【作者】 张斌；

【导师】 赵晶；

【作者基本信息】 沈阳工业大学 ， 机械工程， 2023， 硕士

【摘要】 点阵结构是一种具有良好的力学性能和结构完整性的支撑结构,具有轻质和吸能的应用特性,其内部空间较大,可以在不破坏原始材料性能的前提下,将结构设计成拥有更高的刚度和承载能力。点阵结构通常由多个胞元组成,通过将每个胞元内部的局部结构连接成一个整体来获得更好的力学性能。因此,本文重点分析了晶胞的有效压缩力学行为,建立了能够评估其性能的有限元模型,研究了多层点阵结构在压缩载荷作用下的变形失效机制、压缩和吸能特性。本文研究了两种多杆构型点阵结构(Kagome结构和Bcc结构)的压缩和吸能特性。通过改变胞元的结构参数,并在每层晶胞之间加设2 mm的加固板,共建立了24个点阵结构模型,将其设计相关参数,如支撑杆倾角、支撑杆直径等与各点阵结构的胞元相对密度联系起来。对以上模型进行准静态压缩有限元模拟仿真,并采用聚酰胺12为结构材料,用3D打印方式制作出部分模型并进行试验,验证了有限元仿真的准确性和可靠性。研究得出在胞元高度一定时,支撑杆倾角和截面直径的增大,均会提高多层点阵结构的抗压缩性能,且倾角大小对结构整体等效平压强度的影响要大于杆直径;加固型Kagome多层点阵结构胞元相对密度从16.6%提高到60.7%,整体等效平压模量提高了5.54倍,最大等效平压强度提高了4.52倍;加固型Bcc多层点阵结构胞元相对密度从27.8%增加到97.7%,模型整体等效平压模量提高了4.78倍,最大平压强度提高了4.33倍。整体相对比强度和比刚度与胞元支撑杆倾角和截面直径有关,且均成正相关;当支撑杆倾角较小时,等效平压模量和最大等效平压强度受支撑杆直径的影响也较小,当支撑杆角度变大时,支撑杆直径对等效平压模量和最大等效平压强度的影响也随之增大。此外,本文对Kagome和Bcc加固点阵结构进行了轻质化、交叉组合以及变胞元密度设计。加固板轻质化设计降低了点阵结构整体质量,且压缩仿真与实验结果表明,轻质化设计小幅度提升了点阵结构在压缩坍塌失效之前的等效平压模量、整体比强度、比刚度和单位质量吸收能量等性能;交叉组合模型继承了Kagome和Bcc点阵结构的压缩和吸能特性,不同胞元组合在界面处得到加强,B层增多会提升组合结构的抗压缩性能,k层增多会降低组合结构的整体质量。在结构达到致密化之前的压缩过程中,组合结构的吸能特性相对于原Kagome结构均有不同程度的提高,其中B-k-B点阵结构的单位质量吸能能力最强,且优于原Bcc结构;变胞元相对密度点阵结构的整体相对密度接近中间胞层的整体相对密度,在应变为0.2到致密化之间时,其单位质量吸能能力要优于同参数均匀密度点阵的单位质量吸能能力,因此变胞元相对密度结构的抗压缩性能和优良的吸能能力可以在现实工程的不同物理场中得到更充分的利用。更多还原

【Abstract】 Lattice structure is a support structure with good mechanical properties and structural integrity,with lightweight and energy-absorbing application properties and a large internal space that allows the structure to be designed with higher stiffness and load-bearing capacity without destroying the original material properties.Lattice structures are usually composed of multiple cells,and better mechanical properties are obtained by connecting the local structures inside each cell into a whole.Therefore,this thesis focuses on the effective compressive mechanical behavior of the cells,establishes a finite element model capable of evaluating their performance,and investigates the deformation failure mechanism,compression and energy absorption characteristics of multilayered dot matrix structures under compressive loading.In this thesis,the compressive and energy-absorbing properties of two multi-rod configuration lattice structure(Kagome structure and Bcc structure)are investigated.By changing the structural parameters of the kagome and adding 2 mm reinforcement plates between each layer of kagome,a total of 24 kagome structures were modeled,and their design-related parameters,such as support rod inclination and support rod diameter,were related to the relative density of kagome elements of each kagome structure.The above models were simulated by quasi-static compression finite element simulation,and some models were fabricated and tested by 3D printing using polyamide 12 as the structural material to verify the accuracy and reliability of the finite element simulation.It is concluded that at a certain cell height,the increase of the inclination angle and cross-sectional diameter of the support rod will improve the compression resistance of the multilayer dot matrix structure,and the influence of the inclination angle on the overall equivalent flat compressive strength of the structure is greater than that of the rod diameter;the relative density of the reinforced Kagome multilayer dot matrix structure cell is increased from 16.6% to 60.7%,the overall equivalent flat compressive modulus is increased by 5.54 times,and the maximum equivalent flat compressive strength is increased by 4.52 times.The relative density of reinforced Bcc multilayer dot matrix structure cells increased from 27.8% to 97.7%,and the overall equivalent compressive modulus increased by 4.78 times and the maximum equivalent compressive strength increased by 4.33 times.The overall relative specific strength and specific stiffness are related to the inclination angle and cross-sectional diameter of the cell element,and both are positively correlated;when the inclination angle of the support bar is small,the equivalent flat compressive modulus and the maximum equivalent flat compressive strength are less influenced by the diameter of the support bar,and as the angle of the support bar becomes larger,the effect of the support bar diameter on the equivalent flat compression modulus and the maximum equivalent flat compression strength also increases.In addition,in this thesis,the Kagome and Bcc reinforcement lattice structures are designed with lightweighting,cross-combination,and variable cell density.The lightweight design of the reinforcement plate reduces the overall mass of the lattice structure,and the compression simulation and experimental results show that the lightweight design slightly improves the equivalent flat compressive modulus,overall specific strength,specific stiffness,and energy absorption per unit mass of the lattice structure before compressive collapse failure;the cross-combination model inherits the compression and energy absorption characteristics of the Kagome and Bcc lattice structure,and the combination of different cell elements is strengthened at the interface is strengthened,the increase of B-layer will enhance the compression resistance of the combined structure,and the increase of k-layer will reduce the overall mass of the combined structure.During the compression process before the structure reaches densification,the energy absorption properties of the combined structure are all improved to different degrees relative to the original Kagome structure,in which the B-k-B lattice structure has the strongest energy absorption capacity per unit mass and is better than the original Bcc structure;the overall relative density of the lattice structure with variable cell element relative density is close to the overall relative density of the intermediate cell layer,and between the strain of 0.2 and densification,its the energy absorption capacity per unit mass is better than that of the uniform density dot matrix with the same parameters,so the anti-compression performance and excellent energy absorption capacity of the variable cell element relative density structure can be more fully utilized in different physical field of real engineering.更多还原