Due to the unique deformation characteristics of auxetic materials(Poisson’s ratioμ<0),they have better shock resistance and energy absorption properties than traditional materials.Inspired by the concept of vari...Due to the unique deformation characteristics of auxetic materials(Poisson’s ratioμ<0),they have better shock resistance and energy absorption properties than traditional materials.Inspired by the concept of variable crosssection design,a new auxetic re-entrant honeycomb structure is designed in this study.The detailed design method of re-entrant honeycomb with variable cross-section(VCRH)is provided,and five VCRH structures with the same relative density and different cross-section change rates are proposed.The in-plane impact resistance and energy absorption abilities of VCRH under constant velocity are investigated by ABAQUS/EXPLICIT.The results show that the introduction of variable cross-section design can effectively improve the impact resistance and energy absorption abilities of auxetic re-entrant honeycombs.The VCRH structure has better Young’s modulus,plateau stress,and specific energy absorption(SEA)than traditional re-entrant honeycomb(RH).The influence of microstructure parameters(such as cross-section change rateα)on the dynamic impact performance of VCRH is also studied.Results show that,with the increase in impact velocity andα,the plateau stress and SEA of VCRH increase.A positive correlation is also found between the energy absorption efficiency,impact load uniformity andαunder both medium and high impact speeds.These results can provide a reference for designing improved auxetic re-entrant honeycomb structures.展开更多
Given the significant potential of multi-directional functionally graded materials(MFGMs)for customizable performance,it is crucial to develop versatile material models to enhance design optimization in engineering ap...Given the significant potential of multi-directional functionally graded materials(MFGMs)for customizable performance,it is crucial to develop versatile material models to enhance design optimization in engineering applications.This paper introduces a material model for an MFGM plate described by trigonometric functions,equipped with four parameters to control diverse material distributions effectively.The bending and vibration analysis of MFGM rectangular and cutout plates is carried out utilizing isogeometric analysis,which is based on a novel third-order shear deformation theory(TSDT)to account for transverse shear deformation.The present TSDT,founded on rigorous kinematics of displacements,is demonstrated to surpass other preceding theories.It is derived from an elasticity formulation,rather than relying on the hypothesis of displacements.The effectiveness of the proposed method is verified by comparing its numerical results with those of other methods reported in the relevant literature.Numerical results indicate that the structure,boundary conditions,and gradient parameters of the MFGM plate significantly influence its deflection,stress,and vibration frequency.As the periodic parameter exceeds four,the model complexity increases,causing result fluctuations.Additionally,MFGM cutout plates,when clamped on all sides,display almost identical first four vibration frequencies.展开更多
Based on the traditional re-entrant honeycomb,a novel re-entrant octagon honeycomb(ROH)is proposed.The deformation mode of the honeycomb under quasi-static compression is analyzed by numerical simulation,and the resul...Based on the traditional re-entrant honeycomb,a novel re-entrant octagon honeycomb(ROH)is proposed.The deformation mode of the honeycomb under quasi-static compression is analyzed by numerical simulation,and the results are in good agreement with the experimental ones.The deformation modes,mechanical properties,and energy absorption characteristics of ROH along the impact and perpendicular directions gradient design are investigated under different velocities.The results indicated that the deformation mode of ROH is affected by gradient design along the direction of impact and impact speed.In addition,gradient design along the direction of impact can increase the initial peak stress of ROH and accelerate its densification phase.Gradient design perpendicular to the impact direction can enhance the energy absorption performance of ROH,especially for ROH,with wall thickness increasing from the inside outwards.Compared to ROH with uniform wall thickness at the same relative density,ROH with a gradient design can increase the plateau stress by over half.With the elevation of impact velocity,the plateau stress and specific energy absorption exhibit an upward trend,aligning with the dynamic performance pattern observed in conventional honeycombs.The results can be used as a reference for the design and application of honeycomb and provide a new idea for developing more efficient and reliable energy-absorbing materials.展开更多
This paper proposes a novel method for the continuum topology optimization of transient vibration problem with maximum dynamic response constraint.An aggregated index in the form of an integral function is presented t...This paper proposes a novel method for the continuum topology optimization of transient vibration problem with maximum dynamic response constraint.An aggregated index in the form of an integral function is presented to cope with the maximum response constraint in the time domain.The density filter solid isotropic material with penalization method combined with threshold projection is developed.The sensitivities of the proposed index with respect to design variables are conducted.To reduce computational cost,the second-order Amoldi reduction(SOAR)scheme is employed in transient analysis.Influences of aggregate parameter,duration of loading period,interval time,and number of basis vectors in the SOAR scheme on the final designs are discussed through typical examples while unambiguous configuration can be achieved.Through comparison with the corresponding static response from the final designs,the optimized results clearly demonstrate that the transient effects cannot be ignored in structural topology optimization.展开更多
基金This research is supported by the National Natural Science Foundation of China(No.11902232).
文摘Due to the unique deformation characteristics of auxetic materials(Poisson’s ratioμ<0),they have better shock resistance and energy absorption properties than traditional materials.Inspired by the concept of variable crosssection design,a new auxetic re-entrant honeycomb structure is designed in this study.The detailed design method of re-entrant honeycomb with variable cross-section(VCRH)is provided,and five VCRH structures with the same relative density and different cross-section change rates are proposed.The in-plane impact resistance and energy absorption abilities of VCRH under constant velocity are investigated by ABAQUS/EXPLICIT.The results show that the introduction of variable cross-section design can effectively improve the impact resistance and energy absorption abilities of auxetic re-entrant honeycombs.The VCRH structure has better Young’s modulus,plateau stress,and specific energy absorption(SEA)than traditional re-entrant honeycomb(RH).The influence of microstructure parameters(such as cross-section change rateα)on the dynamic impact performance of VCRH is also studied.Results show that,with the increase in impact velocity andα,the plateau stress and SEA of VCRH increase.A positive correlation is also found between the energy absorption efficiency,impact load uniformity andαunder both medium and high impact speeds.These results can provide a reference for designing improved auxetic re-entrant honeycomb structures.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research(2021B0301030001)the National Key Research and Development Program of China(2021YFA0716304)+3 种基金the project supported by the Space Utilization System of China Manned Space Engineering(KJZ-YY-WCL03)the National Key Laboratory Foundation of Science and Technology on Materials under Shock and Impact(6142902210109)Independent Innovation Projects of the Hubei Longzhong Laboratory(2022ZZ-32)the National Natural Science Foundation of China(Nos.11902232,51972246,and 51521001).
文摘Given the significant potential of multi-directional functionally graded materials(MFGMs)for customizable performance,it is crucial to develop versatile material models to enhance design optimization in engineering applications.This paper introduces a material model for an MFGM plate described by trigonometric functions,equipped with four parameters to control diverse material distributions effectively.The bending and vibration analysis of MFGM rectangular and cutout plates is carried out utilizing isogeometric analysis,which is based on a novel third-order shear deformation theory(TSDT)to account for transverse shear deformation.The present TSDT,founded on rigorous kinematics of displacements,is demonstrated to surpass other preceding theories.It is derived from an elasticity formulation,rather than relying on the hypothesis of displacements.The effectiveness of the proposed method is verified by comparing its numerical results with those of other methods reported in the relevant literature.Numerical results indicate that the structure,boundary conditions,and gradient parameters of the MFGM plate significantly influence its deflection,stress,and vibration frequency.As the periodic parameter exceeds four,the model complexity increases,causing result fluctuations.Additionally,MFGM cutout plates,when clamped on all sides,display almost identical first four vibration frequencies.
基金This work is supported by the National Natural Science Foundation of China(No.11902232).
文摘Based on the traditional re-entrant honeycomb,a novel re-entrant octagon honeycomb(ROH)is proposed.The deformation mode of the honeycomb under quasi-static compression is analyzed by numerical simulation,and the results are in good agreement with the experimental ones.The deformation modes,mechanical properties,and energy absorption characteristics of ROH along the impact and perpendicular directions gradient design are investigated under different velocities.The results indicated that the deformation mode of ROH is affected by gradient design along the direction of impact and impact speed.In addition,gradient design along the direction of impact can increase the initial peak stress of ROH and accelerate its densification phase.Gradient design perpendicular to the impact direction can enhance the energy absorption performance of ROH,especially for ROH,with wall thickness increasing from the inside outwards.Compared to ROH with uniform wall thickness at the same relative density,ROH with a gradient design can increase the plateau stress by over half.With the elevation of impact velocity,the plateau stress and specific energy absorption exhibit an upward trend,aligning with the dynamic performance pattern observed in conventional honeycombs.The results can be used as a reference for the design and application of honeycomb and provide a new idea for developing more efficient and reliable energy-absorbing materials.
基金The authors acknowledge the financial support from the National Natural Science Foundation of China(Grant No.11902232).
文摘This paper proposes a novel method for the continuum topology optimization of transient vibration problem with maximum dynamic response constraint.An aggregated index in the form of an integral function is presented to cope with the maximum response constraint in the time domain.The density filter solid isotropic material with penalization method combined with threshold projection is developed.The sensitivities of the proposed index with respect to design variables are conducted.To reduce computational cost,the second-order Amoldi reduction(SOAR)scheme is employed in transient analysis.Influences of aggregate parameter,duration of loading period,interval time,and number of basis vectors in the SOAR scheme on the final designs are discussed through typical examples while unambiguous configuration can be achieved.Through comparison with the corresponding static response from the final designs,the optimized results clearly demonstrate that the transient effects cannot be ignored in structural topology optimization.
