Impacting mechanism and system for characterization of materials

Abstract

An impacting mechanism for non-destructively testing a sample of material, has: an actuator having a movable member, the actuator configured to move the movable member relative to the sample; a impactor configured for impacting the sample along an impact direction; and a resilient member, the impactor connected to the movable member of the actuator via the resilient member, the resilient member having a stiffness in a direction having a component along the impact direction, the stiffness selected to allow the impactor to bounce off from the sample following an impact between the impactor and the sample to avoid a double impact of the impactor against the sample.

Description

IMPACTING MECHANISM AND SYSTEM FOR CHARACTERIZATION OF MATERIALSCROSS-REFERENCES TO RELATED APPLICATIONS

[0001] The application claims benefit from United States provisional application No. 63 / 726,275 filed on November 28, 2024, the entire contents of which are incorporated by reference herein.TECHNICAL FIELD

[0002] The application relates generally to materials and, more particularly, to systems and methods used to perform non-destructive testing on materials to characterize said materials.BACKGROUND

[0003] Modal analysis of materials require impacting the material with an impactor, such as a hammer. Different systems exist to do so, such as a pendulum system. Sensors, such as accelerometers, are used to record a response of the material to the impact by the impactor. Although existing systems for carrying such modal analysis are satisfactory to some extent, they often lack versatility and repeatability. Hence, improvements are sought.SUMMARY

[0004] There is disclosed a characterization system having an impacting mechanism including a bi-directional actuator, such as a solenoid, equipped with a piston. A resilient member, such as a metallic blade, is secured to an end of the piston and an impactor is secured at a free end of the resilient member. The system may include a positioning mechanism including rails configured for moving the impacting mechanism in three dimensions for proper alignment with a material to be characterized. A linear micrometric system may be used for fine tuning the position of the impactor relative to the material to be characterized. The system may include an electronic circuit including a H-bridge to feed the impacting mechanism. A controller, such as an Arduino™, may be used to control operations of the system. The three parts described above may be modular and each part may be adapted to a specific application. Influence of each parameters, such as distance travelled by the impactor, speed of impactor at the impact, thickness and length of the resilient member, distance between impactor and target, on the impacts may be determined.

[0005] In one aspect, there is provided an impacting mechanism for non-destructively testing a sample of material, comprising: an actuator having a movable member, the actuator configuredto move the movable member relative to the sample; a impactor configured for impacting the sample along an impact direction; and a resilient member, the impactor connected to the movable member of the actuator via the resilient member, the resilient member having a stiffness in a direction having a component along the impact direction, the stiffness selected to allow the impactor to bounce off from the sample following an impact between the impactor and the sample to avoid a double impact of the impactor against the sample.

[0006] The impacting mechanism described above may include any of the following features, in any combinations.

[0007] In some embodiments, the resilient member extends transversally to the impact direction from a first end mounted to the movable member of the actuator to a second end mounted to the impactor.

[0008] In some embodiments, the resilient member is bending upon impact of the impactor against the sample, the stiffness being a flexural stiffness.

[0009] In some embodiments, the resilient member is a metallic blade.

[0010] In some embodiments, the metallic blade is made of steel.

[0011] In some embodiments, the flexural stiffness ranges from 200 n / m to 800 n / m.

[0012] In some embodiments, the actuator is a bi-directional solenoid.

[0013] In some embodiments, the impacting mechanism for non-destructively testing a sample of material further includes a first adaptor for securing the resilient member to the impactor; and a second adaptor for securing the resilient member to the movable member of the actuator.

[0014] In another aspect, there is provided a system for non-destructively testing a sample of material, comprising: an impacting mechanism having: an actuator, a impactor configured for impacting the sample along an impact direction, and a resilient member interconnecting the impactor to the actuator and configured for providing a degree of freedom to the impactor relative to the actuator to allow the impactor to bounce off from the sample following an impact between the impactor and the sample to avoid a double impact of the impactor against the sample; a sensor operatively connected to the sample; and a controller operatively connected to theimpacting mechanism and to the sensor, the controller having a processing unit and a computer- readable medium having instructions stored thereon executable by the processing unit to: cause the impacting mechanism to impact the sample with the impactor, receive a signal from the sensor, the signal indicative of a response of the sample to the impact with the impactor, and characterize the sample based on the response of the sample to the impact.

[0015] The system described above may include any of the following features, in any combinations.

[0016] In some embodiments, the computer-readable medium has the instructions stored thereon to characterize the sample by: determining one or more of resonance frequencies of the sample, mode shapes, damping coefficient, a complex modulus of the sample, and a complex poisson’s ratio of the sample.

[0017] In some embodiments, the resilient member extends transversally to the impact direction from a first end mounted to a movable member of the actuatorto a second end mounted to the impactor.

[0018] In some embodiments, the resilient member is bending upon impact of the impactor against the sample, the resilient member having a flexural stiffness selected to allow the impactor to bounce off from the sample following the impact.

[0019] In some embodiments, the resilient member is a metallic blade.

[0020] In some embodiments, the metallic blade is made of steel.

[0021] In some embodiments, the flexural stiffness ranges from 200 n / m to 800 n / m.

[0022] In some embodiments, the actuator is a bi-directional solenoid.

[0023] In some embodiments, the system for non-destructively testing a sample of material includes a thermal chamber having a heating / cooling system operable to vary a temperature inside the thermal chamber, the impacting mechanism contained in the thermal chamber.

[0024] In some embodiments, the system for non-destructively testing a sample of material includes a positioning mechanism, the impacting mechanism mounted to the positioning mechanism, the positioning mechanism configured for moving the impacting mechanism relative to the sample.

[0025] In yet another aspect, there is provided a method for non-destructively testing a sample of material, comprising: moving an impactor towards the sample with an actuator; after an impact between the impactor and the sample, causing the impactor to bounce off the sample by deformation of a resilient member used as an interface between the actuator and the impactor to avoid a double impact against the sample; and moving the impactor away from the sample with the actuator.

[0026] The method described above may include any of the following features, in any combinations.

[0027] In some embodiments, the causing of the impactor to rebound with the resilient member includes allowing the impactor to rebound with the resilient member having a flexural stiffness ranging from 200 to 800 n / m.DESCRIPTION OF THE DRAWINGS

[0028] Reference is now made to the accompanying figures in which:

[0029] Fig. 1 is a schematic view of a non-destructive characterization system;

[0030] Figs. 2A-2B are a schematic views of a circuit for controlling an actuator of the system of Fig. 1 ;

[0031] Fig. 3 is a three-dimensional view of a positioning mechanism of the system of Fig. 1 ;

[0032] Fig. 4 is a side view of an impacting mechanism of the system of Fig. 1 ;

[0033] Figs. 5A and 5B are three dimensional views of adaptors to secure an impactor to the actuator of the system of Fig. 1 ;

[0034] Figs. 6A to 6D are three dimensional and side views of an adaptor in accordance with another embodiment to secure the impactor to the actuator of the system of Fig. 1 ;

[0035] Figs. 7A to 7E are graphs illustrating results of the characterization performed with the system of Fig. 1 ;

[0036] Fig. 8 is a flowchart illustrating steps of a method of non-destructively testing a sample of a material; and

[0037] Fig. 9 is a schematic representation of a controller for the system of Fig. 1 .DETAILED DESCRIPTIONIntroduction

[0038] Impact resonance tests are modal analysis methods used to characterize materials. By causing an impact on the material being tested, its vibrational response is analyzed in the form of a frequency response function, from which resonance frequencies and damping are extracted to determine the desired characteristics of the material. Bituminous materials, as viscoelastic materials, may be characterized by two essential parameters: the complex modulus and the complex Poisson’s ratio, which can be extracted through an impact resonance test.

[0039] The manual execution of the impact in an impact resonance test presents various limitations such as insufficient precision (location of the impact point, angle between the hammer and a specimen of the material, etc.), non-repeatability (especially in terms of force and impact duration), the necessity of human interventions, and the inability to perform the test in a thermal chamber for materials whose properties are temperature-dependent / sensitive. To overcome these challenges, the system presented in this disclosure aims to automate these tests. To this end, an automated impact system has been developed and is presented herein.

[0040] The system may have the following mechanisms: an impact mechanism including an actuator, which may be an electromagnet, coupled to a resilient member, such as a metallic blade or any suitable resilient member as will be discussed below, and an impactor, such as a hammer, secured to a free end of the resilient member; a controller for controlling the actuator; and a positioning mechanism for positioning the impactor at a desired location relative to a sample to test. It will be appreciated that the positioning mechanism may be well suited when it is desired to characterize a material while contained in a thermal chamber, but may be omitted in some configurations.

[0041] In the field of road infrastructure, evaluating the condition of pavements is performed to prevent their degradation and mitigate traffic interruptions due to maintenance work. Therefore, methods to diagnose the condition of pavements without altering them may be beneficial. In an embodiment among others, the present disclosure pertains to a method for verifying the condition of pavements using a dynamic method: the impact resonance test. Other uses are contemplated. A mechanical impact may be applied on a bitumen specimen and the frequency response may be analyzed using an accelerometer or other suitable sensors. It may be particularly desired toperform impact resonance test on asphalt mixes used on roads. These mixes are the top layer of the roads against which vehicles are in contact and may be the first to degrade over time.

[0042] Although the present disclosure pertains to bitumen specimen, it will be appreciated that the disclosed systems and methods may be used for any material to be non-destructively tested and / or characterized.

[0043] These asphalt mixes are temperature-sensitive in that their properties may vary with temperature variations. At low temperatures, asphalt mixes are stiff and fragile, which increase risk of failure under the combined influence of traffic and temperature. This may be alleviated by using asphalts having a lower temperature below which risks of failure increase. However, these asphalts may be susceptible to rutting, which are permanent deformations, at high temperatures.

[0044] These asphalt mixes may also exhibit non-linear viscoelastic characteristics when subjected to deformations of small amplitudes and to a low number of cycles. It may therefore be required to measure the complex module and / or the complex Poisson’s ratio. A modal analysis may be used for this purpose. Modal analysis is a technique used to study the natural vibration modes of a mechanical system. It is based on evaluating the dynamic characteristics of a system, such as its resonance frequencies, mode shapes, and / or damping coefficient. In some variants, to observe a large part of the resonance spectrum, the system may need to be excited by random excitation (e.g., white noise) or by an impulse. The results of this analysis are represented by a frequency response function.

[0045] In materials science, the complex module is a property of viscoelastic materials that describes their response to oscillatory (dynamic) loading. It combines two components: storage modulus (E' or G'), which represents the elastic (energy-storing) part of the material’s behavior — essentially its stiffness, and the loss modulus (E" or G"), which represents the viscous (energydissipating) part — essentially its damping capability. This concept is used in Dynamic Mechanical Analysis (DMA) to characterize polymers, composites, and other viscoelastic materials under cyclic stress. It reflects both stiffness and damping, which vary with frequency and temperature.

[0046] The standard Poisson’s ratio (v) is the negative ratio of transverse strain to axial strain. It measures how much a material contracts laterally when stretched longitudinally (or expands laterally when compressed). For most materials, v ranges from 0 to 0.5, but auxetic materials can have negative values (they expand laterally when stretched). The complex Poisson’s ratio extends this concept to dynamic or viscoelastic conditions, where strains are time-dependent andout of phase with applied stress. In such cases the ratio becomes frequency-dependent and may be represented as a complex quantity combining the in-phase component (elastic response) and the out-of-phase component (viscous response). This is particularly relevant for advanced materials like polymers, composites, and metamaterials under oscillatory loading.

[0047] Impact resonance testing is a specific technique in the field of modal analysis. It involves applying an input force impulse (e.g., impact) and then studying the resulting vibrations exhibited by the material being tested to determine the material’s resonance frequencies and damping through a frequency response function (FRF). The system presented in the present disclosure aims to automate this type of test on asphalt mix samples, but this test may be applied to other materials as well.

[0048] Typical testing of bituminous specimen includes placing the specimen on a foam or other suitable support to support its weight without affecting or restricting its vibration modes. In other words, the specimen is disposed to achieve free boundary conditions. An accelerometer is attached to one of the faces of the specimen, and the impact is carried out using an impact hammer equipped with a force sensor. The force sensor may be used to quantify a magnitude of the impact force. This may help in characterizing the material using the signal generated by the force sensor. These two sensors (e.g., the accelerometer and the force sensor) are connected to a signal conditioner, which is itself connected to a data acquisition module that allows the digitization and transmission of signals to a controller, also referred to as a computer. Understandably, other sensors are considered as discussed below. A thermal chamber may be used to expose the specimen tested to a desired temperature.

[0049] A plurality of factors may influence the quality of the results following such impact resonance testing. These factors include, for instance, the impact force, the angle between the impactor and a surface of the specimen, the location of the impact. These highlight the need for a more automate solution.

[0050] An impact that could be assimilated to a Dirac impulse may be preferred, as it may provide information over a wider frequency spectrum. However, experimentally, producing such impacts is challenging since the contact time between the impactor and the specimen cannot be zero. The longer the duration of the impulses, the more limited the frequency content of the signals; higher frequencies are less excited. It has been observed by the inventors of the presentdisclosure that the duration of the impact may be an influential parameter, if not the most influential parameter, to determine the cutoff frequency of the force spectrum.

[0051] When a resonance frequency is no longer included in the force bandwidth, it disappears from the acceleration spectrum. This is why it may be desired to minimize the duration of the impact to widen the system’s bandwidth and thus allow the visualization of high-frequency resonance peaks.

[0052] There is thus disclosed herein a characterization system configured to accurately position an impact point between the impactor and the sample, to accurately orient the impactor relative to a surface of the specimen, to control the impact force, to select a temperature to carry the testing, and / or to permit an adjustment of the impact force.

[0053] For modal analysis, it is desired to have a system able to repeatedly impact a material at precise locations in determined directions. It may be desired to precisely control amplitudes and durations of the impacts on the material. It may also be desired to remotely trigger the impacts to generate testing at different temperature within a thermal enclosure to test materials that have properties that vary with temperature variations.Characterization system

[0054] Referring to Fig. 1 , a characterization system is shown at 10. The system 10 includes a thermal chamber 11 for receiving a sample S to be characterized. It will be appreciated that, in some embodiments, the thermal chamber 11 may be omitted. The thermal chamber 11 may include a heating / cooling system 12 configured for controlling a temperature inside the thermal chamber 11 . The heating / cooling system 12 may include a heating element, an air conditioning unit, and so on. Any suitable heating / cooling system may be used. An impacting mechanism 20 of the system 19 may be located inside the thermal chamber 1 1 if the latter is present. The impacting mechanism 20 may include an actuator 21 connected to a resilient member 22, which is itself connected to an impactor 23. A controller 30 is operatively connected to the actuator 21 and to the heating / cooling system 12. The controller 30 is optionally configured to trigger the impact generated on the sample S (trigger could be performed in other ways) and to control the temperature inside the thermal chamber 1 1 (if present). One or more sensor(s) 31 are operatively connected to the sample S and to the controller 30. The impactor 23 may also be equipped with a sensor operatively connected to the controller 30 to determine a force of the impact on the sample S. The one or more sensor(s) are configured to generate a signal to the controller 30; thesignal being indicative of a response of the sample S to the impact induced by the impactor 23 with the actuator 21 . A positioning mechanism 40 may be operatively connected to the controller 30 and used to set the impacting mechanism 20 into position relative to the sample S. Again, in some embodiments, the positioning mechanism 40 may be omitted.

[0055] It will be appreciated that, although only one controller 30 is illustrated, each of the different components of the characterization system 10, such as the heating / cooling system 12, the positioning mechanism 40, and the impacting mechanism 20 may each include a respective controller to control them independently. A central controller may coordinate the controlling of all of these other individual controllers. Moreover, the impacting mechanism 20 may be made available without the controller 30.

[0056] In the embodiment shown, the actuator 21 is a bi-directional solenoid. A bi-directional solenoid is configured to move a movable member relative to a housing with a magnetic field. A coil is disposed within the housing and extends around the movable member. By selecting a polarity applied to the coil, it is possible to select a direction of movement of the movable member relative to the coil / housing. Typically, these bi-directional solenoids are devoid of a biasing member engaged to the movable member and rely solely on the magnetic field to move the movable member in both opposite directions. In some alternate embodiments, the actuator 21 may be a piezoelectric actuator. The actuator 21 may be fed by a source of power ranging from 5W to 15W and may have a distance of travel of about 4-6 mm. In the context of the present disclosure, the expression “about” implies variations of plus or minus 10%. As will be discussed below, an electric circuit (e.g., H bridge circuit) may be used to change the direction of movement of the movable member of the bi-directional solenoid. Any linear actuator having a fast response time, able to generate precise movements, and able to generate sufficient force (e.g., about 150 N) may be used without departing from the scope of the present disclosure.

[0057] Referring to Fig. 2A, an electric circuit for the impacting mechanism 20 is shown at 200. The circuit 200 is an H-bridge circuit and includes two power inlets V1 , V2 that are operatively connected to the controller 30. The circuit 200 then includes four transistors X1 , X2, X3, X4 configured to be controlled by the controller 30 to selectively permit or block current transmission. The bi-directional electro magnet is represented by a coil L1 and resistances R7, R8. Four diodes D1 , D2, D3, D4 are used to protect the four transistors X1 , X2, X3, X4.

[0058] In some cases, the response of the bi-directional solenoid is not instantaneous since a certain period of time is required for the current inside the coil to increase. Thus, the magnetic force generated by the coil may be proportional to this current and may take some time to be at its full strength. This time may be function of the time constant of the system. An eighth resistance R8 may be added in serial to the bi-directional solenoid to diminish this time constant. The input voltage may be increased to 48 V to maintain the current in steady state to about 3 A. However, these details are a mere example of a setup, and other circuitry arrangements and operation parameters could be used.

[0059] Fig. 2B illustrates one of the transistors, labelled “Xi” in Fig. 2B, used in the circuit of Fig. 2A. To be able to commute different high intensity current, Darlington transistors are used. These Darlington transistors are, in fact, a combination of two transistors of the same kind. A Darlington transistor is thus a hybrid component. It will be appreciated that the circuits depicted in Figs. 2A-2B are exemplary and any suitable circuits may be used without departing from the scope of the present disclosure.

[0060] Referring now to Fig. 3, the positioning mechanism 40 is described in greater detail. The positioning mechanism 40 may be located inside the thermal chamber 11 , if present. It may include a base 41 for supporting a frame 42. The base 41 may be a plate as depicted, or may be a floor, a table, a wall, and so on onto which the frame 42 may be secured. The base 41 may be part of an enclosure of the thermal chamber 11. The frame 42 may or may not have different interconnected frame members to support a movable fixture 43 that holds the impacting mechanism 20. In the embodiment shown, the frame 42 includes a vertical frame member 42A protruding from the base 41 and a horizontal frame member 42B extending transversally from the vertical frame member 42A. The movable fixture 43 may be slidably engaged to the horizontal frame member 42B and is movable relative thereto to adjust a position of the impacting mechanism 20 relative to the sample S. In some embodiments, only one of the vertical and horizontal frame members may be used depending of the degrees of freedom of movement that are desired in positioning the impacting mechanism 20 relative to the sample S, with an option of having no adjustments possible. This may vary with the kind of samples being tested. The movable fixture 43 may alternatively be slidably engaged to the vertical frame member 42A. Any suitable number of frame members may be used to adjust the position of the impacting mechanism 20 relative to the sample S. Movements of the movable fixture 43 may be induced by one or more actuator 45 engaged to the frame 42 and to the movable fixture 43. These actuators are optionally present, as positional adjustments of the movable fixture 43 may be done manually.These actuators may include, for instance, a motor driving a belt secured to the movable fixture, rack and pinion gears, pulleys, and so on. Fasteners 44 may be used to fix the position of the movable fixture 43 once a desired position has been attained. It will be appreciated that the positioning mechanism disclosed herein is exemplary only and that other configurations are contemplated.

[0061] Referring now to Fig. 4, the impacting mechanism 20 is described in more detail. The impacting mechanism 20, as mentioned above, includes the actuator 21 , which is, in this embodiment, a bi-directional solenoid. Although the below description will focus on the bidirectional solenoid, other kinds of actuating means may be used as elaborated above. The actuator 21 includes a housing 21A secured to the positioning mechanism 40 and a movable member 21 B, such as a shank, slidably received within the housing 21 A and movable relative thereto. The actuator 21 is used to cause the impactor 23 to impact the sample S. The housing 21 A houses coils 21 C configured to move the movable member 21 B relative to the housing 21 A. While the expression housing 21 A is used, the presence of a housing 21 A may be optional, as other supporting structures may be present for the actuator 21 to move its movable member 21 B relative to a structure. The actuator may be configured to cause a rotational movement of the impactor 23 rather than a linear movement in some embodiments. However, care should be taken to ensure that effects of gravity or other considerations are taken into account.

[0062] However, the inventors of the present disclosure observed that, in some cases, the impactor 23 may create double impacts on the sample S. These double impacts may be detrimental to the data gathered by the controller 30 of the characterization system 10. In other words, the double impact may render the data inaccurate or faulty. These double impacts may be caused by delays within the electronic circuit that control the actuator 21. Put differently, the actuator 21 may not be able to withdraw the impactor 23 away from the sample S fast enough to avoid the impactor 23 from impacting the sample S a subsequent time afterthe initial impact (e.g., bouncing on the sample S). Moreover, the hardness of the materials of the impactor 23 and of the sample S can cause the impactor 23 to not withdraw fast enough and thus cause an impact time to be greater than desired.

[0063] To at least partially alleviate this drawback, the impactor 23 is secured to the movable member 21 B via the resilient member 22. The resilient member 22 is configured to render more compliant (e.g., more flexible) a connection between the actuator 21 and the impactor 23. The resilient member has a stiffness in a direction having a component along an impact direction. Theimpact direction may be defined as a direction of a movement of the impactor 23 when it impacts the sample S. In the embodiment of Fig. 4, the impact direction may be normal to a surface of the sample S being impacted, although other angles may be used in some cases. In a variant, the impact direction is substantially horizontal. The stiffness of the resilient member 22 is selected to allow the impactor to bounce off from the sample S following the impact between the impactor 23 and the sample S to avoid a double impact of the impactor 23 against the sample S. The bouncing off of the impactor 23 may exhibit a greater amplitude than it would if the resilient member 22 were absent. Any suitable resilient member exhibiting a stiffness as discussed above and in a direction having a component along the impact direction may be used. For instance, a spring may be used. In some embodiments, an elastomeric material may be used. It will be appreciated that the direction of the stiffness is mainly along the impact direction. Herein, the expression “mainly” implies 50% or more. The direction of the stiffness may be fully along the impact direction.

[0064] The resilient member 22 is, in this embodiment, a metallic blade, but any resilient member able to elastically deform and revert back to its at-rest shape once a force applied thereto has been removed may be used. For instance, a plastic member may be used. Put differently, the resilient member 22 is configured to allow the impactor 23 to bounce off the sample further away than if no resilient member 22 were used. The resilient member 22 is therefore used to limit a restriction to a movement of the impactor 23 following the impact with the sample S. It provides the impactor 23 an ability to move relative to the movable member 21 B of the actuator 21. It provides a degree of freedom between the movable member 21 B and the impactor 23. In other words, the resilient member 22 is selected to avoid causing a rapid double impact against the sample S which would be detrimental in the analysis of the results, i.e., the double impact may be avoided.

[0065] In the embodiment shown, the resilient member 22, is a resilient metallic blade having a thickness of about from 0.2 mm to 0.5 mm and is made of steel. Understandably, other thicknesses may be used if a different material is used for the resilient blade, or if the same material is used, but with an impact force having a different magnitude. Stated otherwise, the resilient member 22 may be any suitable member having a flexural stiffness selected to allow the impactor 23 to bounce off sufficiently far from the surface of the sample S after an impact to avoid a double impact. In some embodiments, the flexural stiffness ranges from about 200 N / m to about 800 N / m. The flexural stiffness may be varied depending of the actuator, the sample tested, the force required at impact, and so on.

[0066] The resilient member 22 may alternatively be referred to as a rebound inducer since it is configured to allow the impactor 23 to bounce off the sample S following an impact therewith. Any suitable rebound inducer may be used. It may be a spring or any other member able to provide the impactor 23 with the ability to move relative to the movable member of the actuator.

[0067] In the context of the present disclosure, the expression “flexural stiffness” or “bending stiffness” represents resistance of the resilient member 22 against bending deflection / deformation when subjected to a force applied in a direction parallel a direction of travel of the impactor 23. In other words, the flexural stiffness is a resistance of the resilient member 22 to a force applied in a direction of the impact between the impactor 23 and the sample S. The flexural stiffness may be function of a length of the resilient member 22 defined between a first attachment point to the actuator 21 and a second attachment point to the impactor 23; a thickness of the resilient member 22, a Young’s modulus of a material of the resilient member 22, and a second moment of inertia, which is function of a cross-sectional shape (e.g., square, rectangle, etc) of the resilient member 22.

[0068] In the present embodiment, the bi-directional solenoid or other actuator 21 is powered to move the impactor 23 in a first direction until it impacts the sample S and then powered to move the impactor 23 in a second opposite direction. The resilient member 22, by being deformable, permits the impactor 23 to rebound on the sample S far enough to give enough time for the solenoid to start withdrawing the impactor 23. Thus, the combination of the fast reaction time of the solenoid 21 and the rebound effect permitted by the resilient member 22 may contribute to keep a time duration during which the impactor 23 is in contact with the sample S as short as possible. Stated differently, the resilient member 22, by allowing the bouncing off of the impactor 23 on the sample S, compensates for a lack of responsiveness of the solenoid or equivalent actuator 21 and electric circuit to avoid a second impact by the impactor 23.

[0069] Still referring to Fig. 4, the impactor 23 includes an effector end 23A that will contact the sample upon impact, and one or more sensors 23B configured for measuring a force of the impact. The one or more sensors 23B may include one or more of a laser sensor, a microphone, an accelerometer, a geophone, a piezoelectric sensor, and so on. Any sensor able to provide a signal indicative of a force of an impact generated between the impactor 23 and the sample S may be used. These same type of sensors (e.g., a laser sensor, a microphone, an accelerometer, a geophone, a piezoelectric sensor, and so on) may be operatively connected (e.g., affixed) to the sample S to measure a response of the sample S to the impact.

[0070] Any suitable fastening means, such as glue, may be used to secure the resilient member 22 to both of the actuator 21 and the impactor 23. In the embodiment shown, two threaded inserts 26 are used. One of the two threaded inserts 26 is glued directly on the impactor23 and the other of the two threaded inserts 26 is glued on the movable member 21 B of the actuator 21 . The two threaded inserts 26 receive each a respective correspondingly-threaded fastener to secure the resilient member 22 to the movable member 21 B and to the impactor 23. In other words, these inserts 26 provide an interface via which a threaded fastener may be used to secure the resilient member 22 to the movable member 21 B and to the impactor 23.

[0071] Referring to Figs. 5A-5B, in some embodiments, a first adaptor 24 is used for securing the resilient member 22 to the impactor 23 and a second adaptor 25 is used for securing the resilient member 22 to the actuator 21 . In other words, the first adaptor 24 is used as an interface between the impactor 23 and the resilient member 22. The first adaptor 24 has a body 24A having a rear face 24B and a front face 24C opposite the rear face 24B. A recess 24D is provided at the front face 24C and extends toward the rear face 24B. An aperture 24E extends through the body from the front face 24C to the rear face 24B. The aperture 24E is in register with the recess 24D. The rear face 24B of the first adaptor 24 abuts the resilient member 22. The impactor 23, which is substantially L-shaped, is received in the recess 24D of the first adaptor 24. The recess 24D is dimensioned to accommodate the impactor 23. The aperture 24E is used to receive a fastener (e.g., bolt) to secure the first adaptor 24 to the resilient member 22. Put differently, the first adaptor24 may be positioned such that the rear face 24B abuts the resilient member 22 and a fastener inserted through an aperture of the resilient member 22 to be threadingly engaged to the first adaptor 24 via the aperture 24E, which may be correspondingly threaded. The first adaptor 24 thus has the recess 24D oriented suitably to receive therein the impactor 23. In some embodiments, the aperture 24E may be omitted and the first adaptor 24 may be secured to the resilient member 22 using other means, such as welding, brazing, gluing, interlocked using a keyway engagement, a snap fit connection, or any other suitable means.

[0072] In some embodiments, glue may be used to secure the impactor 23 in the recess 24D of the first adaptor 24. Any other means for securing the impactor 23 in the recess 24D of the first adaptor are contemplated, such as, for instance, a snap-fit connection, a strap, a bracket, and so on.

[0073] The second adaptor 25 may be a cylinder defining a central bore 25A coincident with a central axis of the cylinder and sized for receiving the movable member 21 B of the actuator 21 .The second adaptor 25 has two opposite end faces 24B being transverse to the central axis of the cylinder. One of these two end faces 24B may be abutted against the resilient member 22 and a fastener, such as a screw, may be inserted through an aperture defined through the resilient member 22 and through the central bore 25A and threadingly engaged to a correspondingly- threaded aperture defined by the movable member 21 B of the actuator 21 . In otherwords, looking at Fig. 4, the fastener may be inserted from left to right through the aperture defined through the resilient member 22, through the central bore 24A of the second adaptor 25

[0074] These adaptors 24, 25 may be made of polylactic acid (PLA), but other materials are contemplated. The adaptors 24, 25 house each a respective one of the threaded inserts 26. However, these adaptors 24, 25 may be manufacture to themselves define threads so that the threaded inserts 26 may be omitted. The adaptors may be omitted in some embodiments. It may be preferable to manufacture these adaptors out of more stiff material, such as a metallic material. The adaptors 24, 25 are only provided as examples, and other devices or means may be used to secure the impactor 23 to the resilient member 22, such as those shown in Figs. 6A-6D.

[0075] Referring to Figs. 6A to 6D, another embodiment of the first adaptor is shown at 124. The first adaptor 124 is used as an interface between the resilient member 22 and the impactor 23 as described previously. The first adaptor 124 includes a body 124A, which may be made of acrylonitrile butadiene styrene (ABS) or other suitable material, having a back plate 124B and a wall 124C protruding transversally to the back plate 124B to enclose a cavity 124D sized for receiving the impactor 123. The wall 124C may be interrupted to define an opening 124E to allow connectors of the impactor 23 to pass therethrough. This opening 124E may be omitted in some configurations. Moreover, the wall 124C may be replaced by clips or other means for retaining the impactor 23 inside the cavity 124D. The back plate 124B defines an aperture 124F for receiving a fastener 124G, such as a screw. In the embodiment shown, the fastener 124G is inserted through the aperture 124F of the back plate 124B and inserted through an aperture defined by the resilient member 22. At which point, a nut 124H is threaded on the fastener to sandwich the resilient member 22 between the back plate 124B and the nut 124H. A washer may be used in some embodiments. The back plate 124B may define threads within the aperture 124F to be threadingly engaged by the fastener 124G. Alternatively, a threaded insert may be press-fit into the aperture 124F of the back plate 124B.

[0076] Referring to Figs. 7A to 7E, results of a plurality of impact resonance tests performed with the system of Fig. 4 are presented, and are merely provided as an example, with these testsperformed under particular settings. The graphs illustrate the impact force as a function of time in Fig. 7 A; an acceleration of the sample S as a function of time in Fig. 7B and measured using a sensor (e.g., accelerometer) affixed to the sample S, a force as a function of a frequency in Fig. 7C, an acceleration as a function of the frequency in Fig. 7D; and a frequency response function (FRF) of the system 10 in Fig. 7E. Fig. 7E illustrates a transfer function describing the structural response to an applied force. In this case, the sample S is a cylindrical asphalt sample. The results provided in these graphs show that the measurements are repeatable with variations around 2%, the bandwidth are also satisfactory. Hence, the system 10 disclosed herein may permit accurate impact resonance testing.

[0077] The disclosed impacting mechanism 20 may increase repeatability of the tests. Impact times of around 0.05-0.06 milliseconds have been obtained. The mechanism 20 may present the ability to be used in the thermal chamber 11 , which may increase repeatability and accuracy of the testing using the positioning mechanism 40. The system 10 may allow the characterization of materials with minimal quality loss compared to manual tests.Method

[0078] Referring now to Fig. 8, a method for non-destructively testing a sample of material is shown at 800. The method 800 includes moving the impactor 23 towards the sample S with the actuator 21 at 802; after an impact between the impactor 23 and the sample S, causing the impactor 23 to bounce off the sample S with the resilient member 22, or rebound inducer, used as an interface between the actuator 21 and the impactor 23 to avoid a double impact against the sample S at 804, the causing include an elastic deformation of the resilient member 22 as a result of the impact; and moving the impactor 23 away from the sample S with the actuator 21 at 806. It will be appreciated that the steps 802 to 806 are performed very quickly. From a user’s naked eye, the withdrawing of the impactor 23 with the actuator 21 and the impacting of the sample with the impactor 23 occur substantially at the same time, that is, substantially simultaneously. Herein, the expression “simultaneously” implies a time duration in the order of milliseconds or less.

[0079] In some embodiments, the step of moving of the impactor 23 with the actuator 21 includes moving the impactor 23 with the bi-directional solenoid.

[0080] The step of causing of the impactor 23 to rebound with the resilient member 22 may include causing the impactor to rebound with the metallic blade, which may be made of steel and which may have a thickness of from 0.2 mm to 0.5 mm. Any resilient member 22 having a suitableflexural stiffness may be used. As mentioned above, a flexural stiffness ranging from 200 to 800 N / m is considered.

[0081] As shown in Fig. 1 , the controller 30 is operatively connected to the one or more sensor 31 and to the impacting mechanism 20. The controller 30 is configured to: cause the impacting mechanism 20 to impact the sample S with the impactor 23; receive a signal from the sensor 31 , the signal indicative of a response of the sample S to an impact with the impactor 23; and characterize the sample based on the response of the sample to the impact.

[0082] The characterization of the sample based on the response may include determining properties of the sample S such as its complex modulus, complex Poisson’s ratio, stiffness, and so on.

[0083] The controller 30 may also control the temperature inside the thermal chamber 11 with the heating / cooling system 12 to characterize the sample S at a plurality of temperatures, but this operation could be done manually. The controller 30 may vary a position of the impacting mechanism 20 using the positioning mechanism 40 to characterize the sample S at a plurality of locations, but this operation could be done manually.Controller

[0084] With reference to Fig. 9, an example of a computing device 900 is illustrated. For simplicity only one computing device 900 is shown but the system may include more computing devices 900 operable to exchange data. The computing devices 900 may be the same or different types of devices. The controller 30 may be implemented with one or more computing devices 900.

[0085] The computing device 900 comprises a processing unit 902 and a memory 904 which has stored therein computer-executable instructions 906. The processing unit 902 may comprise any suitable devices configured to implement the method described herein such that instructions 906, when executed by the computing device 900 or other programmable apparatus, may cause the functions / acts / steps performed as part of the method as described herein to be executed. The processing unit 902 may comprise, for example, any type of general-purpose microprocessor or microcontroller, a digital signal processing (DSP) processor, a central processing unit (CPU), an integrated circuit, a field programmable gate array (FPGA), a reconfigurable processor, other suitably programmed or programmable logic circuits, or any combination thereof.

[0086] The memory 904 may comprise any suitable known or other machine-readable storage medium. The memory 904 may comprise non-transitory computer readable storagemedium, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. The memory 904 may include a suitable combination of any type of computer memory that is located either internally or externally to device, for example random-access memory (RAM), read-only memory (ROM), compact disc read-only memory (CDROM), electro-optical memory, magnetooptical memory, erasable programmable read-only memory (EPROM), and electrically-erasable programmable read-only memory (EEPROM), Ferroelectric RAM (FRAM) or the like. Memory 904 may comprise any storage means (e.g., devices) suitable for retrievably storing machine-readable instructions 906 executable by processing unit 902.

[0087] The methods and systems described herein may be implemented in a high level procedural or object oriented programming or scripting language, or a combination thereof, to communicate with or assist in the operation of a computer system, for example the computing device 900. Alternatively, the methods and systems described herein may be implemented in assembly or machine language. The language may be a compiled or interpreted language. Program code for implementing the methods and systems described herein may be stored on a storage media or a device, for example a ROM, a magnetic disk, an optical disc, a flash drive, or any other suitable storage media or device. The program code may be readable by a general or special-purpose programmable computer for configuring and operating the computer when the storage media or device is read by the computer to perform the procedures described herein. Embodiments of the methods and systems described herein may also be considered to be implemented by way of a non-transitory computer-readable storage medium having a computer program stored thereon. The computer program may comprise computer-readable instructions which cause a computer, or more specifically the processing unit 902 of the computing device 900, to operate in a specific and predefined manner to perform the functions described herein, for example those described in the method 800.

[0088] Computer-executable instructions may be in many forms, including program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform particular tasks or implement particular abstract data types. Typically the functionality of the program modules may be combined or distributed as desired in various embodiments.

[0089] The embodiments described herein are implemented by physical computer hardware, including computing devices, servers, receivers, transmitters, processors, memory, displays, and networks. The embodiments described herein provide useful physical machines and particularlyconfigured computer hardware arrangements. The embodiments described herein are directed to electronic machines and methods implemented by electronic machines adapted for processing and transforming electromagnetic signals which represent various types of information. The embodiments described herein pervasively and integrally relate to machines, and their uses; and the embodiments described herein have no meaning or practical applicability outside their use with computer hardware, machines, and various hardware components. Substituting the physical hardware particularly configured to implement various acts for non-physical hardware, using mental steps for example, may substantially affect the way the embodiments work. Such computer hardware limitations are clearly essential elements of the embodiments described herein, and they cannot be omitted or substituted for mental means without having a material effect on the operation and structure of the embodiments described herein. The computer hardware is essential to implement the various embodiments described herein and is not merely used to perform steps expeditiously and in an efficient manner.

[0090] The term “connected” or "coupled to" may include both direct coupling (in which two elements that are coupled to each other contact each other) and indirect coupling (in which at least one additional element is located between the two elements).

[0091] The technical solution of embodiments may be in the form of a software product. The software product may be stored in a non-volatile or non-transitory storage medium, which can be a compact disk read-only memory (CD-ROM), a USB flash disk, or a removable hard disk. The software product includes a number of instructions that enable a computer device (personal computer, server, or network device) to execute the methods provided by the embodiments.

[0092] It is noted that various connections are set forth between elements in the preceding description and in the drawings. It is noted that these connections are general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. A coupling between two or more entities may refer to a direct connection or an indirect connection. An indirect connection may incorporate one or more intervening entities. The term “connected” or "coupled to" may therefore include both direct coupling (in which two elements that are coupled to each other contact each other) and indirect coupling (in which at least one additional element is located between the two elements).

[0093] It is further noted that various method or process steps for embodiments of the present disclosure are described in the preceding description and drawings. The description may presentthe method and / or process steps as a particular sequence. However, to the extent that the method or process does not rely on the particular order of steps set forth herein, the method or process should not be limited to the particular sequence of steps described. As one of ordinary skill in the art would appreciate, other sequences of steps may be possible. Therefore, the particular order of the steps set forth in the description should not be construed as a limitation.

[0094] Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. As used herein, the terms “comprises”, “comprising”, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0095] While various aspects of the present disclosure have been disclosed, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the present disclosure. For example, the present disclosure as described herein includes several aspects and embodiments that include particular features. Although these particular features may be described individually, it is within the scope of the present disclosure that some or all of these features may be combined with any one of the aspects and remain within the scope of the present disclosure. References to “various embodiments,” “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. The use of the indefinite article “a” as used herein with reference to a particular element is intended to encompass “one or more” such elements, and similarly the use of the definite article “the” in reference to a particular element is not intended to exclude the possibility that multiple of such elements may be present.

[0096] The embodiments described in this document provide non-limiting examples of possible implementations of the present technology. Upon review of the present disclosure, a person of ordinary skill in the art will recognize that changes may be made to the embodiments described herein without departing from the scope of the present technology. Yet furthermodifications could be implemented by a person of ordinary skill in the art in view of the present disclosure, which modifications would be within the scope of the present technology.

Claims

CLAIMS1 . An impacting mechanism for non-destructively testing a sample of material, comprising: an actuator having a movable member, the actuator configured to move the movable member relative to the sample; a impactor configured for impacting the sample along an impact direction; and a resilient member, the impactor connected to the movable member of the actuator via the resilient member, the resilient member having a stiffness in a direction having a component along the impact direction, the stiffness selected to allow the impactor to bounce off from the sample following an impact between the impactor and the sample to avoid a double impact of the impactor against the sample.

2. The impacting mechanism of claim 1 , wherein the resilient member extends transversally to the impact direction from a first end mounted to the movable member of the actuator to a second end mounted to the impactor.

3. The impacting mechanism of claim 2, wherein the resilient member is bending upon impact of the impactor against the sample, the stiffness being a flexural stiffness.

4. The impacting mechanism of claim 3, wherein the resilient member is a metallic blade.

5. The impacting mechanism of claim 4, wherein the metallic blade is made of steel.

6. The impacting mechanism of claim 3, wherein the flexural stiffness ranges from 200 N / m to 800 N / m.

7. The impacting mechanism of any one of claims 1 to 6, wherein the actuator is a bidirectional solenoid.

8. The impacting mechanism of any one of claims 1 to 7, further comprising: a first adaptor for securing the resilient member to the impactor; and a second adaptor for securing the resilient member to the movable member of the actuator.

9. A system for non-destructively testing a sample of material, comprising: an impacting mechanism having: an actuator, a impactor configured for impacting the sample along an impact direction, and a resilient member interconnecting the impactor to the actuator and configured for providing a degree of freedom to the impactor relative to the actuatorto allow the impactor to bounce off from the sample following an impact between the impactor and the sample to avoid a double impact of the impactor against the sample; a sensor operatively connected to the sample; and a controller operatively connected to the impacting mechanism and to the sensor, the controller having a processing unit and a computer-readable medium having instructions stored thereon executable by the processing unit to: cause the impacting mechanism to impact the sample with the impactor, receive a signal from the sensor, the signal indicative of a response of the sample to the impact with the impactor, and characterize the sample based on the response of the sample to the impact.

10. The system of claim 9, wherein the computer-readable medium has the instructions stored thereon to characterize the sample by: determining one or more of resonance frequencies of the sample, mode shapes, damping coefficient, a complex modulus of the sample, and a complex Poisson’s ratio of the sample.1 1 . The system of claim 9 or claim 10, wherein the resilient member extends transversally to the impact direction from a first end mounted to a movable member of the actuator to a second end mounted to the impactor.

12. The system of claim 11 , wherein the resilient member is bending upon impact of the impactor against the sample, the resilient member having a flexural stiffness selected to allow the impactor to bounce off from the sample following the impact.

13. The system of claim 12, wherein the resilient member is a metallic blade.

14. The system of claim 13, wherein the metallic blade is made of steel.

15. The system of claim 12, wherein the flexural stiffness ranges from 200 N / m to 800 N / m.

16. The system of any one of claims 9 to 15, wherein the actuator is a bi-directional solenoid.

17. The system of any one of claims 9 to 16, comprising a thermal chamber having a heating / cooling system operable to vary a temperature inside the thermal chamber, the impacting mechanism contained in the thermal chamber.

18. The system of any one of claims 9 to 17, comprising a positioning mechanism, the impacting mechanism mounted to the positioning mechanism, the positioning mechanism configured for moving the impacting mechanism relative to the sample.

19. A method for non-destructively testing a sample of material, comprising: moving an impactor towards the sample with an actuator; after an impact between the impactor and the sample, causing the impactor to bounce off the sample by deformation of a resilient member used as an interface between the actuator and the impactor to avoid a double impact against the sample; and moving the impactor away from the sample with the actuator.

20. The method of claim 19, wherein the causing of the impactor to rebound with the resilient member includes allowing the impactor to rebound with the resilient member having a flexural stiffness ranging from 200 to 800 N / m.

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