System and method for calculating stress and strain of specimen

Abstract

The present invention relates to a system and a method for calculating stress and strain of a specimen. The system and method for calculating the stress and strain of a specimen are structured to calculate the stress and strain of a specimen by forming a protrusion on a set portion of the specimen and measuring the rate of strain on the protrusion as same is subjected to a load.

Description

System and method for calculating stress and strain of specimens

[0001] The present invention relates to a system and method for calculating stress and strain of a specimen, and more specifically, to a system and method capable of accurately calculating the stress and strain of a specimen while enabling a quick and simple indentation test on the specimen.

[0002] The non-destructive testing method for the plastic properties of specimens using the indentation test is one of the common methods for testing specimen properties.

[0003] These indentation testing methods include instrumented indentation techniques and surface shape-based indentation testing methods. The instrumented indentation technique predicts the contact area between the specimen and the indenter based on the indentation load-displacement relationship when indenting the specimen, and calculates the strain of the specimen using conventionally established mathematical formulas and correction functions to predict the representative stress and representative strain of the specimen.

[0004] However, since the instrumented indentation technique is configured to predict the deformation shape of the specimen using mathematical formulas and correction functions after indentation, there is a problem in that it is difficult to apply to specimens of various materials.

[0005] In addition, since the instrumented indentation technique requires extracting a specimen from a structure such as a pipe and then performing an indentation test on the extracted specimen, there is a problem of cost and time required to extract the specimen.

[0006] Meanwhile, the surface shape-based indentation test method is a method in which the deformation shape of a specimen is directly scanned via physical methods or measured via optical methods after the specimen is indented. Since the surface shape of the specimen can be directly measured, the strain of the specimen can be predicted based on more accurate information regarding the surface shape.

[0007] However, surface shape-based indentation testing methods require the use of equipment to accurately measure the surface shape of a specimen, but there is a problem in that it is difficult to utilize portable equipment for measuring the surface shape when a specimen with a relatively large volume is compressed.

[0008] In addition, the surface shape-based indentation test method has the problem that relatively high precision and expensive equipment must be used because the surface shape must be measured precisely.

[0009] Furthermore, the surface shape-based indentation test method requires performing finite element inverse analysis to obtain information regarding the strain of the specimen from information regarding the surface shape of the specimen; however, there is a problem in that the time required for the finite element inverse analysis increases in order to improve the accuracy of the finite element inverse analysis, which prevents the indentation test from being performed quickly.

[0010] Therefore, there is a need to develop a system and method for calculating the stress and strain of a specimen that can perform indentation tests on the specimen simply and quickly, while also accurately calculating the stress and strain of the specimen.

[0011] One objective of the present invention is to provide a system and method capable of easily and quickly calculating the stress and strain of a specimen.

[0012] Another objective of the present invention is to provide a system and method capable of accurately calculating the stress and strain of a specimen.

[0013] Another objective of the present invention is to provide a portable system capable of calculating the stress and strain of a specimen.

[0014] The problems of the present invention are not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0015] As a technical means for solving the above-mentioned technical problem, a system for calculating stress and strain of a specimen according to one embodiment of the present invention may include: a polishing module that polishes a predetermined portion of the surface of the specimen so that a predetermined portion becomes flat; a cutting module that cuts at least a portion of the predetermined portion so that a cylindrical protrusion with a circular cross-section parallel to the predetermined portion is formed on the predetermined portion; a compression module that presses the protrusion in a direction perpendicular to the predetermined portion; a load, which is pressure applied to the protrusion by the compression module; a measuring module that measures a first height, which is the height before the load is applied, and a second height, which is the height after the load is applied, among the heights, which are the vertical lengths of the protrusion; and a control module that controls the operation of the polishing module, the cutting module, the compression module, and the measuring module, and calculates the stress of the specimen and the strain of the specimen according to the stress based on information regarding the load, the first height, and the second height.

[0016] In addition, the control unit can calculate the nominal stress acting on the specimen using the following mathematical formula 1, calculate the nominal strain of the specimen using the following mathematical formula 2, calculate the true stress acting on the specimen using the following mathematical formula 3, and calculate the true strain of the specimen using the following mathematical formula 4.

[0017] Additionally, the cutting module may include a cutting member that is rotatable about a rotation axis parallel to the vertical direction and cuts the predetermined portion.

[0018] Additionally, the cutting member may include a recess formed by recessing at least a portion of one end that cuts the predetermined portion, and a cutting portion installed on the outer periphery of the recess and capable of cutting the predetermined portion by rotating and contacting the predetermined portion.

[0019] In addition, the above-mentioned depression may be formed with the same shape as the protrusion so as to accommodate the protrusion.

[0020] Additionally, the compression module includes a contact portion that contacts the protrusion, and the contact portion may have a contact surface formed flatly so as to be parallel to the parallel direction, which contacts the protrusion to press the protrusion.

[0021] Additionally, the contact surface may be formed such that the area of ​​the contact surface is larger than the area of ​​the cross-section of the projection and smaller than the area of ​​the predetermined portion, and when the projection is pressed, it contacts the entire cross-section of the projection while preventing contact with the predetermined portion.

[0022] In addition, the measurement module may include a pressure measurement sensor for measuring the load and a height measurement sensor for measuring the height.

[0023] In addition, it may further include a power module that supplies power to the grinding module, the cutting module, the compression module, the measuring module, and the control module.

[0024] As a technical means for solving the above-mentioned technical problem, a method for calculating stress and strain of a specimen according to an embodiment of the present invention may include: a grinding step of grinding a predetermined portion of the surface of the specimen so that a predetermined portion becomes flat; a cutting step of cutting at least a portion of the predetermined portion so that a cylindrical protrusion with a circular cross-section parallel to the predetermined portion is formed on the predetermined portion; a compression step of applying pressure to the protrusion in a direction perpendicular to the predetermined portion; a load, which is the pressure applied to the protrusion by the compression step; a measurement step of measuring a first height, which is the height before the load is applied, and a second height, which is the height after the load is applied, among the heights, which are the vertical lengths of the protrusion; and a calculation step of calculating the stress of the specimen and the strain of the specimen according to the stress based on information regarding the load, the first height, and the second height.

[0025] In addition, the above calculation step may calculate the nominal stress acting on the specimen using the following mathematical formula 1, calculate the nominal strain of the specimen using the following mathematical formula 2, calculate the true stress acting on the specimen using the following mathematical formula 3, and calculate the true strain of the specimen using the following mathematical formula 4.

[0026] In addition, the cutting step may cut at least a portion of the predetermined part using a cutting member rotatable about a rotation axis parallel to the vertical direction.

[0027] Additionally, the cutting member may include a recess formed by recessing at least a portion of one end that cuts the predetermined portion, and a cutting portion installed on the outer periphery of the recess and capable of cutting the predetermined portion by rotating and contacting the predetermined portion.

[0028] In addition, the above-mentioned depression may be formed with the same shape as the protrusion so as to accommodate the protrusion.

[0029] Additionally, the compression step presses the projection using a contact portion that contacts the projection, and the contact portion may form a contact surface that is formed flatly so as to be parallel to the parallel direction while contacting the projection to press the projection.

[0030] Specific details of other embodiments for solving the problem are included in the description of the invention and the drawings.

[0031] According to the means for solving the problem of the present invention described above, the system and method for calculating stress and strain of a specimen according to the present invention calculates the stress and strain of the specimen acting on the specimen by utilizing the strain of the protrusion according to the load applied to the protrusion formed on a predetermined part of the specimen, thereby providing the effect of being able to calculate the stress and strain of the specimen acting on the specimen simply and quickly.

[0032] In addition, since the stress and strain of the specimen can be calculated based only on the load applied to the protrusion formed on a specific part of the specimen and the strain of the protrusion according to the load, it provides the effect of accurately measuring the stress and strain of the specimen acting on the specimen even when using equipment with relatively low precision and cost.

[0033] In addition, since the stress and strain of the specimen are calculated using the strain of the protrusions and mathematical formulas, it provides the effect of accurately calculating the stress and strain of the specimen.

[0034] In addition, the stress and strain calculation system for a specimen according to the present invention calculates the stress and strain of the specimen using a protrusion having a relatively small volume, thereby providing the effect of being portable as it is manufactured to have a relatively small volume.

[0035] FIG. 1 is a block diagram illustrating a system for calculating stress and strain of a specimen according to one embodiment of the present invention.

[0036] FIG. 2 is a drawing illustrating a polishing module that polishes a specific part of a specimen.

[0037] Figure 3 is a drawing illustrating a cutting member.

[0038] Figure 4 is an enlarged view of A in Figure 3.

[0039] FIG. 5 is a drawing showing a cutting module that cuts a predetermined part of a specimen while rotating around a rotation axis.

[0040] Figure 6 is a drawing showing a protrusion formed on a specific part of a specimen by a cutting module.

[0041] Figure 7 is a diagram illustrating a compression module.

[0042] Figure 8 is a drawing showing a protrusion before a load is applied by a compression module.

[0043] Figure 9 is a drawing showing the protrusion after a load is applied by a compression module.

[0044] FIG. 10 is a graph showing a comparison between the stress of a specimen and the corresponding strain of the specimen calculated through a stress and strain calculation system of a specimen according to one embodiment of the present invention, and the actual strain of the specimen corresponding to the stress of the specimen.

[0045] FIG. 11 is a drawing illustrating a polishing module that polishes a predetermined part of a specimen having a protrusion formed thereon.

[0046] FIG. 12 is a flowchart illustrating a method for calculating stress and strain of a specimen according to one embodiment of the present invention.

[0047] Embodiments of the present invention are described below with reference to the attached drawings to enable those skilled in the art to easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification are denoted by similar reference numerals.

[0048] Throughout this specification, when a part is described as being "connected" to another part, this includes not only cases where they are "directly connected," but also cases where they are "electrically connected" with other elements interposed between them.

[0049] Throughout this specification, when a component is described as being located “on” another component, this includes not only cases where a component is in contact with another component, but also cases where another component exists between the two components.

[0050] Throughout this specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Throughout this specification, terms of degree such as "about," "substantially," etc., are used to mean at or near the stated value when inherent manufacturing and material tolerances are presented in the said meaning, and are used to prevent unscrupulous infringers from unfairly exploiting the disclosure in which precise or absolute values ​​are mentioned to aid in understanding this specification. Throughout this specification, terms of degree such as "step of" or "step of" do not mean "step for."

[0051] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings and the contents described below. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Throughout the specification, the same reference numerals indicate the same components.

[0052] Hereinafter, the configuration of a stress and strain calculation system for a specimen according to one embodiment of the present invention will be described.

[0053] FIG. 1 is a block diagram illustrating a system for calculating stress and strain of a specimen according to one embodiment of the present invention.

[0054] Referring to FIG. 1, the stress and strain calculation system (1) of a specimen includes a grinding module (100), a cutting module (200), a compression module (300), a measurement module (400), a control module (500), and a power module (600).

[0055] First, the polishing module (100) will be described.

[0056] The polishing module (100) can perform the function of polishing the surface of a specimen (10) and can be composed of a conventional polishing device capable of polishing the surface of an object such as a specimen (10).

[0057] FIG. 2 is a drawing illustrating a polishing module that polishes a specific part of a specimen.

[0058] Specifically, as shown in FIG. 2, the polishing module (100) can be moved toward the specimen (10) to polish a predetermined portion of the surface of the specimen (10) so that a predetermined portion is made flat by the polishing module (100).

[0059] Next, the cutting module (200) will be described.

[0060] The cutting module (200) can perform the function of forming a protrusion (12) on a predetermined part of the flattened specimen (10).

[0061] Specifically, the cutting module (200) can cut at least a portion of a predetermined part so that a cylindrical projection (12), having a circular cross-section in a direction parallel to the predetermined part, is formed in the predetermined part.

[0062] This cutting module (200) may be composed of a cutting device capable of cutting an object such as a specimen (10).

[0063] Figure 3 is a drawing illustrating a cutting member.

[0064] For example, referring to FIG. 3, the cutting module (200) may include a cutting member (210) that is rotatable about a rotation axis parallel to a direction perpendicular to a predetermined part and cuts the predetermined part.

[0065] Figure 4 is an enlarged view of A in Figure 3.

[0066] As shown in FIG. 4, such a cutting member (210) may include a recess (212) formed by recessing at least a portion of one end that cuts a predetermined part, and a cutting part (214) installed on the outer periphery of the recess (212) and capable of cutting a predetermined part by rotating and contacting the predetermined part.

[0067] At this time, the recess (212) may be formed in the same shape as the protrusion (12) so as to accommodate the protrusion (12), and the cutting portion (214) may be configured to include a plurality of blades.

[0068] The cutting module (200) can form a protrusion (12) on a predetermined part using a cutting member (210).

[0069] FIG. 5 is a drawing showing a cutting module that cuts a predetermined part of a specimen while rotating around a rotation axis.

[0070] Specifically, as illustrated in FIG. 5, the cutting module (200) can move the cutting member (210) toward a predetermined part while rotating it around a rotation axis (R). At this time, it is preferable that the rotation axis (R) be parallel to a direction perpendicular to the predetermined part.

[0071] As the cutting member (210) moves, the cutting portion (214) in contact with the predetermined portion cuts the predetermined portion, and a portion of the predetermined portion that is not cut is accommodated inside the recess (212) formed in the cutting member (210).

[0072] Figure 6 is a drawing showing a protrusion formed on a specific part of a specimen by a cutting module.

[0073] And, as shown in FIG. 6, when the cutting module (200) moves the cutting member (210) in a direction away from a predetermined part, a part of the predetermined part that was received in the recess (212) can form a protrusion (12).

[0074] Meanwhile, depending on the shape of the recess (212), the shape of the protrusion (12) received in the recess (212) may vary. In the stress and strain calculation system (1) of a specimen according to one embodiment of the present invention, it is preferable that the recess (212) be formed such that the protrusion (12) has a circular cross-section in a direction parallel to a predetermined part.

[0075] Next, the compression module (300) will be described.

[0076] The compression module (300) can perform the function of pressing the protrusion (12) and can be composed of a pressing device capable of pressing an object such as a specimen (10).

[0077] Figure 7 is a diagram illustrating a compression module.

[0078] For example, referring to FIG. 7, the compression module (300) may include a contact portion (310) that contacts the protrusion (12), and the contact portion (310) may have a contact surface (312) formed flatly so as to be parallel to a direction parallel to a predetermined portion, which presses the protrusion (12) by contacting the protrusion (12).

[0079] Meanwhile, although the direction in which the compression module (300) presses the protrusion (12) may vary, in the stress and strain calculation system (1) of a specimen according to one embodiment of the present invention, it is preferable that the compression module (300) presses the protrusion (12) in a direction perpendicular to a predetermined part.

[0080] Figure 8 is a drawing showing a protrusion before a load is applied by a compression module.

[0081] For example, as illustrated in FIG. 8, the compression module (300) can move the contact portion (310) perpendicular to a predetermined portion and in a direction toward the protrusion (12). At this time, the height of the protrusion (12) before the load, which is the pressure applied to the protrusion (12) by the compression module (300), is applied may be a first height (h1).

[0082] Figure 9 is a drawing showing the protrusion after a load is applied by a compression module.

[0083] Next, as illustrated in FIG. 9, the compression module (300) can move to press the protrusion (12) in a direction perpendicular to a predetermined part to the contact surface (312) of the contact part (310) that is in contact with the protrusion (12). At this time, the height of the protrusion (12) after the load, which is the pressure applied to the protrusion (12) by the compression module (300), is applied may be a second height (h2).

[0084] Next, the measurement module (400) will be described.

[0085] The measuring module (400) can measure the load, which is the pressure applied to the protrusion (12) by the compression module (300), and the height, which is the length in a direction perpendicular to a predetermined part of the protrusion (12), and may include a pressure measuring sensor capable of measuring the load and a height measuring sensor capable of measuring the height.

[0086] The pressure measuring sensor can measure the load, which is the pressure applied to the protrusion (12) by the compression module (300). For example, the pressure measuring sensor may be composed of a load cell installed in the compression module (300).

[0087] The height measuring sensor can measure the height of the protrusion (12). For example, the height measuring sensor may be composed of a non-contact height measuring device that measures the height of an object using the principle of optical triangulation with a laser, or a displacement measuring device that uses a voltage difference.

[0088] Next, the control module (500) will be described.

[0089] The control module (500) can perform the function of controlling the operation of the grinding module (100), cutting module (200), compression module (300), and measuring module (400), and may include a computer, etc.

[0090] And, the control module (500) can calculate the stress of the specimen (10) and the strain of the specimen (10) according to the stress based on information regarding the load acting on the protrusion (12) and the height of the protrusion (12) (first height and second height).

[0091] Specifically, the control module (500) can calculate the nominal stress acting on the specimen (10) using the following mathematical formula 1, and calculate the nominal strain of the specimen (10) using the following mathematical formula 2.

[0092] [Mathematical Formula 1]

[0093] σ e = f / A

[0094] (here, σe is the nominal stress, f is the load, and A is the cross-sectional area of ​​the projection before the load is applied.

[0095] [Mathematical Formula 2]

[0096] ε e = d / L

[0097] (here, ε e ε is the nominal strain, d is the length obtained by subtracting the second height from the first height, and L is the vertical length of the projection before the load is applied.

[0098] Next, the control module (500) can calculate the true stress, which is the value obtained by dividing the load acting on the specimen (10) by the actual cross-sectional area of ​​the protrusion (12) changed by the load, using the following mathematical formula 3, and calculate the true strain of the specimen (10) using the following mathematical formula 4.

[0099] [Mathematical Formula 3]

[0100] σ t = σ e *(1+ε e )

[0101] (here, σ t is true stress, σ e is the nominal stress, ε e is the nominal strain)

[0102] [Mathematical Formula 4]

[0103] ε t = ln(1+ε e )

[0104] (here, ε t is the true strain, ε e is the nominal strain)

[0105] FIG. 10 is a graph showing a comparison between the stress of a specimen and the corresponding strain of the specimen calculated through a stress and strain calculation system of a specimen according to one embodiment of the present invention, and the actual strain of the specimen corresponding to the stress of the specimen.

[0106] As shown in FIG. 10, the true strain of the specimen (10) deformed by the true pressure applied to the specimen (10) calculated by the control module (500) is almost identical to the value of the actual strain of the specimen (10) according to the actual stress (load) applied to the specimen (10).

[0107] That is, by using the stress and strain calculation system (1) of a specimen according to one embodiment of the present invention, the strain of a specimen (10) deformed by pressure can be accurately calculated.

[0108] Next, the power module (600) will be described.

[0109] The power module (600) can perform the function of supplying power to the grinding module (100), cutting module (200), compression module (300), measurement module (400), and control module (500), and can be composed of a power supply device such as a battery.

[0110] Meanwhile, the polishing module (100) can polish a predetermined part of the specimen (10) again after the strain of the specimen (10) is calculated.

[0111] FIG. 11 is a drawing illustrating a polishing module that polishes a predetermined part of a specimen having a protrusion formed thereon.

[0112] For example, as illustrated in FIG. 11, after the strain of the specimen (10) is calculated, the polishing module (100) may move to a specific part of the specimen (10) and polish a specific part of the specimen (10) so that the protrusion (12) formed on the specimen (10) disappears.

[0113] Hereinafter, the configuration of a method for calculating stress and strain of a specimen according to one embodiment of the present invention will be described.

[0114] FIG. 12 is a flowchart illustrating a method for calculating stress and strain of a specimen according to one embodiment of the present invention.

[0115] Referring to FIG. 12, the method for calculating stress and strain of a specimen includes a grinding step (S100), a cutting step (S200), a compression step (S300), a measurement step (S400), and a calculation step (S500).

[0116] First, the polishing step (S100) is described.

[0117] The polishing step (S100) is a step of polishing a predetermined portion of the surface of the specimen (10) so that a predetermined portion becomes flat.

[0118] Next, the cutting step (S200) is described.

[0119] The cutting step (S200) is a step of cutting at least a portion of a predetermined part so that a cylindrical projection (12), having a circular cross-section in a direction parallel to the predetermined part, is formed on the predetermined part.

[0120] For example, in the cutting step (S200), at least a portion of a predetermined part can be cut using a cutting member (210) that is rotatable around a rotation axis parallel to a direction perpendicular to a predetermined part.

[0121] At this time, the cutting member (210) may include a recess (212) formed by recessing at least a portion of one end that cuts a predetermined part, and a cutting part (214) installed on the outer periphery of the recess (212) that can cut the predetermined part by rotating and contacting the predetermined part.

[0122] The specific configuration of the depression (212) and the cutting portion (214) and the configuration for forming the protrusion (12) using the cutting member (210) is the same as the specific configuration of the depression (212) and the cutting portion (214) and the configuration for forming the protrusion (12) using the cutting member (210) described in the stress and strain calculation system (1) of the specimen above.

[0123] Next, the compression step (S300) is described.

[0124] The compression step (S300) is a step of applying pressure to the projection (12) in a direction perpendicular to a predetermined part.

[0125] For example, the compression step (S300) may press the protrusion (12) using a compression module (300). The compression module (300) may include a contact portion (310) that presses the protrusion (12) by contacting it and may include a contact surface (312) formed flatly so as to be parallel to a direction parallel to a predetermined portion.

[0126] The configuration for applying pressure to the protrusion (12) using the contact portion (310) of the compression module (300) is the same as the configuration for applying pressure to the protrusion (12) using the contact portion (310) of the compression module (300) described in the stress and strain calculation system (1) of the specimen described above.

[0127] Next, the measurement step (S400) is described.

[0128] The measurement step (S400) is a step of measuring the first height (h1), which is the height before the load is applied, and the second height (h2), which is the height after the load is applied, among the height, which is the vertical length of the protrusion (12), and the load applied, which is the pressure applied to the protrusion (12) by the compression step (S300).

[0129] This measurement step (S400) can measure the load, the first height (h1), and the second height (h2) using a pressure measuring sensor capable of measuring the load and a height measuring sensor capable of measuring the height.

[0130] Next, the output step (S500) is explained.

[0131] The calculation step (S500) is a step of calculating the stress of the specimen (10) and the strain of the specimen (10) according to the stress, based on information regarding the load, the first height (h1) and the second height (h2).

[0132] Specifically, the calculation step (S500) can calculate the nominal stress acting on the specimen (10) using the following mathematical formula 1, and calculate the nominal strain of the specimen (10) using the following mathematical formula 2.

[0133] [Mathematical Formula 1]

[0134] σ e = f / A

[0135] (here, σ e is the nominal stress, f is the load, and A is the cross-sectional area of ​​the projection before the load is applied.

[0136] [Mathematical Formula 2]

[0137] ε e = d / L

[0138] (here, ε e ε is the nominal strain, d is the length obtained by subtracting the second height from the first height, and L is the vertical length of the projection before the load is applied.

[0139] Next, the calculation step (S500) can calculate the true stress, which is the value obtained by dividing the load acting on the specimen (10) by the actual cross-sectional area of ​​the protrusion (12) changed by the load, using the following mathematical formula 3, and calculate the true strain of the specimen (10) using the following mathematical formula 4.

[0140] [Mathematical Formula 3]

[0141] σ t = σ e *(1+ε e )

[0142] (here, σ t is true stress, σ e is the nominal stress, ε e is the nominal strain)

[0143] [Mathematical Formula 4]

[0144] ε t = ln(1+ε e )

[0145] (here, ε t is the true strain, ε eis the nominal strain)

[0146] Hereinafter, the operation and effects of a stress and strain calculation system for a specimen according to one embodiment of the present invention and a stress and strain calculation method for a specimen according to one embodiment of the present invention will be described.

[0147] First, a specific portion of the specimen (10) is polished. At this time, the specific portion can be polished so that it becomes flat.

[0148] Then, a predetermined portion of the specimen (10) is cut. At this time, the predetermined portion can be cut so that a cylindrical projection (12) with a circular cross-section in a direction parallel to the predetermined portion is formed.

[0149] When a protrusion (12) is formed on a specific part of the specimen (10), the protrusion (12) is pressed. At this time, the load applied to the protrusion (12) and the height of the protrusion (12) can be measured.

[0150] Next, the strain of the specimen (10) due to the load is calculated. Specifically, based on information regarding the load, the first height (h1) of the protrusion (12), and the second height (h2) of the protrusion (12), the stress of the specimen (10) and the strain of the specimen (10) according to the stress can be calculated using a mathematical formula.

[0151] Thus, the system and method for calculating stress and strain of a specimen according to the present invention calculates the stress and strain of the specimen using the strain of a protrusion according to a load applied to a protrusion formed in a predetermined part of the specimen, thereby providing the effect of being able to calculate the stress and strain of the specimen acting on the specimen simply and quickly.

[0152] In addition, since the stress and strain of the specimen are calculated using the strain of the protrusions and mathematical formulas, it provides the effect of accurately calculating the stress and strain acting on the specimen.

[0153] In addition, the stress and strain calculation system for a specimen according to the present invention calculates the stress and strain of the specimen using a protrusion having a relatively small volume, thereby providing the effect of being portable as it is manufactured to have a relatively small volume.

[0154] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single unit may be implemented in a distributed manner, and components described as distributed may likewise be implemented in a combined form.

[0155] The scope of the present invention is defined by the claims set forth below rather than by the detailed description above, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention.

Claims

1. A polishing module that polishes a predetermined portion of the surface of a specimen so that the predetermined portion becomes flat; A cutting module that cuts at least a portion of a predetermined part so that a cylindrical projection, having a circular cross-section in a direction parallel to the predetermined part, is formed on the predetermined part; A compression module that applies pressure to the above-mentioned protrusion in a direction perpendicular to the above-mentioned predetermined part; A measuring module for measuring a load, which is pressure applied to the projection by the compression module, a first height, which is the height before the load is applied, and a second height, which is the height after the load is applied, among the height, which is the vertical length of the projection; and A system for calculating stress and strain of a specimen, comprising a control module that controls the operation of the grinding module, the cutting module, the compression module, and the measuring module, and calculates the stress of the specimen and the strain of the specimen according to the stress based on information regarding the load, the first height, and the second height.

2. In Paragraph 1, A stress and strain calculation system for a specimen, wherein the control unit calculates the nominal stress acting on the specimen using the following mathematical formula 1, calculates the nominal strain of the specimen using the following mathematical formula 2, calculates the true stress acting on the specimen using the following mathematical formula 3, and calculates the true strain of the specimen using the following mathematical formula 4. [Mathematical Formula 1] s e = f / A (here, σ e is the nominal stress, f is the load, and A is the cross-sectional area of ​​the projection before the load is applied. [Mathematical Formula 2] e e = d / L (here, ε e ε is the nominal strain, d is the length obtained by subtracting the second height from the first height, and L is the vertical length of the projection before the load is applied. [Mathematical Formula 3] s t = σ e *(1+e e ) (here, σ t is true stress, σ e is the nominal stress, ε e is the nominal strain) [Mathematical Formula 4] e t = ln(1+ε e ) (here, ε t is the true strain, ε e is the nominal strain) 3. In Paragraph 2, The above cutting module is, A system for calculating stress and strain of a specimen, comprising a cutting member that is rotatable about a rotation axis parallel to the above-mentioned vertical direction and cuts the above-mentioned predetermined portion.

4. In Paragraph 3, The above cutting member is, A recess formed by the recessing of at least a portion of one end that cuts the above-mentioned predetermined portion; and A system for calculating stress and strain of a specimen, comprising a cutting part installed on the outer periphery of the above-mentioned depression and capable of cutting the above-mentioned predetermined part by rotating and contacting the said predetermined part.

5. In Paragraph 4, The above-mentioned depression is, A stress and strain calculation system for a specimen, formed in the same shape as the protrusion so as to accommodate the protrusion.

6. In Paragraph 5, The above compression module includes a contact portion that contacts the above protrusion, and A system for calculating stress and strain of a specimen, wherein the above contact portion contacts the above protrusion to press the above protrusion and forms a contact surface that is formed flatly so as to be parallel to the above parallel direction.

7. In Paragraph 6, The above contact surface is, The area of ​​the contact surface is formed to be larger than the area of ​​the cross-section of the projection and smaller than the area of ​​the predetermined portion, A stress and strain calculation system for a specimen, formed such that when the above-mentioned protrusion is pressed, it contacts the entire cross-section of the above-mentioned protrusion, but prevents contact with the above-mentioned predetermined portion.

8. In Paragraph 7, The above measurement module is, A pressure measuring sensor for measuring the above load; and A system for calculating stress and strain of a specimen, comprising a height measuring sensor for measuring the height.

9. In Paragraph 7, A system for calculating stress and strain of a specimen, further comprising a power module that supplies power to the grinding module, the cutting module, the compression module, the measuring module, and the control module.

10. A polishing step of polishing a predetermined portion of the surface of a specimen so that the predetermined portion becomes flat; A cutting step of cutting at least a portion of the predetermined portion so that a cylindrical projection having a circular cross-section in a direction parallel to the predetermined portion is formed in the predetermined portion; A compression step of applying pressure to the above-mentioned projection in a direction perpendicular to the above-mentioned predetermined part; A measurement step for measuring a load, which is the pressure applied to the projection by the compression step, a first height, which is the height before the load is applied, and a second height, which is the height after the load is applied, among the height, which is the vertical length of the projection; and A method for calculating stress and strain of a specimen, comprising a calculation step of calculating the stress of the specimen and the strain of the specimen according to the stress based on information regarding the load, the first height, and the second height.

11. In Paragraph 10, A method for calculating stress and strain of a specimen, wherein the above calculation step calculates the nominal stress acting on the specimen using the following mathematical formula 1, calculates the nominal strain of the specimen using the following mathematical formula 2, calculates the true stress acting on the specimen using the following mathematical formula 3, and calculates the true strain of the specimen using the following mathematical formula 4. [Mathematical Formula 1] s e = f / A (here, σ e is the nominal stress, f is the load, and A is the cross-sectional area of ​​the projection before the load is applied. [Mathematical Formula 2] e e = d / L (here, ε e ε is the nominal strain, d is the length obtained by subtracting the second height from the first height, and L is the vertical length of the projection before the load is applied. [Mathematical Formula 3] s t = σ e *(1+e e ) (here, σ t is true stress, σ e is the nominal stress, ε e is the nominal strain) [Mathematical Formula 4] e t = ln(1+ε e ) (here, ε t is the true strain, ε e is the nominal strain) 12. In Paragraph 11, The above cutting step is, A method for calculating stress and strain of a specimen by using a cutting member rotatable about an axis of rotation parallel to the above vertical direction to cut at least a portion of the above-mentioned predetermined part.

13. In Paragraph 12, The above cutting member is, A recess formed by the recessing of at least a portion of one end that cuts the above-mentioned predetermined portion; and A method for calculating stress and strain of a specimen, comprising a cutting portion installed on the outer periphery of the above-mentioned depression and capable of cutting the above-mentioned predetermined portion by rotating and contacting the above-mentioned predetermined portion.

14. In Paragraph 13, The above-mentioned depression is, A method for calculating stress and strain of a specimen formed with the same shape as the protrusion so as to accommodate the protrusion.

15. In Paragraph 14, The above compression step applies pressure to the projection using a contact portion that contacts the projection, and A method for calculating stress and strain of a specimen, wherein the above contact portion contacts the above protrusion to press the above protrusion and forms a contact surface that is formed flatly parallel to the above parallel direction.

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