Research On Biomimetic Design And Wearable Application Based On Multi Material Additive Manufacturing Technology

With the advent of the information age,the wearable applications serves as a control between the human and information,playing an important role in civil,art,medical and military fields.For example,the wearable safety,wearable medical device,wearable protection,wearable aesthetic applications and so on.In bionics,the excellent structures(layered,gradient,honeycomb,and flexible structure,etc.)and functions(self-protection,drag reduction,functional surface and stealth,etc.)provide us the effective inspirations and references.Besides,the combination design of multi-material and micro-structure was also demonstrated to be an effective way to enhance and/or realize the performance and/or functions.Although many biomimetic materials and structures have been developed and applied in the wearable field,the traditional design and manufacturing technologies still have disadvantages such as limited performance and uncontrollable functions in the diversified environment,which cannot meet the flexibility requirements with the applications in military,medical,civilian wearables.Additive manufacturing(AM),as one important technology of integrated rapid prototyping,provides an important method for the collaborative design of complex structures with multi-material.The research work of this thesis is mainly divided into two levels: the biomimetic research of wearable mechanical properties based on polymetallic materials,and wearable protection functions based on polymer.The former mainly researches how to improve the anti-damage mechanics and flexibility in the wear through the AM of multi-materials and structures,and the latter is based on the same method of electromagnetic protection function to meet the requirements of wearable applications.Therefore,the main research contents and contributions of this thesis are as follows:(1)For the application of anti-injury protection in wear,a method of integrated forming of biological composite layered structure based on multi-material metal paste injection 3D technology was proposed.The impact factors of metal multi-materials dense forming was discussed through the printing and degreasing experiments.And the different layered bionic structures of hexagonal,concentric,cross and spiral were designed by borrowing the microstructure characteristics with special damage resistance in the composite properties of biomaterials.The target impact damage process,impact protection ability,and damage resistance mechanism were analyzed by finite element simulation,which extended the application of biological model.(2)For the application of flexible characteristics in wear,the precise integrated forming method of flexible structure in multi-materials was proposed based on metal powder selective laser melting technology.The flexible chain distribution structure with different element shapes(three,four and hexagon)were designed by imitating the characteristics of biological natural flexible leather armor,which has the advantages of non-damage in bending and self-supporting in AM process.The causal relationships between the process parameters and the features of bending flexibility,tensile strength,friction resistance were discussed.Besides,the multi-material integrated molding test was carried out for the preparation of layered flexible structure with multi-colors,which increased tensile strength by 80.7% compared with that of single material.(3)For the application of magnetic protection for information interference in wearable devices,a multi-material forming method based on digital stereo lithography technology was proposed.The influential relationships between slurry solidification and the printing parameters of photoinitiator concentration,exposure time were researched for the successfully preparation of the black slurry system with high solid content.Besides,the characteristics of butterfly organisms were imitated,which was the one of most effective antireflective structures in nature,for the material/structure optimized experiment.And the absorbing reflection loss and effective bandwidth of obtained sample were increased by 32.35% and 90.26%,respectively.(4)For the civil and/or military magnetic protection in wear,a novel flexible honeycomb structure with directional arranged carbon fiber was proposed by selective laser sintering technology.By combining the biological flexibility and invisibility,the polymer-based flexible honeycomb structure with different cell characteristics(full solid,half hole,full hole and gradient hole structures)were designed,which realized the flexible compressive self-recovery performance,breaking the limitation of low mechanical properties of traditional thesis/textile-based flexible absorber.In addition,the absorbing experiment in 0-150° conformal bending angles of the flexible structure were performed,realizing the the high absorption performance(minimum reflection loss of-47 d B,broadband absorption of 13.2 GHz)at high bending angle of 150°,which greatly widens the universality of magnetic protection in wearable applications.In conclusion,this thesis puts forward a variety of bionic strategies and design methods to improve mechanical and/or functional properties for diverse applications in wearables via co-optimization of preparation process and material/structure design in additive manufacturing technology.And the novel method/insight may has useful potential applications in the high-tech composites preparation,new rapid prototyping design mode and future wearables development.