【作者】 孙健；

【导师】 邓大祥；

【作者基本信息】 哈尔滨工业大学 ， 机械工程（专业学位）， 2023， 硕士

【摘要】 4D打印是目前十分热门的研究领域,它在3D打印的基础上添加了时间维度,其可以通过喷嘴的剪切力以及与基板之间的拉力沉积墨水,层层堆叠得到三维结构,是软体机器人驱动结构的理想制备方式。液晶弹性体是一种能够通过外界刺激进行响应,发生相变来实现可逆大变形的高分子聚合物材料,在软体机器人领域应用前景十分广阔。本文利用可墨水直写4D打印的光热响应的液晶弹性体墨水,分析墨水直写4D打印工艺参数对样品形貌和驱动性能影响,通过光/热刺激对打印样品驱动能力进行分析测试。主要内容包括以下几部分:基于液晶弹性体材料填充光热填料多壁碳纳米管,采用物理共混方法制备可用于墨水直写4D打印的墨水。对前驱体墨水进行流变、热学性能表征,流变结果表明打印样品70℃以下存在剪切变稀特性,适合于墨水直写4D打印;热学性能测试两种墨水的相变温度玻璃化温度为-18℃左右,向列相-各向同性相转变温度为90℃左右。研究墨水直写4D打印过程中的工艺参数包括打印温度、打印压力、打印速度对墨水成型和交联样品驱动性能影响。单因素实验结果表明,打印样品长宽随打印温度、打印压力升高而升高、随打印速度升高而下降。正交实验结果表明打印温度对样品变形率影响最大,其次是速度和压力。同时针对样品自身形状的设计分析对驱动性能的影响发现,改变样品打印长宽比、样品路径和层厚对样品变形率影响较小。表征优选打印参数下的打印样品的光、力学性能。表征结果得到,样品含碳量增加导致光吸收率增加,且打印取向通过偏光显微镜观察良好,WAXS测试得到结果计算得到取向度为0.48。力学性能实验结果表明,样品掺碳量改变材料力学性能并且打印路径对应力应变影响较大。搭建光热响应测试平台,通过该平台进行打印样品的驱动测试,阐明打印路径对打印变形的影响,设计长条、金字塔和卷筒三种不同打印路径下的不同变形趋势样品并对其在热/光刺激下的运动进行记录,实验结果表明,光/热刺激都能使其发生变形并实现恢复。针对液晶弹性体驱动变形原理,设计了不同光热响应结构的样品且证明不同结构下有不同的运动趋势;并且基于花瓣开合设计仿软体机器人多关节光热响应驱动结构;对所设计结构进行验证,通过照射光热响应结构不同位置,实现不同角度的弯曲;通过滚珠丝杠调整透镜位置,实现编程规定动作。更多还原

【Abstract】 4D printing is a trendy research field at present.It adds a time dimension based on 3D printing.It can deposit ink through the shear force of the nozzle and the tension between the substrate and the substrate and stack layers to obtain a three-dimensional structure.It is an ideal preparation method for the driving structure of soft robots.Liquid crystal elastomer is a polymer material that can respond to external stimuli and undergo a phase transition to achieve large reversible deformation.It has broad application prospects in the field of soft robots.In this paper,the photothermal response liquid crystal elastomer ink of direct ink writing 4D printing is used to analyze the influence of direct ink writing 4D printing process parameters on sample morphology and driving performance.The driving ability of the printed sample is analyzed and tested by light or thermal stimulation.The main contents include the following parts :Based on the liquid crystal elastomer material filled with photothermal filler multi-walled carbon nanotubes,the ink for direct ink writing 4D printing was prepared by the physical blending method.The rheological and thermal properties of the precursor ink were characterized.The rheological results show that the printed sample has shear thinning characteristics below 70 °C,which is suitable for direct ink4 D printing.Thermal performance test The glass transition temperature of the two inks is about-18 °C,and the nematic-isotropic phase transition temperature is about90 °C.The effects of process parameters such as printing temperature,printing pressure,and printing speed on the ink forming and cross-linked sample driving performance during direct ink writing 4D printing were studied.The results of the single-factor experiment showed that the length and width of printed samples increased with the increase in printing temperature and printing pressure and decreased with the increase in printing speed.Orthogonal experimental results show that the printing temperature significantly influences the sample deformation rate,followed by speed and pressure.At the same time,the influence of the design and analysis of the shape of the sample on the driving performance is found that changing the aspect ratio of the sample printing,the sample path and the layer thickness have little effect on the sample deformation rate.To characterize the optical and mechanical properties of the printed sample under the preferred printing parameters.The characterization results show that the increase in the carbon content of the sample leads to an increase in light absorption rate,and a polarizing microscope well observes the printing orientation.The orientation degree is 0.48,calculated by the WAXS test.The experimental results of mechanical properties show that the sample’s carbon content changes the material’s mechanical properties,and the printing path significantly influences the stress and strain.The photothermal response test platform is built,and the driving test of the printed sample is carried out through the platform to clarify the influence of the printing path on the printing deformation.The samples with different deformation trends under three different printing paths of a long strip,pyramid and reel are designed,and their motion under thermal or light stimulation is recorded.The experimental results show that light and thermal stimulation can deform and recover.According to the driving deformation principle of liquid crystal elastomer,samples with different photothermal response structures were designed and proved to have different motion trends under different structures.The soft robot’s multi-joint photothermal response driving structure is designed based on petal opening and closing.The designed structure is verified to realize bending at different angles by irradiating different positions of the photothermal response structure.The ball screw adjusts the lens position to realize the programmed action.更多还原