Test apparatus and method for determining at least one characteristic of a plurality of test specimens

A test apparatus and method for determining at least one characteristic of a test specimen. An exemplary test specimen is a shape memory metal alloy and an exemplary characteristic is a transformation temperature of the shape memory metal alloy. The test apparatus may include a chiller unit including a tank containing a chilling medium, such as isopropyl alcohol or denatured alcohol, which holds a removable fixture tray that can accommodate up to ten specimens, or more. The fixture tray holds the test specimens in an initial deformed condition, and the cooling medium may be gradually heated to induce transformation of the specimens. The test apparatus may include a vision-based optical system which includes a camera that tracks the specimens within its field of view.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a test apparatus and method for determining at least one characteristic of a test specimen, and in one application, relates to a test apparatus and method for determining a transformation temperature of a shape memory metal alloy. An exemplary application is a test apparatus and method for determining the martensite-to-austenite transformation temperatures of nickel titanium alloys.

2. Description of the Related Art

ASTM Method F2082 is a test method for the determination of transformation temperatures of nickel titanium shape memory metal alloys by bend and free recovery. This test method involves cooling a test specimen to its nominally fully martensite phase, deforming the specimen, and heating the specimen to its fully austenite phase. During heating, the motion of specimen is measured and is plotted versus specimen temperature for determining the martensite-to-austenite transformation temperatures.

A test apparatus for carrying out this method is contemplated in ASTM Standard F2082, and generally includes a fixture in which a specimen is held, the fixture submerged in a cooling bath. The specimen is deformed in the bath, and placed on the fixture which holds the specimen so as to not interfere with the free recovery of the specimen on heating. The bath is heated, and a thermocouple is used to measure the temperature of the bath. A transducer is used to detect the change in shape of the specimen as the specimen straightens, and displacement and temperature are measured and plotted versus one another to determine physical characteristics of the specimen, such as the martensite-to-austenite transformation temperature.

One known test device for implementing ASTM Standard F2082 is the Shape Track™ device, available from Confirmd LLC of San Carlos, Calif., and is similar to the test apparatus contemplated by ASTM Standard F2082. This device is based on the use of a linear variable differential transducer (LVDT) which is placed in contact with the test specimen to measure displacement. However, it is thought that contact of the transducer with the specimen could adversely affect the accuracy of the test data. Also, liquid nitrogen is used to cool the bath, which can be both hazardous and costly. Further, the bath temperature is not accurately controlled per the ASTM specification, as a hotplate is used, which cannot provide uniform and consistent temperature changes. Finally, this apparatus can only test one specimen at a time.

What is needed is a test apparatus and method for determining transformation temperatures of shape memory metal alloys which is an improvement over the foregoing.

SUMMARY OF THE INVENTION

In an exemplary embodiment of the present disclosure, a test apparatus for monitoring at least one characteristic of a test specimen is provided. The test apparatus may test the test specimen in a non-contact method while the test specimen is submerged in a bath. The test apparatus may test multiple test specimens at the same time.

In another exemplary embodiment of the present disclosure, a method for monitoring at least one characteristic of a test specimen is provided. The method may be a non-contact method for monitoring the test specimen while the test specimen is submerged in a bath. The method may test multiple test specimens at the same time.

In a further exemplary embodiment of the present disclosure, a method for testing at least one characteristic of a plurality of test specimens is provided. The plurality of test specimens being shape memory alloys, The method comprising the steps of: supporting the plurality of test specimens on a fixture in a spaced apart relationship; positioning the plurality of test specimens within a liquid bath; setting the temperature of the liquid bath at a first temperature; altering a shape of each of the plurality of test specimens while positioned in the liquid bath; capturing at least one image of each of the plurality of test specimens within the liquid bath when the liquid bath is at the first temperature; changing the temperature of the liquid bath to a second temperature; capturing at least one image of each of the plurality of test specimens within the liquid bath when the liquid bath is at the second temperature; and determining the at least one characteristic of the plurality of test specimens based on the images of the plurality of test specimens. In one example, the fixture includes a plurality of mandrels and the step of altering the shape of each of the plurality of test specimens while positioned in the liquid bath includes the step of bending each of the plurality of test specimens against a respective one of the plurality of mandrels. In another example, the method further comprises the steps of: positioning a camera above the plurality of test specimens; while the liquid bath is at the first temperature, moving the camera such that each of the plurality of test specimens is within a field of view of the camera. The plurality of test specimens including a first test specimen and a second test specimen. The camera being moved to a first position to bring the first specimen within the field of view of the camera and being moved to a second position to bring the second specimen within the field of view of the camera. The method further comprising the step of while the liquid bath is at the second temperature, moving the camera such that each of the plurality of test specimens is within a field of view of the camera. The camera being moved to the first position to bring the first specimen within the field of view of the camera and being moved to the second position to bring the second specimen within the field of view of the camera. In a further example, the at least one characteristic of the plurality of test specimens is a transformation temperature.

In yet another exemplary embodiment of the present disclosure, an apparatus for testing at least one characteristic of a plurality of test specimens is provided. The plurality of test specimens being shape memory alloys. The apparatus comprising a chiller unit having a tank with liquid medium therein. The chiller unit including a cooling unit which is configured to lower a temperature of the liquid medium and a heating unit which is configured to raise the temperature of the liquid medium. The apparatus further comprising a removable fixture having a plurality of stations. Each station being capable of holding at least one test specimen. The removable fixture being positionable within the tank of the chiller unit such that the at least one test specimen is submerged in the liquid medium. The apparatus further comprising a camera positioned above the tank and having a field of view directed at a top side of the fixture; a rotational base coupled to the camera and configured to move the camera to position the field of view of the camera sequentially at each station which is holding at least one test specimen, the camera capturing at least one image of the test specimen at each station; and an electronic controller operatively coupled to the chiller unit to control the temperature of the liquid medium, operatively coupled to the rotational base to position the field of view of the camera, and operatively coupled to the camera to receive information regarding each test specimen. In one example, each of the plurality of stations of the removable fixture has a test specimen held thereby, a first end of each test specimen being held by the removable fixture and a second end of each test specimen being unsupported and able to move relative to the first end. In another example, a first number of the plurality of stations of the removable fixture has a test specimen held thereby. The first number being less than all of the plurality of stations. The electronic controller receiving at least one input which indicates the first number of stations and the electronic controller instructing the rotational base to move past stations not included in the first number of stations. In a further example, the electronic controller is operatively coupled to the camera through a wireless connection. In still another example, the test specimens include at least two groups, a first group having a first diameter and a second group having a second diameter. The first group and the second group being held by the removable fixture at the same time.

In yet a further exemplary embodiment of the present disclosure, a fixture for holding a plurality of test specimens is provided. The fixture comprising a base member; a central hub having a plurality of holders each of which holds a first end of a respective test specimen; and a plurality of mandrels spaced-apart from the central hub, each of the plurality of mandrels having a profile about which a respective test specimen may be shaped. In one example, the plurality of holders are radial openings in the central hub. In another example, the plurality of mandrels are removably coupled to the base member. In a further example, the central hub is removably coupled to the base member. In still a further example, the fixture further comprises a handle extending above the plurality of holders of the central hub. In yet another example, a second end of each of the plurality of test specimens is unsupported. In still another example, a center of each of the mandrels is equally spaced from a center of the base member of the fixture. In yet still another example, a center of a first mandrel is equidistant from two adjacent mandrels.

In a further exemplary embodiment of the present disclosure, a test apparatus and method for the determination of transformation temperatures of shape memory metal alloys are provided. In one embodiment, the test apparatus is designed to very accurately implement ASTM Standard F2082, and generally includes a chiller unit including a tank containing a chilling medium, such as isopropyl alcohol or denatured alcohol, which holds a removable fixture tray that can accommodate up to ten specimens, or more. The fixture tray holds the test specimens in an initial deformed condition, and the cooling medium may be gradually heated to induce transformation of the specimens. A vision-based optical system includes a camera which tracks the specimens within its field of view, and associated software operates with the camera to detect and plot shape changes of the specimens versus temperature to very accurately determine transformation temperatures of the specimens.

In still another exemplary embodiment of the present disclosure, a test apparatus for determining a transition temperature of a shape memory metal alloy is provided. The test apparatus including a temperature control device including a container with a liquid medium; a specimen holding member removably positionable in the container, the specimen holding member capable of holding a plurality of test specimens; a camera system including a camera having a field of view encompassing at least one test specimen of the specimen holding member; and a software program controlling the temperature control device and the camera system, the software program concurrently measuring temperature changes and shape changes of the specimens to determine a transition temperature of at least one of the specimens.

In yet another exemplary embodiment of the present disclosure, a method for testing at least one characteristic of a plurality of test specimens is provided. The method comprising the steps of: supporting the plurality of test specimens on a fixture in a spaced apart relationship; setting an environmental characteristic of a region surrounding the plurality of test specimens to a first value; capturing at least one image of each of the plurality of test specimens at the first value of the environmental characteristic of the region surrounding the plurality of test specimens; changing the environmental characteristic of the region surrounding the plurality of test specimens to a second value; capturing at least one image of each of the plurality of test specimens at the second value of the environmental characteristic of the region surrounding the plurality of test specimens; and determining the at least one characteristic of the plurality of test specimens based on the images of the plurality of test specimens at the first value of the environmental characteristic of the region surrounding the plurality of test specimens and the second value of the environmental characteristic of the region surrounding the plurality of test specimens.

The exemplification set out herein illustrates one embodiment of the invention, and such exemplification is not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF THE DRAWINGS

For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings, which are described below. The embodiments disclosed below are not intended to be exhaustive or limit the invention to the precise form disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may utilize their teachings. It will be understood that no limitation of the scope of the invention is thereby intended. The invention includes any alterations and further modifications in the illustrated devices and described methods and further applications of the principles of the invention which would normally occur to one skilled in the art to which the invention relates.

The present invention provides a test apparatus and method for the determination of at least one characteristic of a plurality of test specimens. In one embodiment, an environmental characteristic of a region surrounding the plurality of test specimens is changed over time. An exemplary environmental characteristic is temperature. An exemplary test specimen is a shape memory alloy and an exemplary characteristic is a transformation temperature of the shape memory alloy. Other exemplary characteristics may also be monitored.

In one embodiment, the test apparatus is designed to very accurately implement ASTM Standard F2082, and generally includes a chiller unit including a tank containing a chilling medium. An exemplary chilling medium is isopropyl alcohol. Another exemplary chilling medium is denatured alcohol. The test specimens are supported on a removable fixture tray. In one embodiment, the fixture tray may hold up to ten test specimens. Of course, the fixture tray may be configured to hold more or less test specimens. In one embodiment, the test specimens are wires having a diameter in the range of about 0.002 inches to about 0.040 inches.

In the case of determining a transition temperature of a shape memory alloy, the fixture tray holds the test specimens in an initial deformed condition and the cooling medium is gradually heated to induce transformation of the test specimens. A vision-based optical system includes a camera which tracks the test specimens within its field of view, and associated software executed by an electronic controller determines the transformation temperatures of the test specimens. The electronic controller communicates with the chiller to control the temperature of the liquid chilling medium and communicates with the camera to receive information regarding the shape of the test specimens. The electronic controller operates with the camera to detect and plot shape changes of the test specimens versus temperature to very accurately determine transformation temperatures of the specimens.

The present apparatus has several distinct advantages over the known apparatuses described in the Background section above. In one embodiment, the present test apparatus utilizes machine vision to accurately measure displacement of the test specimens without physical contact with the specimens. In one embodiment, the present apparatus also makes use of a two-stage chiller unit to cool the bath to the appropriate temperature, and may continually and accurately adjust the bath temperature throughout the test cycle to adhere to the ASTM Standard F2082 specifications. In one embodiment, the present apparatus may also simultaneously test ten or more specimens.

Referring toFIG. 1, a portion of a test apparatus20is shown. Test apparatus20includes an exemplary temperature control device, shown as a chiller unit22, which includes a tank24that contains a liquid medium23. An exemplary liquid medium23is isopropyl alcohol. Another exemplary liquid medium is denatured alcohol. Tank24also contains a specimen holding member, shown as a removable fixture tray26. The fixture tray26may hold up to ten wire test specimens28. The wire specimens28are held by a center hub30of fixture tray26and are bent around outer mandrels32once in the martensitic state. The ASTM Standard F2082 calls for an outer fiber strain of 2-2.5%, which is 39-49 times the wire diameter. The individual mandrels32are interchangeable to include different size mandrels, providing the ability to test specimens of various diameters.

Referring toFIG. 2, a representative view of test apparatus20is shown. Chiller unit22includes a cooling unit50which interacts with liquid medium23to lower a temperature of liquid medium23and a heating unit52which interacts with liquid medium23to raise a temperature of liquid medium23. In one embodiment, a magnetic stirrer or other device is provided in a bottom portion of tank24to assist in keeping the temperature of the bath at a uniform temperature. The operation of cooling unit50and heating unit52is controlled by an electronic controller54. An exemplary chiller unit22is model MC880, available from FTS of Stone Ridge, N.Y. In one embodiment, cooling unit50is a two stage compressor which can lower the temperature of liquid medium23to a minimum of −80° C. in tank24. The electronic controller54uses heating unit52to raise a temperature of liquid medium23. In one embodiment, the temperature of liquid medium23is raised by electronic controller54at a rate no greater than 4° C./min.

In one embodiment, electronic controller54receives instructions on the desired temperature of liquid medium23from an electronic controller60of test apparatus20. Exemplary electronic controllers include personal computers and other suitable electronic devices which may be programmed to execute software. Although electronic controller60is illustrated as a single controller, it should be understood that multiple computing systems may be used together, such as over a network or other methods of transferring data. In one embodiment, electronic controller60is coupled to electronic controller54through a wired serial connection61. Other wired or wireless connections may be made between electronic controller54and electronic controller60as opposed to or in addition to wired serial connection61.

Electronic controller60has access to a memory62which includes test control software64, data files66, and report files68. Electronic controller60executes test control software64stored on memory62. Memory62is a computer readable medium and may be a single storage device or may include multiple storage devices, located either locally with electronic controller60or accessible across a network. Computer-readable media may be any available media that may be accessed by electronic controller60and includes both volatile and non-volatile media. Further, computer readable-media may be one or both of removable and non-removable media. By way of example, computer-readable media may include, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, Digital Versatile Disk (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which may be used to store the desired information and which may be accessed by computing system100.

Memory62includes operating system software (not shown). An exemplary operating system software is a WINDOWS operating system available from Microsoft Corporation of Redmond, Wash. Memory62further includes communications software (not shown) which controls the communication between electronic controller60and electronic controller54and between electronic controller60and other devices.

As stated herein, memory62includes test control software64. Although described as software, it is understood that at least portions of test control software64may be implemented as hardware. As explained herein, test control software64based on a plurality of inputs determines at least one characteristic of a plurality of test specimens28.

Electronic controller60is further coupled to a rotational base70. Rotational base70includes a first stationary portion72and a second movable portion74. Second movable portion74is rotatable about an axis76relative to second movable portion74. Axis76is vertical and generally normal to a top surface of a base member150(seeFIG. 4) of fixture tray26. In one embodiment, rotational base70is a rotary servo table, such as model ADRS200, available from Aerotech, Inc. of Pittsburgh, Pa. Electronic controller60is connected to rotational base70through a wired serial connection78. Electronic controller60controls the angular position of second movable portion74relative to first stationary portion72through wired serial connection78. Other wired or wireless connections may be made between rotational base70and electronic controller60as opposed to or in addition to wired serial connection78.

A camera34is coupled to rotational base70. An exemplary camera is model T27, available from PPT Vision, Inc. of Eden Praire, Minn. Camera34is oriented to image at least a portion of fixture tray26when positioned in tank24. Camera34includes a lens system80which may be adjusted to vary a field of view of camera34. A light ring82is mounted to a front of lens system80and illuminates at least the portion of fixture tray26being imaged by camera34.

Both camera34and light ring82receive power from a DC power supply84. In one embodiment, DC power supply84is mounted to rotational base70. Rotational base70is also powered by DC power supply84. In one embodiment, AC power is fed via slip rings to the DC power supply84when DC power supply84is mounted to second movable portion74. Camera34communicates with electronic controller60through a wireless router86which communicates with a wireless communication device88accessible by electronic controller60. In one embodiment, electronic controller60and camera34communicate via wireless Ethernet.

Electronic controller60also is coupled to at least one user input device90. Exemplary user input devices90include buttons, knobs, keys, switches, a mouse, a roller ball, and other suitable devices for providing an input to electronic controller60. Electronic controller60is further coupled to at least one user output devices92. Exemplary user output devices include display screens, printers, lights, and other suitable devices for providing an output from electronic controller60. In one embodiment, user input device90and user output device92are combined into a single user interface device94. An exemplary user interface device94is a touch screen interface. In one embodiment, electronic controller60and single user interface device94are shown as a panel PC98(seeFIG. 3).

Referring toFIG. 3, test apparatus20includes a frame100which supports rotational base70. Frame100also supports a plurality of side walls102and a roof104. The plurality of side walls102and roof104form an enclosure106in which chiller unit22is positioned. Enclosure106includes a door108which permits ingress and egress relative to an interior of enclosure106, such as tank24of chiller unit22. Enclosure106is shown supported on a moveable cart110which permits test apparatus20to be transported from place to place as desired.

Referring toFIG. 4, an exemplary embodiment of fixture tray26is shown. Fixture tray26includes a base member150. Base member150is shown as a circular plate having a central opening152, a plurality of openings154which will position outer mandrels32, and a plurality of openings156. Openings156receive couplers158which couple to leg members160. Leg members160support base member150off of a bottom of tank24. In one embodiment, fixture tray26is made of a non-metallic material. Exemplary materials include materials with low specific heat capacity, such as ultra-high molecular weight (UHMW) plastic.

Referring toFIG. 5, openings154are each an equal distance from central opening152and are equally spaced relative to each other. In the illustrated embodiment, openings154are arranged such that each of openings154are separated by 36 degrees. In one embodiment, the spacing of openings154is not constant.

Returning toFIG. 4, pins162are received in openings154. Pins162also are received in corresponding openings164in outer mandrels32. In one embodiment, pins162are press fit into openings164of outer mandrels32and removably received in openings154of base member150. In one embodiment, pins162are press fit into openings154of base member150and are removably received in openings164of outer mandrels32. In either case outer mandrels32are removably coupled to openings156.

Center hub30is coupled to openings156through a coupler166which is threaded into an underside of center hub30. A handle168is coupled to a top portion of center hub30. Handle168provides an operator with an easy way to lift fixture tray26out of tank24and to place fixture tray26within tank24. Center hub30includes a plurality of radial openings170provided in a side wall172(seeFIG. 4) of center hub30. Referring toFIG. 6, there is one radial opening170for each outer mandrel32. Further, radial openings170are positioned such that a test specimen28extending straight radially outward from a respective radial opening170is positioned along a first side of the corresponding outer mandrel32. In one embodiment, fixture tray26is keyed relative to tank24so that fixture tray26may be repeatably positioned within tank26.

Referring toFIG. 7, three wire specimens,28A,28C, and28J, are coupled to fixture tray26. Each of wire specimens28A,28C, and28J are shown having a first end received in their respective radial opening170A,170C, and170J of center hub30and a second end bent relative to their respective mandrel32A,32B, and32J. In the illustrated embodiment ofFIG. 7, each of outer mandrels32are the same size. In one embodiment, outer mandrels32may be of differing size such that a first test specimen28, such as wire specimen28J, may be bent at a different radius than a second test specimen28, such as wire specimen28C.

The bent shape of the test specimens28inFIG. 7is the initial position of test specimens28during a testing procedure discussed in conjunction withFIGS. 11A and 11Bto determine a transition temperature of test specimens28. As a temperature of liquid medium23in tank24is raised, a temperature of test specimens28is also raised eventually causing test specimens28to straighten as shown inFIG. 8.

Returning toFIG. 7, a field of view178of camera34is shown. In the illustrated embodiment, field of view178is sized and positioned to image a single test specimen28at a time. The field of view178of the camera34may be made quite small due to lens choice, in order to provide a 4 pixel resolution for a 0.002″ diameter test specimen28. In one embodiment, field of view178is sized and positioned to image multiple test specimens28at a time. As illustrated inFIG. 7, field of view178is moved to image different test specimens28. Each position of field of view178corresponds to a station180of test apparatus20. In one embodiment, field of view178is moved by moving camera34. Camera34is moved by indexing rotational base70. In the illustrated example with ten stations180, rotational base70indexes 36° to move from a current station180to an adjacent station180. By moving camera34instead of fixture tray26, the fluid flow relative to the test specimens28is minimized.

Referring toFIGS. 11A and 11Ban exemplary test procedure200is shown. If test apparatus20is not currently running, a power up sequence is performed, as represented by block202. In one embodiment, during the power up sequence, electronic controller60, chiller unit22, camera34and rotational base70are initialized. An operator of test apparatus20then provides an input to enable the servos of rotational base70and to start chiller unit22. Referring toFIG. 10, an exemplary screen204of a touch interface94is shown. With touch interface94, an operator may touch soft button206which corresponds to instructing electronic controller60to enable the servos of rotational base70. Further, an operator may touch soft button208which corresponds to instructing electronic controller60to start chiller unit22.

Returning toFIG. 10, a start temperature setpoint is provided to electronic controller60for the test procedure, as represented by block210. The start temperature setpoint corresponds to a temperature that liquid medium23should be at to begin the testing procedure. In one embodiment, the value of the start temperature setpoint is stored in memory62. In one embodiment, an operator selects a start setpoint soft button212provided on touch interface94as shown inFIG. 10. Touch interface94then provides the operator with one or more inputs to adjust the value of the start temperature setpoint. This value is then stored in memory62.

In addition, an end temperature setpoint is provided to electronic controller60for the test procedure, as represented by block214. The end temperature setpoint corresponds to a temperature that liquid medium23should be at when the testing procedure is completed. In one embodiment, the value of the end temperature setpoint is stored in memory62. In one embodiment, an operator selects an end setpoint soft button216provided on touch interface94as shown inFIG. 10. Touch interface94then provides the operator with one or more inputs to adjust the value of the end temperature setpoint. This value is then stored in memory62.

Once the start temperature setpoint and the end temperature setpoint have been received, electronic controller60controls chiller unit22to reduce the temperature of liquid medium23to the start temperature setpoint value, as represented by block220. In one embodiment, electronic controller60instructs the chiller unit22to begin the cool down in response to soft touch button226(seeFIG. 10) of touch interface94being selected. An operator also assembles wire test specimens28to fixture tray26, as represented by block222. The operator may couple a single wire test specimen28to one of radial openings170of fixture tray26up to a wire test specimen28to each of radial openings170of fixture tray26.

The operator provides an input to electronic controller60of which stations180have wire specimens coupled thereto, as represented by block224. In this manner, electronic controller60when it instructs rotational base70to move camera34, it has rotational base70skip unused stations180. In one embodiment, the input regarding enabled stations180is provided through screen204of touch interface94. As shown, inFIG. 10, ten soft buttons labeled S1-S10correspond to the ten stations180. The operator enables a given station180by pressing the corresponding soft button. When selected to enable the station180, the soft button changes state. In one embodiment, the soft button changes state by changing its displayed color to green. In one embodiment, the operator also enters an order number or other identifying information for the specimen of a given station180. Once test specimens28are assembled to fixture tray26, fixture tray26is placed in tank24such that test specimens28are submerged within liquid medium23.

Chiller unit22provides an input to electronic controller60when liquid medium23has reached the start temperature setpoint, as represented by block230. Electronic controller60provides an indication to the operator that the start temperature setpoint has been reached, as represented by block232. In one embodiment, the indication is a message of ‘Cool Down Complete’ is displayed with touch interface94. Other exemplary indications include audio indications, visual indications, tactile indications, and combinations thereof.

The operator then bends each of test specimens28relative to their respective outer mandrels32, as represented by block234. Once all of the test specimens28are properly bent, the operator provides an input to electronic controller60to begin the testing procedure, as represented by block236. In one embodiment, the input is provided to electronic controller60by the selection of a soft touch button236(seeFIG. 10) of touch interface94being selected. At anytime during testing, the operator may stop the test by selecting a soft button238of touch interface94and resume a test by selecting a soft button240of touch interface94.

Electronic controller60moves rotational base70to a home position, if rotational base70is not already at the home position, as represented by block250. In one embodiment, the home position is the zero angle position of rotational base70. In one embodiment, the home position corresponds to station180A. Electronic controller60based on the input provided by the operator determines if the home position corresponds to an enabled station180, as represented by block252. If not, electronic controller60through the control of rotational base70moves camera34to the first enabled station180, as represented by block254.

In one embodiment, camera34sends the images to electronic controller60for processing regarding the position of test specimens28. In one embodiment, camera34includes a controller which executes software to analyze the position of the imaged test specimen28. The image is processed by the controller of camera34to determine the presence of test specimens28, as represented by block260. If test specimen28is found in the image, then an angle of deflection for test specimens28is recorded in a table of a memory associated with the controller of camera34, as represented by block262. The angle of deflection is determined by detecting the free end of test specimens28and determining an angle that the free end of the test specimens28makes with the radial direction of radial openings170(the other end of test specimens28). This value is recorded as the angle of deflection. An angle of deflection of 180° corresponds to test specimens28being straight, such as inFIG. 8. If the presence of test specimens28is not detected, a deflection angle value of 0° is recorded in the table, as represented by block264. The angle of deflection is determined for each enabled station180, as represented by block266and the return back to block254. If at any time, rotational base70is unable to reach a given station180, the servo of the rotational base70performs a homing routine wherein the rotational base70returns to the home position (0 degrees) and starts the testing over again. This eliminates the possibility of mixing station data during the test.

Once all of the enabled stations180have been imaged with camera34, the table values corresponding to the angle of deflection for each station180is transmitted to electronic controller60via wireless router86, as represented by block268. Electronic controller60determines if liquid medium23is currently at the end setpoint temperature, as represented by block270.

If not at the end setpoint temperature, electronic controller60instructs chiller unit22to raise the bath temperature to the next temperature, as represented by block272. In one embodiment, the temperature of liquid medium23is changed in increments of about 1 degree between the start temperature setpoint and the end temperature setpoint. The angle of deflection values received from camera34are stored in data files66along with the temperature of the liquid medium23corresponding to the values, as represented by block274. Further, electronic controller60updates the graph outputs for each enabled station, as represented by block276. Electronic controller60then instructs camera34to determine the angle of deflection values for each enabled station180at the new temperature (once the bath is at the new temperature), as represented by the return to block250.

An exemplary graph280for a first enabled station180is shown inFIG. 9. Graph280may be selected through input278on touch interface94. Graph280provides the angle of deflection for a given station180as a function of temperature, as represented by graph line282. The station180being graphed is identified by textual label284. An operator may select an earlier station180or a later station180through inputs286and288of touch interface94, respectively. Further, an operator may close graph280by selecting input290of touch interface94. The operator may send the chart to an accessible printer for printing by selecting input292of touch interface94.

In one embodiment, the temperature of liquid medium23is changed in increments of 1 degree between the start temperature setpoint and the end temperature setpoint. The angle of deflection values received from camera34are stored in data files66along with the temperature of the liquid medium23corresponding to the values, as represented by block274. Further, electronic controller60updates the graph outputs for each enabled station, as represented by block276. Electronic controller60then instructs camera34to determine the angle of deflection values for each enabled station180at the new temperature (once the bath is at the new temperature), as represented by the return to block250.

Returning toFIG. 11B, if the temperature of liquid medium23is at the end setpoint temperature, electronic controller60performs an Af calculation for each of test specimens28, as represented by block300. In one embodiment, the controller60utilizes regression analysis to identify two subsets of data. One subset represents the data collected while the specimen was moving (the sloped portion of the graph), the second is the data collected when the specimen was finished moving (the end more flat portion of the graph). A best fit line is then determined for each subset and the Af is determined as the intersection point of the two best fit lines. A report file68is generated for each enabled station180, as represented by block302. In one embodiment, the report file is a PDF document which includes a data table, a graph, a Af value, and order number. In one embodiment, the Af value is given to the nearest degree Centigrade. In one embodiment, the specification of the specimen, lot number and heat treatment are explicitly included. In one embodiment, the specification of the specimen, the lot number, and the heat treatment are specified or tied to the order number. The data stored in data files66is cleared, as represented by bock304and the temperature of liquid medium23is again reduced to start temperature setpoint to prepare for the next test procedure, as represented by the return to block220. In one embodiment, data in data files66for each station is maintained until ‘Start Test’ button is pressed again in block236.

Another exemplary test procedure includes the following steps:Cool bath of chiller unit22to −55° C.;Cut sample wire specimens28and place them in fixture tray26;Submerge fixture tray26into cooled bath;Bend wire specimens28around mandrels32to achieve the 2-2.5% strain;Close test set door and initiate test via PC98touchscreen;The servo/camera system34,36will find home position and begin indexing to each station, capturing image and transmitting data. With all 10 stations enabled it takes about 25 seconds to complete 1 rotation;While the camera34continuously indexes, the bath is being warmed at the specified rate; andWhen the bath reaches ending temperature (˜30° C.), the test is terminated. Graphs and data for each station are prepared.