Apparatus and method for fillet punch creep testing

An improved apparatus and method for fillet punch creep testing of a small specimen comprises, in one implementation, a testing unit secured to a top end and a bottom end of a structural support unit, and configured to conduct creep testing on a specimen. The testing unit includes a loading unit, a fillet punch unit, a thermal unit, and a measuring unit. A filleted punch of the fillet punch unit transfers an applied pressure from the loading unit to the specimen clamped between an upper die and a filleted lower die of the fillet punch unit while the thermal unit surrounds the fillet punch unit, and heats the specimen during testing. The optimized filleted edges on the filleted punch and the filleted lower die eliminate stress concentration against the specimen resulting in stable measurements, and thus, reduce the dispersion of applied load during creep testing. Finally, an application of a constant load on the filleted punch prevents dispersion in the measured data being analyzed by the measuring unit, and allows creep testing to be repeated to predict a remaining life of in-service parts of a system.

TECHNICAL FIELD

The present disclosure relates generally to creep testing and, more particularly, to evaluating creep properties of small specimen by using miniaturized fillet punch creep testing.

BACKGROUND

Creep testing provides a powerful tool when evaluating a remaining life of in-service components of a system used in different industries, such as oil and gas, and power plants. Conventional creep testing machines are focused on predicting creep properties of a sample material based on standard tests. The most commonly used standard testing method is a conventional Uniaxial Creep Test, which not only requires a large amount of sample material, but also involves a destructive and time-consuming process; thus, it cannot be used to predict the remaining life of in-service parts of a system. As such, a considerable research and development has been done in recent years to improve current creep testing methods.

Recent development has offered a significant promise to establish miniaturized testing methods that require a small amount of sample material to predict creep properties. Some of the most popular miniaturized creep testing techniques include Indentation Creep Test, Impression Creep Test, Shear Punch Creep Test, and Small Punch Creep Test. Despite their powerful tools for evaluating creep characteristics of materials, these methods reveal some problems and limitations. For example, based on the spherical or pyramidal shape of the indenter in the Indentation Creep Test, the contact area with the specimen increases over time, and thus, the stress level decreases, which makes it difficult to control such contact stress, and leads to higher stress concentration. Even though the cylindrical indenter shape in the Compression Creep Test resolves such issue, both indentation methods still rely on compressive forces for testing, which ultimately cannot provide a third stage of a creep curve for analysis. Similarly, the sharp edges in the cylindrical punch and in the die of the Shear Punch Creep Test result in high stress concentration on the contact area and high dispersion in the measured data making it questionable to repeat the creep testing to produce a reliable creep curve. Nonetheless, a first stage of the creep curve cannot also be determined using the Shear Punch Creep Test. Likewise, while the spherical shape punch in the Small Punch Creep Test reduces the amount of dispersion in the measured data, local failures can still occur. Also, the contact area of the punch in the Small Punch Creep Test increases over time, as does the amount of applied stress on the specimen, which ultimately leads to difficulty in controlling the applied stress. Moreover, the changing geometry in the specimen during such creep testing method must be taken into consideration for data analysis.

Finally, to interpret the results of all these miniaturized testing methods, it is necessary to obtain a relationship between an applied force in a miniaturized testing machine and stresses in the standard creep testing machine. As such, this data transformation can always encounter difficulty when using these miniaturized testing techniques. Therefore, the entire process can lead to increase in testing time and labor intensity, and thus cost inefficiency. Due to all these shortcomings, there remains a need to develop an improved miniaturized process to obtain creep testing measurements with higher stability and reliability while being timely and cost effective.

Accordingly, the present disclosure addresses providing an improved apparatus and method of miniaturized creep testing method using a Fillet Punch Creep Test, while offering a non-destructive and time efficient process.

SUMMARY

In one general aspect, described is an improved apparatus configured for fillet punch creep testing on a specimen. In one implementation, the apparatus for fillet punch creep testing may comprise a structural support unit and a testing unit. The testing unit can be secured to a top end and a bottom end of the structural support unit, and can be configured to conduct creep testing on a specimen. The structural support unit can include an upper plate, a lower plate, a plurality of columns, a plurality of column supports, a top quartz pipe, a bottom quartz pipe, and a plurality of quartz supports. Each column can extend between the upper and lower plates, and can be connected to such plates by a corresponding one of the column supports. The top and bottom quartz pipes can be connected respectively from one end to the upper and lower plates by a corresponding one of the quartz supports.

In an aspect, the testing unit can include a loading unit, a fillet punch unit, a thermal unit, and a measuring unit. The loading unit can include a loading weight, a loading rod, and a supporting rod, and can be secured to the structural support unit, and can apply load to the specimen. The thermal unit may surround the fillet punch unit and be secured to a holder unit, and can be configured to heat the specimen. The measuring unit can be in contact with the fillet punch unit, and can be configured to monitor and measure displacement, and to produce a creep curve.

In a related aspect, the fillet punch unit may include an upper die, an upper die holder, a filleted lower die, a lower die holder, and a filleted punch in which the specimen can be clamped between the upper die and the filleted lower die. A top end of the upper die may extend to the top end of the fillet punch unit, and a bottom end of the upper die may in contact with a top end of the filleted lower die, and the upper die may be secured to the upper die holder. A bottom end of the filleted lower die may extend to the bottom end of the fillet punch unit, and the filleted lower die may be secured to the lower die holder. A top end of the filleted punch may be in contact with the bottom end of the loading rod, and a bottom end of the filleted punch may be in contact with the specimen to transfer the applied load from the loading unit to the specimen.

In a further aspect, filleted edges in the filleted lower die and the filleted punch can eliminate stress concentration in the specimen resulting in stable measurements, and thus, reducing the number of tests required for reliable results. The specimen can also include a small amount with no constraint in thickness and no need for special specimen preparation, which can result in a non-destructive and less time-consuming process to produce different stages of the creep curve during creep testing. The loading weight can also apply a constant load from the loading rod to the filleted punch, and subsequently to the specimen, which in turn can prevent dispersion in the measured data, and can make the fillet punch creep testing to be done repeatedly in order to predict a remaining life of in-service parts of a system.

In another general aspect, described is an improved method of fillet punch creep testing. In one implementation, the method of fillet punch creep testing may include the steps of loading a specimen into a fillet punch unit, and the fillet punch unit may be secured to a structural support unit, and can include an upper die, an upper die holder, a filleted lower die, a lower die holder, and a filleted punch. The specimen can be in contact with a bottom end of the filleted punch, and can be clamped between the upper die and the filleted lower die, and the combination of which can be secured to the surrounding upper and lower die holders.

In an aspect, the method of fillet punch creep testing may also include applying load to the specimen by a loading unit in which the loading unit may be secured to the structural support unit, and can include a loading weight, a loading rod, and a supporting rod. The loading rod can be arranged to transfer the applied load from the loading weight to a top end of the filleted punch down to the specimen.

In a related aspect, the method of fillet punch creep testing may also include heating the specimen by a furnace in which the furnace may surround the fillet punch unit and can be secured to a holder unit. The method of fillet punch creep testing can further include controlling temperature of the specimen by a furnace controller in which the furnace controller can be in contact with a thermocouple inside the furnace.

In a further aspect, the method of fillet punch creep testing may also include measuring displacement of the specimen by a motion sensor in which the motion sensor can be in contact with the loading rod. The method of fillet punch creep testing can further include producing a creep curve for the specimen by analyzing the displacement data, which can be transferred in real-time to a data storage unit.

The foregoing and other objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description of the present application when taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are set forth by way of examples in order to provide a thorough understanding of the relevant teachings. However, it should be apparent to those skilled in the art that the present teachings may be practiced without such details. In other instances, well known methods, procedures, components, and/or circuitry have been described at a relatively high-level, without detail, in order to avoid unnecessarily obscuring aspects of the present teachings. As part of the description, some of this disclosure's drawings represent structures and devices in block diagram form in order to avoid obscuring the invention. In the interest of clarity, not all features of an actual implementation are described in this specification. Moreover, the language used in this disclosure has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter, resort to the claims being necessary to determine such inventive subject matter. Reference in this disclosure to “one embodiment” or to “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention, and multiple references to “one embodiment” or “an embodiment” should not be understood as necessarily all referring to the same embodiment.

A solution is proposed herein to resolve the above-motioned issues and others by providing an improved apparatus and method of fillet punch creep testing. Principles of the present invention will now be described in detail with reference to the examples illustrated in the accompanying drawings and discussed below.FIG. 23Aillustrates an exemplary miniaturized creep testing machine300(hereinafter “system300”) depicting prior art. System300includes a structural support unit310and a testing unit350. The testing unit350extends between a top end and a bottom end of the structural support unit310, and is configured to conduct creep testing on a specimen305. The structural support unit310includes an upper plate315, a lower plate320, a plurality of columns325, a plurality of column supports330, a top quartz pipe335, a bottom quartz pipe340, and a plurality of quartz supports345. Each column325extends between the upper and lower plates,315and320, and is connected to such plates by a corresponding one of the column supports325. The top and bottom quartz pipes,335and340, are connected respectively from one end to the upper and lower plates,315and320, by a corresponding one of the quartz supports345.

In one implementation, the testing unit350includes a loading unit360, a fillet punch unit370, a thermal unit380and a measuring unit390. The loading unit360includes a loading weight361, a loading rod362, a supporting rod363and a loading lever364, and is secured to the structural support unit310and arranged to apply lever loading to the specimen305. The thermal unit380surrounds the fillet punch unit370and is secured to a holder unit381, and configured to heat the specimen305. The measuring unit390is in contact with the fillet punch unit370, and is configured to monitor and measure displacement, and to produce a creep curve.

FIG. 23Billustrates an exemplary fillet punch unit370that is arranged to secure the specimen305, and to transfer the applied load from the loading unit360to such specimen. The fillet punch unit370includes an upper die371, an upper die holder372, a filleted lower die373, a lower die holder374, a filleted punch375and a holder rod376in which the specimen305is clamped between the upper die371and the filleted lower die373. A top end of the upper die371extends to the top end of the fillet punch unit370, and a bottom end of the upper die371is in contact with a top end of the filleted lower die373, and the upper die371is secured to the upper die holder372. A bottom end of the filleted lower die373extends to the bottom end of the fillet punch unit370, the filleted lower die371is secured to the lower die holder374and the holder rod376. A top end of the filleted punch375is in contact with the bottom end of the loading rod362, and a bottom end of the filleted punch375is in contact with the specimen305to transfer the applied load.

To apply constant loading via a direct loading mechanism instead of the lever loading mechanism used in the prior art system300, a fillet punch creep testing machine is described herein.FIG. 1Aillustrates an exemplary miniaturized creep testing machine100(hereinafter “system100”) depicting a fillet punch creep testing machine that can be configured to use a direct loading mechanism during creep testing. In this exemplary embodiment, system100may include a structural support unit110and a testing unit150. In one implementation, the testing unit150can extend between a top end and a bottom end of the structural support unit110, and can be configured to conduct creep testing on a specimen105. The structural support unit110can include an upper plate115, a lower plate120, a plurality of columns125, a plurality of column supports130, a top quartz pipe135, a bottom quartz pipe140, and a plurality of quartz supports145. Each column125can extend between the upper and lower plates,115and120, and can be connected to such plates by a corresponding one of the column supports125. The top and bottom quartz pipes,135and140, can be connected respectively from one end to the upper and lower plates,115and120, by a corresponding one of the quartz supports145.

In one implementation, the testing unit150can include a loading unit160, a fillet punch unit170, a thermal unit180and a measuring unit190. The loading unit160can include a loading weight161, a loading rod162and a supporting rod163, and can be secured to the structural support unit110and arranged to apply direct loading to the specimen105. The thermal unit180may surround the fillet punch unit170and be secured to a holder unit181, and can be configured to heat the specimen105. The measuring unit190can be in contact with the fillet punch unit170, and can be configured to monitor and measure displacement, and to produce a creep curve.

FIG. 1Billustrates an exemplary fillet punch unit170that can be arranged to secure the specimen105, and to transfer the applied load from the loading unit160to such specimen. In this exemplary embodiment, the fillet punch unit170may include an upper die171, an upper die holder172, a filleted lower die173, a lower die holder174, a filleted punch175and a holder rod176in which the specimen105can be clamped between the upper die171and the filleted lower die173. In one implementation, a top end of the upper die171may extend to the top end of the filleted punch unit170, and a bottom end of the upper die171may be in contact with a top end of the filleted lower die173, and the upper die171may be secured to the upper die holder172. A bottom end of the filleted lower die173may extend to the bottom end of the fillet punch unit170, the filleted lower die171may be secured to the lower die holder174and the holder rod176. A top end of the filleted punch175may be in contact with the bottom end of the loading rod162, and a bottom end of the filleted punch175may be in contact with the specimen105to transfer the applied load.

To apply constant loading via a direct loading mechanism as well as to minimize stress concentration against the specimen and to increase stability in the experimental results during miniaturized creep testing, an improved fillet punch creep testing machine and process, in accordance with aspects of the invention, is described herein.FIG. 2Aillustrates an exemplary improved apparatus and method of fillet punch creep testing machine that can be configured to conduct creep testing on a small sample material with no need to constrain the thickness of such sample. In this exemplary embodiment, the improved fillet punch creep testing machine200(hereinafter “system200”) may include a structural support unit210and a testing unit250. In one implementation, the testing unit250as shown can extend between a top end and a bottom end of the structural support unit210, and can be configured to conduct creep testing on a specimen205. The structural support unit210can include an upper plate215, a lower plate220, a plurality of columns225, a plurality of column supports230, a top quartz pipe235, a bottom quartz pipe240, and a plurality of quartz supports245. Each column225can extend between the upper and lower plates,215and220, and can be connected to such plates by a corresponding one of the column supports225. The top and bottom quartz pipes,235and240, can be connected respectively from one end to the upper and lower plates,215and220, by a corresponding one of the quartz supports245.

In one implementation, the testing unit250can include a loading unit260, a fillet punch unit270, a thermal unit280and a measuring unit290. The loading unit260can include a loading weight261, a loading rod262and a supporting rod263, and can be secured to the structural support unit210and arranged to apply direct loading to the specimen205. The thermal unit280may surround the fillet punch unit270and be secured to a holder unit281, and can be configured to heat the specimen205. The measuring unit290can be in contact with the fillet punch unit270through the loading rod262, and can be configured to monitor and measure displacement, and to produce a creep curve.

FIG. 2Billustrates an exemplary fillet punch unit270that can be arranged to secure the specimen205, and to transfer the applied load from the loading unit260to such specimen. In this exemplary embodiment, the fillet punch unit270may include an upper die271, an upper die holder272, a filleted lower die273, a lower die holder274and a filleted punch275in which the specimen205can be clamped between the upper die271and the filleted lower die273. In one implementation, a top end of the upper die271may extend to the top end of the fillet punch unit270, and a bottom end of the upper die271may be in contact with a top end of the filleted lower die273, and the upper die271may be secured to the upper die holder272. A bottom end of the filleted lower die273may extend to the bottom end of the fillet punch unit270, the filleted lower die271may be secured to the lower die holder274. A top end of the filleted punch275may be in contact with the bottom end of the loading rod262, and a bottom end of the filleted punch275may be in contact with the specimen205to transfer the applied load.

FIG. 3AthroughFIG. 3Care exemplary schematic drawings of the upper plate215that can be configured to provide support to the top end of the structural support unit210. In this exemplary embodiment,FIG. 3AthroughFIG. 3Crespectively illustrate a perspective view, a side view, and a top view of the upper plate215. In one implementation, the upper plate215may include a central opening215A, a plurality of central connections215B, and a plurality of peripheral connections215C. The central opening215A may be arranged to allow the loading rod262to move through the top end of the structural support unit210. Each central connection215B can be configured to connect the upper plate215to a top end of the top quartz pipe235, and each peripheral connection215C can be configured to connect the upper plate215to a top end of one of the corresponding columns225by the corresponding column supports230. As one example, specific dimensions for the components of the upper plate215are shown inFIG. 3AthroughFIG. 3C.

FIG. 4AthroughFIG. 4Care exemplary schematic drawings of the lower plate220that can be configured to provide support to the bottom end of the structural support unit210. In this exemplary embodiment,FIG. 4AthroughFIG. 4Crespectively illustrate a perspective view, a side view, and a top view of the lower plate220. In one implementation, the lower plate220may include a central opening220A, a plurality of central connections220B, and a plurality of peripheral connections220C. The central opening220A may be arranged to secure the supporting rod263to the bottom end of the structural support unit210. Each central connection220B can be configured to connect the lower plate220to a bottom end of the bottom quartz pipe240, and each peripheral connection220C can be configured to connect the lower plate220to a bottom end of one of the corresponding columns225by the corresponding column supports230. As one example, specific dimensions for the components of the lower plate220are shown inFIG. 4AthroughFIG. 4C.

FIG. 5AthroughFIG. 5Care exemplary schematic drawings of each column225that can be configured to provide lateral support to the structural support unit210. In this exemplary embodiment,FIG. 5AthroughFIG. 5Crespectively illustrate a perspective view, a side view, and a top view of the column225. In one implementation, each column225may be arranged to connect the upper and lower plates,215and220, together. As one example, specific dimensions for the components of each column225are shown inFIG. 5AthroughFIG. 5C.

FIG. 6AthroughFIG. 6Care exemplary schematic drawings of each column support230that can be configured to connect each column225to the structural support unit210. In this exemplary embodiment,FIG. 6AthroughFIG. 6Crespectively illustrate a perspective view, a side view, and a top view of the column support230. In one implementation, each column support230may be arranged to connect the upper and lower plates,215and220, to one of the corresponding column225. As one example, specific dimensions for the components of each column support230are shown inFIG. 6AthroughFIG. 6C.

FIG. 7AthroughFIG. 7Care exemplary schematic drawings of the top and bottom quartz pipes,235and240, that can be configured to provide support respectively to the loading and supporting rods,262and263. In this exemplary embodiment,FIG. 7AthroughFIG. 7Crespectively illustrate a perspective view, a side view, and a top view of the top and bottom quartz pipes,235and240. In one implementation, the top and bottom quartz pipes,235and240, may be made of quartz glass to eliminate atmospheric contact with the loading and supporting rods,262and263. As one example, specific dimensions for the components of the top and bottom quartz pipes,235and240, are shown inFIG. 7AthroughFIG. 7C.

FIG. 8AthroughFIG. 8Care exemplary schematic drawings of each quartz support245that can be configured to connect the top and bottom quartz pipes,235and240, to the structural support unit210. In this exemplary embodiment,FIG. 8AthroughFIG. 8Crespectively illustrate a perspective view, a side view, and a top view of the quartz support245. In one implementation, each quartz support245may be arranged to connect the upper and lower plates,215and220, respectively to the top and bottom quartz pipes,235and240. As one example, specific dimensions for the components of each quartz support245are shown inFIG. 8AthroughFIG. 8C.

FIG. 24AthroughFIG. 24Care exemplary schematic drawings of the loading rod362in the prior art system300that is configured to transfer applied load to the specimen305. In this exemplary embodiment,FIG. 24AthroughFIG. 24Crespectively illustrate a perspective view, a side view, and a top view of the loading rod362. In one implementation, a top end of the loading rod362is in contact with the loading lever364, and a bottom end of the loading rod362in contact with a top end of the fillet punch unit370, and the loading rod362is surrounded by the top quartz pipe335. The loading rod362has a cylindrical shape, and includes a bearing connection362A, which secures the loading rod362to the upper plate315, and eliminates resistance force at such connection. As one example, specific dimensions for the components of the loading rod362are shown inFIG. 24AthroughFIG. 24C.

FIG. 9AthroughFIG. 9Care exemplary schematic drawings of the loading rods,162and262, in the system100as well as in the improved system200that can be configured to transfer applied load to the specimens,105and205. In this exemplary embodiment,FIG. 9AthroughFIG. 9Crespectively illustrate a perspective view, a side view, and a top view of the loading rod262. In one implementation, a top end of the loading rods262may be connected to a bottom end of the loading weight261, and a bottom end of the loading rod262may be in contact with a top end of the fillet punch unit270, and the loading rod262may be surrounded by the top quartz pipe235. The loading rod262may be of a cylindrical shape, and can include a bearing connection262A, which can move freely to secure the loading rod262to the upper plate215, and to eliminate resistance force at such connection. In an aspect, the loading weight261can apply a constant load on the loading rod262, which in turn can prevent dispersion in the testing results, and can allow creep testing to be repeated. As one example, specific dimensions for the components of the loading rod262are shown inFIG. 9AthroughFIG. 9C.

FIG. 10AthroughFIG. 10Care exemplary schematic drawings of the supporting rod263that can be configured to provide support to the fillet punch unit270and the surrounding thermal unit280. In this exemplary embodiment,FIG. 10AthroughFIG. 10Crespectively illustrate a perspective view, a side view, and a top view of the supporting rod263. In one implementation, a top end of the supporting rod263may be connected to a bottom end of the fillet punch unit270, and a bottom end of the supporting rod263may be connected to the lower plate220, and the supporting rod263may be surrounded by the bottom quartz pipe240. As one example, specific dimensions for the components of the supporting rod263are shown inFIG. 10AthroughFIG. 10C.

FIG. 25AthroughFIG. 25Care exemplary schematic drawings of the upper die371in the prior art system300that is configured to provide support to the clamped specimen305. In this exemplary embodiment,FIG. 25AthroughFIG. 25Crespectively illustrate a perspective view, a side view, and a top view of the upper die371. In one implementation, the upper die371has a cylindrical shape, and includes a central opening371A that has a diameter of, e.g., 3.52 mm to serve as a guideline for the filleted punch375. As one example, specific dimensions for the components of the upper die371are shown inFIG. 25AthroughFIG. 25C.

FIG. 11AthroughFIG. 11Care exemplary schematic drawings of the upper die171in the system100that can be configured to provide support to the clamped specimen105. In this exemplary embodiment,FIG. 11AthroughFIG. 11Crespectively illustrate a perspective view, a side view, and a top view of the upper die171. In one implementation, the upper die171may be of a cylindrical shape, and can include a central opening171A and a coaxial cylinder of different radii171B in which the central opening171A can have a diameter of, e.g., 3.52 mm to serve as a guideline for the punch175. As one example, specific dimensions for the components of the upper die171are shown inFIG. 11AthroughFIG. 11C.

FIG. 12AthroughFIG. 12Care exemplary schematic drawings of the upper die271in the improved system200that can be configured to provide support to the clamped specimen205. In this exemplary embodiment,FIG. 12AthroughFIG. 12Crespectively illustrate a perspective view, a side view, and a top view of the upper die271. In one implementation, the upper die271may be of a cylindrical shape, and can include a central opening271A and a coaxial cylinder of different radii271B in which the central opening271A can have a diameter of, e.g., 3.22 mm to serve as a guideline for the filleted punch275. In an aspect, the upper die271can be cut using a wire-cut machine with an accuracy of, e.g., 0.01 mm. As one example, specific dimensions for the components of the upper die271are shown inFIG. 12AthroughFIG. 12C.

FIG. 13AthroughFIG. 13Care exemplary schematic drawings of the upper die holder272that can be configured to surround and secure the upper die271. In this exemplary embodiment,FIG. 13AthroughFIG. 13Crespectively illustrate a perspective view, a side view, and a top view of the upper die holder272. As one example, specific dimensions for the components of the upper die holder272are shown inFIG. 13AthroughFIG. 13C.

FIG. 26AthroughFIG. 26Care exemplary schematic drawings of the filleted lower die373in the prior art system300that is configured to provide support to the clamped specimen305. In this exemplary embodiment,FIG. 26AthroughFIG. 26Crespectively illustrate a perspective view, a side view, and a top view of the lower die373. In one implementation, the lower die373has a cylindrical shape of, e.g., 10 mm in height, and includes a central opening373A with a diameter of, e.g., 3.6 mm, and filleted edges of, e.g., 0.2 mm in radius. As one example, specific dimensions for the components of the lower die373are shown inFIG. 26AthroughFIG. 26C.

FIG. 14AthroughFIG. 14Care exemplary schematic drawings of the filleted lower die173in the system100that can be configured to provide support to the clamped specimen105. In this exemplary embodiment,FIG. 14AthroughFIG. 14Crespectively illustrate a perspective view, a side view, and a top view of the lower die173. In one implementation, the lower die173may be of a cylindrical shape of, e.g., 10 mm in height, and can include a central opening173A and a coaxial cylindrical recess173B in which the central opening173A may have a diameter of, e.g., 3.6 mm, and filleted edges of, e.g., 0.2 mm in radius. As one example, specific dimensions for the components of the lower die173are shown inFIG. 14AthroughFIG. 14C.

FIG. 15AthroughFIG. 15Care exemplary schematic drawings of the filleted lower die273in the improved system200that can be configured to provide support to the clamped specimen205. In this exemplary embodiment,FIG. 15AthroughFIG. 15Crespectively illustrate a perspective view, a side view, and a top view of the lower die273. In one implementation, the filleted lower die273may be of a cylindrical shape of, e.g., 22 mm in height, and can include a central opening273A and a coaxial cylindrical recess273B in which the central opening273A may have a diameter of, e.g., 3.25 mm, and filleted edges of, e.g., 0.1 mm in radius. The filleted edges of the filleted lower die273may eliminate stress concentration against the specimen205resulting in stable measurements, and thus, reducing an amount of required applied load during creep testing. In an aspect, the filleted lower die273can be cut using a wire-cut machine with an accuracy of, e.g., 0.01 mm. As one example, specific dimensions for the components of the filleted lower die273are shown inFIG. 15AthroughFIG. 15C.

FIG. 16AthroughFIG. 16Care exemplary schematic drawings of the lower die holder274that can be configured to surround and secure the filleted lower die273. In this exemplary embodiment,FIG. 16AthroughFIG. 16Crespectively illustrate a perspective view, a side view, and a top view of the lower die holder274. As one example, specific dimensions for the components of the lower die holder274are shown inFIG. 16AthroughFIG. 16C.

FIG. 17AthroughFIG. 17Care exemplary schematic drawings of the holder rods,176and376, in the system100as well as in the prior art system300that can be configured to provide support to the lower die173. In this exemplary embodiment,FIG. 17AthroughFIG. 17Crespectively illustrate a perspective view, a side view, and a top view of the holder rod176. As one example, specific dimensions for the components of the holder rod176are shown inFIG. 17AthroughFIG. 17C.

FIG. 27AthroughFIG. 27Care exemplary schematic drawings of the filleted punch375in the prior art system300that is configured to transfer the applied load from the loading rod362to the specimen305. In this exemplary embodiment,FIG. 27AthroughFIG. 27Crespectively illustrate a perspective view, a side view, and a top view of the punch375. In one implementation, the punch375includes a cylinder shape with a diameter of, e.g., 3.5 mm, and filleted edges of, e.g., 0.2 mm in radius at a bottom end. As one example, specific dimensions for the components of the punch375are shown inFIG. 27AthroughFIG. 27C.

FIG. 18AthroughFIG. 18Care exemplary schematic drawings of the filleted punch175in the system100that can be configured to transfer the applied load from the loading rod162to the specimen105. In this exemplary embodiment,FIG. 18AthroughFIG. 18Crespectively illustrate a perspective view, a side view, and a top view of the punch175. In one implementation, the filleted punch175can include a top cylinder175A and a bottom cylinder175B in which a bottom end of the bottom cylinder175B may have a diameter of, e.g., 3.5 mm, and filleted edges of, e.g., 0.2 mm in radius. As one example, specific dimensions for the components of the punch175are shown inFIG. 18AthroughFIG. 18C.

FIG. 19AthroughFIG. 19Care exemplary schematic drawings of the filleted punch275in the improved system200that can be configured to transfer the applied load from the loading rod262to the specimen205. In this exemplary embodiment,FIG. 19AthroughFIG. 19Crespectively illustrate a perspective view, a side view, and a top view of the filleted punch275. In one implementation, a top end of the filleted punch275can be in contact with the bottom end of the loading rod262, and a bottom end of the filleted punch275can be in contact with the specimen205, and the filleted punch275can be arranged to freely pass through the central opening271A of the upper die271without resistance. The filleted punch275can be made of ceramic, and can include a top cylinder275A and a bottom cylinder275B in which a bottom end of the bottom cylinder275B may have a diameter of, e.g., 3.2 mm, and filleted edges of, e.g., 0.1 mm in radius. The filleted edges of the filleted punch275may eliminate stress concentration against the specimen205resulting in stable measurements, and thus, reducing an amount of required applied load during creep testing. As one example, specific dimensions for the components of the filleted punch275are shown inFIG. 19AthroughFIG. 19C.

FIG. 20AthroughFIG. 20Care exemplary schematic drawings of a furnace282of the thermal unit280that can be arranged to surround the fillet punch unit270, and to heat the specimen205. In this exemplary embodiment,FIG. 20AthroughFIG. 20Crespectively illustrate a perspective view, a side view, and a top view of the furnace282. In one implementation, the thermal unit280may include the holder unit281shown inFIG. 2A, the furnace282, a thermocouple283, and a furnace controller284. The furnace282may be secured to the holder unit281, and the thermocouple283inside the furnace282can be adjusted to a desired temperature directed by the furnace controller284. In an aspect, the furnace282may include an electrical furnace with a digital display to track temperature of the furnace282measured in real-time by the thermocouple283. In a further aspect, a top end of the thermal unit280, as shown inFIG. 2A, may be secured to a bottom end of the top quartz pipe235, and a bottom end of the thermal unit280may be secured to a top end of the bottom quartz pipe240in which the top and bottom quartz pipes,235and240, can be made of quartz glass and placed in a refractory core to protect the thermal unit280from outside temperature interference. As one example, specific dimensions for the components of the furnace282are shown inFIG. 20AthroughFIG. 20C.

FIG. 21AthroughFIG. 21Care exemplary schematic drawings of the test specimen205that can be configured to be clamped between the upper die271and the filleted lower die273during creep testing. In this exemplary embodiment,FIG. 21AthroughFIG. 21Crespectively illustrate a perspective view, a side view, and a top view of the specimen205. In one implementation, the specimen205may include a small amount with no constraint in thickness and no need for special specimen preparation, which can result in a non-destructive and timely process to produce different stages of the creep curve during creep testing. As one example, specific dimensions for the components of the specimen205are shown inFIG. 21AthroughFIG. 21C.

FIG. 22is an exemplary schematic drawing of the measuring unit290that can be configured to measure and analyze testing results during creep testing. In this exemplary embodiment,FIG. 22illustrate a perspective view of the measuring unit. In one implementation, the measuring unit290may include a motion sensor291and a data storage unit292in which the motion sensor291can be in contact with the loading rod262, and can be configured to instantaneously measure an amount of displacement of the loading rod262. The data storage unit292can be connected to the motion sensor291to analyze the measured data, and to produce different stages of a creep curve for the specimen205. In an aspect, the data storage unit292can be a personal computer. In a related aspect, the motion sensor291can measure displacements, for example, in every 30 seconds during creep testing. The motion sensor291can be an extensometer, and have a minimum accuracy of, e.g., 5 μm. As one example, specific dimensions of the motion sensor291are shown inFIG. 22.

To investigate the applicability of the improved method of fillet punch creep testing, the method was applied to a sample specimen made of aluminum alloy (A12024-T851). Creep properties of such sample were then compared to the prior art creep testing method in order to determine the effects of the improved method.FIG. 28AandFIG. 28Bare exemplary creep curves for the sample tested using the improved Fillet Punch Creep Test (FPCT) as compared to prior art method.

FIG. 29AandFIG. 29Bare exemplary analytical stress variation creep curve over time for the improved vs. prior art FPCT. In this exemplary illustration, the variation of stresses during creep testing may represent axial and shear stresses in which the shear stresses in the improved FPCT with fillet radii of 0.1 mm represent a much closer harmony to the obtained numerical values when compared to that of in the prior art FPCT with fillet radii of 0.2 mm. In an aspect, the curves may be produced using a numerical package technique such as Finite Element Method.

Accordingly, the improved apparatus and method for fillet punch creep testing machine in the present invention can provide an efficient mechanism for conducting creep testing by using a small specimen with no constraint in thickness and no need for special specimen preparation, which results in a non-destructive and less time-consuming process to produce different stages of a creep curve during creep testing. The evident results reveal that eliminating stress concentration against the specimen can result in stable measurements, and thus, can reduce the dispersion of applied load on the specimen during creep testing. Also, the application of a constant load from the loading weight on the loading rod to the filleted punch, and subsequently to the specimen can prevent dispersion in the measured data, and can allow creep testing to be repeated to predict a remaining life of in-service parts of a system. Finally, the fillet punch creep testing functions based on pure shear force, and thus, can enable a comparison of creep testing measurements with a Standard Creep Test.

The separation of various components in the examples described above should not be understood as requiring such separation in all examples, and it should be understood that the described components and systems can generally be integrated together in a single packaged into multiple systems.