Materials Today: Proceedings xxx (xxxx) xxx
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Structural analysis of femur bone to predict the suitable alternative
material
K.C. Nithin Kumar a,⇑, Narendra Griya a, Amir Shaikh a, Vaishali Chaudhry a, Subhash Chavadaki b
a
b
Graphic Era Deemed to be University, Dehradun, India
School of Technology, GITAM (Deemed to be University), Bengaluru, India
a r t i c l e
i n f o
Article history:
Received 15 November 2019
Received in revised form 26 November 2019
Accepted 4 December 2019
Available online xxxx
Keywords:
Femur bone
Biomechanical analysis
Biomaterials
FEA
MSC Nastran
a b s t r a c t
This study is based on the biomechanical analysis of femur bone using Finite Element technique. Real life
activities are taken as boundary conditions and the weight of a person is considered as load for walking,
standing and jumping. For biomechanical analysis, three-dimensional CAD model of human femur bone
is modelled from MRI/CT Scan data using ITK-Snap software. Pre-processing and post-processing operations are done using HYPERWORKS whereas the solver is NASTRAN 10.0. Analysis is done using three
materials- natural bone material, AZ31 (magnesium alloy), CP Ti (Commercially Pure Titanium Alloy).
Comparative study shows that CP-Ti material generates minimum stresses for jumping, standing and
walking, which are 5.69, 5.34 and 5.71 MPa respectively. And also minimum displacements for jumping,
standing and walking are 0.146, 0.0583 and 0.0623 mm respectively. It is found that AZ31 is the best suited material for Bone implants and as its weight is approximately same as natural bone.
Ó 2019 Elsevier Ltd. All rights reserved.
Selection and of the scientific committee of the 10th International Conference of Materials Processing and
Characterization.
1. Introduction
Biomechanics is a branch of engineering which applies principles of mechanical engineering to analyze the biological system.
It is not easy to apply mechanical laws to biological objects, but
nowadays, FEM has developed as an effective analysis tool to
model and simulate biological objects. Artificial objects are simple
and can be easily modelled but biological objects are difficult. Anisotropic and non-linear natures of biological objects create problems in meshing and analysis. For this, FEM is the excellent way
for linear analysis and non-linear analysis of biological objects [1].
Femur is the strongest and longest bone in human anatomy.
Femur is thigh bone which is extended from hip-joint to the knee.
It can withstand 800–1100 kg of compressive load. It is the bone
which provides support to body while performing daily activities
like jumping, standing and walking. Femur shape is complex and
it has different composition. Thickness of femur bone varies from
4 to 8 mm and length varies from 260 to 293 mm [2].
Various finite element techniques are employed to analyse the
human femur bone behaviour under different loading conditions.
⇑ Corresponding author.
CAD model of femur bone is created using CT and MRI scan data
and then generating the finite element mesh and at last assigning
the inhomogeneous property to the bone material Geometric 3D
model is created by utilizing solid works, CATIA and Materialize
MIMICS [3]. Also created CAD model of femur bone in partial with
volume rendering by treating Computer Tomography (CT) images
[4,5]. Author utilizes Pro/Engineer under restyle feature environment, which is a reverse engineering tool, to convert the polygon
model of human femur bone into 3D CAD model [6]. From CT Scan
data three-dimensional CAD model of bone was created using
marching cubes algorithm in Visualization Toolkit (VTK) [7]. Inhomogeneous property is assigned to the bone material with the help
of an empirical relationship in terms of modulus of elasticity and
bone density. Both isotropic and orthotropic materials are considered for bone [8]. Author uses different bio-ceramic composites for
the bone replacement operation of human. Bio-ceramic composite
material combines with the human tissue and fluid in the body so
that they can improve and replace anatomical elements of the
human body. Some of the bio ceramic composite used are AISI
316L, CoCrMo, Ti6Al4V, UHMWPE, Alumina, Mg–Nd–Zn–based
Magnesium alloy, CP Ti grade 2 (Commercially Pure Titanium
Alloy) [9]. Hydroxyapatite bio ceramic material is also utilized
for teeth and bone implants because of its excellent biocompatibil-
E-mail address: kcnkumar@ymail.com (K.C. Nithin Kumar).
https://doi.org/10.1016/j.matpr.2019.12.031
2214-7853/Ó 2019 Elsevier Ltd. All rights reserved.
Selection and of the scientific committee of the 10th International Conference of Materials Processing and Characterization.
Please cite this article as: K. C. Nithin Kumar, N. Griya, A. Shaikh et al., Structural analysis of femur bone to predict the suitable alternative material, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.031
2
K.C. Nithin Kumar et al. / Materials Today: Proceedings xxx (xxxx) xxx
ity and bio activity [10]. Three-dimensional CAD model of human
femur bone was imported to different FEM software where pre
and post-processing is carried out, such as ANSYS, ABAQUS,
HYPERWORKS [11,12]. FEA is applied to analyze stress distribution
during normal walking, standing up, stair climbing and knee-bend
boundary condition [13–15]. To analyze the stress and displacement 2500 N force is applied on the femur head and bottom of
femur is kept fixed [16,17]. Analysis is done for walking condition
with average speed of 3.9 km/h and standing up condition with
height of chair 50 cm and arms kept at height of chest [10,18].
2. Materials and method
In any studies selections of materials and methods are most
important. In this work the materials and method are chosen based
on the previous work. Speciality of this study is that three dimensional models are prepared from CT-scan data using ITKSNAP open
source software. This 3D model is imported in hyperworks for Preprocessing.
2.1. Materials
There are different materials which are already in use for medical implants. Two of which, other than natural bone material,
AZ31 and CP Ti are utilized here to show whose mechanical behaviour is closest to the bone material.
2.1.1. Material properties of femur bone
Bone is porous in nature but for this analysis it is taken as isotropic material and its properties are taken from Amrita Francis
et al. [2] which is given in Table 1
2.1.2. Material properties of AZ31 (magnesium alloy)
Magnesium shows high strength and low weight ratio and
because of which it has important application in automotive and
aerospace industry. Magnesium is suitable for biodegradable
medicinal implants, mainly to fix the fractured bones. Biodegradable implants slowly degrade in human body with time and are
replaced by the evolving hard tissues. The material Properties of
AZ31 are [22] shown in Table 2
2.1.3. Material properties of CP titanium
CP Ti has four grades and grade 1, 2 and 3 of the first four grades
is the one which is softer and much ductile in nature. It has the
strongest formability, corrosion resistance and high impact toughness. Because of the above-mentioned qualities, Grade 1, 2 and 3 is
the material which can be used for any application where formability is required and commonly available as titanium plates.
This material is generally used in making medical implants and
its mechanical properties are taken from Virginia Saenz et al.
[19,20,23] shown in Table 3.
2.2. Boundary condition
The boundary condition plays an importation role in the FE
analysis. These boundary conditions are generally selected based
on the working conditions of the femur bone to be analysed. In this
study the following boundary conditions used are shown in Table 4
[21,24,10].
3. Results and discussion
The boundary conditions are applied for the natural bone, AZ31
and CP Ti. The results are discussed under following heads.
3.1. Natural bone
The results are shown for the natural femur bone analysis for
the real-life activities like jumping, standing and walking as
boundary conditions. Von-Misses stresses and displacement are
obtained for different boundary conditions.
Fig. 1 and Fig. 2 show stress and displacement during jumping is
6.38 Mpa and 3.48 mm respectively and as compared to the literature it is the optimal solution [24,25].
Fig. 3 and Fig. 4 show stress and displacement during standing
is 5.29 Mpa and 2.88 mm respectively and as compared to the literature it is the optimal solution [24,25].
Fig. 5 and Fig. 6 show stress and displacement during walking is
5.65 Mpa and 3.08 mm respectively and as compared to the literature it is the optimal solution [24,25].
3.2. AZ31 biomaterial
The results shown below (Figs. 7–12) show that when AZ31
Magnesium alloy is used for standing, normal walking and jumping
as boundary conditions. Von-Misses stress and displacement
obtained are low as compared to that of natural bone.
Table 1
Material properties of Femur Bone.
Properties of Femur Bone
Modulus of Elasticity E (GPa)
Poisson’s Ratio (c)
Ultimate Tensile Strength (MPa)
Ultimate Yield Strength (MPa)
Density (q) (g/cm3)
3–20
0.33
135
130–193
1.8–2.1
Modulus of Elasticity E (GPa)
Poisson’s Ratio (c)
Properties of AZ31
Ultimate Tensile Strength (MPa)
Ultimate Yield Strength (MPa)
Density (q) (g/cm3)
45
0.35
260
160
1.81
Modulus of Elasticity E (GPa)
Poisson’s Ratio (c)
Ultimate Tensile Strength (MPa)
Ultimate Yield Strength (MPa)
Density (q) (g/cm3)
110–117
0.37
397.2
758–1117
4.4
Table 2
Material properties of AZ31.
Table 3
Material properties of CP Titanium.
Properties of CP Titanium
Please cite this article as: K. C. Nithin Kumar, N. Griya, A. Shaikh et al., Structural analysis of femur bone to predict the suitable alternative material, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.031
K.C. Nithin Kumar et al. / Materials Today: Proceedings xxx (xxxx) xxx
3
Table 4
Boundary conditions.
Conditions
Load (N)
Loading End
Fixed end
Jumping
Standing
Walking
850
705
750
Knee joint
Knee joint
Knee joint
Femur Head
Femur Head
Femur Head
Fig. 5. Stress during walking for bone.
Fig. 1. Stress during jumping for bone.
Fig. 6. Displacement during walking for bone.
Fig. 2. Displacement during jumping for bone.
Fig. 7. Stress during jumping for AZ31.
Fig. 3. Stress during standing for bone.
Fig. 8. Displacement during walking for AZ31.
Fig. 4. Displacement during standing for bone.
Fig. 7 and Fig. 8 show stress and displacement during jumping is
6.42 Mpa and 0.165 mm respectively and as compared to the literature it is the optimal solution [24–27].
Fig. 9 and Fig. 10 show stress and displacement during standing
is 5.32 Mpa and 0.137 mm respectively and as compared to the literature it is the optimal solution [24–27].
Fig. 9. Stress during standing for AZ31.
Please cite this article as: K. C. Nithin Kumar, N. Griya, A. Shaikh et al., Structural analysis of femur bone to predict the suitable alternative material, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.031
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K.C. Nithin Kumar et al. / Materials Today: Proceedings xxx (xxxx) xxx
Fig. 10. Displacement during standing for AZ31.
Fig. 11. Stress during walking for AZ31.
Fig. 14. Displacement during jumping for CP Ti.
Fig. 15. Stress during standing for CP Ti.
Fig. 16. Displacement during standing for CP Ti.
Fig. 12. Displacement during walking for AZ31.
Fig. 11 and Fig. 12 show stress and displacement during walking
is 5.69 Mpa and 0.146 mm respectively and as compared to the literature it is the optimal solution [24–27].
3.3. CP Ti biomaterial
The results shown below shows that when Commercially Pure
Titanium (CP Ti) used for standing, normal walking and jumping
like real life activities, Von-Misses stress and displacement
obtained are comparatively low as compared to natural bone.
Fig. 13 and Fig. 14 show stress and displacement during jumping is 5.69 Mpa and 0.146 mm respectively and as compared to the
literature it is the optimal solution [24–27].
Fig. 13. Stress during jumping for CP Ti.
Fig. 15 and Fig. 16 show stress and displacement during standing is 5.34 Mpa and 0.058 mm respectively and as compared to the
literature it is the optimal solution [24–27].
Fig. 17 and Fig. 18 show stress and displacement during walking
is 5.71 Mpa and 0.0623 mm respectively and as compared to the
literature it is the optimal solution [24–27].
The results are shown in Table 5. The Von-Misses stresses and
displacement are obtained for different boundary conditions for
the natural bone AZ31 and CP Ti. The stress is optimal for AZ31
as compared to CP Ti.
The stresses are minimal at the femur head where it is fixed for
the given materials and at the loading end (the Knee joint) minimal
displacement can be observed.
Fig. 17. Stress during walking for CP Ti.
Please cite this article as: K. C. Nithin Kumar, N. Griya, A. Shaikh et al., Structural analysis of femur bone to predict the suitable alternative material, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.031
K.C. Nithin Kumar et al. / Materials Today: Proceedings xxx (xxxx) xxx
Fig. 18. Displacement during walking for CP Ti.
Table 5
Comparison of stress and displacement for different materials.
Parameters
Boundary
conditions
Natural
Bone
AZ31
CP Ti
Maximum stress (MPa)
Jumping
Standing
Walking
Jumping
Standing
Walking
6.38
5.29
5.65
3.48
2.88
3.08
6.42
5.32
5.69
0.165
0.137
0.146
5.69
5.34
5.71
0.146
0.0583
0.0623
Maximum
displacement (mm)
The designers must consider the manufacturability and cost
while suggesting any new materials for the biomedical applications. Considering cost and manufacturability, AZ31 is best suited
material for Bone implants. It has low stress and displacement in
comparison to natural Bone and CP Ti [24–27].
4. Conclusions
The current study elaborates the behaviour of Human femur
bone for different loading conditions. There was a slight variation
in the stresses due to modelling errors. This work mainly focuses
on understanding the behaviour of Femur bone for daily life activities, which were assumed as boundary conditions for analysis and
muscle effect on femoral bone is neglected to understand behaviour of the bone for different loading conditions. If muscle effect
is considered, then stresses will decrease by 30% [24–27]. Obtained
results in above analysis could be utilized to find the displacement,
stress and frequency at which fracture occurs in femur bone and
also helps to decide thickness and type of material required for
implantation. The Weight of natural Femur bone is 1.28 kg, AZ31
materials 1.14 kg and whereas CP Ti the weight is 2.89 kg. AZ31
is the best materials for the artificial bone implants and also it
degrades over the time in the body. The CAD model developed
from CT-scan data will be used to in making exact femur bone
for an individual.
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared
to influence the work reported in this paper.
Acknowledgements
The authors are thankful to Management of Graphic Era
Deemed to be University, Dehradun for their motivation towards
the publication of this work.
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Please cite this article as: K. C. Nithin Kumar, N. Griya, A. Shaikh et al., Structural analysis of femur bone to predict the suitable alternative material, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.031