1. 1 Copyright © 2014 by ASME
ASME 2014 International Mechanical Engineering Conference and Exposition
IMECE2014
November 14-20, 2014, Montreal, Canada
IMECE2014-40268
DEVELOPING A PHYSICAL MODEL OF AN ELECTROMECHANICALLY ACTUATED
VALVE TO MODEL VALVE DISEASE IN VITRO
Krishna Chaitanya Manthripragada
Department of Mechanical Engineering
University of Louisiana at Lafayette
Lafayette, LA, USA
Chandler P. Lagarde
Department of Mechanical Engineering
University of Louisiana at Lafayette
Lafayette, LA, USA
Charles E. Taylor, Ph.D.
Department of Mechanical Engineering
University of Louisiana at Lafayette
Lafayette, LA, USA
ABSTRACT
Onset of valve disease, mainly stenosis, is common in post
left ventricular assist device (LVAD) implantation.
Hydraulically, this condition manifests itself as a change in the
opening profile of the heart valve; smaller effective hydraulic
diameters. Studying the onset of this disease during mock
circulatory loop analysis of an LVAD design enables the
cardiovascular condition changes to be more appropriately
modeled. This would provide insight to the impact on changes
in operating demands for a device over the course of its use;
power demand and performance impact. The challenge of
producing a valve that can control its opening profile to mimic
both healthy and stenosis states is difficult due to the low valve
differential pressures experienced in vivo (<1 psi). A novel
design of a mono-leaflet swing valve that is
electromechanically actuated is being developed to simulate
onset of stenosis in a human aortic valve. Finite element
analysis (FEA) was employed to produce a computational fluid
dynamics (CFD) model of the design for the purpose of
estimating the torque delivered to the actuator by the fluid flow
against the leaflet. Modeling a wide range of flow rates through
various valve angles of operation provided data on the full
operating range for the device. Calculation of the torque on the
driveshaft manipulating the leaflet angle was derived from
pressure data for 38 points on the valve’s surface. Utilizing this
data in a Simulink Simscape physical model of the
electromechanical system enables accurate control architecture
to be developed for the device through the use of design
optimization. Discussion of the CFD model results and how to
employ them in the Simscape model will be discussed.
Performance of the physical model in a pulsatile flow study,
analogous to the human circulatory system, will be presented
illustrating the ability of the design to model onset of stenosis
in an aortic valve.
INTRODUCTION
A heart valve acts as a check valve that prevents blood
regurgitating backwards into the heart chambers. During
systole, the blood leaves the left ventricle and enters the aorta
which supplies blood to the systemic circulation. This is when
the aortic heart valve opens to allow this passage of blood to
occur. At the end of systole, the aortic valve closes preventing
the backward flow while the left ventricle prepares for the next
fill cycle (diastole) [1]. Under diseased conditions, these heart
valves sometimes are partially occluded (stenosis) or their
movement is hindered due to stiffening (sclerosis). This
deviation from complete natural movement in turn affects the
flow of blood through these diseased valves [2].
Diseased heart valves must be diagnosed as their condition
leads to poor circulation and possibly congestive heart failure.
The treatment could demand a heart valve replacement surgery.
This is an invasive technique, where the valve is replaced by an
artificial heart valve. These artificial heart valves are classified
as either mechanical or tissue (bioprosthetic) heart valves. Each
of which has their own advantages and disadvantages [2]. The
mechanical heart valves last longer than the tissue valves, but
exhibit the risks of thromboembolism and prolonged use of
anticoagulants. Tissue valves do not require the use of
anticoagulants, but are at higher risk for material failure and
immune response [3].

2. 2 Copyright © 2014 by ASME
The ability to simulate various cracking pressures and
opening profiles of aortic heart valves is essential to the in vitro
assessment of medical devices that may be affected by valve
health states. Valvular disease manifests itself in the
mechanical operation of the anatomy through the modification
of the differential pressure and flow rate relationship. Sclerosis
defines a stiffened state of the leaflet tissue, which impacts
opening profile through the increase in force to obtain the same
leaflet motion. Stenotic valves are those that have their
opening impinged such that there fully opened profile is limited
[4]. Conjugation of these two states can occur to provide a
limited and suppressed opening profile; defined as flow area as
a function of differential valve pressure. Constructing an in
vitro device that is capable of simulating normal heart valve
function, and pathological states, is imperative in the
development of a fully capable cardiovascular medical device
assessment system.
The challenge of achieving the mechanical simulation of
heart valve leaflet motion lies in the material properties of the
tissues. Leaflet tissue is a thin membrane that is relatively stiff;
the total mass of a leaflet is very small (~100 mg).
Consequently, using classical materials (e.g. Aluminum) to
construct the assembly inhibits the ability of this engineered
piece to replicate the leaflet motion due to the differences in
geometry and density. The need to supplement the passive
response of this mechanical system with actuation, moderated
by finely tuned control logic, becomes indispensable.
In order to perform these varying cracking pressures, a
mono-leaflet valve was designed for in vitro simulation
purposes. This design would allow for the leaflets to be
independently controlled via a microprocessor. The actuation
for this is made possible using external small diameter DC
motors. Feedback of the differential pressure across the valve
will be supplied by upstream and downstream pressure
transducers. The control architecture will be developed and
tuned in Simulink (MathWorks, Natick, MA) against a physical
model of the hydro-mechanical system. Engineering tools for
design such as SolidWorks (Dassault Systemes, Waltham, MA)
and Flow Simulation (Dassault Systemes, Waltham, MA) have
been used to design the unit. However, this CAD environment
does not allow the assembly to be integrated with control
design tools. Importing the assembly as a rigid body using the
SimMechanics Link (MathWorks, Natick, MA) and
incorporating the data from the CFD performed refines the
acuity of the Simulink model of the system by including the
body mass and fluid pressure effects.
This paper demonstrates complete numerical body of work
of designing the Electro mechanically actuated mono leaflet
valve and the extraction of the characterized torque needed for
the actuation using data derived from the CFD experiments
performed on the design. Thus created leaflet model is then
imported into the Physical modeling system utilizing
simmechanics to test its behavior in a pulsating system.
MATERIALS AND METHOD
The scope of this study encompasses the design of the
valve assembly in SolidWorks, evaluation of the hydraulic
performance through CFD analysis, and the implementation of
those results in a Simulink physical model using Simscape
library components. The outcome of this work should elucidate
a design path for performing active hydraulic component
design and assessment of those designs when interfaced with
control architectures.

(a) (b)
FIGURE 1: ACTIVE TILTING DISK VALVE DESIGN SHOWN IN ISOMETRIC PERSPECTIVE (A) AND ISOMETRIC
PERSPECTIVE WITH SECTIONED VIEW (B). THE SECTIONED VIEW ALLOWS THE INNER COMPONENTS OF THE DESIGN
TO BE SEEN: CASING (1), DISK ROTATIONAL HARD STOP (2), SHAFT BEARING GUIDE SERVING AS THE AXIS OF
ROTATION IN THE MODEL (3), TILTING DISK LEAFLET (4). ABSENT IS THE MOTOR AND DRIVESHAFT ASSEMBLY WITH
SEALS, AS THIS MANUSCRIPT DEALS WITH THE MODELING OF THE HYDRAULIC COMPONENTS.

3. 3 Copyright © 2014 by ASME
Design of the Mono-Leaflet Valve
The valve was sized with respect to a human aortic valve
(Fig. 1). The valve casing has an outer diameter of 22.85 mm
with an inner diameter of 18.50 mm and is 15 mm tall. The
mono-leaflet inside the valve has a diameter of 18.48 mm and it
is 1.5 mm thick. The valve is created on a circular base with a
30 mm diameter that has four equally mounting holes of 2 mm
diameter that can be used to attach the whole valve to a support
fixture.
The leaflet will be controlled by a motor; holes the size of
the motor shaft have been drilled though the valve casing and
the leaflet where the shaft will connect. Shaft guides are used to
align the motor and provide seal points. The shaft seal between
the motor and the wetted components of the valve is critical,
but must not produce too much stiction to the actuator.
The mono leaflet inside the valve revolves freely around
the motor shaft axis. In order to restrict this according to the
required motion limits, interior stop constructions have been
implemented in the design of the inner valve walls. The
orientation of the leaflet has been restricted to 0-90 degrees
with use of these interior stops to employ these angular limit
constraints.
Computational Fluid Dynamics (CFD) Model
In order to calculate the torque generated in the valve, FEA
was employed to develop a CFD model of the flow through this
valve. SolidWorks Flow Simulation 2013 was used to perform
the computations and post-analysis. To develop the CFD model,
the liquid domain of the model was chosen as the interior of the
valve assembly with the casing and leaflet forming non-
movable boundaries [5]. An elongated casing was used for the
CFD analysis to ensure that recirculative regions downstream
of the valve would be far enough from the outlet so as to be
properly characterized (Fig. 2).
Boundary conditions were established for a wide range of
inlet pressures: -5, -1, 1, 5, 15 and 25 liters per minute. An
environmental pressure at the outlet with convergence goals of
mass and velocity flow rates were used for the computational
analysis. The flow simulation was run for the inlet pressures at
each of the different angles: 0, 30, 60 and 75 degrees.
Exception was made to the 15 and 25 liters per minute studies
at 0 and 30 degree valve angles. These flow rates would not be
present for these particular angles, and were deemed
unnecessary. The values of pressure imparted on the valve
leaflet and differential pressure (difference of boundary
averages) were measured and have been used to calculate the
(a) (b)
FIGURE 2 (a) : EXEMPLARY RESULTS FROM A CFD FLOW ANALYSIS OF THE MONO-LEAFLET VALVE SHOWN WITH A
LONGITUDINAL CROSS-SECTION OF THE MODEL GEOMETRY. A 60 DEGREE VALVE ANGLE WITH A BULK FLOW RATE
OF 15 LITERS PER MINUTE EXITING TO ATMOSPHERIC PRESSURE (101325 PA) WERE THE CONDITIONS FOR THE
STUDY DEPICTED IN THE FIGURE. THE STREAMLINES INDICATE THE FLOW PAST THE LEAFLET IN THE DIRECTION OF
THE ARROWS; INLET ON THE LEFT OF THE ILLUSTRATION AND OUTLET ON THE RIGHT. THE COLORATION OF THE
STREAMLINES INDICATES THE PRESSURE ALONG THAT LINES PATH; RED BEING THE HIGHER PRESSURE AND CYAN
BEING THE LOWEST. A LOW PRESSURE RECIRCULATION ZONE IS WITNESSED DOWNSTREAM OF THE VALVE AND
THE MAJORITY OF THE FLOW BEING DIRECTED OVER THE TOP OF THE LEAFLET (AS DEPICTED ABOVE). (b): DEPICTS
THE LEAFLET AND PRESSUE CONTURES FOR A FLOW OF 15 LITERS PER MINUTE EXITING TO ATMOSPHERIC
PRESSURE (101325 PA). PRESSURES AT RANDOM POINTS HAVE BEEN CHOSEN TO USE THEM IN FINDING THE
TORQUE FOR THE ACTUATION. THE AREAS OF RED INDICATED HIGH PRESSURE REGIONS WHILE DECREASING
YELLOW, GREEN, AND BLUE INDICATE AREAS OF LOWER PRESSURE ON THE CONTURE.

4. 4 Copyright © 2014 by ASME
torque on the leaflet axis of rotation and equivalent hydraulic
orifice for the assembly.
The torque for each value of inlet pressure for a certain angle
have been derived and recorded for further use. In order to
calculate the torque, 38 points on each side of the valve leaflet
have been chosen. As shown in Figure 2 the flow pattern is not
reflected about the leaflet. This necessitates the use of pressure
values from both sides of the leaflet. The distance from the
axis of rotation and pressure valves at each of these 38 points
have been measured to provide the necessary information for
determining total torque acting on the leaflet shaft. These
values have been used to derive the torque delivered to the
actuator by the fluid flow against the leaflet.
Simscape Physical Model
MathWork’s Simulink offers a series of toolboxes for
physical modeling called Simscape, which has been used for
this model. Simscape provides a platform that allows for
models of physical systems with multiple domains that
interface each other to be constructed. Simscape provides
FIGURE 3: SIMULINK MODEL WITH SIMSCAPE PHYSICAL MODELING ELEMENTS. SINE WAVE BLOCK (FAR LEFT)
DRIVES AN IDEAL PRESSURE SOURCE THAT PRODUCES FLOW IN THE SEGMENTED PIPE SECTION LEADING TO THE
VARIABLE AREA HYDRAULIC ORIFICE. IMMEDIATELY DOWNSTREAM OF THE ORIFICE IS THE FLOW METER
FOLLOWED BY A PIPE ELEMENT THAT CONNECTS TO THE HYDRAULIC REFERENCE (ATMOSPHERE). SIMULINK
LOOKUP TABLES ARE EMPLOYED TO RELATE THE VALUES DERIVED THROUGH CFD TO THIS PHYSICAL MODEL;
MAINLY TORQUE FROM FLOW, LEAFLET ANGLE AT DIFFERENTIAL PRESSURE, AND EQUIVALENT HYDRAULIC
DIAMETER OF A LEAFLET ANGLE.
FIGURE 4: SUBASSEMBLY FROM FIG. 3 USED TO MODEL THE RIGID BODY MOTION OF THE LEAFLET. THE BLUE
BLOCKS REPRESENT THE ELEMENTS THAT WERE IMPORTED FROM SOLIDWORKS USING THE SIMMECHANICS LINK.
THE REMAINING BLOCKS ARE SIMULINK AND SIMSCAPE BLOCKS RESPONSIBLE FOR INITIALIZING AND INTERFACING
THE ASSEMBLY. A TRANSFER FUNCTION IS USED TO MODEL THE DELAYED RESPONSE OF THE VALVE ASSEMBLY TO
CHANGES IN FLOW.

5. 5 Copyright © 2014 by ASME
foundation libraries for basic domain elements, or more
sophisticated domain assemblies (e.g. valves, rigid body
elements.). Custom blocks can be programmed with
constitutive equations, giving the flexibility needed to design
custom systems [6].
The physical system modeled constructed for this
application seeks to simulate the opening profile of the electro-
mechanical valve. The opening profile depends upon the
pressure, flow rate and the torque applied to the leaflet axis.
Thus, the liquid and mechanical domains must be characterized
appropriately to allow for the fine control of the leaflet motion
needed for this application. .
For this study, an ideal physical system has been
constructed (Fig. 3 and Fig. 4). Friction from seals, motor
response, and fixed time step control architecture has not been
considered. This study seeks to model the assembly for future
work towards implementing the design. The model consists of
loops work from differential pressure across and flow through
the valve to control the opening profile of the valve through the
manipulation of the area of the hydraulic orifice. A sine wave
block outputs a sinusoidal wave form which acts as a drive
signal for the system. A simulated 60 beats per minute with
50% time in systole was chosen to represent a normal cardiac
cycle period. The use of an oscillating pressure source centered
about zero was chosen to assess the operation of the design
through in vitro testing conditions. It has been shown that
cardiac simulators can produce high negative pressures during
diastole, as they are timing driven designs that do not operate
under positive pressure filling [7], [8]. A variable area
hydraulic orifice block is used to simulate the valve. The
variable area hydraulic orifice block is fed by the hydraulic
pressure source from the SimHydraulics library and the
hydraulic diameter from the look up table equating the leaflet
angle to the effective hydraulic diameter.
The Valve SolidWorks subassembly is based on a
SimMechanics blockset constructed from an exported model
from SolidWorks into Simulink using the SimMechanics Link
for SolidWorks. This linkage assembly uses Sensor and
Actuator blocks to connect to normal Simscape blocks [9].
SimMechanics also provides 3D animations of the assembly to
view the model during the simulation. The leaflet angle is a
result of the kinematic solution provided by the SolidWorks
valve subassembly shown in Fig. 4. The rotation of the leaflet
is driven by a torque that is the sum of the flow induced torque
and that delivered by the actuator, in this the case the PI
controller block representing an ideal actuator. A rotational
hard stop is included to enforce the limits of rotation, and allow
for a contact stiffness to be simulated.
The torque from the flow about the leaflet, as determined
by the CFD analysis, is driven by the flow rate block coming
from the variable hydraulic orifice and the theta produced the
solid works valve. The 2D lookup table values and breakpoints
are shown in Table 1. Linear interpolation and extrapolation
were used to allow for more continuity in the table output. It is
important to include a memory block on the theta feedback to
the table input, as this will break the algebraic loop that would
otherwise result.
The ideal actuator controlling the operation of the leaflet is
based on the opening profile chosen (Fig. 5) that is driven by
the differential pressure of the valve through a 1D lookup table.
These profiles were chosen to illustrate the ability of this design
to be driven by a parameterized opening profile based on
different aortic valve morphologies [10]. The error
TABLE 1: TORQUE VALUES (N*M) DETERMINED FROM
THE CFD STUDIES IN RELATION TO THE VALVE
ANGLE AND BULK FLOW RATE CONDITIONS.
LPM 0
o
30
o
60
o
75
o
-5 -2.79E-05 -5.43E-09 -2.08E-10 -6.52E-11
-1 -1.12E-06 -2.26E-10 -9.14E-12 -2.80E-11
1 2.22E-06 2.13E-10 5.15E-11 3.14E-12
5 5.52E-05 5.06E-09 2.31E-10 7.08E-11
15 N/A N/A 2.08E-09 6.46E-10
25 N/A N/A 5.77E-09 1.80E-09
TABLE 2: DETERMINED HYDRAULIC DIAMETERS FOR
LEAFLET GEOMETRY BASED ON DATA FROM 5 LPM
STUDIES.
Angle
[degrees]
Hydraulic Diameter
[m
2
]
0 6.50E-07
30 1.77E-4
75 1.26E-3
FIGURE 5: TWO VALVE OPENING PROFILES THAT
WERE TESTED IN THIS ANALYSIS. THESE PROFILES
ARE USED IN THE "DP TO THETA" LOOKUP TABLE OF
FIG. 3. THE BLUE LINE REPRESENTS A HEALTHY
AORTIC VALVE PROFILE. THE DASHED RED LINE
ILLUSTRATES A STENOTIC STATE THAT REQUIRES
MUCH HIGHER PRESSURES TO ACHIEVE THE SAME
HYDRAULIC DIAMETER.
0 20 40 60 80
0
500
1000
1500
2000
2500
3000
3500
Valve Angle [degrees]
DifferentialPressure[Pa]

6. 6 Copyright © 2014 by ASME
determination for the proportional controller is the desired
leaflet angle from the opening profile lookup table and the
readback leaflet angle from the SolidWorks Valve subassembly.
The ideal proportional controller chosen for this analysis is a
continuous controller with a gain of 5.12. This gain value was
calculated by the Control Design tools within Simulink.
Driving the variable hydraulic orifice block is the readback
of the leaflet angle correlated to the effective hydraulic
diameter at that particular position through a 1D lookup table.
The values for this lookup table were determined from a
single CFD study at the 5 lpm flow rate (Table 2).
Solver configuration blocks are used to identify the
Simscape physical networks through their connection to each
closed network present in the model. The solver used for this
study was the ode23t, known as the variable step moderately
stiff/trapezoidal solver. Simscape models are inherently stiff
due to their numerous implicit definitions and require the use of
a stiff solver. All solver settings remained in their default
configuration with no use of local solvers in the model.
Simulation time was chosen to be 4 seconds, as this would
capture the behavior required for this analysis while allowing
for initialization transients to be overcome.
RESULTS
The analysis performed in the course of executing the
methods described was concluded satisfactorily. It will be
shown that the feasibility of implementing CFD results in a
Simscape physical network is achievable and viable means of
evaluating controller designs.
FIGURE 6: TIME COURSE PLOTS OF THE SIMSCAPE MODEL SIMULATION RESULTS. THE TOP GRAPH INDICATES THE
SINUSOIDAL PRESSURE SIGNAL THAT WAS USED TO PRODUCE FLOW IN THE HYDRAULIC SECTION OF THE MODEL.
THE FLOW RATE SENSOR OUTPUT IS SHOWN IN THE SECOND FIGURE WITH RED BEING THE PATHOLOGICAL STATE
AND THE BLUE REPRESENTING THE NORMAL STATE. FOR AN IDENTICAL PRESSURE SOURCE, THE PATHOLOGICAL
STATE RESTRICTS THE PEAK FLOW RATE REDUCING THE CARDIAC OUTPUT. THE DIFFERENTIAL VALVE PRESSURE IS
DEPICTED IN THE THIRD GRAPH. THE PATHOLOGICAL VALVE HAS HIGHER DIFFERENTIAL PRESSURES DURING
SYSTOLE, DUE TO THE SMALLER HYDRAULIC DIAMETER. THE LARGE PEAK DIASTOLE PRESSURE VALUES ARE DUE
TO THE IDEAL PRESSURE SOURCE ACTING AGAINST A FULLY CLOSED VALVE WITH THE INERTIAL EFFECTS OF THE
DOWNSTREAM PIPE ELEMENTS MAGNIFYING THIS DIFFERENTIAL. THE VALVE ANGLE GRAPH AT THE BOTTOM IS THE
CLEAREST INDICATION OF THE PERFORMANCE DIFFERENCE BETWEEN THE TWO OPENING PROFILES; THE
PATHOLOGICAL CURVE DOES NOT ALLOW THE VALUE TO OPEN AS FAR AS THE NORMAL STATE. THIS IS A CLEAR
REPRESENTATION OF A STENOTIC VALVE PROFILE.
0 0.5 1 1.5 2 2.5
-1
-0.5
0
0.5
1
x 10
4
PressureSource[Pa]
0 0.5 1 1.5 2 2.5
-10
0
10
20
30
Flowrate[lpm]
0 0.5 1 1.5 2 2.5
-15000
-10000
-5000
0
5000
ValvePressure[Pa]
0 0.5 1 1.5 2 2.5
0
10
20
30
40
ValveAngle[degrees]
Time [sec]

7. 7 Copyright © 2014 by ASME
Torque Calculation
The torque produced by the flow over the leaflet face is
calculated based on the following formula (Eq. 1) that assesses
each point pressure as discrete moment with the total torque
being a sum of those moments:
𝑜𝑟𝑞𝑢𝑒 ∑ 𝑑𝑖 𝑃𝑖 (
𝜋𝑟
𝑁
) (1)
𝑑𝑖 √[(𝑋 𝑜 − 𝑋𝑖)2 + (𝑌𝑜 − 𝑌𝑖)2] (2)
𝑑𝑖 𝑝𝑒𝑟𝑝𝑒𝑛𝑑𝑖𝑐𝑢𝑙𝑎𝑟 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑓𝑟𝑜𝑚 𝑎𝑥𝑖𝑠 𝑜𝑓 𝑟𝑜𝑡𝑎𝑡𝑖𝑜𝑛𝑃𝑖
𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒 𝑣𝑎𝑙𝑢𝑒 𝑎𝑡 𝑎 𝑝𝑜𝑖𝑛𝑡
𝜋𝑟2
𝑎𝑟𝑒𝑎 𝑜𝑓 𝑎 𝑙𝑒𝑎𝑓𝑙𝑒𝑡 𝑓𝑎𝑐𝑒
𝑁 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒 𝑝𝑜𝑖𝑛𝑡𝑠 𝑡𝑎𝑘𝑒𝑛 𝑜𝑛 𝑎 𝑓𝑎𝑐𝑒
𝑋 𝑜, 𝑌𝑜 𝑙𝑒𝑎𝑓𝑙𝑒𝑓𝑡 𝑐𝑒𝑛𝑡𝑟𝑜𝑖𝑑 (𝑙𝑖𝑒𝑠 𝑜𝑛 𝑟𝑜𝑡𝑎𝑡𝑖𝑜𝑛𝑎𝑙 𝑎𝑥𝑖𝑠)
𝑋𝑖, 𝑌𝑖 𝑚𝑒𝑠ℎ 𝑝𝑜𝑖𝑛𝑡 𝑐𝑜𝑜𝑟𝑑𝑖𝑛𝑎𝑡𝑒
Point pressures were derived from the values of the CFD
simulation results at the computational mesh points on the faces
of the leaflets. For this calculation, 38 equally spaced mesh
points have been considered on the leaflet, which were chosen
by the SolidWorks Flow Simulation analysis tools. The values
were exported as .csv files and imported into Matlab to execute
the equivalent torque calculation.
Simscape Model
The physical model performance was exceptional (Fig. 6).
The model did not suffer from ringing due to the stiff nature of
the physical network and interfaces. The latency of the valve
response to the changes in hydraulic conditions was appropriate
and the inertial effects of the hydraulic network were accurate
in reproducing the amplified diastole differential pressure drop.
The limited opening of the valve to no more than 40 degrees for
the normal opening profile was consistent with the cardiac
conditions chosen for this analysis; peak flow rate did not
surpass 21 lpm. This would be indicative of an individual that
is suffering from congestive heart failure, which is an
appropriate operating condition for this device.
DISCUSSIONS AND CONCLUSION
Utilization of the SimMechanics Link for SolidWorks and
Flow Simulation data to construct a representative model of an
active hydraulic valve was a success. The analysis performed
enables these investigators to continue with the development of
the unit, as the proof of concept through a Simscape physical
model has been concluded. This design represents a geometry
and function that is capable of being used to profile various
aortic valve morphologies in an in vitro pulsatile mock
circulatory loop. The methods utilized in this study illustrate
the development process for producing a Simscape physical
model from CFD data to replicate the effects of the hydraulic
interaction on actuated assemblies, which is an exciting
capability for device designers seeking to evaluate their control
logic on designs that do not conform to standard model element
behavior. This work will lead to experimental validation in the
near future.
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