A method of identifying ultrasonic stress

Abstract

The application discloses a method for identifying ultrasonic stress, comprising the following steps: S1, according to the contact characteristics of the chip and the rake face of the tool, the chip is divided into a shear region and a slip region, and the length of the boundary A1A2 of the shear region and the slip region is obtained; S2, according to the force balance relationship of the slip region, the stress of the boundary A1A2 of the shear region is obtained; S3, the stress of the boundary BC and CA1 of the shear region is obtained; S4, according to the stress of the boundary A1A2, BC and CA1, σ x ,σ y ,τ xy are obtained; S5, according to the energy conservation of the shear region, the temperature T of the shear region is obtained; S6, the ultrasonic stress τ ts is obtained. The application establishes an ultrasonic vibration wave material flow stress model. The research can provide a method for the acoustic characteristic research of subsequent aviation parts under different strains, strain rates and temperatures in ultrasonic speed movement.

Description

Technical Field

[0001] The present invention relates to the field of machining, and in particular to a method for identifying ultrasonic stress. Background Art

[0002] Ultrasonic stress is a key parameter in a material's acoustic properties. Based on the authors' research, there are some theoretical models for the effect of ultrasonic vibration waves on material stress. However, these are all based on acoustic theory and experiments. No theoretical model or identification method for the effect of ultrasonic vibration waves on material flow has been established from the perspective of ultrasonic cutting. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a method for identifying ultrasonic stress.

[0004] A method for identifying ultrasonic stress according to an embodiment of the first aspect of the present invention includes the following steps:

[0005] S1, according to the contact characteristics between the chip and the tool rake face, the chip is divided into the shear area and the slip area, and the length of the boundary A1A2 between the shear area and the slip area is obtained

[0006] S2, based on the force balance relationship in the slip region, obtain the stress at the boundary A1A2 of the shear region;

[0007] S3, obtain the stresses at the boundaries BC and CA1 of the shear region;

[0008] S4, obtain σ based on the stresses at the boundaries A1A2, BC, and CA1 x ,σ y ,τ xy ;

[0009] S5, according to the energy conservation of the shear region, obtain the temperature T of the shear region;

[0010] S6, obtain ultrasonic stress τ ts .

[0011] A method for identifying ultrasonic stress according to an embodiment of the present invention has at least the following technical benefits: Based on the effects of ultrasonic vibrations on transient characteristics of the cutting process, cutting deformation, acoustic softening, and thermal softening, the method identifies the impact of ultrasonic vibration waves on material flow stress and establishes an ultrasonic vibration wave material flow stress model. This research may provide a method for subsequent studies of the acoustic properties of aviation parts under different strains, strain rates, and temperatures during supersonic motion.

[0012] In some embodiments of the present invention, in step S2, the normal stress and shear stress of the slip region on the shear region are:

[0013]

[0014]

[0015] F σ3-1 and F τ3-1 are the normal force and tangential force exerted by the slip region on the shear region; b is the chip width.

[0016] In some embodiments of the present invention, the normal force and shear force exerted by the chip shearing region on the slipping region are respectively:

[0017]

[0018]

[0019] And F σ3-1 =-F σ3 ;

[0020] F τ3-1 =-F τ3

[0021] φ fi It is the shear angle of material outflow during cutting;

[0022] F σ4 、F τ4 are the normal force and tangential force acting on the chip sliding area, α v is the tool rake angle, F ax and F ay F is the force in the X and Y directions used by the tool to accelerate the chip; σ3-1 and

[0023] F τ3-1 are the normal force and tangential force exerted by the slip region on the shear region, respectively.

[0024] In some embodiments of the present invention, the forces applied by the tool to accelerate the chips in the X and Y directions are:

[0025] F ax =ρbhl2(vsinα v -v c )v c / 2l2;

[0026] F ay =ρbhl2vcosα v v c / 2l2;

[0027] h is the chip thickness, ρ is the density of the workpiece material, v is the cutting speed of the tool, l2 is the contact length between the tool rake face and the chip sliding area, vc is the speed of the chips.

[0028] In some embodiments of the present invention, in step S4, the following formula can be obtained based on the stress state of the shear region unit:

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035] Where σ1 and τ1 are the normal stress and shear stress of the shear region at the boundary BC respectively; BC , α A1A2 , α CA1 are the angles between sections BC, A1A2, CA1 and the X-axis, σ 3-1 and τ 3-1 are the normal stress and shear stress of the slip region on the shear region, respectively; σ x ,σ y ,τ xy The x-direction principal stress, y-direction principal stress and shear stress of the shear element are σ5 and τ5, respectively, which are the normal stress and shear stress of the tool on the boundary CA1 of the shear area.

[0036] In some embodiments of the present invention, in step S5, the temperature T of the shearing area is expressed as follows:

[0037]

[0038] T r is room temperature °, η e is the ultrasonic energy, F s,v Shear force in ultrasonic vibration cutting, v s is the shear velocity of the shear surface, ΔT is the temperature rise, C s is the specific heat capacity of the workpiece material, G is the shear modulus, ρ is the density of the material, U is the velocity of a specific particle in the material, c is the transmission speed of sound in the medium, ξ is the deformation distance, L BC is the length of the boundary BC, L A1A2 is the length of the boundary A1A2, and l1 is the contact length between the tool rake face and the chip shearing area.

[0039] In some embodiments of the present invention, the length of the boundary A1A2 According to the following relationship:

[0040]

[0041] h v is the thickness of the undeformed chips during ultrasonic machining, φ v is the shear angle, α v is the tool rake angle, and π is the pi.

[0042] In some embodiments of the present invention, τ ts =τ xy -τ BC , τ xy is the shear stress of the shear element in the shear region, τ BC is the shear stress of the shear element flowing into the boundary BC;

[0043]

[0044] T m , T r , E u , ε v1 are respectively the melting point of the material, room temperature, ultrasonic vibration energy density, strain rate, strain, is the reference strain rate. A1 is the yield strength of the material, T1 is the temperature of the shear zone considering only the changes in cutting parameters and cutting process caused by ultrasonic vibration, B1 is the hardening modulus of the material, and C is the coefficient of the influence of thermal softening of the material. n1 is the material hardening coefficient considering the changes in cutting parameters, cutting process volume, and ultrasonic vibration waves caused by ultrasonic vibration. m2 is the strain rate hardening coefficient considering the changes in cutting parameters, cutting process volume, and ultrasonic vibration waves caused by ultrasonic vibration.

[0045] In some embodiments of the present invention, step S7 is further included to obtain the influence of ultrasonic vibration on the thermal softening coefficient, strain rate hardening coefficient, and material hardening coefficient of the material.

[0046] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The present invention will be further described below with reference to the accompanying drawings and examples.

[0048] Figure 1 It is a schematic diagram of the contact area between the chip, workpiece and tool;

[0049] Figure 2 is the force diagram of the chip’s sliding area;

[0050] Figure 3 is the force diagram of the chip shear area;

[0051] Figure 4 It is the stress state diagram of the shear zone element of the chip. DETAILED DESCRIPTION

[0052] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0053] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, features defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0054] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0055] A method for identifying ultrasonic stress according to an embodiment of the present invention includes the following steps:

[0056] S1, according to the contact characteristics between the chip and the tool rake face, the chip is divided into the shear area and the slip area, and the length of the boundary A1A2 between the shear area and the slip area is obtained

[0057] S2, based on the force balance relationship in the slip region, obtain the stress at the boundary A1A2 of the shear region;

[0058] S3, obtain the stresses at the boundaries BC and CA1 of the shear region;

[0059] S4, obtain σ based on the stresses at the boundaries A1A2, BC, and CA1 x ,σ y ,τ xy ;

[0060] S5, according to the energy conservation of the shear region, obtain the temperature T of the shear region;

[0061] S6, obtain ultrasonic stress τ ts .

[0062] At a certain cutting speed, when the tool is cutting, there will be an area on the tool rake face that changes color due to frictional heat. Since the workpiece material in the chip shearing area undergoes shear deformation with the tool rake face, and the cutting force is mainly concentrated here, a large amount of cutting heat accumulates here, which causes the color of the tool surface to change. The chip and the tool do not slide relative to each other, so there are no scratches. That is, the area where the tool rake face changes color but no scratches appear corresponds to the chip shearing area. The contact length between the tool rake face and the chip shearing area is l1. There is also an area on the tool rake face that does not change color but has obvious scratches. This area corresponds to the chip sliding area. The contact length between the tool rake face and the chip sliding area is l2. Since the workpiece material in the tool and chip sliding area undergoes certain shear deformation, the chip slides on the tool, and there is a certain temperature increase, but it does not cause the color of the tool rake face to change. The chip slides on the tool, resulting in scratches on the tool. That is, l2 is the length of the chip sliding friction on the tool. Both l1 and l2 can be obtained through cutting experiments and then measured directly on the tool, and their average values ​​can be obtained through multiple sets of experiments. Figure 1 As shown, the contact boundary between the shearing area and the workpiece to be cut is BC, the contact boundary between the tool and the chip shearing area is CA1, and the contact boundary between the shearing area and the slip area is A1A2.

[0063] The length of the boundary A1A2 between the shear region and the slip region is It can be obtained through the following relationship:

[0064]

[0065]

[0066] h v is the thickness of the undeformed chips during ultrasonic machining, φ v is the shear angle, α v is the effective tool rake angle in ultrasonic vibration cutting, and π is the pi.

[0067] like Figure 1As shown, φ fi 、φ mid and φ in They are the shear angle of material outflow during cutting, the shear angle during inflow, and the shear material inflow angle. The difference between the three will not exceed 3°. The difference has very little effect on the sine and cosine values, so φ v The value of φ can be obtained by mid The value of .

[0068] like Figure 2 As shown in the figure, the normal force and tangential force of the tool acting on the chip sliding area are F σ4 、F τ4 .

[0069]

[0070]

[0071] The normal force and tangential force of the tool acting on the chip shearing area are F σ5 、F τ5 .

[0072]

[0073]

[0074] σ4 and τ4 are the principal stress and shear stress of the tool acting in the chip sliding area, respectively. σ5 and τ5 are the principal stress and shear stress of the tool acting in the chip shearing area, respectively. b is the chip width, and is an integral micro unit.

[0075] Ultrasonic vibration accelerates the movement of chips, and the flow speed of chips changes from the initial cutting speed to the final cutting speed.

[0076] The force accelerating the chip motion is assumed to be constant. Based on the governing equation of momentum balance, the relationship between the chip slip area is as follows:

[0077] mvsinα v =mv c +F ax t a ;

[0078] mvcosα v =0+F ay t a .

[0079] Drawing on the relationship between acceleration and displacement, the relationship between chip acceleration a and displacement l2 is:

[0080]

[0081] vc =t a a;

[0082]

[0083] v c is the speed of the chip, the displacement of the tool to accelerate the chip movement is l2, t a The time it takes for the tool to accelerate the chip movement.

[0084] The force used to accelerate the chip is

[0085] F ax =ρbhl2(vsinα v -v c )v c / 2l2;

[0086] F ay =ρbhl2vcosα v v c / 2l2;

[0087] h is the chip thickness, ρ is the density of the workpiece material, and v is the cutting speed of the tool.

[0088] based on Figure 2 The force balance relationship in the chip sliding area can be established as follows:

[0089] F x =0=(F σ3 +F ax )sinφ fi -(F τ3 +F ay )cosφ fi -F σ4 cosa v -F τ4 sinα v ;

[0090] F y =0=(F σ3 +F ax )cosφ fi +(F τ3 +F ay )sinφ fi +F σ4 sina v -F τ4 cosα v .

[0091] According to the above formula, the normal force and shear force exerted by the chip shear region on the slip region are

[0092]

[0093]

[0094] exist Figure 3 In the figure, it is the force diagram of the chip shearing area, where F σ3 With F σ3-1 、F τ3 With F τ3-1 are two pairs of reaction forces, so

[0095] F σ3-1 =-F σ3 ;

[0096] F τ3-1 =-F τ3 .

[0097] The normal stress and shear stress of the slip region on the shear region are

[0098]

[0099]

[0100] based on Figure 3 In the equilibrium conditions of the shear region in the x and y directions, we can obtain:

[0101] 0=(F σ1 -F σ3-1 )sinφ v -(F τ1 -F τ3-1 )cosφ v -F σ5 cosα v -F τ5 sinα v ;

[0102] 0=(F σ1 -F σ3-1 )cosφ v -(F τ1 -F τ3-1 )sinφ v +F σ5 sinα v -F τ5 cosα v .

[0103] The normal force and shear force in the shear region at the boundary BC are

[0104]

[0105]

[0106] The normal stress and shear stress in the shear region at the boundary BC are

[0107]

[0108]

[0109] The normal stress and shear stress on the shear region boundary CA1 are:

[0110]

[0111]

[0112] Figure 4 is the stress-strain diagram of the shear band element. The stress components at sections BC, CA1, and A1A2 are:

[0113]

[0114]

[0115]

[0116]

[0117]

[0118]

[0119] where α BC , α A1A2 , α CA1 They are the angles between sections BC, A1A2, and CA1 and the X-axis respectively.

[0120] Combining the above formulas and solving them, we can calculate the stress component σ of the shear element x ,σ y ,τ xy , σ x ,σ y ,τ xy are the x-direction principal stress, y-direction principal stress and shear stress of the shear element respectively.

[0121] In ultrasonic vibration-assisted cutting, the total input energy is ultrasonic vibration and shear force, and the total output energy is heat and strain energy. Most of the energy is used for shear deformation, while a smaller amount is used for normal deformation. Based on the energy conservation principle of shear deformation in the shear region during ultrasonic cutting, the following relationship can be established:

[0122]

[0123] F s,vShear force in ultrasonic vibration cutting, v s It is the shear velocity of the shear surface, that is, the movement speed of the chip of the tool relative to the workpiece.

[0124]

[0125]

[0126] E u =ρcU 2 ;

[0127] U=ωξ=2πfξ;

[0128] E u is the ultrasonic intensity, also known as ultrasonic power, that is, ultrasonic energy, and f is the frequency of ultrasonic vibration.

[0129] The temperature of the shear band is

[0130]

[0131] T r is room temperature, η e is the ultrasonic energy, ΔT is the temperature rise, Cs is the specific heat capacity of the workpiece material, G is the shear modulus, ρ is the density of the material, U is the velocity of a specific particle in the material, c is the transmission speed of sound in the medium, ξ is the deformation distance, which is equivalent to the ultrasonic vibration amplitude, L BC is the length of the border BC.

[0132] On the other hand, the modified model of material shear stress is as follows:

[0133]

[0134]

[0135] τ and τ i is the same stress, is the same stress obtained using different calculation models.

[0136] Where τ and τ i Has the following relationship:

[0137] τ=τ i ;(3)

[0138]

[0139] T m , T r , E u , ε v1 are respectively the melting point of the material, room temperature, ultrasonic vibration energy density, strain rate, strain, is the reference strain rate. A1 is the material's yield strength, B1 is the material's hardening modulus, C is the coefficient accounting for the material's thermal softening effect under normal conditions, n is the material's hardening coefficient, and m1 is the strain rate hardening coefficient. c1 is the coefficient that considers the effect of ultrasonic vibration waves on the material's thermal softening, and c2 is the coefficient that excludes the effect of ultrasonic vibration waves on the material's thermal softening. d and e are the coefficients that ultrasonic vibration affects the material's flow stress, with the constant e being 1. The constant d can be obtained by linearly regressing the stress under ultrasonic vibration with the stress under non-ultrasonic vibration.

[0140] The embodiment of the present invention also includes step S7, obtaining the influence of ultrasonic vibration on the thermal softening coefficient, strain rate hardening coefficient, and material hardening coefficient of the material, that is, obtaining three influence functions C(x), n(x), and m(x).

[0141] According to formulas (1), (2), (3) and (4), the relationship between C1 and C2 can be obtained by fitting calculations through multiple sets of data under different working conditions, and C2 = C(x)C1 can be obtained, where C(x) is the thermal softening coefficient influence function of the material under ultrasonic vibration.

[0142] Since the temperature terms in formulas (1) and (2) take into account the effects of ultrasonic vibration energy, strain, and strain rate, and the effects of strain and strain rate only consider the effects of changes in cutting parameters caused by ultrasonic vibration, this stress should be the stress that takes into account the effects of ultrasonic softening and hardening caused by ultrasonic vibration. The stress calculated by formulas (6-27) to (6-29) should take into account the effects of strain hardening and softening caused by ultrasound, as well as the effects of changes in cutting parameters and cutting process caused by ultrasonic vibration.

[0143] The stresses that only consider the cutting parameters and cutting process caused by ultrasonic vibration are the following two formulas:

[0144]

[0145]

[0146] τ BC and τ 1-1 is the same stress, is the same stress obtained using different calculation models.

[0147] By setting τ BC =τ 1-1 , and obtain the influence of ultrasound on the material hardening coefficient and strain rate hardening coefficient.

[0148] These two formulas only consider the stress caused by the changes in cutting parameters and cutting process caused by ultrasonic vibration and the influence of ultrasonic softening.

[0149] Where n1 is the material hardening coefficient, which takes into account the influence of ultrasonic vibration on cutting parameters, cutting process variables, and ultrasonic vibration waves; m2 is the strain rate hardening coefficient, which takes into account the influence of ultrasonic vibration on cutting parameters, cutting process variables, and ultrasonic vibration waves; C is the thermal softening coefficient of the material; n2 is the material hardening coefficient, which takes into account the influence of ultrasonic vibration on cutting parameters and cutting process variables; m3 is the strain rate hardening coefficient, which takes into account the influence of ultrasonic vibration on cutting parameters and cutting process variables. C and e are both obtained through experiments; T1 is the temperature of the shear zone, which only considers the influence of ultrasonic vibration on cutting parameters and cutting process variables.

[0150] Through formula (6-36-a) and formula (6-36-b) and multiple sets of operating data.

[0151] get:

[0152] n1=n(x)n2;

[0153] m2=m(x)m3.

[0154] n(x) is the function of the influence of the vibration wave in ultrasonic vibration on the material hardening coefficient.

[0155] m(x) is the influence function of the vibration wave in ultrasonic vibration on the strain rate hardening coefficient of the material

[0156] Where T1 is the temperature of the shear region considering only the cutting parameters and cutting process changes caused by ultrasonic vibration, which is

[0157]

[0158] in is the Taylor-Quinney coefficient, which can be obtained through experiments and is generally 0.85. τ is the yield strength of the material, which is experimental data and can be obtained through experiments.

[0159] Then the material stress caused by the transmission of ultrasonic vibration waves in the medium is

[0160] τ ts =τ xy -τ BC (6-38)

[0161] τ xy is the shear stress of the shear element in the shear region, τ BC is the shear stress of the shear element flowing into the boundary BC. BC is the shear stress of formula (6-36-a), considering only the influence of cutting parameters and cutting process changes caused by ultrasonic vibration on stress, τ xyThe shear stress obtained by solving the simultaneous equations (6-27-a) to (6-29-b) takes into account (1) the effect of changes in cutting parameters and cutting process caused by ultrasonic vibration on stress and (2) the effect of ultrasonic waves on material stress. By comparing these two, the ultrasonic stress model is obtained.

[0162] Throughout this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" indicate that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, illustrative uses of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0163] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A method for identifying ultrasonic stress, characterized in that: The steps include: S1, according to the contact characteristics between the chip and the tool rake face, the chip is divided into the shear area and the slip area, and the length of the boundary A1A2 between the shear area and the slip area is obtained ; S2, based on the force balance relationship in the slip region, obtain the stress at the boundary A1A2 of the shear region; S3, obtain the stresses at the boundaries BC and CA1 of the shear region; S4, obtained based on the stresses at the boundaries A1A2, BC, and CA1 , , ; S5, according to the energy conservation of the shear region, obtain the temperature of the shear region ; S6, obtain ultrasonic stress ; The normal force and shear force exerted by the chip shear region on the slip region are: ； ； and ; ； It is the shear angle of material outflow during cutting; 、 are the normal force and tangential force acting on the chip sliding area, is the tool rake angle, and The X and Y direction forces of the tool used for chip acceleration; and are the normal force and tangential force exerted by the slip region on the shear region, respectively; The forces used by the tool to accelerate the chip in the X and Y directions are: ； ； is the chip thickness, is the density of the workpiece material, is the cutting speed of the tool, is the contact length between the tool rake face and the chip sliding area, is the speed of the chips.

2. The method for identifying ultrasonic stress according to claim 1, wherein: In step S2, the normal stress and shear stress of the slip region on the shear region are: ； ； and are the normal force and tangential force exerted by the slip region on the shear region; b is the chip width.

3. The method for identifying ultrasonic stress according to claim 1, characterized in that: In step S4, according to the stress state of the shear region unit, the following formula can be obtained: ； ； ； ； ； ； in and Normal stress and shear stress in the shear region at boundary BC respectively; in , , are the angles between sections BC, A1A2, CA1 and the X-axis, and are the normal stress and shear stress of the slip region on the shear region, respectively; , , are the x-direction principal stress, y-direction principal stress and shear stress of the shear element respectively; and are the normal stress and shear stress of the tool on the boundary CA1 of the shearing area, respectively.

4. The method for identifying ultrasonic stress according to claim 3, wherein: In step S5, the temperature of the shearing area The relationship is as follows: ； is room temperature °, is the ultrasonic energy, Shear force in ultrasonic vibration cutting, is the shear velocity of the shear plane, is the temperature rise, is the specific heat capacity of the workpiece material, G is the shear modulus, is the density of the material, is the length of the boundary BC, is the length of the boundary A1A2, It is the contact length between the tool rake face and the chip shearing area.

5. The method for identifying ultrasonic stress according to claim 1, wherein: Length of boundary A1A2 According to the following relationship: ; is the thickness of the undeformed chips during cutting during ultrasonic machining, is the shear angle, is the tool rake angle, is pi.

6. The method for identifying ultrasonic stress according to claim 1, wherein: ， is the shear stress of the shear element in the shear region, is the shear stress of the shear element flowing into the boundary BC; ； , , , are respectively the melting point of the material, room temperature, strain rate, strain, is the reference strain rate, A1 is the yield strength of the material, is the temperature of the shear zone considering only the cutting parameters and cutting process changes caused by ultrasonic vibration, B1 is the hardening modulus of the material, and C is the coefficient of the influence of thermal softening of the material; In order to consider the cutting parameters caused by ultrasonic vibration, the changes in cutting process volume, and the material hardening coefficient affected by ultrasonic vibration waves; In order to consider the cutting parameters caused by ultrasonic vibration, the changes in cutting process volume and the strain rate hardening coefficient affected by ultrasonic vibration waves.

7. The method for identifying ultrasonic stress according to claim 1, wherein: The method further includes step S7 of obtaining the influence of ultrasonic vibration on the thermal softening coefficient, strain rate hardening coefficient, and material hardening coefficient of the material.

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