Alignment device and method for test system

Abstract

A method of operating a test machine includes obtaining, from a first load sensor, a first sensor output indicative of a force on a sensor of the first load sensor at a first end of a test specimen mounted in a first jig of the test machine. The method further includes obtaining, from a second load sensor, a second sensor output indicative of a force on a sensor of the second load sensor at a second opposite end of the test specimen mounted in a second jig of the test machine. Forces at the sensor of the first load sensor and the sensor of the second load sensor are determined from the first sensor output and the second sensor output. The test specimen is coaxially aligned with the first and second clamps along the axis by adjusting at least one of at least one of the alignment devices of the test machine or the position of the test specimen in the first clamp or the second clamp.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority benefit of 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. Background of the Invention

[0003] The following discussion is provided only for general background information and is not intended to assist in determining the scope of the claimed subject matter.

[0004] Testing machines or devices 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 specimens). Generally, a testing machine includes one or more actuators for applying input loads and displacements. The specimen is held in a fixture, and alignment problems can cause specimen damage and / or incorrect measurements. Summary of the Invention

[0005] The summary of the invention and the abstract herein are used to introduce a selected set of concepts in a simplified form, which will be further described in the detailed description below. The summary of the invention and the abstract are not intended to identify the key features or essential features of the claimed subject matter, nor are they intended to assist in determining the scope of the claimed subject matter. The claimed subject matter is not limited to embodiments that solve any or all of the disadvantages noted in the background art.

[0006] In one aspect, a method of operating a testing machine includes obtaining a first sensor output from a first load sensor indicative of a force on the sensor of the first load sensor at a first end of a test specimen mounted in a first fixture of the testing machine. The method further includes obtaining a second sensor output from a second load sensor indicative of a force on the sensor of the second load sensor at a second opposite end of the test specimen mounted in a second fixture of the testing machine. The forces at the sensors of the first load sensor and the second load sensor are determined based on the first sensor output and the second sensor output. The test specimen is coaxially aligned with the first fixture and the second fixture along an axis by adjusting at least one of an alignment device of the testing machine, a position of the test specimen in the first fixture, and a position of the test specimen in the second fixture.

[0007] The embodiments may include one or more of the following features. The foregoing method of coaxial alignment at the alignment device of the testing machine may include moving one of the first fixture or the second fixture of the testing machine. Coaxial alignment may include laterally adjusting one of the first fixture and the second fixture in at least one of two directions orthogonal to the axis. Coaxial alignment of the test specimen may include adjusting the orientation or angle of the test specimen within the tolerance of the testing machine in at least one of the first fixture or the second fixture.

[0008] Obtaining a first sensor output indicative of a force on a sensor of a first load sensor at a first end of a test specimen from the first load sensor may include sensing a first force in a first lateral direction and a second lateral direction orthogonal to the first lateral direction. Different types of strain sensing sensors (such as, but not limited to, strain gauges) may be used to sense the force on the sensor of the first load sensor. Obtaining a second sensor output indicative of a force on a sensor of a second load sensor at a second opposite end of the test specimen from the second load sensor may include sensing a second force in the first lateral direction and the second lateral direction. Different types of strain sensing sensors (such as, but not limited to, strain gauges) may be used to sense the force on the sensor of the second load sensor.

[0009] If desired, coaxial alignment may include reducing a lateral force in at least one of the first lateral direction and the second lateral direction.

[0010] The method may include applying a load to the test specimen, specifically, measuring a lateral force on the test specimen during and / or after the test to determine misalignment. Determining misalignment may include using a moment determined based on the first sensor output and the second sensor output to determine the type of bending in the test specimen. Determining the type of bending may include determining an S-type bend based on moments in opposite directions at opposite ends of the test specimen and determining a C-type bend based on moments in the same direction at opposite ends of the test specimen.

[0011] In another aspect, a load sensor for use in a tensile testing machine includes a load sensor body configured to engage a fixture at a first end and one of a load sensor of the tensile testing machine or an actuator of the tensile testing machine at a second end along an axis extending from the first end to the second end opposite the first end.

[0012] Embodiments may include one or more of the following features. The load cell body may include: a first set of sensors configured to sense a first force in a first lateral direction orthogonal to the axis; and a second set of 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 may include: a first set of sensors operatively coupled to the flexure and configured to sense a first force in a first lateral direction orthogonal to the axis; and a second set of sensors operatively 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 first set of sensors may be different types of strain sensing sensors, such as but not limited to strain gauges. Similarly, the second set of sensors may be different types of strain sensing sensors, such as but not limited to strain gauges. The load cell body may include torque limiters connected to the first and second ends and configured to inhibit rotation of the first or second end about the axis.

[0013] In another aspect, a method of aligning a test specimen in a testing machine includes mounting the test specimen in a fixture of the testing machine and applying a load to the test specimen. Lateral forces on the test specimen are measured during and / or after the test to determine misalignment.

[0014] This summary is not intended to describe every disclosed embodiment or every implementation of sensing lateral forces and adjusting the alignment of test specimens or components of a testing machine. Many other novel advantages, features, and relationships will become apparent as this description proceeds. The following figures and description more particularly illustrate example embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic diagram of a testing machine for controlling the operation of a testing device;

[0016] Figure 2 is a block diagram of a computer on which embodiments of the present disclosure may be implemented;

[0017] Figure 3 is an elevation view of a fixture and sensor assembly according to an embodiment of the present disclosure;

[0018] Figure 4 is a front view of a pair of load cells according to an embodiment of the present disclosure;

[0019] Figure 5 is Figure 4 an isometric view of the pair of load cells shown in

[0020] Figure 6 is a cross-sectional view of a load cell taken along line 6-6 Figure 4 ;

[0021] Figure 7 and Figure 8 is a circuit diagram of a Wheatstone bridge used to measure a lateral displacement force in an embodiment of the present disclosure;

[0022] Figure 9 is an isometric view of a load cell having a torque limiter according to an embodiment of the present disclosure;

[0023] Figure 10 is Figure 9 a front view of the load cell having a torque limiter;

[0024] Figure 11 is a flowchart of a method according to an embodiment of the present disclosure; and

[0025] Figure 12 is a schematic view of an asymmetric specimen to which an embodiment of the present disclosure can provide analysis. DETAILED DESCRIPTION

[0026] Figure 1 Illustrates a test machine system 8 according to one embodiment, the test machine system 8 including a computing device 9 for generating a GUI 47 ( Figure 2 ), the computing device 9 allowing a user to interact with and / or control the test machine 12, and / or calibrate or adjust the test machine 12. The test 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 Figure 1 shown, 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 a displacement or load to a test specimen 18. In one embodiment, the coupling mechanism includes a specimen fixture for holding the specimen. Additional components include one or more transducers 20, 22, and 24 as described below for measuring various loads, including for example loads in three orthogonal directions, a load along the specimen axis (sensor 20), and loads along two additional axes that are mutually orthogonal and orthogonal to the specimen axis. 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 (e.g., shown in Figure 3 ).

[0027] In Figure 1In the schematic diagram, the actuator system 13 is represented by an actuator 15 (located in a base 30 not shown in its entirety), which in turn represents one or more actuators in any testing machine that are directly or indirectly coupled to a test specimen 18. A controller 14 provides an actuator command signal 19 to a controlled device 25 (schematically shown, e.g., a servo valve, a power controller) to operate the actuator 15, which in turn excites the test specimen 18. It should be noted that the controller 14 has a design suitable for controlling the type of actuator employed. Appropriate feedback 15A can be provided to the controller 14 from the actuator 15 or from other sensors. One or more remote transducers on the test specimen 18 or the physical system 10, such as displacement sensors, strain gauges, accelerometers, load cells, thermometers, etc., provide a measured or actual response 21 to a system controller 23. In an exemplary embodiment, load cells 20, 22, and 24 provide responses 20A, 22A, and 24A to the system controller 23 (and can be considered part of the actual response 21, but the signals 20A, 22A, 24A are shown separately). The system controller 23 receives the actual response 21 as feedback for the response of the actuator 17, where the drive 17 is an input to the servo controller 14. In Figure 1 the illustration, the signal 17 is a reference signal, the signal 19 is a manipulated variable (command to the actuator device), and the signal 15A is a feedback variable. Although Figure 1 illustrated for a single-channel case, multi-channel embodiments where the signal 15A includes N feedback components and the signal 19 includes M manipulated variable components are typical and are considered another embodiment of the present invention. The test specimen 18 can take any number of forms, such as but not limited to a material sample, a sub-structure, or a component. Generally, the types of loads that can be applied to or exerted on the test specimen 18 include tension, compression, and / or torsion in one or more degrees of freedom applied individually or simultaneously. The test specimen 18 can also or alternatively undergo controlled displacements in one or more degrees of freedom applied individually or simultaneously. Although the actuator 15 and the controlled device 25 are shown at the bottom or base 30, it should be understood that the actuator 15 or additional actuators can be positioned or attached to the crosshead 110. This may require inverting the fixture and the sensor assembly 50 (see Figure 3 and discussed further below) in the testing machine without departing from the scope of the present disclosure.

[0028] The computing device 9, the controller 14, and the system controller 23 can all be implemented on digital and / or analog computers. Figure 2And the related discussion provides a brief general description of a suitable computing environment in which the computing device 9, the controller 14, and the system controller 23 can all be implemented. Although not required, the test computing device 9 will be described at least in part in the general context of computer-executable instructions (such as program modules) being executed by the computer 19A. In general, 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 into computer-executable instructions that can be stored on a computer-readable medium. In addition, those skilled in the art will understand that the present invention can be implemented with other computer system configurations, including multiprocessor systems, networked personal computers, microcomputers, 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 memory storage devices and remote memory storage devices.

[0029] Figure 2 The computer 19A illustrated in [reference number] 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 variety of bus structures, including a memory bus or memory controller using any of a variety of bus architectures, a peripheral bus, and a local bus. The memory 33 includes read-only memory (ROM) and random access memory (RAM). A basic input / output (BIOS) containing basic routines that help transfer information between elements within the computer 19A during startup is stored in the ROM. Storage devices 37, such as hard disks, floppy disk drives, optical disk drives, etc., are coupled to the system bus 35 and are used to store programs and data. Those skilled in the art should understand that other types of computer-readable media accessible by a computer, such as magnetic tape cartridges, flash memory cards, digital video disks, random access memories, read-only memories, etc., can also be used as storage devices. Typically, programs are loaded into the memory 33 from at least one of the storage devices 37, with or without data.

[0030] It should be noted that there seems to be a missing reference number in the description of "The computer 19A illustrated in [reference number]" in the original text. I have translated it as it is for now. If you can provide the correct reference number, it can be further improved.Input devices such as keyboard 41 and pointing device (mouse) 43 allow a user to provide commands to computer 19A. Monitor 45 or other type of output device is further connected to system bus 35 via a suitable interface and provides feedback to the user. If monitor 45 is a touch screen, pointing device 43 can be combined therewith. Monitor 45 and a typical input pointing device 43 (such as a mouse) together with the corresponding software drivers form a graphical user interface (GUI) 47 for computer 19A, and graphical user interface (GUI) 47 is particularly useful for the aspects described below.

[0031] Interfaces 49 on each of computing device 9 and system controller 23 allow communication between computing device 9 and system controller 23. Similarly, interfaces 49 on each of system controller 23 and controller 14 allow communication between system controller 23 and controller 14. Interface 49 also represents circuitry for transmitting signal 19 or receiving signals 15 and 21 as described above and other parameters of the physical system (such as the state of locks, doors, indicators, whether power is applied, etc.). Generally, such circuitry includes well-known digital-to-analog converters (D / A) and analog-to-digital (A / D) converters. Controller 14 may also include a well-known analog controller with or without digital supervision. The functions of computing device 9, controller 23, and controller 14 can be combined into one computer system. In another computing environment, controller 14 is a single-board computer operable on the network bus of another computer, and this single-board computer can be controller 23 or another supervisory computer. Figure 2 The schematic diagram is intended to generally represent a computer for these and other suitable computing environments.

[0032] In Figure 1 In an exemplary embodiment, test machine 12 includes a crosshead 110 movable on a vertical column 112. A lock selectively clamps crosshead 110 to vertical column 112, thereby providing a rigid reaction structure. A position sensor monitors the actual state of each lock and provides a corresponding output signal, the state of which is transmitted to computing device 9.

[0033] In yet another exemplary embodiment, actuator assembly 13 can operatively couple one or more actuators to crosshead 110, as an alternative or supplement to actuator 15, and the movement of crosshead 110 applies a load to test specimen 18. Thus, as used herein, test machine and actuator assembly 13 can include different forms of couplings, linkages, bell cranks, etc. (if needed).

[0034] It should be noted that in different figures, the same or similar elements are denoted by the same reference numerals. 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 in a group of elements or steps and do not provide a sequence or numerical limitation to the elements or steps of their embodiments. For example, the "first", "second", and "third" elements or steps do not necessarily occur in that order, and their embodiments are not necessarily limited to three elements or steps. It should also be understood that unless otherwise indicated, any labels (such as "left", "right", "front", "back", "top", "bottom", "forward", "reverse", "clockwise", "counterclockwise", "up", "down") or other similar terms (such as "upper", "lower", "rear", "front", "vertical", "horizontal", "proximal", "distal", "intermediate", etc.) are used for convenience and are not intended to imply, for example, any particular fixed position, orientation, or direction. Instead, such labels are used to reflect, for example, relative position, orientation, or direction. It should also be understood that unless the context clearly indicates otherwise, the singular forms "a", "an", or "the" include plural referents.

[0035] Now referring to Figure 3 , additional details of the physical system 10 and components therein are shown. As Figure 3 illustrated therein, a fixture and sensor assembly 50 is shown. The fixture and sensor assembly 50 includes elements of the physical system that measure a load, hold a test specimen 18, and apply a load to the test specimen 18 when the test specimen 18 is mounted in the fixture, and includes adjustment elements for adjusting, for example, the alignment of the physical system 10, particularly with respect to the z-axis 102 in the illustrated embodiment. Specifically, in one embodiment, the fixture and sensor assembly 50 includes a plurality of components along the z-axis 102, which components include, for example, elements 28, 20, 22, 26A, 18, 26B, and 24. Element 28 is an adjustment element or device, such as having a movable set screw 29 for adjusting 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 the z-axis load sensor 20, which is used to measure the force along the z-axis 102. The first lateral sensing load sensor 22 is adjacent to or connected to the load sensor 20 and has a sensor 104 for measuring the force along the x-axis 108 and a sensor 106 for measuring the force along the y-axis 110 at the first end of the test specimen 18 mounted in the first fixture 26A.

[0036] In many cases, the adjustment element 28 is mounted on the end of the fixture opposite the actuator 15 and sensor assembly 50, or in other words, adjacent to the substantially fixed fixture herein mounted on the crosshead 110. However, in an alternative embodiment, if the actuator 15 is mounted in the crosshead 110, it may be desirable to mount the adjustment element 28 on the base 30. In many applications, it is preferred to mount the adjustment element 28 on a fixed or reaction element of the test machine 12 so that there is no additional moving mass during the test. However, it should be understood that this is not restrictive and, if desired, the adjustment element 28 can be mounted on the actuator 15.

[0037] The first lateral load cell 22 shown has one end 114 adjacent to or connected to the fixture 26A and an opposite end 116 adjacent to or connected to the z-axis load cell 20. One end of the test specimen 18 is mounted in the fixture 26A and the second end is also mounted in a second fixture 26B which in turn is adjacent to or connected to a second lateral load cell 24 which also has a sensor 104 for measuring the force along the x-axis 108 and a sensor 106 for measuring the force along the y-axis 110 at the second end of the test specimen 18 mounted in the second fixture 26B. The second lateral load cell 24 can be substantially the same as the first lateral load cell 22 and is shown with its end 114 adjacent to or connected to the fixture 26B and its end 116 adjacent to or connected to the actuator 15.

[0038] Figure 4 is a front view of the first and second load cells 22 and 24 separated from the remainder of the fixture and sensor assembly 50. Figure 5 is Figure 4 an isometric view of the first and second load cells 22 and 24. In one embodiment, the first and second load cells 22 and 24 are the same but are inverted relative to each other in the fixture and sensor assembly 50.

[0039] Figure 6 is a cross-sectional view of the load cell 24 (substantially the same as the load cell 22) along Figure 4 line 6-6. Figure 6 shows one layout of the sensors 104 and 106 in the load cells 22, 24. The sensor 104 for measuring the lateral force on the x-axis 108 forms a branch of a conventional Wheatstone bridge 160 as shown in Figure 7 and the sensor 106 for measuring the lateral force on the y-axis 110 forms a branch of a Wheatstone bridge as shown in Figure 8Branches of the conventional Wheatstone bridge 170 shown in []. Applying these forces to each of the two load cells 22, 24 allows determination of alignment issues relative to the specimen 18.

[0040] Each load cell 22, 24 is shown as being usable in a tensile testing machine 12. In one embodiment, each load cell 22, 24 includes a load cell body 100 configured such that its first end 114 engages a fixture 26. The load cell body is configured such that its second opposite end 116 engages one of the load cell 24 of the testing machine 12 or an 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 connected to and extending along the axis 102. The flexure 103 complies with forces in the x - direction 108 orthogonal to the axis 102 and complies with forces in the y - direction 110 orthogonal to the x - direction and orthogonal to the axis 102. The flexure 103 is rigid with respect to forces along the axis 102 to transfer the load to the specimen 18. In one embodiment, the load cell body 100 includes 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, which is 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 variety of forms known in the art. Generally, the sensors 104, 106 are strain gauges; however, other sensors such as, but not limited to, capacitance - based or optically - based sensors can be used.

[0041] Using two transducers (each having two orthogonal measurement axes) allows determination of the type of bending relative to each axis in the test specimen, such as an "S" - type bend, or a "banana" - type bend or a "C" - type bend on one or both axes. In particular, moments in the same direction at the specimen ends represent a "banana" - type or "C" - type bend, while moments in opposite directions at the specimen ends represent an "S" - type bend. Since there are two orthogonal directions, the type of bending is independent in each direction. Thus, the test specimen can exhibit no bending, bending in one or two directions, or an "S" - type bend or a "C" - type bend in each direction.

[0042] Each load cell 22, 24 may further include a torque limiter 120 that is connected to a first end 114 and a second end 116 of its respective load cell 22, 24. In one embodiment, the torque limiter 120 is configured to inhibit rotation of the first end 114 and / or the second end 116 about an axis 102. The torque limiter 120 is advantageous because it protects the flexure 103 from torques about the axis 102. Also, if desired, the torque limiter 120 transfers the torque about the axis 102 to the test specimen 18.

[0043] In Figure 9 the isometric view and Figure 10 the front view of Figure 9 and Figure 10 show the load cells 22, 24 with the torque limiter 120. In Figure 1 and

[0044] In Figure 11 shown is a method 200 of operating a tensile testing machine, such as machine 12. In one embodiment, method 200 includes obtaining, in block 202, a first sensor output from a first load cell 22, the first sensor output indicating a force on sensors 104, 106 of the first load cell 22 at a first end of a test specimen 18 mounted in a first fixture 26A of the test machine 12. In block 204, the method further includes obtaining a second sensor output from a second load cell 24, the second sensor output indicating a force on sensors 104, 106 of the second load cell 24 at a second, opposite end of the test specimen 18 mounted in a second fixture 26B of the test machine 12. In block 206, based on the first sensor output and the second sensor output, a force at the sensors of the first load cell 22 and at the sensors of the second load cell 24 is determined. In block 208, the test specimen 18 is coaxially aligned with the first fixture 26A and the second fixture 26B along an axis by adjusting at least one of alignment devices of the test machine or a position of the test specimen in the first fixture or the second fixture.

[0045] In one embodiment, coaxial alignment at the alignment device of a testing machine includes making adjustments near the crosshead of the testing system. This can include making lateral adjustments in at least one of two directions that are both orthogonal to axis 102 and orthogonal to each other. In one embodiment, coaxial alignment of a test specimen includes adjusting the orientation or angle of the test specimen in at least one of the first or second fixtures of the testing machine to within the tolerances of the testing machine. The tolerances can be predetermined, and one or more displays (such as display 122) can be used on the testing machine, the GUI of the testing machine, or the load cell itself to indicate alignment and suggest adjustments to the alignment in order to adjust to within the tolerances of the testing machine.

[0046] In one embodiment, obtaining a first sensor output indicative of the force on the sensor of a first load cell at a first end of a test specimen from the first load cell includes 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 measuring device. In one embodiment, obtaining a second sensor output indicative of the force on the sensor of a second load cell at a second opposite end of the test specimen from the second load cell includes 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 measuring device. In one embodiment, coaxial alignment includes reducing the lateral force in at least one of the first lateral direction and the second lateral direction.

[0047] Misalignment can be due to displacement of the test specimen in at least one fixture, or incorrect installation of the test specimen in at least one fixture. Moment changes during the test can also be used to identify specimen failure. An example of monitoring during the test is the propagation of cracks in an asymmetric specimen, as Figure 12 shown. In Figure 12 an asymmetric design has a normal flexure point at 302, and through repeated tensile testing, this normal flexure point can cause cracks to extend to point 304 within the specimen. This will result in different moments and forces measured by the testing system and can alert the user to changes such as partial or impending failure of the specimen. Alternatively, at the end of the test, moment changes or displacement changes can indicate movement of the specimen relative to the fixture, or wear or damage to the fixture itself.

[0048] Accordingly, embodiments of the present disclosure provide methods and systems for sensing lateral forces and adjusting the alignment of elements of a test specimen or a testing machine.

[0049] The subject matter disclosed above should be considered illustrative and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments that fall within the scope of this disclosure. Accordingly, to the maximum extent permitted by law, the scope of this disclosure will be determined by the broadest permissible interpretation of the appended claims and their equivalents and should not be limited or restricted to the foregoing detailed description.

Claims

1. A method of operating a testing machine, comprising: obtaining a first sensor output from a first load sensor indicative of a force on a sensor of the first load sensor at a first end of a test specimen mounted in a first fixture of the testing machine; obtaining a second sensor output from a second load sensor indicative of a force on a sensor of the second load sensor at a second opposite end of the test specimen mounted in a second fixture of the testing machine; determining a force at a sensor of the first load sensor and a force at a sensor of the second load sensor based on the first sensor output and the second sensor output; as well as The test specimen is coaxially aligned with the first fixture and the second fixture along an axis by adjusting at least one of an alignment device of the testing machine or a position of the test specimen in the first fixture or the second fixture.

2. The method of claim 1, wherein: Coaxially aligning at an alignment device of the testing machine includes moving one of the first fixture or the second fixture of the testing machine.

3. The method of claim 2, wherein: Coaxial alignment includes laterally adjusting one of the first clamp and the second clamp in at least one of two directions orthogonal to the axis.

4. The method of claim 2, wherein: Coaxially aligning the test specimen includes adjusting the orientation or angle of the test specimen in at least one of the first fixture or the second fixture to within a tolerance of the testing machine.

5. The method of claim 1, wherein: Obtaining a first sensor output from a first load sensor indicative of a force on a sensor of the first load sensor at a first end of the test specimen includes sensing a first force in the first lateral direction and in a second lateral direction orthogonal to the first lateral direction.

6. The method of claim 5, wherein: The force on the sensor of the first load sensor is sensed with a strain gauge.

7. The method of claim 5, wherein: Obtaining a second sensor output from the second load sensor indicative of a force on a sensor of the second load sensor at a second opposite end of the test specimen includes sensing a second force in the first lateral direction and the second lateral direction.

8. The method of claim 7, wherein: The force on the sensor of the second load sensor is sensed with a strain gauge.

9. The method of claim 5, wherein: The coaxial alignment includes reducing lateral forces in at least one of the first lateral direction and the second lateral direction.

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

11. The method of claim 10, further comprising measuring lateral forces on the test specimen during and / or after testing to determine misalignment.

12. The method of claim 10, further comprising using a moment determined from the first sensor output and the second sensor output to determine a type of bend in the test specimen.

13. The method of claim 12, wherein: Determining the type of bend includes determining an "S" type bend based on moments in opposite directions at opposite ends of the test specimen, and determining a "C" type bend based on moments in the same direction at opposite ends of the test specimen.

14. A load cell body for use in a tensile testing machine, comprising: a body portion configured to engage a fixture at a first end thereof and to engage one of a load cell of the tensile testing machine or an actuator of the tensile testing machine at a second end along an axis extending from a first end thereof to a second end opposite the first end, the load cell body including a flexure connected to and extending along the axis, the flexure compliant with a first force in a first lateral direction orthogonal to the axis and compliant with a second force in a second lateral direction orthogonal to the first lateral direction and orthogonal to the axis, and the flexure being rigid with respect to forces along the axis.

15. The load sensor body of claim 14, further comprising: a set of first sensors operably coupled to the flexure and configured to sense the first force in the first lateral direction orthogonal to the axis; as well as A set of second sensors is operably coupled to the flexure and configured to sense the second force in a second lateral direction orthogonal to the first lateral direction and orthogonal to the axis.

16. The load sensor body of claim 14, wherein: The set of first sensors are strain gauges.

17. The load sensor body of claim 14, wherein: The set of second sensors are strain gauges.

18. The load sensor body of claim 14, further comprising a torque limiter connected to the first end and the second end, the torque limiter configured to inhibit rotation of the first end or the second end about the axis.

19. A method of aligning a test specimen in a testing machine, comprising: installing the test specimen in a fixture of the testing machine; applying a load to the test specimen; as well as The lateral force on the test specimen is measured during and / or after testing to determine misalignment.

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