Numerical Simulation and Experimental Scheme for Monitoring
Hoof Wall Structure and Health in Sport Horses
K. Hanstorp
1
, B. M. Mihiretie
2
, M. Karlsteen
2
, A. Rosén
1
, M. Sundin
1
, D. Cederkrantz
3
,
H. Otterberg
3
, Å. Hinton
4
and B. Berg
4
1
Department of Physics, Göteborg University, SE-41296, Göteborg, Sweden
2
Department of Physics, Chalmers University of Technology, SE-41296, Göteborg, Sweden
3
Hot Disk AB, Chalmers Science Park, SE-41288, Göteborg, Sweden
4
Ale Animal Clinic, Ale, Sweden
Keywords: Equestrian Sport, Hoof Structure, Hoof Capsule Damages, Numerical Simulation, Finite Element Method,
Heat Conduction, Thermal Conductivity, Transient Curve.
Abstract: This study provides a computational model developed to demonstrate the possibility of monitoring hoof
structure and health in equestrian sport. This is achieved by employing finite element simulation of three-
dimensional heat flow from a surface heat source into a hoof structure while simultaneously sensing the
surface temperature. The time evolution of the recorded surface temperature, transient curve, is used to
investigate hoof structure and predict its intactness by comparing these curves for three different models.
We have observed differences between the transient curves obtained from a normal hoof structure, a hoof
structure containing a foreign material and hoof capsule subjected to wall separation. An experimental
method for probing hoof profile was briefly discussed. It uses temperature sensor/heat source. The method
can determine the thermal conductivity of the hoof along the hoof structure from the recorded transient
curve. Thus, it displays the hoof structure by utilizing the thermal conductivity variation between the hoof
parts.
1 INTRODUCTION
In all equestrian sports, the well-being of the horse is
fundamental. Frequently the horse struggles with
hoof problems. Often it is hard to detect the
underlying damages hidden in the internal of the
hoof. The hoof is composed of an external hoof
capsule connected with the internal pedal bone by
horny and fleshy plates (Nassau, 2004). Hoof
capsule damages of different degrees are common in
most horses. Injuries such as wall separation,
submural infections and crack are caused by various
factors including environmental conditions and
specific athletic endeavours (Moyer, 2003),
particularly the latter could disproportionally affect
athletic horses. Here we discuss a computational
method to monitor the status of a hoof by
determining the presence or absence of foreign
object in the structure. This is realized using thermal
waves. The use of thermal wave for health care
inspection can be achieved in several ways: the first
one is thermography. It is a direct imaging of heat
pattern on the surface of objects or scene (Ibarra-
Castanedo, 2013). A second method requires the
recording of the surface temperature to deduce the
thermal transport property of the material,
commonly referred as an inverse problem. The
method proposed in this study belongs to the latter
group. It works by supplying constant heat on the
surface of the object and recording the change in
temperature on the heat source and then predicting
the property of the sample from the recording.
In this work, COMSOL Multiphysics software is
employed to determine the numerical solution of the
temperature distribution of a hoof due to external
heat source and the change in temperature on the
heat source due to its contact with the hoof. The
model consists of concentric heat source placed on
the hoof wall structure and provides constant heat
for few minutes. The change in temperature on the
heat source and the temperature distribution of the
hoof is then retrieved. The above information can be
used to determine the presence or absence injury
(foreign materials or change in structural properties)
in the hoof.
Hanstorp, K., Mihiretie, B., Karlsteen, M., Rosén, A., Sundin, M., Cederkrantz, D., Otterberg, H., Hinton, Å. and Berg, B.
Numerical Simulation and Experimental Scheme for Monitoring Hoof Wall Structure and Health in Sport Horses.
DOI: 10.5220/0006043601710175
In Proceedings of the 4th International Congress on Sport Sciences Research and Technology Support (icSPORTS 2016), pages 171-175
ISBN: 978-989-758-205-9
Copyright
c
2016 by SCITEPRESS Science and Technology Publications, Lda. All rights reserved
171
An experimental approach to investigate the
structural profile of the hoof wall is also included.
The general experimental technique implemented is
referred as hot disk method (Gustafsson, 1991). The
method measures the thermal transport property of
materials by only recording the change in
temperature on the sensor. A recent extension of this
method enables it to thermally profile a material
along its depth. This approximation scheme and
some examples are included in the reference (Sizov,
2016). Further detail examples and description on
the experimental limitation and capabilities of
structural profiling of materials along their structure
is shown in (Mihiretie, 2016).
This contributes in understanding of hoof wall
defects and could potentially help horses to have
longer athletic careers and life.
2 MODEL
Three different models were designed to represent
the situations in a healthy hoof and damaged hooves.
I. Normal hoof structure, fig.1.
II. Hoof structure with a foreign material inside
the hoof capsule, fig.2.
III. Hoof capsule subjected to separation of wall.
Model I, represents a healthy hoof structure. It
consists of three parts: hoof wall; bone and heat
source. The external keratin material (hoof wall),
surrounds the internal bone structure and the double
spiral heat source (nickel wire) is placed on the
outside surface of hoof capsule. In model II, a
spherical foreign material is included in addition to
the parts listed in model I. The foreign material
assume the role of an infected part that developed
some sort of fluid (pus) inside the hoof capsule.
Thermal wave from the heat source travels through
the hoof wall before it spreads to the bone structure.
In model III, since the inside part of the hoof wall is
exposed to air to represent wall separation, the heat
wave is exposed to convective cooling from the
inside part of the hoof capsule.
The models are generated using COMSOL
Multiphysics V.5.2, the software uses the finite
element method to describe the complex problem
with a linear system of equations. This is achieved
by dividing the geometry of the problem at hand into
several subdivisions (elements), called meshing.
Then the relevant quantity is approximated at each
node of the element. Finally the solution for each
element can be collected to form global solution for
the entire geometry (Tabatabaian, 2014). The
validation of COMSOL's heat transfer modules is
documented in different studies (Gerlich, 2013,
Suarez, 2014).
The aim of the simulation is to demonstrate the
utility of the finite element analysis in the
investigation of monitoring the structural integrity of
hooves. This is realized by studying the thermal
response of the hoof structure.
The governing equation that describes transient
heat transfer in solids can be expressed as follows:

(,)

=∇(
(
,
)
+) (1)
Where  is the volumetric specific heat of the
material, T is temperature, t is the test time, K is
thermal conductivity, r is position vector and Q is
the heat source per unit volume.
It is difficult to solve eqn. 1 analytically for the
present geometry, thus a mathematical tool for
numerical solving of such partial differential
equations is employed, using COMSOL.
COMSOL consists of different modules, thus a
typical simulation starts by choosing the physics and
study type. In this study, heat transfer module with
time dependent study is used. Simulation time vector
was introduced for the transient measurement, in the
closed interval [0,320s], with increments of 0.1s
during which a constant power of 0. 5 W is used. For
solving, default solver is used.
Defining the geometry and type of materials
follows naturally. Here they are defined to represent
the different hoof status expressed in the model I-III.
Finally, applying appropriate meshing, boundary and
initial conditions comes to effect. The initial
temperature considered for the entire system was set
to be at room temperature (293.15K), and the
following boundary conditions are considered:
Extremities of the model are insulated.
. = 0 (2)
Where is normal vector and is the heat flux
by conduction.
Thermal contact boundary condition is set
between the heat source and the hoof wall and
also between the hoof capsule and the bone.
−
.
=−
(
−
)
+
(3a)
−
.
=−
(
−
)
+
(
1 + 
)
(3b)
Where h is the conductance; u (up) and d
(down) subscripts refers to the two sides of the
contact.
icSPORTS 2016 - 4th International Congress on Sport Sciences Research and Technology Support
172
The heat source is defined using thin
concentric elements with over all heat
transfer rate.
Heat loss due to convection is considered
in the case of wall separation.
q
=−
(

−
)
(4)
Where q
is convective heat flux and

is external temperature.
Physics controlled finer mesh element size
is adapted for all the domains.
Figure 1: Model of hoof structure. The external blue
structure is hoof capsule (keratin). The internal sliver part
is the bone. The heat source represented by the concentric
circles is placed on the side of the hoof wall.
The second model shown in fig. 2 consist of
spherical object in the hoof capsule filled with fluid.
It represents a possible pus caused by infection. In
the simulation the thermal properties of such fluid is
assumed to be similar to that of water.
Figure 2: Meshed geometry showing the concentric heat
source placed on the hoof surface and spherical foreign
object inside the hoof capsule. Normal size meshing of
COMSOL is used.
Table 1: Characteristic of materials used in the simulation.
Material
Thermal
Conductivit
y W/(m.K)
Heat
capacity
J/(kg.K)
Density
(kg/m
3
)
Keratin 0.45 2000 1200
Bone 0.32 1313 1908
Nickel 90.7 445 8900
Fluid 0.6 4187 1000
Air 0.03 1005 1.2
The properties of keratin and bone were determined
in a separate experiment (Gustavsson, 1994)
whereas, the properties of the rest materials were
imported from COMSOL material list.
3 RESULT AND DISCUSSION
As explained in sec. 2, heat transfer mode and
transient analysis in conduction of heat in solids
have been chosen. The temperature distribution of
the hoof after constant heat supply from source for
320 seconds on a hoof with fluid is shown in fig.3.
Figure 3: Temperature distribution of the hoof (K), at t
=320 sec., with spherical foreign material in the hoof
capsule, model II. Initial temperature of the hoof was
293.15 K.
The highest temperature (315 K, fig.3) which is at
the heat source drops to room temperature as one
goes away from the source.
The heat supplied from the source propagates
into the hoof and cause change in temperature along
Numerical Simulation and Experimental Scheme for Monitoring Hoof Wall Structure and Health in Sport Horses
173
the way. The way heat leaves the source depends on
the thermal property of the hoof composition. Thus,
computing the time evolution of the heat source,
transient curve, one can predict the composition of
the hoof profile. Fig. 4 shows transient curve of the
heat source. The three curves represent the three
different models discussed in sec. 2. The top dotted
line is obtained from hoof subjected to separation of
wall (Model III) whereas the middle solid line is the
transient curve for heat source placed on the healthy
hoof (model I) and the dashed line (Model II) is
retrieved from a hoof with a foreign material inside.
The curves represent the average change in
temperature on the heat source volume in time.
Figure 4: Temperature rise as a function of time. Each
transient curve represents different models. Solid, dashed
and dotted lines represent model I, model II and model III
respectively. Inset: includes only measurements after 3
minute.
The presence of air (model III) instead of bone
inhibits propagation of heat, as air is less thermal
conductor, resulting higher temperature rise on the
heat source compared to the case of a normal hoof
composition (model I). However, in the case of
model II, the fluid is more thermal conducting than
hoof which enhance heat conduction resulting lower
temperature on the source. The clear distinction
between the three curves in fig. 4 occurred due to the
presence of different composition in the hoof
structure. Thus, comparing the transient curve of a
particular hoof with the one obtained from a healthy
hoof, it is possible to predict the intactness of a
given hoof.
4 EXPERIMENTAL WORK
The experiment part of this study consist of thermal
profiling using a transient plane source technique
called hot disk method (Gustafsson, 1991). It is an
ISO standard technique for testing thermal transport
properties of materials (ISO22007, 2008). The
technique works by using a sensor that can supply
constant heat source to the hoof and simultaneously
record the change in temperature. The thermal
conductivity of the material is calculated from the
recorded temperature. The hot disk thermal
constants analyser can detect temperature
differences with an accuracy better than 0.1 mK by
utilising highly sensitive components (ISO22007,
2008). The sensor is made from double spiral nickel
wire covered with thin polymer, kapton, fig. 5.
A special application of hot disk technique enables
to approximate the thermal conductivity of the
material along the heat wave penetration depth
(Mihiretie, 2016), fig. 6.
Figure 5: A hot disk sensor. Spiral wire nickel covered
with polymer kapton.
Applying this technique to horse hoof requires to
place the sensor on the hoof surface and record the
change in temperature on the sensor as current pass
through the sensor. Such experimental profiling was
performed on conserved dead horse hoof. To keep
the hoofs preserved all the measurements were
performed in a fridge with a temperature of around 7
degrees Celsius.
Figure 6: Thermal conductivity profile of conserved hoof.
This hoof capsule is about 7 mm thick. Repetitive
measurements are reproducible.
The experimental work was realized on a healthy
conserved horse hoof. It reveals the hoof profile.
The thermal conductivity plot demonstrate that the
icSPORTS 2016 - 4th International Congress on Sport Sciences Research and Technology Support
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hoof capsule has higher thermal conductivity than
the bone. The thermal conductivity starts to decrease
as the heat wave reaches the bone structure. This
gradual drop instead of sharp change at the interface
is due to the fact that the calculation method uses an
averaging technique. It is also worth to note that
information about the part near the outer wall is
missing due to interference from thermal contact
resistance.
Experimental and modelling parameters were
designed to be equivalent to each other, for instance
the double spiral nickel wires were represented by
concentric circles in the simulation. However, direct
comparison between experiment and simulation is
left for future work. This requires the simulation to
be expressed in terms of thermal conductivity
instead of transient curve. The work is in progress
with this aspect.
5 CONCLUSION
In this article, a computational model supported by
experimental work to thermally profile horse hoof is
presented. The findings from the simulation show
that by using the temperature rise curve of the heat
source one can monitor the structural composition of
the hoof. It is also possible to differentiate between
wall separation and a fluid contained in the hoof by
comparing with the transient of a normal hoof. The
experimental measurement revealed the hoof
structure.
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