10.25394/PGS.11295824.v1
Maryam Sadat Hosseini
Maryam Sadat
Hosseini
On the Mechanics of Non-Interlocking and Interlocking Patterned Interfaces Inspired by Nature
Purdue University Graduate School
2019
Patterned interfaces
Architectured materials
Linear elastic fracture mechanics (LEFM)
Cohesive zone model (CZM)
Damage
Laminated interlocking blades
3D Printing
Toughness
Aerospace Materials
Aerospace Structures
Additive Manufacturing
Biomechanical Engineering
Biomaterials
Civil Engineering not elsewhere classified
Solid Mechanics
Biomechanics
Mechanical Engineering
2019-12-02 15:02:22
Thesis
https://hammer.purdue.edu/articles/thesis/On_the_Mechanics_of_Non-Interlocking_and_Interlocking_Patterned_Interfaces_Inspired_by_Nature/11295824
<div>
<div>
<p> Nature has been adopted several techniques to
survive over the past billion years of evolution. Geometrically patterned
interfaces seem to be a common motif in Nature. In particular, architecture
plays a crucial role in increasing the strength, toughness, and damage
tolerance among different species. For instance, alligator, turtle, armadillo,
sea urchin, ammonite, Ironclad beetle, and boxfish are among species included
patterned interfaces inside their structure. Here, the role of shape, geometry,
and microstructure of both interlocking and non-interlocking patterned
interfaces inspired by Nature is investigated in enhancing the mechanical
properties under multiaxial loading conditions.</p>
<p>The
role of non-interlocking patterned interfaces is studied under remote mode-I
loading conditions. In particular, the role of the shape of the opening crack
behind the crack tip is investigated as the crack propagates along the
interface. The shape of the interface behind the crack tip for different
amplitude-to-wavelength aspect ratios is studied by comparing the results from
two analytical models with finite element simulations through the J-integral
method. Additionally, the role of the material length scale is explored by
investigating the relationship between the geometrical characteristic lengths
and the emerging material length scale using a finite-element-based cohesive
zone model. The results suggest that geometrical toughening is influenced by a
size effect, but it is bounded between two extreme conditions.</p>
<p>The
role of interlocking patterned interfaces is investigated for both boxfish
carapace and Ironclad beetle cuticle. These two species are selected due to
their extraordinary performance against attack and compression loads, which are
fatal to the other species. The boxfish carapace (Lactoria cornuta) contains
hexagonal dermal scutes, a combination of the brittle hexagonal plate
(hydroxyapatite) on top of a very compliant (collagen) material. While the
mineral plates are separated by patterned sutures (triangular patterns), there
is no interphase material connecting them. Instead, the connection between
mineralized plates is done through the collagen base which is different from other
naturally occurring sutures (e.g., sutures in turtle, alligator, armadillo).
The protective role of the boxfish scute architecture in controlling the crack
directions is investigated by employing analytical, numerical, and experimental
tools for different geometrical and material parameters. Further analysis
revealed that this architecture helps to arrest the cracks inside the sutures
area. Additionally, the results confirmed that both architecture and material
properties play a key role in controlling the direction of the crack inside the
brittle plates.</p>
<p>Beetles
are a subclass of arthropod dating back over 300 million years. The complex
cuticle microstructure found within the exoskeleton (elytra) of this specially
adapted insect results in extremely high compressive resistance, far beyond any
other beetle identified to date. Elytra consists of separated parts connected
using dovetail-joints blades and contains a hierarchical assembly of
alpha-chitin fibers embedded within a proteinaceous matrix that provides both
strength and toughness. The architecture of the suture region of the elytra,
modified for terrestrial living, has a unique architecture consisting of
specially modified interlocking blades, whose elliptical geometry, laminated
microstructure, and frictional interfacial features, enhance mechanical
properties such as toughness and load resistance. The presence of
microstructure inside the interlocking joints results in delamination inside
blades and, thus, develops a new competing mechanism that is different from
pull out or fractures. By using a combination of finite element analysis,
experimental methods (i.e., optical and electron microscopy, computed
tomography, and mechanical testing), and 3D printing prototype technique, the
unique adaptations, novel architectural design features and interfacial
structures are revealed within the exoskeleton of Ironclad beetle. The results
from FE simulations and experiments confirmed that the ellipse shape for the
blade has priority over the circular shape in terms of mechanical properties.
Besides, including laminated architecture inside the blade’s geometry can
increase the toughness of the system up to three times in comparison to the
homogenous blades, and this method is beneficial for the materials with limited
ductility. Thus, this model system represents a tough, resistance biological
material that exemplifies a departure from other types of beetles and can be
inspired for future engineering applications.</p>
</div><p>
<br></p>
</div>
<br>