Biomedical Engineering Reference
In-Depth Information
specified. Although FGM subject to thermal loading are excluded from this review,
mentioned here is the work of Bobaru [
69
], which illustrates that the outcome of the
optimization procedure in FGM depends on the micromechanical model employed
in the analysis.
It is noted that optimization of FGM may rely on numerous flexible tools,
including variations of volume fractions, shapes, and orientations of constituent
phases. However, a designer should be aware of limitations superimposed by
manufacturability of such materials, including cost considerations.
2.4.6 Fracture, Stress Concentration, and Contact
Problems in FGM
Among the many studies on fracture in FGM, fracture in an FGM strip with an
arbitrary property variation was considered in [
70
]. The problem of a crack in an
FGM coating inclined relative to a discontinuous interface was analyzed by Li and
Lee [
71
]. An experimental investigation of fracture toughness in FGM consisting of
partially stabilized zirconia and austenitic stainless steel was conducted [
72
],
illustrating the benefits of a fine microstructure in FGM. Besides attempts to reduce
the fracture tendencies along the interface, nanostructural coatings were shown to
significantly increase the hardness of the surface [
73
].
Numerous studies of fracture in piezoelectric FGM have been published in
recent years. The problems of an interfacial crack between an FGM layer and a
dielectric substrate was analyzed for three cases, including a crack located near the
edge of the interface and cracks far from the interface of a thin or thick piezoelectric
layer with the substrate [
74
]. The interaction between parallel cracks in graded
piezoelectric materials was considered in [
75
]. The mode III fracture of an
FGM piezoelectric surface layer bonded to a piezoelectric substrate was studied
in the case where cracks were normal to the interface [
76
]. The mixed-mode
fracture in orthotropic FGM loaded by normal and shear tractions applied at the
crack surface was also analyzed by Dag et al. using both analytical and finite
element methods [
77
].
Mixed-mode fracture problems for penny-shaped and annular cracks in FGM
strips were investigated in [
78
]. Periodic arrays of cracks in an FGM strip bonded to
a homogeneous piezoelectric half-space were considered in [
79
].
Dynamic fracture problems in FGM are represented by several recent studies.
A magnetoelectroelastic half-space with an FGM coating experiencing dynamic
interfacial cracking as a result of impact loading was analyzed and a preferable
coating grading arrangement was demonstrated [
80
]. Transient crack propagation
along the shear modulus grading direction in an FGM was considered for Modes I
and II fracture [
81
]. A dynamic antiplane fracture problem in magnetoelectroelastic
plates with internal or edge cracks oriented in the gradation direction was
Search WWH ::
Custom Search