三维打印贝壳仿生结构的力学性能
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摘要
三维打印是当今最热门的快速成型方法.随着三维打印技术的发展,人们可以将灵感方便快捷地变成现实.受天然贝壳珍珠层高强度高韧性的启发,利用三维打印技术制备仿生复合材料,结合拉伸实验及有限元方法研究微结构对复合材料断裂模式和断裂韧性的影响.本文探索了利用立体光固化成型三维打印技术制备并研究仿生复合材料的科研模式,在实验室条件下实现了电脑设计到人工合成的快速衔接.
Additive manufacturing, or 3D printing, is a rapid prototyping method to fabricate 3D objects by depositing various materials layer by layer. Despite its industrial origin and significant commercial impact, 3D printing technique has found its great potential applications in engineering and scientific research. Here, we demonstrate its application in remodeling nacre-inspired bricked structure. Nacres have extraordinary mechanical properties, such as high fracture toughness and high strength-weight ratio, rooted from its brick-and-mortar structure, with Calcium carbonate platelets as hard bricks alternating with proteins layer as soft mortar. Although it is well proposed that the platelets and mortar serve jointly via shear-lag mechanism, experimental studies on the mechanical effects of brick geometry and stiffness ratio between brick and mortar have been limited. With the help of 3D printing technology, we are now able to fabricate nacre-inspired structures with two types of UVcurable polymers, where stiff plastics as brick and soft rubber as mortar. The geometry of brick and mortar can be tuned in much wider range inaccessible to natural nacre. This allow us a thorough exploration in the parameter space, leading to an understanding of the naturally optimized values found in nacre samples. In the study, 5 samples with nacre-inspired brick-and-mortar composited structures are prepared by Object Connex350(Stratasys, Inc.) 3D printer. The mortar thickness is taken as 0.21 mm limited by the precision of the printer, and the length-to-width ratio of the brick ranges from 3 to 15. These samples are subjected to tensile force until fracture and the whole process are recorded with time lapse camera. We see three distinct regimes of climbing, horizontal, and declining, which can be closely related to elastic deformation, end-rubber fracture, and horizontal-rubber fracture. For different length-to-width ratio, three different fracture modes are observed. When the ratio is small, zigzag tearing path appears across the width, leading to largest yielding strain and smallest yielding strength. When the ratio is intermediate, vertically linear fracture path jointed by inclined tearing arise, corresponding to longest flow horizontal plastic regimes. When the ratio is large, only vertically linear fracture path can be seen, corresponding to longest horizontal plastic regimes, resulting in largest yielding strength and smallest fracture strain. A scaling theory is developed to elucidate mechanism of the three regimes. As complementary to these experimental results, finite element simulation are carried out to explore the stress distribution associated with different parameters of the composited structures. The force ratio transferred by the end and horizontal rubber is seen to saturate exponentially to constant value as the brick-to-rubber stiffness ratio increases. We also find that stress singularity near the end rubber, where the initial crack nucleation appears in experiments. Our work presents a case study demonstrating the powerful strength in studying the mechanics of bio-inspired composited materials, which is unavailable otherwise.
Additive manufacturing, or 3D printing, is a rapid prototyping method to fabricate 3D objects by depositing various materials layer by layer. Despite its industrial origin and significant commercial impact, 3D printing technique has found its great potential applications in engineering and scientific research. Here, we demonstrate its application in remodeling nacre-inspired bricked structure. Nacres have extraordinary mechanical properties, such as high fracture toughness and high strength-weight ratio, rooted from its brick-and-mortar structure, with Calcium carbonate platelets as hard bricks alternating with proteins layer as soft mortar. Although it is well proposed that the platelets and mortar serve jointly via shear-lag mechanism, experimental studies on the mechanical effects of brick geometry and stiffness ratio between brick and mortar have been limited. With the help of 3D printing technology, we are now able to fabricate nacre-inspired structures with two types of UVcurable polymers, where stiff plastics as brick and soft rubber as mortar. The geometry of brick and mortar can be tuned in much wider range inaccessible to natural nacre. This allow us a thorough exploration in the parameter space, leading to an understanding of the naturally optimized values found in nacre samples. In the study, 5 samples with nacre-inspired brick-and-mortar composited structures are prepared by Object Connex350(Stratasys, Inc.) 3D printer. The mortar thickness is taken as 0.21 mm limited by the precision of the printer, and the length-to-width ratio of the brick ranges from 3 to 15. These samples are subjected to tensile force until fracture and the whole process are recorded with time lapse camera. We see three distinct regimes of climbing, horizontal, and declining, which can be closely related to elastic deformation, end-rubber fracture, and horizontal-rubber fracture. For different length-to-width ratio, three different fracture modes are observed. When the ratio is small, zigzag tearing path appears across the width, leading to largest yielding strain and smallest yielding strength. When the ratio is intermediate, vertically linear fracture path jointed by inclined tearing arise, corresponding to longest flow horizontal plastic regimes. When the ratio is large, only vertically linear fracture path can be seen, corresponding to longest horizontal plastic regimes, resulting in largest yielding strength and smallest fracture strain. A scaling theory is developed to elucidate mechanism of the three regimes. As complementary to these experimental results, finite element simulation are carried out to explore the stress distribution associated with different parameters of the composited structures. The force ratio transferred by the end and horizontal rubber is seen to saturate exponentially to constant value as the brick-to-rubber stiffness ratio increases. We also find that stress singularity near the end rubber, where the initial crack nucleation appears in experiments. Our work presents a case study demonstrating the powerful strength in studying the mechanics of bio-inspired composited materials, which is unavailable otherwise.
引文
1 Sachs E M,Haggerty J S,Cima M J,et al.Three-dimensional printing techniques.U.S.Patent 5,204,055.1993-04-20
2 Gross B C,Erkal J L,Lockwood S Y,et al.Evaluation of 3D printing and its potential impact on biotechnology and the chemical sciences.Anal Chem,2014,86:3240-3253
3 Bak D.Rapid prototyping or rapid production?3D printing processes move industry towards the latter.Assembly Automat,2003,23:340-345
4 Houcai L,Jianhua M,Haitao L.A review of three dimensional printing technology and its application.Mech Sci Tech Aerospace Eng,2008,9:015
5 Berman B.3-D printing:The new industrial revolution.Business Horizons,2012,55:155-162
6 Evans M A,Ian Campbell R.A comparative evaluation of industrial design models produced using rapid prototyping and workshop-based fabrication techniques.Rapid Prototyp J,2003,9:344-351
7 Melchels F P W,Feijen J,Grijpma D W.A review on stereolithography and its applications in biomedical engineering.Biomater,2010,31:6121-6130
8 Dimas L S,Bratzel G H,Eylon I,et al.Tough composites inspired by mineralized natural materials:computation,3D printing,and testing.Adv Funct Mater,2013,23:4629-4638
9 Lin E,Li Y,Ortiz C,et al.3D printed,bio-inspired prototypes and analytical models for structured suture interfaces with geometricallytuned deformation and failure behavior.J Mech Phys Solids,2014,73:166-182
10 Cartwright J H E,Checa A G,Escribano B,et al.Spiral and target patterns in bivalve nacre manifest a natural excitable medium from layer growth of a biological liquid crystal.Proc Natl Acad Sci USA,2009,106:10499-10504
11 Luz G M,Mano J F.Biomimetic design of materials and biomaterials inspired by the structure of nacre.Philos T Roy Soc A,2009,367:1587-1605
12 Ji B,Gao H.Mechanical properties of nanostructure of biological materials.J Mech Phys Solids,2004,52:1963-1990
13 Begley M R,Philips N R,Compton B G,et al.Micromechanical models to guide the development of synthetic“brick and mortar”composites.J Mech Phys Solids,2012,60:1545-1560
14 Sun S L,Peng X Q,Guo Z Y,et al.Prediciton on mechanical behavior of mres by using reprehexive volume element approach(in Chinese).J Funct Mater,2015,4:25[孙书蕾,彭雄奇,郭早阳,等.基于RVE方法的磁流变弹性体力学行为的预测.功能材料,2015,4:25]
15 Cox H L.The elasticity and strength of paper and other fibrous materials.Br J Appl Phys,1952,3:72
16 Dasilva L F M,das Neves P J C,Adams R D,et al.Analytical models of adhesively bonded joints-Part I:Literature survey.Int J Adhes Adhes,2009,29:319-330
2 Gross B C,Erkal J L,Lockwood S Y,et al.Evaluation of 3D printing and its potential impact on biotechnology and the chemical sciences.Anal Chem,2014,86:3240-3253
3 Bak D.Rapid prototyping or rapid production?3D printing processes move industry towards the latter.Assembly Automat,2003,23:340-345
4 Houcai L,Jianhua M,Haitao L.A review of three dimensional printing technology and its application.Mech Sci Tech Aerospace Eng,2008,9:015
5 Berman B.3-D printing:The new industrial revolution.Business Horizons,2012,55:155-162
6 Evans M A,Ian Campbell R.A comparative evaluation of industrial design models produced using rapid prototyping and workshop-based fabrication techniques.Rapid Prototyp J,2003,9:344-351
7 Melchels F P W,Feijen J,Grijpma D W.A review on stereolithography and its applications in biomedical engineering.Biomater,2010,31:6121-6130
8 Dimas L S,Bratzel G H,Eylon I,et al.Tough composites inspired by mineralized natural materials:computation,3D printing,and testing.Adv Funct Mater,2013,23:4629-4638
9 Lin E,Li Y,Ortiz C,et al.3D printed,bio-inspired prototypes and analytical models for structured suture interfaces with geometricallytuned deformation and failure behavior.J Mech Phys Solids,2014,73:166-182
10 Cartwright J H E,Checa A G,Escribano B,et al.Spiral and target patterns in bivalve nacre manifest a natural excitable medium from layer growth of a biological liquid crystal.Proc Natl Acad Sci USA,2009,106:10499-10504
11 Luz G M,Mano J F.Biomimetic design of materials and biomaterials inspired by the structure of nacre.Philos T Roy Soc A,2009,367:1587-1605
12 Ji B,Gao H.Mechanical properties of nanostructure of biological materials.J Mech Phys Solids,2004,52:1963-1990
13 Begley M R,Philips N R,Compton B G,et al.Micromechanical models to guide the development of synthetic“brick and mortar”composites.J Mech Phys Solids,2012,60:1545-1560
14 Sun S L,Peng X Q,Guo Z Y,et al.Prediciton on mechanical behavior of mres by using reprehexive volume element approach(in Chinese).J Funct Mater,2015,4:25[孙书蕾,彭雄奇,郭早阳,等.基于RVE方法的磁流变弹性体力学行为的预测.功能材料,2015,4:25]
15 Cox H L.The elasticity and strength of paper and other fibrous materials.Br J Appl Phys,1952,3:72
16 Dasilva L F M,das Neves P J C,Adams R D,et al.Analytical models of adhesively bonded joints-Part I:Literature survey.Int J Adhes Adhes,2009,29:319-330