The effect of various process variables on the law of metal flow for semi-solid rolling 60Si2Mn was studied by finite element method. Semi-solid 60Si2Mn can be described as compressible rigid visco-plastic porous mate...The effect of various process variables on the law of metal flow for semi-solid rolling 60Si2Mn was studied by finite element method. Semi-solid 60Si2Mn can be described as compressible rigid visco-plastic porous material saturated with liquid. In terms of ther-mo-mechanical coupling condition, the distributions of stress, velocity and temperature were studied using software MARC. The simulation results show that the rigid visco-plastic model can accurately describe the semi-solid 60Si2Mn rolling process. The great deformation can achieve completely in view of low flow stress of semi-solid slurry.展开更多
In this study,orthogonal experiments were conducted to investigate the influence of expandable graphite(EG),dimethyl methylphosphonate(DMMP),triethanolamine(TEA),and isocyanate content on the compressive and bonding s...In this study,orthogonal experiments were conducted to investigate the influence of expandable graphite(EG),dimethyl methylphosphonate(DMMP),triethanolamine(TEA),and isocyanate content on the compressive and bonding strengths,oxygen index,and fluidity of rigid polyurethane foam(RPUF).The results revealed that EG significantly increased the oxygen index of RPUF,enlarged the diameter of foam cells,and decreased the cell-closed content in foam;thus,leading to a pressure drop in RPUF.However,excessive EG was capable of reducing the fluidity of polyurethane slurry.TEA exhibited significant influence on the compressive strength of RPUF,which dropped initially,and then increased.DMMP had a remarkable effect on the flame retardant property and compressive strength of RPUF.Compressive strength of RPUF initially displayed an increase followed by a decrease with increasing dosage of DMMP,and achieved the maximum value at DMMP dosage of 4%.DMMP could effectively reduce the diameter of RPUF cells leading to an increase in the percentage of close area in foam.DMMP displayed the flame-retardation effects mainly in the gas phase leading to a significant enhancement in the oxygen index of RPUF.Moreover,the compressive strength and bonding strength of RPUF decrease significantly with the increase of isocyanate content due to the increased blowing efficiency by the CO_2.The oxygen index and flowing length of foam increased with the increase in isocyanate dosage.展开更多
The present study develops a novel type of active joint node-bolt fasten wedge(BFW)active joints,aiming to investigate the load-bearing capacity of a BFW joint in a quantitative way and put forward precise formulas fo...The present study develops a novel type of active joint node-bolt fasten wedge(BFW)active joints,aiming to investigate the load-bearing capacity of a BFW joint in a quantitative way and put forward precise formulas for its yield load and compression rigidity.To achieve this,indoor axial loading tests were conducted on two BFW joints,accompanied by a set of numerical simulations with the finite element approach implemented in ABAQUS.Parametric research was then conducted to assess the impact of various factors on the yield load and initial compression rigidity of BFW joints,leading to the derivation of precise calculation formulas for accurate prediction of these parameters.The key findings indicate that enhancing the bolt strength from 10.9 to 12.9 significantly improves mechanical performance.Under axial compression,the final bearing force,yield load,and initial compression rigidity increase by 0.86,1.06,and 0.15 times,respectively.Numerical models accurately predict joint behavior under axial force,confirming their reliability.Parameter studies reveal that increasing web and eaves thickness,bolt strength,and diameter improves bearing capacity,while splint thickness has little effect.The fitting formulas introduced can precisely estimate yield load and rigidity,providing practical value for engineering applications.展开更多
基金the National Natural Science Foundation of China (No.59995440).
文摘The effect of various process variables on the law of metal flow for semi-solid rolling 60Si2Mn was studied by finite element method. Semi-solid 60Si2Mn can be described as compressible rigid visco-plastic porous material saturated with liquid. In terms of ther-mo-mechanical coupling condition, the distributions of stress, velocity and temperature were studied using software MARC. The simulation results show that the rigid visco-plastic model can accurately describe the semi-solid 60Si2Mn rolling process. The great deformation can achieve completely in view of low flow stress of semi-solid slurry.
基金supported by the National Natural Science Foundation of China(No.51304027)China Postdoctoral Science Foundation(2014M560567 and 2015T80730)+4 种基金Shandong Province Science and Technology Development Plan(2014GSF120012)the State Key Program of Coal Joint Funds of National Natural Science Foundation of China(Nos.51134020 and U1261205)Shandong Province Natural Science Foundation(No.ZR2011EL036)the Doctoral Scientific Research Foundation of Binzhou University(No.2013Y06)the Key Technology Projects for Preventing Major Accident of National Security State Administration of Work Safety
文摘In this study,orthogonal experiments were conducted to investigate the influence of expandable graphite(EG),dimethyl methylphosphonate(DMMP),triethanolamine(TEA),and isocyanate content on the compressive and bonding strengths,oxygen index,and fluidity of rigid polyurethane foam(RPUF).The results revealed that EG significantly increased the oxygen index of RPUF,enlarged the diameter of foam cells,and decreased the cell-closed content in foam;thus,leading to a pressure drop in RPUF.However,excessive EG was capable of reducing the fluidity of polyurethane slurry.TEA exhibited significant influence on the compressive strength of RPUF,which dropped initially,and then increased.DMMP had a remarkable effect on the flame retardant property and compressive strength of RPUF.Compressive strength of RPUF initially displayed an increase followed by a decrease with increasing dosage of DMMP,and achieved the maximum value at DMMP dosage of 4%.DMMP could effectively reduce the diameter of RPUF cells leading to an increase in the percentage of close area in foam.DMMP displayed the flame-retardation effects mainly in the gas phase leading to a significant enhancement in the oxygen index of RPUF.Moreover,the compressive strength and bonding strength of RPUF decrease significantly with the increase of isocyanate content due to the increased blowing efficiency by the CO_2.The oxygen index and flowing length of foam increased with the increase in isocyanate dosage.
基金the financial support provided by Beijing Natural Science Foundation(Grant No.8222005)the Natural Science Foundation of China(Grant No.51978018)Science and Technology Funding Scheme for the Third Construction Engineering Company Ltd.of China Construction Second Engineering Bureau(Grant No.CSCEC2b3c-2021-K-65).
文摘The present study develops a novel type of active joint node-bolt fasten wedge(BFW)active joints,aiming to investigate the load-bearing capacity of a BFW joint in a quantitative way and put forward precise formulas for its yield load and compression rigidity.To achieve this,indoor axial loading tests were conducted on two BFW joints,accompanied by a set of numerical simulations with the finite element approach implemented in ABAQUS.Parametric research was then conducted to assess the impact of various factors on the yield load and initial compression rigidity of BFW joints,leading to the derivation of precise calculation formulas for accurate prediction of these parameters.The key findings indicate that enhancing the bolt strength from 10.9 to 12.9 significantly improves mechanical performance.Under axial compression,the final bearing force,yield load,and initial compression rigidity increase by 0.86,1.06,and 0.15 times,respectively.Numerical models accurately predict joint behavior under axial force,confirming their reliability.Parameter studies reveal that increasing web and eaves thickness,bolt strength,and diameter improves bearing capacity,while splint thickness has little effect.The fitting formulas introduced can precisely estimate yield load and rigidity,providing practical value for engineering applications.
