4D printing technology represents a new generation of additive manufacturing methods that enable three-dimensional(3D)printed structures to change their shapes or properties over time(the fourth dimension)in response ...4D printing technology represents a new generation of additive manufacturing methods that enable three-dimensional(3D)printed structures to change their shapes or properties over time(the fourth dimension)in response to external stimuli such as temperature,magnetic fields,and light.Among the most popular types of 4D-printed structures are thermally responsive bilayer actuators using shape memory polymers,valued for their programmability and convenience.However,achieving precise deformations without collisions is hindered by the nonlinear and time-varying morphing process of these bilayer actuators,which is crucial for creating dynamically controllable shapes on demand in 4D printing.This study presents a rapid and effective design and optimization strategy for 4D printed self-folding structures that can be sequentially and accurately folded.Theoretical analyses were conducted to guide the design of the folding processes.The response surface method(RSM)was used to investigate key parameters affecting the design of 4D-printed bilayer actuators.The results indicate that increasing printing speed enhances internal strain,whereas higher printing temperatures,layer heights,or actuator heights have the opposite effect.The RSM model achieved an R-squared value of 0.983,accurately capturing the coupling effects of these variables on the output responses,thereby enabling controlled timescales for bending motion and sequential folding without collisions.These findings can be applied to enhance the design and acceleration of 4D-printed self-folding structures,ensuring controlled speed of shape transformation.To validate this concept,a self-folding hand-shaped structure with five fingers was designed and fabricated,demonstrating how design and printing parameters can precisely control the timescale of shape changes for each finger based on the design specifications.展开更多
基金supported by National Natural Science Foundation of China(Grant No.52375272)Zhejiang Provincial Natural Science Foundation of China(Grant No.LR22E050006)China Postdoctoral Science Foundation(Grant Nos.2024M751644,2024M754069).
文摘4D printing technology represents a new generation of additive manufacturing methods that enable three-dimensional(3D)printed structures to change their shapes or properties over time(the fourth dimension)in response to external stimuli such as temperature,magnetic fields,and light.Among the most popular types of 4D-printed structures are thermally responsive bilayer actuators using shape memory polymers,valued for their programmability and convenience.However,achieving precise deformations without collisions is hindered by the nonlinear and time-varying morphing process of these bilayer actuators,which is crucial for creating dynamically controllable shapes on demand in 4D printing.This study presents a rapid and effective design and optimization strategy for 4D printed self-folding structures that can be sequentially and accurately folded.Theoretical analyses were conducted to guide the design of the folding processes.The response surface method(RSM)was used to investigate key parameters affecting the design of 4D-printed bilayer actuators.The results indicate that increasing printing speed enhances internal strain,whereas higher printing temperatures,layer heights,or actuator heights have the opposite effect.The RSM model achieved an R-squared value of 0.983,accurately capturing the coupling effects of these variables on the output responses,thereby enabling controlled timescales for bending motion and sequential folding without collisions.These findings can be applied to enhance the design and acceleration of 4D-printed self-folding structures,ensuring controlled speed of shape transformation.To validate this concept,a self-folding hand-shaped structure with five fingers was designed and fabricated,demonstrating how design and printing parameters can precisely control the timescale of shape changes for each finger based on the design specifications.
