an innovative experimental on-road testing method and its

Journal of Mechanical Science and Technology 26 (6) (2012) 1663~1670

www.springerlink.com/content/1738-494x DOI 10.1007/s12206-012-0413-8

An innovative experimental on-road testing method and

its demonstration on a prototype vehicle† José C. Páscoa1,*, Francisco P. Brójo2, Fernando C. Santos1 and Paulo O. Fael1

1Electromechanical Engineering Department, Faculty of Engineering, University of Beira Interior, Covilhã, 6201-001, Portugal 2Aerospace Sciences Department, Faculty of Engineering, University of Beira Interior, Covilhã, 6201-001, Portugal

(Manuscript Received July 2, 2011; Revised February 9, 2012; Accepted February 9, 2012)

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Abstract Ground vehicle drag coefficient is herein obtained using an unconventional on-road test in real scale. At low-Re numbers, and as a

function of velocity variations, transition introduces changes on the vehicle’s drag coefficient. Therefore, the drag coefficient must be obtained as a function of velocity. Traditionally, only an average drag coefficient value is usually obtained using the coast down method. To obtain the on-road, velocity dependent, drag coefficients we introduce a new approach. The aerodynamic resistance coefficient is obtained by towing the vehicle with and without an aerodynamic shield, in order to eliminate the rolling resistance component. A detailed description of the method, its associated techniques, and related errors is presented. We conclude that the present experimental procedure is needed when comparing the experimental drag coefficient against computational results, since numerical computations are usually performed in a velocity dependent framework. Further, the same on-road test procedure is herein used to obtain the rolling and aerody-namic drag coefficient for a prototype vehicle working in the transition regime.

Keywords: Ground vehicle; On-road test; Experimental method; Aerodynamics ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 1. Introduction

Generally speaking, for high-performing cars weight reduc-tion and engine efficiency are usually the two most important bottlenecks affecting fuel consumption, considered typically more important than aerodynamic drag reduction. However, a reduction in drag coefficient remains an important matter to tackle when designing these vehicles. Actually, aerodynamic resistance will certainly result on a measurable gain in per-formance, even if the drive cycle does not comprise high-speed roads. Another consideration, even more important, is that the designer must insure that the aerodynamic perform-ance improvements are transposed to the road conditions and not only achieved on controlled wind tunnel conditions, or in computational fluid dynamics (CFD) simulations. The ex-perimental, or numerical, modeling of the flow around ground vehicles is inherently complex, in particular due to boundary layer separation and ground effects [1]. This triggered the need to develop the means to obtain an accurate drag coeffi-cient in ground vehicles [2].

Most often, aerodynamic flow optimization for ground ve-hicles is usually performed in a wind tunnel, but this approach

is associated to a series of similarity and dimensionality prob-lems. Even if we can ensure that the wind tunnel provides controlled and repeatable conditions, it cannot mimic in full the road conditions. Even in the most realistic case, when us-ing a moving floor wind tunnel, the boundary layer is not completely representative of road conditions. The moving belt floor must be synchronized with free stream, and boundary layer suction must be performed in front of the vehicle. This must be carefully matched, which is very difficult and can introduce difficulties in achieving good dynamic similarity conditions. Besides, the vehicle tires must be rotating in order for taking into account the energy losses due to their rotation. Additionally, blockage effects in full-scale tests for these bluff bodies also strongly affect the achievement of similarity con-ditions. Very often, experimental results obtained in diverse wind tunnels, for the same geometry and at the same Reynolds number, result in a scatter of aerodynamic coefficients by around 5% [3]. Albeit these deficiencies we can still resort to wind tunnel testing in order to improve the aerodynamics of ground vehicles. Considering that the resultant on-road drag coefficient will be slightly different from wind tunnel, but that the performance trends are correlated to the real conditions.

This introduces us to the problem of obtaining the drag co-efficient from road testing. Track tests are complex, time con-suming and introduce problems of controlling the environ-mental conditions. For this kind of testing, coastdown is the

*Corresponding author. Tel.: +351 275 329 763, Fax.: +351 275 329 972 E-mail address: [email protected]

† Recommended by Editor Yeon June Kang © KSME & Springer 2012

1664 J. C. Páscoa et al. / Journal of Mechanical Science and Technology 26 (6) (2012) 1663~1670

most popular technique for studying aerodynamic perform-ance of ground vehicles. The procedure has been continuously improved and was normalized by SAE [4-6]. A basic draw-back of the procedure is that it requires very low, or no wind, conditions. Meanwhile, a new procedure was established, this is named J2263, and it improves the classic method by intro-ducing an on-board anemometer. Using this approach it is possible to obtain acceptable results in low to moderate wind conditions, by applying corrections based on the readings obtained from the on-board anemometer. In addition, the J2264 standard complements the J2263 by introducing a chas-sis dynamometer, to simulate the rolling resistance to be then coupled to a classical coastdown procedure. However, J2264 only applies to two-wheel drive vehicle operation, since it is only based on a single axle electric roll dynamometer.

2. The non-ergodic nature of the aerodynamic coast-

down test

The drag coefficient dependence on velocity, or Reynolds number, is not obtained from results performed using the clas-sic coast-down technique. Actually, the results obtained for aerodynamic drag include bias errors because a time-averaging procedure is applied on a coastdown test. Usually drag is computed using the first two statistical moments, namely mean average value and variance or rms, by assuming that the statistical skewness (symmetry) and kurtosis are Gaussian. However, the average and variance values can only provide physical significance, regarding the drag values ob-tained in the coastdown test, if we assume that the flowfield would be ergodic. If the flow could be considered ergodic, then all data statistics can be calculated from a single data-trace by time averaging. That is not the case as can be seen in Fig. 1, since to be ergodic it is required that all data exhibit no time-dependence in the ensemble (data-set) in any of the sta-tistical moments. Then the ensemble average would provide an accurate estimation of the drag value [7]. This conclusion supports the need to develop a new experimental procedure

for on-road testing of ground vehicles. We can apply Newton’s second law to establish an equation

governing ground vehicle dynamics. Let us consider that the traction force is equal to the sum of all resistive forces,

( ) sinT D edvF F v M Mgdt

θ= + + . (1)

The slope of the track, sinθ , can behave as a resistive or

traction effect depending upon the road slope. It can even be eliminated by choosing a flat road. The effective vehicle mass

eM comprises the actual mass M and the inertia of the rotat-ing components,

4

2 2 .gb fdwe

r r

I GIM MR R

= + + (2)

The inertia includes the inertia of four tires 4wI and also

the inertia of the gearbox gbI , with the corresponding final drive gear ratio being fdG . This later is related to the drive-train chain for the traction tires. We have also included the tire rolling radius as rR .

We can consider a flat road, were sin 0θ = . Then, in order to determine ( )DF v we have to find the other two terms in Eq. (1) or, alternatively, eliminate one of them and determine the other one. This is the approach used in the coast-down technique, in which TF is eliminated by making the traction force equal to zero. In the coast-down technique the drag is related to the time rate of change of linear momentum,

( )D edvF v Mdt

= − . (3)

As an alternative, the drag can also be obtained if we con-

sider a vehicle moving in a steady velocity, thus eliminating ( )eM dv dt . We get as a result an ordinary algebraic equation

( )T DF F v= . This equation is in the origin of the new method proposed in the present paper.

The coastdown test is usually performed by driving the ground vehicle above the maximum velocity, then the traction force is removed. The vehicle coasts freely until it reduces the velocity to a definite specified value, or until zero. By re-cording the velocity over time we are able to determine the drag characteristics. Since we already pointed out that the time rate of change of momentum is equal to resistive forces. The technique requires that several tests be undertaken for the same conditions, in order to achieve an adequate level of sta-tistical confidence on the results. Diverse approaches have been used to implement the coastdown test, most of them differing in the way measurements are made and, in particular, on the type of variables that are acquired [9]. The coast-down test can be performed by measuring the acceleration, the ve-locity, or displacement of the vehicle over a certain time. We can use any of the three cinematic variables. The tests made by measuring acceleration have the advantage of reducing the

Fig. 1. Graphical representation of the main dynamic forces acting onthe vehicle as a function of velocity. Here the aerodynamic drag is aquadratic function. Rolling force comprises a constant, a linear, and aquadratic zone.

J. C. Páscoa et al. / Journal of Mechanical Science and Technology 26 (6) (2012) 1663~1670 1665

complexity of the analysis procedure, because the acceleration can be readily applied to the differential equation, by using Eq. (1). However, in practice, the low levels of acceleration ob-tained on a coast-down experiment introduce errors that sig-nificantly affect this approach. Another alternative is thus to record velocity, but this introduces the need to differentiate the experimental curve in order to obtain the acceleration over time. In this method the accuracy of the differentiation proce-dure must be carefully monitored, since this differentiation step is prone to errors. Alternatively, the coastdown method can be performed by measuring the run distance over time. However, in this case the noisy integration procedure must be repeated twice. After decades of experience, experimentalists concluded that the best performance could be obtained with a velocity over time characteristic curve. In this case, the ex-perimental values of several runs are fitted to an adequate analytical function, which can then be differentiated to obtain the acceleration over time.

Using the coast-down approach we end up with a function representing resistive drag, see Eq. (3). The drag function comprises the mechanical and aerodynamic drag,

( )D M AF v F F= + . (4)

A major problem related to this method is the need to define

an adequate analytical function able to interpolate the experi-mental results, see Fig. 1. This is usually made by fitting a curve to the experimental results, whose general shape is,

aerodynamic dragmechanical drag

20 1 2( ) .DF v A A v A v= + + (5)

The mechanical drag comprises all the forces opposing the

movement except the aerodynamic drag. These include tire rolling and drive-train resistance. Other minor losses can be included, such as bearing friction and energy dissipated in the suspension. The tire rolling resistance accounts for 3/4 of the mechanical losses for a typical vehicle [10].

Generally speaking, the resistant torque of a free rolling tire divided by rolling radius is the tire rolling resistance. When the same tire acts in traction there is also slip between the tire and the road. It is usually accepted that the energy is dissi-pated in the tire by three mechanisms: hysteresis losses due to cyclic tire deformation; slip when in traction mode; and windage aerodynamic losses. However the windage losses are included in the aerodynamic component when performing the coastdown testing. Hysteresis losses are the main tire rolling resistance component, and are strongly dependent upon the normal load, inflation pressure, temperature, speed and road surface material.

The vehicle’s tires are usually made of a reinforced rubber exhibiting the behavior of a viscoelastic material. When they deform a portion of the energy is stored elastically, but the remainder is dissipated as heat due to a cyclic volume defor-mation of the tire material. However, the rolling resistance is

strongly dependent upon the speed, in particular due to hys-teresis. Fig. 2 presents the general shape of the rolling resis-tance as a function of velocity for commercial tires. We can perceive that above a critical velocity threshold there is a strong increase in rolling resistance. Actually, and for heavy-duty trucks, the rolling resistance has only a zero and second order dependence on speed [11]. According to Ref. [8] the temperature and deformation frequency increase with velocity. Thus, temperature introduces a reduction in rolling resistance. However, the deformation frequency has an opposite effect and acts in order to increase rolling resistance. This maintains the rolling resistance almost constant, with only a very smooth increase, see Fig. 1. But, above a certain deformation fre-quency the hysteresis effect introduces an increase in rolling resistance, since in that case it can no longer be compensated by the temperature increase.

In classical coastdown testing, Eq. (5), the quadratic evolu-tion of rolling resistance is usually neglected. Eventually, and at most, only a linear term is included to account for the roll-ing resistance increase with speed,

0 1( )RF Mg A A v= + . (6)

In Ref. [12] Smith et al. introduced a 2v term in their roll-

ing resistance model. Nevertheless, this 2v rolling resistance dependence will introduce problems when applying the coast-down testing, since the aerodynamic coefficients are also de-pendent upon the square of velocity. We can no longer sepa-rate the two terms when performing a curve fit for the experi-mental results [6]. The industry standard procedure for meas-urement of rolling resistance is depicted in SAE J1269 and ISO 8767. The SAE J1269 standard defines a four point test matrix with diverse load and pressure. Consequently, when applying a coast-down procedure we neglect higher order terms and only account for a linear variation in rolling resis-tance. Aerodynamic effects are incorporated in a quadratic curve coefficient,

2

0 1 2( )DF v A A v A v= + + , (7)

Fig. 2. Values of rolling resistance coefficient, as a function of veloc-ity, for typical commercial vehicle tires, adapted from Ref. [10].


( )D edvF v Mdt

= − . (8)

By considering the initial time as zero, we can integrate the

differential equation,

1 1

2 22 2 2

0 1 2

1[( ) ]

v ve

v v

Mt dv dvA A v A v vβ γ α

= =+ + + +∫ ∫ . (9)

The auxiliary variables are

22 0 1

22 24

A AA A

α = − , 2

e

AM

β = , 1

22AA

γ = (10)

and also,

z v γ= + . (11) Thus, we obtain,

1

22 2

1 z

z

dztzβ α

=+∫ . (12)

This can be integrated for 2 0α > , and will result in an

equation for 2v as a function of elapsed time,

( )

1

21

tan( )

1 tan

v tv

v t

γ αβαα γ

γ αβα

⎡ ⎤+⎛ ⎞ −⎜ ⎟⎢ ⎥⎝ ⎠⎢ ⎥= −+⎛ ⎞⎢ ⎥+ ⎜ ⎟⎢ ⎥⎝ ⎠⎣ ⎦

. (13)

This later equation can be used to generate a curve fitting

for the experimental results obtained using the coastdown procedure. In this way we can obtain the mechanical and aerodynamic resistance coefficients of Eq. (5).

3. An alternative to coastdown based on vehicle tow-

ing at constant velocity

Actually, and in alternative to coastdown, the drag charac-teristics of a vehicle can be obtained by towing, either at con-stant force or at constant velocity, see Fig. 3.

A classic application of the constant force towing is used to obtain the added mass of a complex body in a towing tank [13]. The constant velocity approach was used to compute the drag characteristics of high-drag devices, such as parachutes [14]. In this technique, the accurate measurement of the vehi-cle velocity is of great importance. Very small errors in their measurement could shift the data on the velocity axis, result-ing in significant errors for the magnitude of the vehicle’s forces [15].

In the present work, the proposed method is based on a con-stant velocity method, see Figs. 3 and 4. However, in order to obtain the aerodynamic drag we need to obtain the rolling resistance as a function of force.

As can be seen in Fig. 1, the total force is the graphical sum of aerodynamic and rolling resistance. However, and con-versely to coastdown method, in our new approach we do not need to eliminate the quadratic component in the rolling resis-tance. The new analytical equation is,

mechanical drag aerodynamic drag

2 20 1 2 3( ) .TF v A A v A v A v= + + + (14)

The rolling mechanical resistance can be obtained if we in-

troduce a shield in the aerodynamic component. This is repre-sented as,

without shield with shield

. . .( ) ( ) .T aero mech mechF v F F F= + − (15) This has the additional advantage of providing us with a

graph for the rolling resistance dependence on velocity. More-over, and with this technique, we can obtain an aerodynamic drag coefficient dependent on velocity ( )dC v . Using the clas-sic coastdown technique we only get a mean drag coefficient

dC . This average drag coefficient is also for an average veloc-ity, between the maximum velocity at which we remove the traction force and the final velocity to which the vehicle coasts. Since the velocity is non-linear, the average velocity is not the mean value between the initial and final velocity. The drag coefficient obtained by this procedure can be used to compare the aerodynamic performance of diverse vehicles, driving between the same speeds. However, for vehicles working in the transitional Reynolds number this method is not applicable, since drag coefficient changes significantly with velocity. Also, and to be able to compare the experiments with CFD

(a)

(b)

Fig. 3. Towing of a vehicle: (a) constant velocity using an electric motor; (b) constant force using a weight.

Fig. 4. Method used to obtain the rolling resistance as a function of velocity. The test vehicle is towed by another car at constant velocity.


results we do need a velocity dependent drag coefficient, since numerical results are obtained for a specified velocity.

4. Demonstration of the new experimental procedure

for an Eco-marathon vehicle

The Eco-marathon vehicle was completely designed, and built, at University of Beira Interior, see Fig. 5. The main pur-pose of the Shell Eco-marathon competition is to obtain reduced fuel consumption for the vehicle. However, the test vehicle was mainly designed to compete in the aesthetically design competi-tion, also a component of Shell Eco-Marathon competition. This resulted in a less performing vehicle, since more attention was paid to aesthetics at the cost of mechanical and aerodynamic performance reduction. Incidentally, this provided a good test case for aerodynamic performance improvements.

4.1 Data acquisition and instrumentation

Besides the test vehicle, the main component of the system set-up for measurements is the shield. This is to be used in the procedure of acquiring the rolling mechanical force as a func-tion of velocity.

A load cell was used to acquire the force between the test vehicle and the towing traction vehicle. Two strain-gauges are

mounted together in order to perform temperature compensa-tion. The output signal from strain-gauges is further condi-tioned using an instrumentation amplifier based on Texas In-struments “LM124”. The amplified voltage is then feed into one of the analogue channels of a PicoScope board. This later is then connected to a laptop that is carried inside the test ve-hicle. The 50 Newton load cell was calibrated using dead weights, and the corresponding calibration curve allows one to transfer the acquired amplified voltage into force values de-fined in Newtons, ( ) 0001022 ( ) 1.5901738Y V X N= − + . The precision of the data acquisition chain was checked, the error is less than 2%. A roller was used to provide cable force sub-division, allowing us to measure higher values of force.

The second variable to be measured is velocity. Velocity was measured by means of an inductive sensor. Instead of only one, we have used eight magnets equally distributed on the internal surface of the tire. This increased the precision of the velocity measurement. Oscillatory pulsed signals, from the inductive sensor, as it passes by the magnets were acquired by a second analogue input of the PicoScope. This allowed a very fine resolution of velocity with an error of less than 1%.

The PicoScope system allowed us to synchronize the veloc-ity and force. This is very important to achieve a good preci-sion in the force measurements, see Fig. 6. Both signals were saved into a laptop carried within the test vehicle. Data files were treated using a Matlab computer code. The code imple-ments the calibration curve for force and translates the pulse width signals, of the inductive transducer, into linear velocity. In this later case, the code scans for the peaks in the inductive voltage and computes the period between consecutive peaks T(t). These are constantly changing in time. Then, by knowing the radius we obtain instantaneous velocity ( ) 2 8 ( )v t R T tπ= . The vehicle is initially accelerated into a pre-defined velocity; the velocity is then maintained constant until the vehicle is decelerated at the end of track. Average velocity and force are computed for the curve plateau.

Several velocity plateau values can be used to obtain dis-crete values for the ( )dC v and ( )rC v . The precision of the method is strongly dependent on the ability of the towing ve-hicle to maintain constant velocity. In our experiments a vehi-cle equipped with a special sports gearbox was used to main-tain the constant velocity. A longest track length allows ob-

(a)

(b)

Fig. 5. Experimental on-road constant velocity test: (a) Towing atconstant velocity without shield using a very thin cable. The totalresistance is obtained in subsequent tests using a towing vehicle at adistance 10 times the towing vehicle length, to reduce towing vehicleinterference; (b) The vehicle is shielded in order to determine the roll-ing resistance component.

Fig. 6. Graph representing a test run performed for the Eco-marathon vehicle. It is evident the importance of keeping a synchronization between the velocity and force. This allows averaging the force only in the constant velocity plateau.


taining a longer plateau curve, which will significantly con-tribute to achieve better precision in the force measurements.

4.2 Results obtained for the Eco-marathon vehicle

The Eco-marathon vehicle was tested using the procedure highlighted in the previous sections. The Eco-marathon com-petition rules impose that the vehicle can not exceed 50 km/h, and should achieve a mean velocity around 25 km/h. Since the vehicle has 3 meters long and 1 meter height, then Re=4.6x105, based on the characteristic vehicle height and at 25 km/h. This means that the flow around the Eco-marathon vehicle is in the critical Reynolds number region, where drag coefficient defi-nitely is not a constant. The only technique able to extract the

( )dC v is the herein proposed method. We already noticed that the coastdown method results in averaged Cd values be-tween the coasting velocities.

Fig. 7 presents the results obtained for total force as a func-tion of velocity. This experimental curve is presented in di-mensional quantities in order to be able to compare with Fig. 1. For each of the 13, constant velocity, on-road tests we present the average force, and velocity, according to the procedure depicted in Fig. 6. Albeit we have imposed a definite velocity for the vehicle, the final actual test velocity is only obtained in the end from the averaging procedure.

In Table 1 we present the results obtained for the rolling co-efficient, and drag coefficient, as a function of Reynolds num-ber. Here it is evident that the use of a coastdown approach is not adequate to determine the drag coefficient at these low Re conditions, in particular because it only gives a mean value for the drag coefficient. It is now evident that there is a continu-ous increase of the rolling coefficient as a function of velocity.

The same holds true for the drag coefficient, the obvious con-clusion is that we are in the transitional regime where signifi-cant changes is aerodynamic drag coefficient take place as a function of Reynolds number.

One of the drawbacks of the present approach is related to the need to insure no wind conditions, which can compromise the accuracy of total resultant force. By performing a repeat-ability test we end up with variations of around 4% in the total force measurement. These can be due to minor wind effects during track testing, and also to minor changes when trying to pursue the same path of the track test. This later is important to ensure repeatability of rolling force coefficients.

5. Conclusions

In the present work we have proposed an alternative ap-proach to the standard on-road coastdown test used in automo-tive industry and in ground vehicle research.

A detailed description of both methods is provided in order to highlight the advantages and drawbacks of each one. A most desirable feature of the present approach is its ability to provide the rolling and aerodynamic drag coefficients as a function of velocity. These values are important if we intend to compare on-road tests to computational results, since these are usually obtained for a predefined velocity. Changes in drag coefficient are mostly noticed in the critical transitional flow regime. Further, the present approach also enables to accu-rately incorporate the quadratic change in rolling resistance, since this is usually not taken into account in coastdown tests.

The new approach was implemented in order to compute the rolling and aerodynamic coefficients for an Eco-marathon vehicle designed and built at University of Beira Interior. The approach successful demonstrated the ability of the method to define the most adequate drive velocity for the vehicle. Since one of the primary goals of Eco-marathon competition is to achieve a reduction in fuel consumption. The definition of the most efficient driving speed, i.e. lower drag and rolling resis-tance, is very important to achieve good results.

Acknowledgment

This work was supported by CAST-Center for Aerospace Science and Technology, FCT Research Unit Nº151.

Nomenclature------------------------------------------------------------------------

A : Projected frontal vehicle area [m2]

Cr : Rolling coefficient rr

FCMg

=

Cd : Drag coefficient aero.20.5 vd

FCAρ

=

FD. : Aerodynamic drag [N] FM : Mechanical forces [N] Fr : Rolling force [N]

Table 1. Results for the rolling and aerodynamic coefficients obtained for the Eco-marathon vehicle.

Re Cr(v) Cd(v)

1.46x105 0.025 0.398

3.66x105 0.030 0.433

5.66x105 0.041 0.423

Fig. 7. Results obtained for 13 test runs, each of constant velocity, between 12.24 km/h and 32.4 km/h. A linear and a quadratic curve fitting were attempted. Results are for total force, including the aero-dynamic and rolling mechanical components.


FT : Tractive force acting on the vehicle [N] Gfd : Drive-train ratio H : Vehicle height [m] I4w : Inertia of four tires [m4] Igb : Inertia of the gear-box [m4] Me : Effective vehicle mass [kg]

Re : Reynolds number vHReν

=

Rr : Tire rolling radius [m]

References

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José Carlos Páscoa is currently an Assis-tant Professor at University of Beira Inte-rior in Portugal. He conducts research at the nationally funded Center for Aero-space Sciences and Technology, where he also serves as the secretary of the center’s scientific council. His main research inter-ests are numerical and experimental aero-

dynamics José Páscoa holds a doctorate degree in Mechanical Engineering. Since 1997, he has been involved in several re-search projects. In 2002, he was a visiting academic at Rolls-Royce UTC of Loughborough University in UK.

Francisco Brójo is a tenured Assistant Professor on the Department of Aero-space Sciences of the University of Beira Interior and a member of the Aeronautics and Astronautics Research Center (AeroG) and of the Associated Laboratory for Energy, Transports and Aeronautics (LAETA). He graduated in

Mechanical Engineering (1991) at Coimbra University (Por-tugal), specialized in Energy (1996) at Beira Interior Univer-sity (Portugal), and received his PhD in Mechanical Engineer-ing (2004) at Cranfield University (UK). His current research interests include propulsion systems, internal combustion en-gines, heat transfer and industrial maintenance. Prof. Brójo is member of the American Institute of Aeronautics and Astro-nautics and the Portuguese Society of Mechanical Engineers.


Fernando C. Santos is an Assistant Professor in the Department of Electromechanical Engineering of the University of Beira Interior and a member of the Industrial Management and Engineering Research Centre and of the Technological Forecasting and The-ory Research Group. He graduated in

Industrial Production and Management Engineering (1995) at Beira Interior University (Portugal). He received an MSc in Mechanical Engineering at Beira Interior University in 2001 and his PhD in Production Engineering (2009). During this period he was coordinator of more than a dozen of applied research projects in the processes optimization and operations scheduling always in industrial environment.

Paulo Fael is an Assistant Professor on the Department of Electromechanics Engineering of the University of Beira Interior and a member of CAST- Center for Aerospace Sciences and Technology. He graduated in Mechanical Engineer-ing (1983) at Coimbra University (Por-tugal), and received his PhD in Me-

chanical Engineering (2007) at Beira Interior University (Por-tugal). His current research interests include Polymeric Com-posites, dynamics and structures of vehicles and mechanics of materials.

an innovative experimental on-road testing method and its

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