An investigation is conducted on the static ultimate limit state assessment of ship hull plates with elastically restrained edges subjected to axial compression.Both material and geometric non-linearities were conside...An investigation is conducted on the static ultimate limit state assessment of ship hull plates with elastically restrained edges subjected to axial compression.Both material and geometric non-linearities were considered in finite element(FE)analysis.The initial geometric imperfection of the plate was considered,while the residual stress introduced by welding was not considered.The ultimate strength of simply supported ship hull plates compared well with the existing empirical formula to validate the correctness of the applied boundary conditions,initial imperfection and mesh size.The extensive FE calculations on the ultimate strength of ship hull plates with elastically restrained edges are presented.Then a new simple empirical formula for plate ultimate strength is developed,which includes the effect of the rotational restraint stiffness,rotational restraint stiffness,and aspect ratios.By applying the new formula and FE method to ship hull plates in real ships,a good coincidence of the results between these two methods is obtained,which indicates that the new formula can accurately predict the ultimate strength of ship hull plates with elastically restrained edges.展开更多
In order to describe the thermal–mechanical behavior of the ship plate steel continuous casting slab during solidification end heavy reduction(HR)process accurately,its constitutive behavior was investigated by a sin...In order to describe the thermal–mechanical behavior of the ship plate steel continuous casting slab during solidification end heavy reduction(HR)process accurately,its constitutive behavior was investigated by a single-pass thermal compression experiment.According to the deformation features of wide thick continuous casting slab with HR,the simulation temperature ranged from 1173 to 1573 K with strain rates of 0.0001,0.001,0.01 and 0.1 s^(-1).Three different constitutive models,the modified Johnson–Cook(JC)model,the modified Zerilli–Armstrong(ZA)model and the Arrhenius model,were established according to the obtained true stress–strain curves.The average relative error of the modified JC model,the modified ZA model and the Arrhenius model are 10.82%,9.96%and 6.21%,respectively.Considering the obvious softening effect of the flow curve at a low strain rate,the secondary softening factor under the interaction of low strain rate and the temperature was introduced in the original Arrhenius model.Compared to the Arrhenius model,the modified Arrhenius model error decreased from 6.21%to 4.73%.展开更多
The problem of ship hull plate processing surface fairing with constraints based on B-spline is solved in this paper. The algorithm for B-spline curve fairing with constraints is one of the most common methods in plan...The problem of ship hull plate processing surface fairing with constraints based on B-spline is solved in this paper. The algorithm for B-spline curve fairing with constraints is one of the most common methods in plane curve fairing. The algorithm can be applied to global and local curve fairing. It can constrain the perturbation range of the control points and the shape variation of the curve, and get a better fairing result in plane curves. In this paper, a new fairing algorithm with constraints for curves and surfaces in space is presented. Then this method is applied to the experiments of ship hull plate processing surface. Finally numerical results are obtained to show the efficiency of this method.展开更多
Ships and other mobile pollution sources emitted massive ultrafine and low-resistivity particles containing black carbon(BC),which were harmful to human health and were difficult to capture by conventional electrostat...Ships and other mobile pollution sources emitted massive ultrafine and low-resistivity particles containing black carbon(BC),which were harmful to human health and were difficult to capture by conventional electrostatic precipitators(ESPs).In this study,nanoscale carbon black was adopted as simulated particles(SP)with similar physicochemical properties for black carbon emitted from ships(SP-BC)to investigate the feasibility of using an ESP with square-grooved collecting plates for the removal of SP-BC at low backpressures.The increased applied voltage significantly improved the total collection of SP-BC whereas may also promote the conversion of relatively larger particle size SP-BC into nano-size below 20nm.The outlet number concentration of SP-BC under 27 kV at 130℃was three times that of the inlet.While the reduction of the flow rate could strengthen the capture of SP-BC below20 nm,and under the combined action of low flow rate and maximum applied voltage,the collection efficiency of 20-100 nm SP-BC could exceed 90%.In addition,the escape and capture characteristics of SP-BC under long-term rapping were revealed.The square-grooved collecting plate could effectively restrain the re-entrainment of collected SP-BC generated by rapping,and the nanoscale SP-BC was trapped in the grooves after rapping.The results could provide insights into the profound removal of massive nanoscale black carbon emissions from mobile sources.展开更多
文摘An investigation is conducted on the static ultimate limit state assessment of ship hull plates with elastically restrained edges subjected to axial compression.Both material and geometric non-linearities were considered in finite element(FE)analysis.The initial geometric imperfection of the plate was considered,while the residual stress introduced by welding was not considered.The ultimate strength of simply supported ship hull plates compared well with the existing empirical formula to validate the correctness of the applied boundary conditions,initial imperfection and mesh size.The extensive FE calculations on the ultimate strength of ship hull plates with elastically restrained edges are presented.Then a new simple empirical formula for plate ultimate strength is developed,which includes the effect of the rotational restraint stiffness,rotational restraint stiffness,and aspect ratios.By applying the new formula and FE method to ship hull plates in real ships,a good coincidence of the results between these two methods is obtained,which indicates that the new formula can accurately predict the ultimate strength of ship hull plates with elastically restrained edges.
基金The present work was financially supported by the National Natural Science Foundation of China(Nos.51974078 and U20A20272)Science and Technology Planning Project of Liaoning Province(Nos.2022JH2/101300002 and 2022JH25/10200003)the Fundamental Research Funds for the Central Universities of China(No.N2125018).
文摘In order to describe the thermal–mechanical behavior of the ship plate steel continuous casting slab during solidification end heavy reduction(HR)process accurately,its constitutive behavior was investigated by a single-pass thermal compression experiment.According to the deformation features of wide thick continuous casting slab with HR,the simulation temperature ranged from 1173 to 1573 K with strain rates of 0.0001,0.001,0.01 and 0.1 s^(-1).Three different constitutive models,the modified Johnson–Cook(JC)model,the modified Zerilli–Armstrong(ZA)model and the Arrhenius model,were established according to the obtained true stress–strain curves.The average relative error of the modified JC model,the modified ZA model and the Arrhenius model are 10.82%,9.96%and 6.21%,respectively.Considering the obvious softening effect of the flow curve at a low strain rate,the secondary softening factor under the interaction of low strain rate and the temperature was introduced in the original Arrhenius model.Compared to the Arrhenius model,the modified Arrhenius model error decreased from 6.21%to 4.73%.
基金Supported by Hi -tech Research and Development Program of China(No. 2001AA421200).
文摘The problem of ship hull plate processing surface fairing with constraints based on B-spline is solved in this paper. The algorithm for B-spline curve fairing with constraints is one of the most common methods in plane curve fairing. The algorithm can be applied to global and local curve fairing. It can constrain the perturbation range of the control points and the shape variation of the curve, and get a better fairing result in plane curves. In this paper, a new fairing algorithm with constraints for curves and surfaces in space is presented. Then this method is applied to the experiments of ship hull plate processing surface. Finally numerical results are obtained to show the efficiency of this method.
文摘通过焊接热模拟研究了在超大线能量下焊接时Al元素、Mg元素和Ti元素含量对EH36高强船板钢热影响区粗晶区组织、性能的影响规律,采用Thermo-Calc热力学计算与SEM,EDS测试相结合的方法揭示了Al元素、Mg元素和Ti元素含量与母材中氧化物类型、尺寸、数量及粗晶区相变的关系.结果表明,Al_(2)O_(3)无法诱导针状铁素体相变,当Al元素质量分数低于0.005%时,钢中可形成Mg元素、Ti元素或其复合氧化物,可促进粗晶区针状铁素体相变.Mg元素和Ti元素联合添加时,当Mg元素质量分数由0.0042%降低为0.0013%,氧化物类型由MgO转变为Mg_(2)TiO_(4),经统计20个视场内的氧化物数量由408个提高到503个,平均直径由1.37μm减小到1.10μm,显著提高了非均匀形核的比表面积,抑制了晶界铁素体的形成,使t8/5=300 s时粗晶区热模拟试样-20℃冲击吸收能量由43 J提升到127 J.
基金supported by the National Natural Science Foundation (No.52076191)Key Research&Development Plan of Shandong Province (No.2020CXGC011401)。
文摘Ships and other mobile pollution sources emitted massive ultrafine and low-resistivity particles containing black carbon(BC),which were harmful to human health and were difficult to capture by conventional electrostatic precipitators(ESPs).In this study,nanoscale carbon black was adopted as simulated particles(SP)with similar physicochemical properties for black carbon emitted from ships(SP-BC)to investigate the feasibility of using an ESP with square-grooved collecting plates for the removal of SP-BC at low backpressures.The increased applied voltage significantly improved the total collection of SP-BC whereas may also promote the conversion of relatively larger particle size SP-BC into nano-size below 20nm.The outlet number concentration of SP-BC under 27 kV at 130℃was three times that of the inlet.While the reduction of the flow rate could strengthen the capture of SP-BC below20 nm,and under the combined action of low flow rate and maximum applied voltage,the collection efficiency of 20-100 nm SP-BC could exceed 90%.In addition,the escape and capture characteristics of SP-BC under long-term rapping were revealed.The square-grooved collecting plate could effectively restrain the re-entrainment of collected SP-BC generated by rapping,and the nanoscale SP-BC was trapped in the grooves after rapping.The results could provide insights into the profound removal of massive nanoscale black carbon emissions from mobile sources.
