Alignment apparatus and methods for testing system

Abstract

To provide a method of operating a testing machine, a load cell body, and a method of aligning a test specimen in the testing machine.SOLUTION: A method of operating a testing machine includes obtaining first sensor outputs from a first load cell indicative of forces on sensors of the first load cell at a first end of a test specimen mounted in a first grip of the testing machine. The method further includes obtaining second sensor outputs from a second load cell indicative of forces on sensors of the second load cell at a second opposite end of the test specimen mounted in a second grip of the testing machine. The test specimen is coaxially aligned with the first and second grips along an axis by adjusting at least one of an alignment device of the testing machine or at least one of a position of the test specimen in the first or second grip.SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This application claims the benefit of priority from U.S. Provisional Patent Application No. 63 / 600,385, filed on November 17, 2023, entitled "Alignment Apparatus and Methods for Testing System", the content of which is incorporated herein by reference in its entirety.

Background Art

[0002] The following discussion is provided only for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.

[0003] Testing machines or apparatuses are used to test the parameters and / or performance of materials, components, consumer products, electronic devices, materials, and medical devices and other devices (i.e., test samples). Typically, a testing machine includes one or more actuators for applying input loads and displacements. The sample is held in a grip, and alignment problems can cause issues related to sample damage and / or inaccurate measurements.

Summary of the Invention

[0004] This summary and abstract herein are provided to introduce, in simplified form, selected concepts that are further described below in the detailed description. This summary and abstract are not intended to identify key or essential features of the claimed subject matter, nor are they intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all of the disadvantages described in the background art.

[0005] In one aspect, a method of operating a testing machine includes obtaining, from a first load cell, a first sensor output indicative of a force on a sensor of the first load cell at a first end of a test specimen attached to a first grip of the testing machine. The method further includes obtaining, from a second load cell, a second sensor output indicative of a force on a sensor of the second load cell at a second, opposite end of the test specimen attached to a second grip of the testing machine. The forces at the sensors of the first load cell and the second load cell are determined from the first sensor output and the second sensor output. The test specimen is aligned coaxially with the first grip and the second grip along an axis by adjusting at least one of the alignment device of the testing machine or at least one of the positions of the test specimen in the first grip or the second grip.

[0006] Embodiments can include one or more of the following features. The method of aligning coaxially in the alignment device of the testing machine can include moving one of the first grip or the second grip of the testing machine. Aligning coaxially can include laterally adjusting one of the first grip and the second grip in at least one of two directions orthogonal to the axis. Aligning the test specimen coaxially can include adjusting the orientation or angle of the test specimen in at least one of the first grip or the second grip within the tolerance of the testing machine.

[0007] Obtaining a first sensor output indicating the force on the sensor of the first load cell at the first end of the test sample from the first load cell can include sensing a first force in a first lateral direction and a second lateral direction orthogonal to the first lateral direction. The force on the sensor of the first load cell can be sensed using various types of strain sensing sensors such as, but not limited to, strain gauges. Obtaining a second sensor output indicating the force on the sensor of the second load cell at the second opposite end of the test sample from the second load cell can include sensing a second force in the first lateral direction and the second lateral direction. The force on the sensor of the second load cell can be sensed using various types of strain sensing sensors such as, but not limited to, strain gauges.

[0008] If desired, coaxial alignment can include reducing the lateral force in at least one of the first lateral direction and the second lateral direction.

[0009] The method can include applying a load to the test sample, particularly measuring the lateral force applied to the test sample during and / or after the test to determine misalignment. Determining misalignment can include determining the type of bending of the test sample using the moment determined from the first sensor output and the second sensor output. Determining the type of bending can include determining an s-type bend from the moments at both ends of the test sample in opposite directions and determining a c-type bend from the moments at both ends of the test sample in the same direction.

[0010] In another aspect, a load cell for use in a tensile testing machine includes a load cell body configured to engage with a grip at its first end and with one of a load cell for the testing machine or an actuator for the testing machine at its second opposite end along an axis extending from the first end to the second end.

[0011] An embodiment can include one or more of the following features. The load cell body can include a set of first sensors configured to sense a first force in a first lateral direction orthogonal to the axis, and a set of second sensors configured to sense a second force in a second lateral direction orthogonal to the first lateral direction and orthogonal to the axis. The load cell body can include a set of first sensors operably coupled to the flexure and configured to sense a first force in a first lateral direction orthogonal to the axis, and a set of second sensors operably coupled to the flexure and configured to sense a second force in a second lateral direction orthogonal to the first lateral direction and orthogonal to the axis. The set of first sensors can be various types of strain sensing sensors such as, but not limited to, strain gauges. Similarly, the set of second sensors can be various types of strain sensing sensors such as, but not limited to, strain gauges. The load cell body can include a moment restraint portion connected to the first end and the second end, and the moment restraint portion is configured to prevent rotation of the first end or the second end about the axis.

[0012] In another aspect, a method for aligning a test sample in a testing machine includes attaching the test sample to a grip of the testing machine and applying a load to the test sample. The lateral force applied to the test sample is measured during and / or after the test to determine misalignment.

[0013] This summary is not intended to describe every embodiment or all aspects of the disclosed embodiments that sense lateral forces and adjust the alignment of test samples or elements of a testing machine. Many other novel advantages, features, and relationships will become apparent as this description proceeds. The following drawings and description illustrate exemplary embodiments more specifically.

Brief Description of the Drawings

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Best Mode for Carrying Out the Invention

[0025] FIG. 1 shows a testing machine system 8 according to one embodiment. The testing machine system 8 includes a computing device 9 for generating a GUI 47 (FIG. 2) that enables a user to interact with and / or control and / or calibrate or adjust the testing machine 12. The testing machine 12 includes a plant or physical system 10. In an exemplary embodiment, the physical system 10 generally includes controllable elements such as an actuator system, a motor, etc. As shown in FIG. 1, the actuator system or assembly 13 includes a controller 14, an actuator 15 (hydraulic, pneumatic, and / or electric), and a mechanism for coupling the actuator to any movable member to apply displacement or load to the test specimen 18. The coupling mechanism includes, in one embodiment, a specimen grip for holding the specimen. Further components include one or more transducers 20, 22, and 24 as described below for measuring various loads, including loads in three orthogonal directions, loads along the axis of the specimen (transducer 20), and loads along two additional axes orthogonal to each other and to the axis of the specimen. These axes may be referred to as the z-axis 102 (along the axis of the specimen) and the x-axis 108 and y-axis 110 (as shown, for example, in FIG. 3).

[0026] In the schematic diagram of FIG. 1, the actuator system 13 is represented by an actuator 15 (located within a base 30 not shown in its entirety), and the actuator 15 represents one or more actuators within any test machine directly or indirectly coupled to the test sample 18. The controller 14 provides an actuator command signal 19 to a device under control 25 (schematically shown, e.g., a servo valve, a power controller), operates the actuator 15, and in turn, excites the test sample 18. It should be noted that the controller 14 is of a design suitable for controlling the type of actuator used. Appropriate feedback 15A can be provided from the actuator 15 to the controller 14 or from other sensors. One or more remote transducers on the test sample 18 or the physical system 10, such as displacement sensors, strain gauges, accelerometers, load cells, thermometers, etc., provide the measured or actual response 21 to the system controller 23. In an exemplary embodiment, load cells 20, 22, and 24 provide responses 20A, 22A, and 24A to the system controller 23 (which can be considered part of the actual response 21, although the signals 20A, 22A, 24A are shown separately). The system controller 23 receives the actual response 21 as feedback in response to the drive 17 as an input to the servo controller 14. In the example of FIG. 1, the signal 17 is a reference signal, the signal 19 is a manipulated variable (command to the device being actuated), and the signal 15A is a feedback variable. Although shown in FIG. 1 for a single channel, a multi-channel embodiment having a signal 15A including N feedback components and a signal 19 including M manipulated variable components is typical and considered another embodiment of the present invention. The test sample 18 can take any number of forms, such as, but not limited to, a material sample, a substructure, or a component. Typically, the types of loads that can be applied or imparted to the test sample 18 include tension, compression, and / or torsion in one or more degrees of freedom applied separately or simultaneously. The test sample 18 can similarly or alternatively receive displacements controlled in one or more degrees of freedom applied separately or simultaneously.Actuator 15 and the device 25 to be controlled are shown at the bottom or base 30, but it should be understood that actuator 15 or additional actuator(s) (if any) can be disposed or connected to crosshead 110. This can be accompanied by the gripper and sensor assembly 50 (see FIG. 3 and further described below) being inverted within the testing machine without departing from the scope of the present disclosure.

[0027] Computing device 9, controller 14, and system controller 23 can each be implemented on a digital computer and / or an analog computer. FIGS. 2 and the related description provide a concise and general description of a suitable computing environment in which computing device 9, controller 14, and system controller 23 can each be implemented. Although not essential, test computing device 9 is described in the general context of computer-executable instructions, such as program modules, executed at least in part by computer 19A. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Those skilled in the art can implement the following description and / or block diagrams in computer-executable instructions storable on a computer-readable medium. Further, those skilled in the art will understand that the present invention can be implemented in other computer system configurations including multiprocessor systems, networked personal computers, minicomputers, mainframe computers, etc. Aspects of the present invention can also be implemented in a distributed computing environment where tasks are performed by remote processing devices linked through a communication network. In a distributed computer environment, program modules can be located in both local and remote memory storage devices.

[0028] The computer 19A shown in FIG. 2 includes a conventional computer having a central processing unit (CPU) 27, a memory 33, and a system bus 35 that couples various system components including the memory 33 to the CPU 27. The system bus 35 can be any of a plurality of types of bus structures including a memory bus or memory controller, a peripheral bus, and a local bus using any of a variety of bus architectures. The memory 33 includes a read only memory (ROM) and a random access memory (RAM). Basic input / output (BIOS) including basic routines that help transfer information between elements within the computer 19A during startup and the like is stored in the ROM. Storage devices 37 such as hard disks, floppy (registered trademark) disk drives, optical disk drives, etc. are coupled to the system bus 35 and used for storing programs and data. Those skilled in the art should understand that other types of computer-readable media accessible by a computer, such as magnetic cassettes, flash memory cards, digital video disks, random access memories, read only memories, etc., can also be used as storage devices. Generally, programs are loaded into the memory 33 from at least one of the storage devices 37, with or without data.

[0029] Input devices such as a keyboard 41 and a pointing device (mouse) 43 enable a user to give commands to the computer 19A. A monitor 45 or other type of output device is further connected to the system bus 35 via an appropriate interface to provide feedback to the user. If the monitor 45 is a touch screen, the pointing device 43 can be incorporated therewith. The monitor 45 and an input pointing device 43, typically a mouse, etc., together with corresponding software drivers, form a graphical user interface (GUI) 47 for the computer 19A that is particularly useful in the manner described below.

[0030] The interfaces 49 on each of the computing device 9 and the system controller 23 enable communication between the computing device 9 and the system controller 23. Similarly, the respective interfaces 49 of the system controller 23 and the controller 14 enable communication between the system controller 23 and the controller 14. The interface 49 is also used to transmit the signal 19 as described above, or to receive the signals 15 and 21, and represents other parameters of the physical system such as the state of locks, doors, indicators, whether power is applied, etc. Generally, such circuitry includes digital-to-analog (D / A) converters and analog-to-digital (A / D) converters, as is well known in the art. The controller 14 can also include, as is known, an analog controller with or without digital monitoring. The functions of the computing device 9, the controller 23, and the controller 14 can be combined in one computer system. In another computing environment, the controller 14 is a single-board computer operable on a network bus of another computer that can be the controller 23 or another monitoring computer. The schematic diagram of FIG. 2 is intended to generally represent a computer for these and other suitable computing environments.

[0031] In the exemplary embodiment of FIG. 1, the testing machine 12 includes a crosshead 110 movable on a vertical column 112. A lock selectively clamps the crosshead 110 to the vertical column 112 to provide a rigid reaction structure. A position sensor monitors the actual state of each lock and provides a corresponding output signal, the status of which is communicated to the computing device 9.

[0032] In yet another exemplary embodiment, the actuator assembly 13 can operably couple one or more actuators to the crosshead 110, and its movement can apply a load to the test sample 18 instead of, or in addition to, the actuator 15. Thus, the testing machine and the actuator assembly 13 used herein can include various forms of couplers, links, bell cranks, etc. as needed.

[0033] Note that the same reference numerals are used for the same or similar elements in different drawings. It should also be understood that the terms used herein are for the purpose of describing embodiments and are not intended to be limiting. Unless otherwise indicated, ordinal numbers (e.g., first, second, third, etc.) are used to distinguish or identify different elements or steps within a group of elements or steps and do not give a limitation or numerical limitation that the elements or steps of that embodiment are consecutive. For example, the "first", "second", and "third" elements or steps do not necessarily appear in that order, and the embodiment is not necessarily limited to three elements or steps. Also, unless otherwise indicated, any notations such as "left", "right", "front", "back", "top", "bottom", "forward", "reverse", "clockwise", "counterclockwise", "up", "down", etc., or other similar terms such as "upper", "lower", "rearward", "forward", "vertical", "horizontal", "proximal", "distal", "intermediate", etc. are used for convenience and are not intended to mean, for example, any particular fixed position, orientation, or direction. Instead, such notations are used, for example, to reflect relative positions, orientations, or directions. Also, the singular forms "a", "an", and "the" are to be understood to include references to the plural unless the context clearly dictates otherwise.

[0034] Next, referring to FIG. 3, further details of the physical system 10 and its components are shown. As shown in FIG. 3, a grip and sensor assembly 50 is shown. The grip and sensor assembly 50 includes an element of the physical system that measures a load, holds the test sample 18, and applies a load to the test sample 18 when the test sample 18 is attached to the grip, and an adjustment element, for example, for adjusting the alignment of the physical system 10 with respect to the z-axis line 102, particularly in the illustrated embodiment. Specifically, in one embodiment, the grip and sensor assembly 50 includes several components along the z-axis line 102, for example, elements 28, 20, 22, 26A, 18, 26B, and 24. Element 28 is, for example, an adjustment element or device having a set screw 29 movable to adjust the lateral alignment of the test system in the x-direction 108 and / or the y-direction 110. The adjustment element 28 is shown adjacent to or connected to a z-axis load cell 20 used to measure a force along the z-axis line 102. The first lateral sensing load cell 22 is adjacent to or connected to the load cell 20 and has a sensor 104 for measuring a force along the x-axis line 108 and a sensor 106 for measuring a force along the y-axis line 110 at a first end of the test sample 18 attached to the first grip 26A.

[0035] In many cases, the adjustment element 28 is attached to the end of the grip and sensor assembly 50 opposite the actuator 15, or in other words, adjacent to a grip that is substantially stationary in this specification and attached to the crosshead 110. However, in an alternative embodiment, when the actuator 15 is attached to the crosshead 110, it may be desirable to attach the adjustment element 28 to the base 30. In many applications, it is preferred to attach the adjustment element 28 to a stationary or reaction element of the testing machine 12 so as not to have additional moving mass during testing. However, it should be understood that this is not limiting and the adjustment element 28 can be attached to the actuator 15 if desired.

[0036] The first lateral sensing load cell 22 is shown as having an end 114 adjacent to or connected to the grip 26A and an opposite end 116 adjacent to or connected to the z-axis line load cell 20. The test sample 18 is attached to one end of the grip 26A and also to a second end of a second grip 26B, which is adjacent to or connected to a second lateral sensing load cell 24. The second lateral sensing load cell 24 also has a sensor 104 for measuring a force along the x-axis line 108 and a sensor 106 for measuring a force along the y-axis line 110 at the second end of the test sample 18 attached to the second grip 26B. The second lateral sensing load cell 24 may be substantially the same as the first lateral sensing load cell 22, shown with its end 114 adjacent to or connected to the grip 26B and its end 116 adjacent to or connected to the actuator 15.

[0037] FIG. 4 is a front view of the first sensing load cell 22 and the second sensing load cell 24 separated from the remainder of the grip and sensor assembly 50. FIG. 5 is an isometric view of the first sensing load cell 22 and the second sensing load cell 24 of FIG. 4. In one embodiment, the first sensing load cell 22 and the second sensing load cell 24 are identical but are inverted with respect to each other within the grip and sensor assembly 50.

[0038] FIG. 6 is a cross-sectional view of the load cell 24 (the load cell 22 is substantially identical) along line 6-6 of FIG. 4. FIG. 6 shows one layout of the sensors 104 and 106 within the load cells 22, 24. The sensor 104 for measuring the lateral force on the x-axis line 108 forms a branch of a conventional Wheatstone bridge 160 as shown in FIG. 7. The sensor 106 for measuring the lateral force on the y-axis line 110 forms a branch of a conventional Wheatstone bridge 170 as shown in FIG. 8. By using these forces for each of the two load cells 22, 24, it becomes possible to determine alignment problems with respect to the sample 18.

[0039] Each load cell 22, 24 is shown to be usable in the tensile testing machine 12. Each load cell 22, 24, in one embodiment, comprises a load cell body 100 configured to engage with the grip 26 at its first end 114. At its second opposite end 116, the load cell body is configured to engage with one of the load cell 24 of the testing machine 12 or the actuator 15 for the testing machine 12 along an axis 102 extending from the first end 114 to the second end 116. The load cell body 100 includes a flexure 103 joined to and extending along the axis 102. The flexure 103 is compliant (has followability or compliance) with respect to a force in the x-direction 108 orthogonal to the axis 102 and is also compliant with respect to a force in the y-direction 110 orthogonal to the x-direction and orthogonal to the axis 102. The flexure 103 is rigid with respect to a force along the axis 102 and transmits the load to the sample 18. The load cell body 100, in one embodiment, comprises a set of first sensors 104 and a set of second sensors 106. The set of first sensors 104 is configured to sense a first force in a first transverse (x-axis) direction 108 orthogonal to the axis 102. The set of second sensors 106 is configured to sense a second force in a second transverse (y-axis) direction 110 orthogonal to the first transverse direction 108 and orthogonal to the axis 102. The sensors 104, 106 of the load cells 22, 24 can take a number of forms as known in the art. Typically, the sensors 104, 106 are strain gauges, but other sensors such as, but not limited to, capacitance-based or optically-based sensors can also be used.

[0040] By using two transducers each having two orthogonal measurement axes, it becomes possible to determine the type of bending of the test sample with respect to each axis, for example, an "S" type bend at one or both axes, or a "banana" type or "C" type bend. In particular, the moment at the sample end in the same direction represents a "banana" type or "C" type bend, and the moment at the sample end in the opposite direction represents an "S" type bend. Since there are two orthogonal directions, the type of bend is independent in each direction. Thus, the test sample can exhibit bending in 0, 1, or 2 directions, where each direction is an "S" type or "C" type bend.

[0041] Each load cell 22, 24 can further include a moment restraint 120 connected to the first end 114 and the second end 116 of the respective load cells 22, 24. In one embodiment, the moment restraint 120 is configured to prevent rotation of the first end 114 and / or the second end 116 about the axis 102. The moment restraint 120 is advantageous as it protects the flexure 103 from moments about the axis 102. Similarly, the moment restraint 120 can transmit moments about the axis 102 to the test sample 18 if desired.

[0042] The load cells 22, 24 having the moment restraint 120 are shown in isometric view in FIG. 9 and in front view in FIG. 10. A representative display 122 showing representative forces in the x and y directions to the user is shown in FIGS. 9 and 10. Such a display 124 can be powered by a battery or other power source 124 in some embodiments. The battery or other power source 124 further provides power to sensors such as the sensors 104, 106 shown herein by way of example. Alternatively or additionally, a connector 126 for outputting sensor measurements from the sensors 104, 106 can be provided attached to the load cell body 100 in one embodiment. The sensor wires extend from the sensors 104, 106 through the body 100 to the connector 126 and then along connections such as 22A, 24A as shown in FIG. 1.

[0043] A method 200 for operating a tensile testing machine such as the machine 12 is shown in FIG. 11. In one embodiment, the method 200 includes, at block 202, obtaining a first sensor output indicative of the force on sensors 104, 106 of a first load cell 22 at a first end of a test sample 18 attached to a first grip 26A of the testing machine 12 from the first load cell 22. At block 204, the method further includes obtaining a second sensor output indicative of the force on sensors 104, 106 of a second load cell 24 at a second opposite end of the test sample 18 attached to a second grip 26B of the testing machine 12 from the second load cell 24. At block 206, the forces at the sensors of the first load cell 22 and the second load cell 24 are determined from the first sensor output and the second sensor output. At block 208, the test sample 18 is aligned coaxially with the first grip 26A and the second grip 26B along an axis by adjusting at least one of the alignment device of the testing machine or at least one of the positions of the test sample in the first grip or the second grip.

[0044] Aligning coaxially with the alignment device of the testing machine includes, in one embodiment, adjusting in proximity to the crosshead of the test system. This can include adjusting laterally in at least one of two directions each orthogonal to the axis 102 and to each other. Aligning the test sample coaxially includes, in one embodiment, adjusting the orientation or angle of the test sample in at least one of the first grip or the second grip of the testing machine within the tolerance of the testing machine. The tolerance may be determined in advance, and one or more displays such as the display 122 may be used on the testing machine, the GUI of the testing machine, or on the load cell itself to indicate the alignment and suggest adjustments thereto to adjust within the tolerance of the testing machine.

[0045] Obtaining a first sensor output indicative of a force on a sensor of a first load cell at a first end of a test sample from the first load cell includes, in one embodiment, sensing a first force in a first lateral direction and a second lateral direction orthogonal to the first lateral direction. The force on the sensor of the first load cell can be sensed using a strain gauge or other strain measurement device. Obtaining a second sensor output indicative of a force on a sensor of a second load cell at a second, opposite end of the test sample from the second load cell includes, in one embodiment, sensing a second force in the first lateral direction and the second lateral direction. The force on the sensor of the second load cell can be sensed using a strain gauge or other force measurement device. Aligning coaxially includes, in one embodiment, reducing a lateral force in at least one of the first lateral direction and the second lateral direction.

[0046] Misalignment can be due to displacement of the test sample in at least one grip or an attachment error of the test sample in at least one grip. Changes in moment during the test can also be used to identify sample breakage. An example of monitoring during the test is crack propagation in an asymmetric sample as shown in FIG. 12. In FIG. 12, the asymmetric design has a normal flexion point at 302, which can extend a crack to point 304 within the sample through repeated tensile testing. This results in different moments and forces measured by the test system and can alert the user to changes such as partial or imminent failure of the sample. Alternatively, at the end of the test, a change in moment or a change in displacement can indicate movement of the sample relative to the grip or wear or damage of the grip itself.

[0047] Accordingly, embodiments of the present disclosure provide a method and system therefor for sensing lateral forces and adjusting the alignment of a test sample or elements of a testing machine.

[0048] The above-disclosed subject matter is to be considered illustrative and not restrictive, and the appended claims are intended to cover all such variations, improvements, and other embodiments that fall within the true scope of this disclosure. Accordingly, to the maximum extent permitted by law, the scope of this disclosure should be determined by the broadest permissible interpretation of the appended claims and their equivalents, and should not be limited or restricted by the foregoing detailed description.

Claims

1. 1. A method of operating a testing machine, comprising: obtaining a first sensor output from a first load cell indicative of a force on a plurality of sensors of the first load cell at a first end of a test sample attached to a first grip of the testing machine; obtaining a second sensor output from a second load cell indicative of a force on a plurality of sensors of the second load cell at a second opposite end of the test specimen attached to a second grip of the testing machine; determining a force at the sensor of the first load cell and a force at the sensor of the second load cell from the first sensor output and the second sensor output; aligning the test sample coaxially with the first grip and the second grip by adjusting at least one of an alignment device of the testing machine or at least one of a position of the test sample in the first grip or the second grip; A method comprising:

2. 2. The method of claim 1, wherein coaxial alignment in an alignment device of the testing machine includes moving one of the first grip or the second grip of the testing machine, e.g., adjusting one of the first grip and the second grip laterally in at least one of two directions perpendicular to the axis, and / or adjusting an orientation or angle of the test sample in at least one of the first grip or the second grip within a tolerance of the testing machine.

3. 2. The method of claim 1, wherein obtaining a first sensor output from a first load cell indicative of a force on a sensor, such as a strain gauge, of the first load cell at a first end of the test sample includes sensing a first force in a first lateral direction and a second lateral direction perpendicular to the first lateral direction.

4. 4. The method of claim 3, wherein obtaining a second sensor output from a second load cell indicative of a force on a sensor, e.g., a strain gauge, of the second load cell at a second opposite end of the test sample includes sensing a second force in the first lateral direction and in the second lateral direction.

5. The method of claim 3 , wherein coaxially aligning comprises reducing lateral forces in at least one of the first lateral direction and the second lateral direction.

6. The method of claim 1 further comprising applying a load to the test specimen.

7. The method of claim 6 further comprising measuring lateral forces on the test specimen during and / or after testing to determine misalignment.

8. The method of claim 6 , further comprising determining a type of bending of the test specimen using a moment determined from the first sensor output and the second sensor output.

9. 9. The method of claim 8, wherein determining the type of bend includes determining an "S" type bend from opposing moments at opposite ends of the test specimen and determining a "C" type bend from co-directional moments at opposite ends of the test specimen.

10. A load cell body for use in a tensile testing machine, comprising: a body portion configured to engage a grip at a first end of the body portion and one of a load cell for the tensile tester or an actuator for the tensile tester at a second end opposite the first end along an axis extending from the first end to the second end, the load cell body comprising a flexure joined to and extending along the axis, the flexure being compliant to a first force in a first lateral direction perpendicular to the axis and being compliant to a second force in a second lateral direction perpendicular to the first lateral direction and perpendicular to the axis, the flexure being stiff against forces along the axis. Load cell body.

11. Furthermore, a set of first sensors operably coupled to the flexure, the set of first sensors configured to sense the first force in the first lateral direction perpendicular to the axis; a set of second sensors operably coupled to the flexures, the set of second sensors configured to sense the second force in the second lateral direction perpendicular to the first lateral direction and perpendicular to the axis; The load cell body of claim 10 comprising:

12. The load cell body of claim 10 , wherein the first sensor of the set is a strain gauge.

13. The load cell body of claim 10 , wherein the second set of sensors are strain gauges.

14. 11. The load cell body of claim 10, further comprising a moment restraint connected to the first end and the second end, the moment restraint configured to prevent rotation of the first end or the second end about the axis.

15. 1. A method of aligning a test specimen in a testing machine, comprising the steps of: mounting the test specimen in a plurality of grips of the testing machine; applying a load to the test specimen; measuring lateral forces on the test specimen during and / or after testing to determine misalignment; A method comprising:

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