Six-degree-of-freedom load sensor main body

Abstract

A load sensor body configured for use with a test sample is disclosed, the load sensor body including a first member, a second member, and a flexural arrangement disposed between the first member and the second member. The flexure arrangement includes a pair of aggregated flexure assemblies, each of which has a flexure axial plane. The flexural axial planes intersect at a straight line whose midpoint defines an origin of the coordinate system. The test sample is configured to be positioned such that a center of the test sample is located at an origin. In another aspect, a machine includes a platform, a crossbeam, and a load sensor body. A load sensor body is disposed on the platform, and a test sample is configured to contact the load sensor body.

Description

Background Art

[0001] The following discussion is provided for general background information only and is not intended to be used to assist in determining the scope of the claimed subject matter. The present disclosure relates to a transducer formed as a load cell body equipped with a suitable sensor that transmits and measures linear forces along up to three orthogonal axes and moments about up to three orthogonal axes. Transducers or load cells for determining forces along and about orthogonal axes are known. Two such load cells are disclosed in commonly owned U.S. Patents 4,640,138 and 4,821,582, which are incorporated herein by reference.

[0002] U.S. Patent 4,640,138 shows a multi-axis load sensing sensor having a central member and peripheral members joined by a pair of axially spaced arms. The arms are integral with the central member and connected to the peripheral member by a flexible band, with the ends of the band fixed to the peripheral member. Each arm is fixed to the center of the associated band. The load is sensed as a function of the bending on the arm.

[0003] U.S. Patent No. 4,821,582 shows a load sensor that measures linear forces in three axes and moments about two of these axes. The sensor has an inner structure and an outer structure connected by a load-sensitive arm or shear beam. When the inner structure is loaded in a direction along an axis perpendicular to the plane of the arm, the outer ends of the arm are connected to outer links, which are rigid. Summary of the invention

[0004] In one aspect, a load sensor body is configured for use with a test sample, the load sensor body comprising a first member, a second member, and a flexure arrangement disposed between the first member and the second member. The flexure arrangement comprises a pair of clustered flexure assemblies, each of the clustered flexure assemblies having a flexure axial plane. The flexure axial planes intersect at a straight line, the midpoint of the straight line defining an origin of a coordinate system. The test sample is configured to be positioned so that a center of the test sample is located at the origin.

[0005] In another aspect, a machine is configured for use with a test sample. The machine includes a platform, a crossbar, and a load sensor body. The test sample is configured to be received between the platform and the crossbar. The load sensor body is disposed on the platform, and the test sample is configured to contact the load sensor body. The load sensor body includes a pair of concentrated flexure assemblies, each of which has a flexure axial plane. The flexure axial planes intersect at a straight line; the midpoint of the straight line defines the origin of the coordinate system. The test sample is configured to be positioned so that the center of the test sample is located at the origin.

[0006] The present invention is provided to introduce concepts in a simplified form, and these concepts will be further described in the specific embodiments below. The present invention is not intended to identify the key features or essential features of the disclosed or claimed subject matter, nor is it intended to describe each disclosed embodiment or each implementation of the disclosed or claimed subject matter. Specifically, the features disclosed herein for one embodiment may be equally applicable to another embodiment. Further, the present invention is not intended to be used to help determine the scope of the claimed subject matter. As this description proceeds, many other novel advantages, features, and relationships will become apparent. The following figures and descriptions illustrate illustrative embodiments in more detail. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The disclosed subject matter will be further explained with reference to the accompanying drawings, wherein similar structures or system elements are denoted by similar reference numerals in each view. Unless otherwise specified, all descriptions apply to similar and similar structures in each embodiment.

[0008] Figure 1 is a perspective view of an exemplary multi-axial elastomer testing system with a load cell unit and bushing test specimen mounted thereon.

[0009] Figure 2 is a perspective view of a bushing test specimen showing a typical orientation in a test system.

[0010] Figure 3 is a front right perspective view of an exemplary load sensor.

[0011] Figure 4 is an end perspective view of an exemplary load sensor showing the orientation of its focused flexure arm.

[0012] Figure 5 is a front elevation view of an exemplary load sensor.

[0013] Figure 6 yes Figure 3 An enlarged portion of FIG. 1 with exemplary inductor markings on the load sensor body.

[0014] Figure 7 is along Figure 3 A cross-sectional stereogram taken along line 7-7.

[0015] Figure 8 is along Figure 3 A cross-sectional stereogram taken along line 8-8.

[0016] Fig. 9 A typical strain gauge bridge circuit for sensing load is shown, with the selection of gauges being dependent upon the post or beam associated with the particular desired measurement of force and moment.

[0017] Although the above drawings illustrate one or more embodiments of the load sensor, other embodiments are also contemplated. The present disclosure presents the disclosed subject matter by way of representation and not limitation. It should be appreciated that many other modifications and embodiments can be designed by those skilled in the art that fall within the scope of the principles of the present disclosure.

[0018] The drawings may not be drawn to scale. In particular, some features may be enlarged relative to other features for clarity. In addition, when terms such as above, below, over, under, top, bottom, side, right, left, vertical, horizontal, etc. are used, it should be understood that they are only used to facilitate understanding of the description. It is contemplated that the structure can be oriented in other ways.

[0019] The term used herein is used to describe the purpose of the embodiment, and the term is not intended to be restrictive. Unless otherwise indicated, ordinal numbers (e.g., first, second, third, etc.) are used to distinguish or identify different elements or steps in a group of elements or steps, and do not provide sequence or numerical restrictions for the elements or steps of its embodiments. For example, "first", "second", and "third" elements or steps do not necessarily appear in this order, and its embodiments are not necessarily limited to three elements or steps. Unless otherwise indicated, any label (such as "left", "right", "front", "back", "top", "bottom", "forward", "reverse", "clockwise", "counterclockwise", "up", "down") or other similar terms (such as "upper", "lower", "back", "front", "vertical", "horizontal", "proximal", "distal", "middle", etc.) are used for convenience, and are not intended to, for example, imply any specific fixed position, orientation or direction. Alternatively, such labels are used to reflect, for example, relative position, orientation or direction. Unless the context clearly indicates otherwise, "one (a)", "a kind of (an)" or "the (the)" in the singular form include plural references. DETAILED DESCRIPTION

[0020] Figure 13 is a front perspective view of an exemplary test system 30 including the disclosed load cell 10 that detects forces applied to a test specimen 32 held in a fixture 34. A suitable machine 36 for use in the test system 30 is a Model 836 Multi-Axis Elastomer Test System commercially available from MTS Systems of Eden Prairie, Minnesota. However, it should be understood that other test machines may be used in the system 30. The illustrated MTS Model 836 test machine 36 is designed to provide durability testing for an elastomer test specimen 32 and operates with six full degrees of freedom. The MTS Model 83 includes an inductor at each of the actuators 42, 44, 46.

[0021] Although the illustrated test specimen 32 is configured as a suspension bushing, it should be understood that the test machine 36 having the disclosed load sensor 10 may also be used for other components, not limited to including elastomeric parts. The test machine 36 and load sensor 10 are configured to withstand high load capacity and wide frequency band to meet a wide range of testing requirements, including elastomeric parts for vehicle ride and handling applications. In the illustrated system 30, using the load sensor 10 as a supplement or replacement for an inductor at the actuator can produce optimized results, as further described herein.

[0022] Figure 2 A typical orientation of the test specimen 32 when oriented in the machine 36 is shown; a coordinate system 12 is provided to illustrate the linear force (F) detected by the disclosed load sensor 10. X , F y , F z ) and rotational torque (M X , M y , M z ) direction. The exemplary test system 30 uses a test machine 36 having the disclosed load sensor 10 to test a sample 32, which may or may not be equipped with an adapter or fixture 34. The fixture 34 maintains the test sample 32 in a proper orientation relative to the load sensor 10. The load sensor 10, the fixture 34, and the test sample 32 are disposed between a platform 38 and a crossbar 40. In the present disclosure, forces and moments are measured relative to a stationary orthogonal coordinate system 12 including mutually orthogonal X-axis, Y-axis, and Z-axis.

[0023] In the exemplary system 30, forces are applied to the specimen 32 by a plurality of actuators; these forces are detected by the load cell 10. In the illustrated machine 36, a single actuator 42 is provided to move the specimen 32 in a reciprocating (forward and backward) motion via a strut 42a. X In the exemplary embodiment, two actuators 44 (via struts 44a) are arranged in a reciprocating F ZAlso, in the exemplary embodiment of the machine 36, three actuators 46 (via struts 46a) are provided in a reciprocating F Y A force is applied in the direction (at the center and each end of the beam 40).

[0024] The controller of the test machine 36 can control each actuator 42, 44, 46 individually. Thus, for example, if the two Z actuators 44 move the left and right portions of the crossbar 40 in different ways, a moment (M) about Y can be applied to the test specimen 32. Y If the three Y actuators 46 move the left, right, or top portion of the beam 40 in different ways, a moment (M) about Z can be applied to the test specimen 32. Z ) and / or the moment about X (M X ).

[0025] Figures 3 to 8 Various views of an exemplary load sensor 10 suitable for use with the system 30 are shown. In an exemplary embodiment, the load sensor 10 includes a one-piece body 14 that is preferably formed from a solid block or mass of material. For example, suitable materials include ductile metals such as steel or titanium. The unitary body 14 machined from a single piece of material reduces hysteresis in operation, improves repeatability, and provides adequate low-force response. The one-piece machined construction of the body 14 also increases durability by eliminating welding, brazing, adhesives, and bolted joints. The one-piece machined body 14 allows for a small package size that provides high stiffness in all directions.

[0026] The monolithic construction of the body 14 eliminates creep, hysteresis, and damping from bolted joints. These effects are eliminated by rigid machined joints with virtually no slip. In addition, the concentrated flexure assembly 48 eliminates the effects of F Y The large overturning moment of M X Measuring. This makes M X The measurement is very sensitive. In this way, the output can be up to five times that of conventional methods. In addition, due to the compact and rigid design of the load cell 10 with minimal series path, the load cell can have a high natural frequency, which eliminates dynamic errors in force and moment measurements. The combination of stiffness and parasitic loading adjustments minimizes the combined load error over the entire calibration space.

[0027] like Figure 3 and Figure 4As shown, in the exemplary embodiment, two axial planes 49 of the focused flexure assembly 48 intersect in a straight line. The midpoint of this straight line defines the center or origin of the control coordinate system 12. The origin of the coordinate system 12 is also located directly above the center of the body 14 in the XY plane (in the Z direction). In the test system 30, the center of the test sample 32 will be placed at this focal origin by a fixture or adapter 34. Therefore, although the coordinate system 12 is depicted in many of the figures in the drawings to show the orientation of the illustrated structure, its origin is correctly placed at the center of the sample 32, located at the intersection of the planes 49 with the flexure axes of the focused flexure assembly 48, as shown in FIG. Figures 2 to 4 shown.

[0028] In an exemplary embodiment of the sensor or load cell 10, the body 14 is equipped with a plurality of inductors 50. In the exemplary embodiment, the sensor 10 provides six measurements, including moment and axial measurements in three principal axes (X, Y, and Z), with very low crosstalk or the likelihood that the reading in one axis will be affected by the load in another axis; this is a result of the isolation feature obtained by using a flexure bending beam for supporting the connected load bearing member.

[0029] In the exemplary embodiment, the body 14 is configured in the form of a frame or cage having a cavity 64 within the boundaries of the first member 20, the second member 24, the two opposing convergence flexure assemblies 48, and the two opposing end wall flexure assemblies 58. In the exemplary embodiment, the components 20, 24, 48, 58 are integral with each other and are formed from a single unitary body. However, in another embodiment, the components 20, 24, 48, 58 or portions thereof may be manufactured as separate elements.

[0030] In an exemplary embodiment, if Figures 3 to 8 As shown, the first member 20 is connected to the second member 24 via the flexure arrangement 22. In the exemplary embodiment, each of the first member 20 and the second member 24 includes a substantially planar loading surface 16, 18, respectively. In the application of the load sensor 10, the force transmitted between the connected components via the loading surfaces 16, 18 is sensed and measured by the inductor 50 located on the flexure arrangement 22 of the sensor body 14.

[0031] The load sensor 10 is capable of sensing forces and moments in up to six degrees of freedom when equipped with a suitable sensing device 50. In a suitable embodiment, the second member 24 is grounded or otherwise fixed relative to the axis set 12, and the first member 20 moves relative to the second member 24, supported on the second member 24 by the flexure arrangement 22. This is only one embodiment, and if desired, the first member 20 can be fixed relative to the axis set 12 and the second member 24 moves relative thereto.

[0032] In an exemplary embodiment, the flexure arrangement 22 includes two opposing converging flexure assemblies 48 and two opposing end wall flexure assemblies 58. In an exemplary embodiment of the converging flexure assemblies 48, two upper hinges 26 and two lower hinges 28 extend along the length of the body 14 (parallel to the x-axis). In an exemplary embodiment, each of the linear hinges 26, 28 is configured as a thinned portion of the body 14 located between two curved machined grooves 27. In an exemplary embodiment, each of the grooves 27 is symmetrically arcuate about an axial plane 49 of the converging flexure assembly 48. This produces a uniform strain flow through the ends of the flexures, thereby making the center of the flexure assembly 48 more stable and constant. Therefore, the flexure assembly 48 has no nonlinear effects in its response to loading, thereby eliminating nonlinear crosstalk in its measurement.

[0033] In such Figure 6 In the exemplary embodiment shown, each focus flexure assembly 48 includes a hole 52 extending therethrough that opens into a cavity 64. In the exemplary embodiment, each focus flexure assembly 48 includes a pair of posts 54 and a pair of beams 56. In the exemplary embodiment, each end wall flexure assembly 58 includes a hole 62 that includes a beam 66. The posts 54 and beams 56, 66 are labeled with primary forces (the sensors 50 on the posts and beams are designed to measure the primary forces), as further described below.

[0034] The load cell 10 having a sensor body 14 with an inductor 50 thereon allows the performance of an elastomeric test specimen 32 (such as a bushing) to be characterized over a wide frequency range by measuring forces and moments at both high and low frequencies. It also provides a sensor output for acceleration compensation. It is able to measure forces and moments at large deflections with high fidelity and low noise while maintaining a high natural frequency by using a focused flexure assembly 48. With this structure, the focused flexure assembly 48 has a rigid load path with high sensitivity to provide a low noise measurement signal with a wide dynamic range.

[0035] For example, the inductor 50 may be based on strain measurement and / or may be a piezoelectric sensor.Some of the measurement outputs will be fatigue or wear characteristics of the elastomer test specimen 32, as well as frequency content and transmissibility of the elastomer in six degrees of freedom.

[0036] The environment of the test system 30 can be quite harsh, including high loads and large moment arms relative to the size of the load cell 10. In the load cell 10, the thermal load from the sample 32 is attenuated as a high frequency dynamic load. Even under challenging environmental conditions, the load cell 10 maintains thermal stability, high natural frequency, high output, low noise, long life, low crosstalk, and low static measurement errors. In an exemplary embodiment, the sensor body 14 is made of steel, which is selected because of its durability limit. If the applied stress is below this limit, the body will have a useful life with no calculable end point in terms of fatigue. The use of steel also increases the elastic modulus, which is superior to other materials, and provides a space-saving rigid beam while promoting low parasitic loading.

[0037] In an exemplary embodiment, the load sensor 10 measures six degrees of freedom by isolating the load. Generally speaking, the load sensor 10 includes a pair of concentrated flexure assemblies 48 having a plurality of groups of posts 54 and a plurality of groups of beams 56 on which inductors 50 are carried. The concentrated flexure assemblies 48 are subjected to forces applied at a focal point above the load sensor 10. By isolating the degrees of freedom along the coordinate system, the measurement performance of the natural frequency can be increased, with lower noise, higher output, lower static measurement error, and lower thermal error. F X 、F Y 、F Z 、M Y and part M Z The load in the flexure assembly 48 is divided so that the column 54 can measure F Y 、F Z and M Y This provides M X The sensor output is not affected by F Y The load multiplied by the overturning moment effect at the center of the load cell coordinate system. Without this feature, M X The measurement will be lost in the noise.

[0038] In the exemplary embodiment, each concentrated flexure assembly 48 includes two "push-pull" (PP) beams 56 and two "axial Poisson" (P / A) posts 54. The two PP beams 56 on a single concentrated flexure assembly 48 are considered a group. The PP beam group generates a signal by causing one of the beams 56 to react in compression and the other PP beam 56 to react in tension. Therefore, the inductors 50 (such as strain gauges 72) placed on these beams 56 are subjected to compressive and tensile strains. This produces a change in resistance and generates a signal output in a Wheatstone bridge.

[0039] A set of PP beams 56 measure F by providing a rigid load path along the X axis.X and M Z Since the two sets of PP beams 56 are offset (along the y-axis) on two converging flexure assemblies 48 located on opposite sides of the sensor body 14, they react to the moment M Z These PP beams 56 are compliant in the other four degrees of freedom by utilizing the lateral compliance from the bending beams. Increasing the length of these PP beams 56 reduces the orthogonal stiffness as the cube of the length. However, the axial stiffness is only a function of the cross-sectional area divided by the length; high axial stiffness can be achieved while maintaining low orthogonal stiffness. This produces high natural frequencies along the length of the beam 56 with low parasitic loading on the other degrees of freedom, thereby reducing thermal drift and stress caused by the other degrees of freedom.

[0040] Another set of PP beams 66 are located in the end wall flexure assembly 58. These PP beams 66 are of the same form of "push-pull" beams with high axial stiffness and low orthogonal stiffness. Y 、M X and M Z However, due to the high stiffness of the aggregate flexure assembly 48 in the Y direction, most of the F Y The load is divided by the concentrated flexure assembly 48, and this group of beams 66 and F Y Load isolation. However, since the body flexure assembly 48 has no rotational stiffness about X (largely due to the hinges 26, 28), M X The load is transmitted via beams 66. These beams 66 are not rotationally rigid, but axially rigid. Furthermore, they are located at the origin of the measurement coordinate system 12 (located at Figure 4 The load cell 10 shown is above the bottom (in the Z direction), thereby allowing the beams 66 to react to the moment with an axial load. In addition, the two sets of beams 66 on the opposite end wall flexure assembly 58 are offset in the X direction; therefore, they carry the moment M Z The height of these beams 66 helps to suppress the load from M Z crosstalk and increase M X Output.

[0041] The two groups of PP beams 66 each bear M Z With respect to the measurements being made on these PP beams 66, M Z The loads can be very large. In this configuration, the beams are able to share between them an M proportional to their relative stiffnesses. Z load. This makes F X and M X The output has a relatively high sensitivity compared to what is expected.

[0042] In the exemplary embodiment, two sets of PP beams 56 are located on the cluster flexure assembly 48 and two sets of PP beams 66 are located on the end wall flexure assembly 58. In the exemplary embodiment, each of the PP beams 56 and 66 has a strain gauge 72 placed on each of its respective top and bottom surfaces. The four sets of PP beams 56, 66 produce four bridge outputs that are summed and differentiated to measure M Z Outputs. It is possible to take outputs from only two sets of PP beams; however, this can cause thermal drift issues because the internal force loops take parallel paths when the ends of the load cell 10 experience thermal warping. Therefore, by taking all four bridge outputs in a bridge output and assigning appropriate gains, these internal force loops can be offset to produce stability.

[0043] The two opposing focused flexure assemblies 48 carry four P / A posts 54 which, due to the high axial stiffness of the posts and the compliance in other degrees of freedom, bear loads in the direction of the axis 49 of the respective posts. The P / A posts 54 are wider than the PP beams 56, 66 so that the P / A posts 54 bear stiffness in the direction of the loads which is orthogonal to the axial direction 49 of the posts 54 and also orthogonal to the X direction so that the focused flexure assemblies 48 do not buckle under load and produce nonlinearities or produce low resonant modes. The P / A posts 54 are subjected to axial strains measured by axial and Poisson instruments.

[0044] like Figure 6 As indicated, in the exemplary embodiment, the sensor 50 of the column 54 includes an axial gauge 68 placed in the direction of the axial strain and a Poisson gauge 70 placed orthogonally to the axis of the column 54 to measure the Poisson strain from the material due to maintaining a constant volume proportional to the Poisson's ratio of the sensor material under deformation. At the Poisson's ratio of the material used for the sensor body 14, the axial strain exceeds the Poisson strain. By taking all of the outputs from the P / A column 54 and summing them, it is possible to measure F Z The difference between the front and rear bridges in the X direction is used to obtain M Y The difference between the left and right bridges in the Y direction is calculated to obtain F Y . Then take all of those outputs and run them through an amplifier or some signal conditioning and convert them to engineering units through a transform function.

[0045] In the exemplary embodiment, the load sensor 10 uses a set of eight Wheatstone bridges. These bridges are then summed and differentiated to produce the output for the calibration function to convert to engineering units. In the exemplary embodiment, each set of two PP beams 56 has four gauges 72, which form a bridge; thus, the two sets of PP beams 56 on the two clustered flexure assemblies 48 thus form two bridges. In the exemplary embodiment, each set of two PP beams 66 has four gauges 72, which form a bridge; thus, the two sets of PP beams 66 on the two end wall flexure assemblies 58 thus form another two bridges. In the exemplary embodiment, each P / A post 54 has two axial gauges 68 and two Poisson gauges 70, which form a bridge; thus, the four P / A posts 54 on the two clustered flexure assemblies 48 thus form another four bridges.

[0046] When the applied load is asymmetrical on loading surface 16 relative to loading surface 18, the acceleration of the active portion of load sensor 10 will be measured. An algorithm is used to correct for the resonance of the measurement system to eliminate these errors from the load measurement. Additional details regarding the calculations used with the load sensor are provided in the following commonly owned U.S. patents, which are hereby incorporated by reference: U.S. Patent 4,640,138, entitled "Multiple Axis Load Sensitive Transducer"; U.S. Patent 4,821,582, entitled "Load Transducer"; and U.S. Patent 10,545,062, entitled "Multi Axis Load Cell Body".

[0047] It should be noted that the shape of the posts 54 and beams 56, 66, when viewed in cross-section, can take a variety of different forms. For example, the cross-section of the posts can have a constant area, or the posts can taper as shown, which reduces the stress gradients through the posts or beams caused by bending from off-axis loads and end effects. In addition, the load carrying capacity of the posts and beams can be adjusted depending on the forces to be measured.

[0048] In an exemplary embodiment of the sensor body 14, temperature control features may be provided on one or both of the first member 20 and the second member 24. In an exemplary embodiment, one or more of the members 20, 24 include channels for pumping a coolant fluid (e.g., such as water). Thus, the temperature control members 20, 24 on the top and bottom of the load sensor 10 provide high fidelity control of the load sensor temperature such that thermal equilibrium exists between the first member 20 and the second member 24. By eliminating thermal gradients through the load sensor 10, thermal errors will not occur. In contrast, when there is a thermal gradient through the load sensor, a strain condition will exist on the beam and column that results in a load-dependent deflection due to thermal warping.

[0049] In the disclosed load cell 10, all degree of freedom bridges are isolated from each other by reducing the orthogonal stiffness of each of the beams and columns, thereby eliminating most of the parasitic loading. The ends of each of the beams and columns are designed with sufficient cantilever stiffness to ensure that the beams and columns experience double cantilever bending rather than pure cantilever bending, so that there is a well-defined inflection point in the beam rather than some constantly changing center that otherwise exists in a cantilever beam. Therefore, the disclosed structure produces very low crosstalk in the load cell 10 with high orthogonal outputs and therefore very stable load measurement capabilities.

[0050] The load sensor 10 performs in both the AC and DC components of the load. The load sensor 10 measures low frequency, quasi-static loads while maintaining a high natural frequency to measure dynamic loads. The geometry of the sensor body 14 allows for a high level of flexure isolation and adjusted beam and column positions to provide low crosstalk, low thermal errors, and low noise in the measurement setup.

[0051] Fig. 9 A typical strain gauge bridge circuit for sensing load is shown, with the choice of gauge being dependent upon the column or beam associated with the particular desired measurement of force and moment. "C" denotes a compression gauge and "T" denotes a tension gauge. To obtain a signal representative of the force acting on the sensor, a resistor consisting of resistors R1-R4 (corresponding to Fig. 9 Several strain gauge bridges are formed by strain gauges in selected bridge arms represented by C1, T1, C2, and T2 of FIG. Each bridge output will provide a signal indicative of various forces, from which moments about two of the coordinate axes (e.g., such as X and Z) can be determined, and separate bridges can be used to determine moments about the remaining axes (e.g., such as Y).

[0052] In the exemplary embodiment, the tension gauges are located in opposite arms of the bridge and the compression gauges are also located in opposite arms of the bridge. The unitary (single piece) construction of the body 14 including the mass flexure assembly 48 and the end wall flexure assembly 58 on which the sensors / gauges 50, 68, 70, 72 are located allows the loads to be isolated from each other to minimize cross coupling and reduce hysteresis and other operational problems.

[0053] An exemplary, non-limiting embodiment of a load sensor 10 including a body 14 with an inductor 50 thereon is described. In the exemplary embodiment, the load sensor body 14 is configured for use with a test sample 32, and the load sensor body 14 includes a first member 20, a second member 24, and a flexure arrangement 22 disposed between the first member 20 and the second member 24. In the exemplary embodiment, the flexure arrangement 22 includes a pair of focused flexure assemblies 48, each of the focused flexure assemblies 48 having a flexure axis 49, wherein the flexure axial planes 49 of the pair of focused flexure assemblies 48 intersect in a focal line, and wherein the midpoint of the line defines the origin of the coordinate system 12. In the exemplary embodiment, the test sample 32 is configured to be positioned so that the center of the test sample 32 is located at the origin.

[0054] In an exemplary embodiment, the coordinate system 12 includes mutually orthogonal X-axis, Y-axis, and Z-axis, and at least one of the concentrated flexure assemblies 48 includes a hinge 26, 28 extending parallel to the X-axis. In an exemplary embodiment, at least one of the concentrated flexure assemblies 48 includes a first post 54 extending parallel to the flexure axis 48 and a first beam 56 extending parallel to the X-axis. In an exemplary embodiment, the sensor 50 is disposed on at least one of the first post 54 and the first beam 56. In an exemplary embodiment, the sensor 50 includes a strain gauge 72 disposed on the first beam 56. In an exemplary embodiment, the sensor 50 includes an axial gauge 68 disposed on the first post 54 and aligned with the flexure axis 49. In an exemplary embodiment, the sensor 50 includes a Poisson gauge 70 disposed on the first post 54 and orthogonal to the axial gauge 68.

[0055] In the exemplary embodiment, the flexure arrangement 22 includes a pair of end wall flexure assemblies 58, each of which is located at an end of the pair of cluster flexure assemblies 48. In the exemplary embodiment, at least one of the end wall flexure assemblies 58 includes a first beam 66 extending parallel to the Y-axis. In the exemplary embodiment, the sensor 50 is disposed on the first beam 66. In the exemplary embodiment, the sensor 50 includes a pair of strain gauges 72 disposed on opposite sides of the first beam 66.

[0056] In an exemplary embodiment, the flexure arrangement 22 includes at least two pairs of support columns 54 and four pairs of beams 56, 66. In an exemplary embodiment, each of the support columns 54 extends parallel to the flexure axis 49. In an exemplary embodiment, each of the beams 56, 66 extends parallel to the X-axis or parallel to the Y-axis. In an exemplary embodiment, two pairs of opposing beams 56, 66 of the four pairs of beams are disposed at equal distances from the origin of the coordinate system 12. In an exemplary embodiment, two opposing pairs of beams 56 are located on the pair of gathering flexure assemblies 48. In an exemplary embodiment, two opposing pairs of beams 66 are located on the pair of end wall flexure assemblies 58. In an exemplary embodiment, the first member 20, the second member 24, and the flexure arrangement 22 are integrally formed from a single unitary block including the internal cavity 64.

[0057] Although the subject matter has been described in language specific to structural features and / or methodological acts, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above that the court has determined. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims. In addition, any feature disclosed with respect to one embodiment may be included in another embodiment, and vice versa. All references mentioned in this disclosure are hereby incorporated by reference.

Claims

1. A load sensor body configured for use with a test specimen, the load sensor body comprising: first component; The second component; as well as a flexure arrangement disposed between the first member and the second member, the flexure arrangement comprising: A pair of concentrated flexure assemblies, each of the concentrated flexure assemblies having flexure axial planes, wherein the flexure axial planes intersect at a straight line, and wherein the midpoint of the straight line defines an origin of a coordinate system, and wherein the test sample is configured to be positioned so that the center of the test sample is located at the origin.

2. The load sensor body according to claim 1, wherein: The coordinate system includes mutually orthogonal X-axis, Y-axis and Z-axis, and wherein at least one of the focusing flexure assemblies includes a hinge extending parallel to the X-axis.

3. The load sensor body according to claim 1, wherein: The coordinate system includes mutually orthogonal X-axis, Y-axis and Z-axis, and wherein at least one of the focused flexure assemblies includes a first column extending parallel to the flexure axis plane and a first beam extending parallel to the X-axis.

4. The load sensor body as described in claim 3 includes an inductor arranged on at least one of the first column and the first beam, the inductor preferably includes a strain gauge arranged on the first beam, and optionally includes an axial gauge arranged on the first column and aligned parallel to the flexural axial plane, or a Poisson gauge arranged on the first column and orthogonal to the flexural axial plane.

5. The load sensor body according to any one of claims 1 to 4, wherein: The flexure arrangement comprises a pair of flexure end wall assemblies, each of which is located at the end of the pair of clustered flexure assemblies, and preferably wherein the coordinate system comprises mutually orthogonal X-axis, Y-axis and Z-axis, and wherein at least one of the flexure end wall assemblies comprises a first beam extending parallel to the Y-axis.

6. A load sensor body as claimed in claim 4, comprising an inductor disposed on the first beam, and preferably wherein the inductor comprises a pair of strain gauges disposed on opposite sides of the first beam.

7. The load sensor body according to any one of claims 1 to 6, wherein: The coordinate system comprises mutually orthogonal X-axis, Y-axis and Z-axis, and wherein the flexure arrangement comprises at least: two pairs of support posts, each of the support posts extending parallel to a respective axial plane of flexure; and Four pairs of beams, each of the beams extending parallel to the X-axis or parallel to the Y-axis.

8. The load sensor body according to claim 7, wherein: Two opposing pairs of beams out of the four pairs of beams are arranged at equal distances from the origin of the coordinate system, and preferably wherein the two opposing pairs of beams are located on the pair of converging flexure assemblies.

9. The load sensor body of claim 8, wherein: The flexure arrangement comprises a pair of flexure end wall assemblies, each of the flexure end wall assemblies being located at an end of the pair of converging flexure assemblies; and The two opposing beam pairs are located on the pair of flexure end wall assemblies.

10. The load sensor body according to any one of claims 1 to 9, wherein: The first member, the second member and the flexure arrangement are integrally formed from a single unitary piece including an internal cavity.

11. A machine configured for use with a test sample, the machine comprising: a platform and a beam, wherein the test specimen is configured to be received between the platform and the beam; and a load sensor body disposed on the platform, wherein the test sample is configured to contact the load sensor body, the load sensor body comprising: A pair of concentrated flexure assemblies, each of the concentrated flexure assemblies having flexure axial planes, wherein the flexure axial planes intersect at a straight line, and wherein the midpoint of the straight line defines an origin of a coordinate system, and wherein the test sample is configured to be positioned so that the center of the test sample is located at the origin.

12. The machine of claim 11, wherein: The coordinate system includes mutually orthogonal X-axis, Y-axis, and Z-axis, and wherein the machine includes an actuator configured to apply a force to the test sample in the X-axis.

13. The machine of claim 11, wherein: The coordinate system includes mutually orthogonal X-axis, Y-axis, and Z-axis, and wherein the machine includes an actuator configured to apply a force to the test sample in the Y-axis.

14. The machine of claim 11, wherein: The coordinate system includes mutually orthogonal X-axis, Y-axis, and Z-axis, and wherein the machine includes an actuator configured to apply a force to the test specimen in the Z-axis.

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