aug 28 when I met with Michael Crook and his mother,Isabel Crook,the recent recipient of the Friendship Medal of the People’s Republic of China,on the campus of Beijing Foreign Studies University.
基金funded by the National Basic Research program of China(973 Program)(No.2009CB219403)Applied Basic Research Project of CNPC(No:2011B-3706)School Fund of SWPU,and Earth Exploration and Information Technology of Sichuan Provincial Key Disciplines Construction Program
文摘The complex geological conditions in doubly complex areas tend to result in difficult surface survey operations and poor target layer imaging in the subsurface which has a great impact on seismic data quality. In this paper, we propose an optimal crooked line survey method for decreasing the surface survey operational difficulties and improving the sub-layer event continuity. The method concentrates on the surface shooting conditions, first, selecting the proper shot positions based on the specific surface topographic features to reduce the shot difficulties and then optimizing the receiver positioning to meet the prerequisite that the subsurface reflection points remain in a straight line. Using this method cannot only lower the shooting difficulty of rough surface condition areas but also overcome the subsurface reflection point bending problem appearing in the traditional crooked line survey method. On the other hand, we use local infill shooting rather than conventional overall infill shooting to improve sublayer event continuity and uniformity with lower survey operation cost. A model has been calculated and processed with the proposed optimal crooked line survey and local infill shooting design method workflow and the results show that this new method can work for seismic surveys in double complex areas.
