WO2017077668A1 - 情報処理装置、情報処理方法、及びプログラム - Google Patents
情報処理装置、情報処理方法、及びプログラム Download PDFInfo
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- WO2017077668A1 WO2017077668A1 PCT/JP2016/003457 JP2016003457W WO2017077668A1 WO 2017077668 A1 WO2017077668 A1 WO 2017077668A1 JP 2016003457 W JP2016003457 W JP 2016003457W WO 2017077668 A1 WO2017077668 A1 WO 2017077668A1
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
- G06F30/23—Design optimisation, verification or simulation using finite element methods [FEM] or finite difference methods [FDM]
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
- G01N2203/006—Crack, flaws, fracture or rupture
- G01N2203/0062—Crack or flaws
- G01N2203/0066—Propagation of crack
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/0202—Control of the test
- G01N2203/0212—Theories, calculations
- G01N2203/0214—Calculations a priori without experimental data
Definitions
- the present technology relates to an information processing apparatus, an information processing method, and a program that can predict a crack generated in a structure.
- various structures such as semiconductor devices are subjected to various stresses such as mechanical stresses during the manufacturing process.
- a crack may occur in the structure.
- a technique for predicting cracks that may occur in the structure in advance is used.
- Patent Document 1 discloses a technique for predicting a crack that may occur in a structure.
- the progress of a crack in a structure is predicted using an algorithm using a J integral value or a stress intensity factor.
- the technique according to Patent Document 1 cannot predict cracks that straddle the interfaces of a plurality of types of materials.
- Patent Document 2 discloses a technique capable of predicting a crack that straddles an interface between a plurality of types of materials.
- an energy release rate when a crack is virtually advanced inside the structure is calculated, and it is predicted that the crack progresses in a direction in which the energy release rate is large.
- Patent Documents 1 and 2 can predict cracks due to brittle fracture, they cannot predict cracks due to ductile fracture. In metal materials and resin materials, cracks due to ductile fracture are likely to occur. For this reason, it is difficult for the technique according to Patent Document 2 to accurately predict a crack that may occur in a structure formed using a metal material or a resin material.
- an object of the present technology is to provide an information processing apparatus, an information processing method, and a program capable of quickly predicting a crack caused by ductile fracture occurring in a structure.
- an information processing apparatus includes a model acquisition unit and a crack prediction unit.
- the model acquisition unit acquires a structure model corresponding to a predetermined structure.
- the crack prediction unit is set at each position of the structure model, and is set at each position of the structure model and a term proportional to the time derivative of a crack variable expressing the presence or absence of a crack, and is dissipated during plastic deformation.
- the crack generated in the structure is predicted by calculating a differential equation including a term proportional to the plastic dissipation energy expressing the energy using the crack variable.
- cracks due to ductile fracture are calculated by calculating a differential equation using crack variables expressing the presence or absence of cracks and plastic dissipation energy expressing energy dissipated during plastic deformation using crack variables. Can be predicted. For this reason, the crack which generate
- the plastic dissipation energy may be set using an amount obtained by integrating the equivalent stress by a minute increment of the equivalent plastic strain.
- the plastic dissipation energy is set using the product of the difference between the equivalent stress and the yield stress and the equivalent plastic strain, and may be zero when the equivalent stress is smaller than the yield stress. In these configurations, the plastic dissipation energy can be set based on the relationship between the equivalent stress and the equivalent plastic strain at each position of the structure model.
- the differential equation may further include a diffusion term proportional to the second derivative of the spatial coordinates.
- a structure model corresponding to a predetermined structure is acquired.
- a term that is set at each position of the structure model and is proportional to the time derivative of the crack variable expressing the presence or absence of a crack, and the energy that is set at each position of the structure model and is dissipated during plastic deformation is the crack variable.
- a program includes a term proportional to a time derivative of a crack variable that is set at each position of a structure model corresponding to a predetermined structure and that represents the presence or absence of a crack in the information processing apparatus, By calculating a differential equation including a term proportional to the plastic dissipation energy set at each position of the structure model and expressing the energy dissipated during plastic deformation using the crack variable, Predict cracks to occur.
- the energy F in the structure D is expressed by the formula (1) using the barrier energy f doub , the gradient energy f grad , and the elastic energy f elast . ... (1)
- the differential equation (2) can be derived from the equation (1). ... (2)
- the left side of the differential equation (2) is composed of the product of the reciprocal of the mobility M and the time derivative of the crack variable ⁇ representing the presence or absence of cracks.
- the right side of the differential equation (2) is composed of a second-order differential diffusion term ⁇ ( ⁇ 2 ⁇ ) in space coordinates, a barrier energy f doub differential term, and an elastic energy f elast differential term.
- the differential term of the elastic energy f elast, release rate of elastic energy f elast are expressed.
- a crack variable ⁇ is first set at each position of the structure D. More specifically, a different crack variable ⁇ is set between a position having no crack and a position having a crack. For example, the crack variable ⁇ at the position having no crack is set to “0”, and the crack variable ⁇ at the position having the crack is set to “1”.
- the crack can be predicted quickly by calculating the differential equation (2).
- a crack that straddles the interface of a plurality of types of materials can be predicted, so that a crack generated in the structure D composed of a plurality of materials can be predicted.
- high versatility can be obtained.
- a crack due to brittle fracture can be predicted by the release rate of the elastic energy f elast expressed by the differential term of the elastic energy f elast included in the differential equation (2).
- the differential equation (2) since the differential equation (2) does not include a term corresponding to plastic deformation, it is impossible to predict a crack due to ductile fracture accompanied by plastic deformation.
- the inventor of the present technology applies the concept of the phase field method, and the energy dissipated mainly as heat during the plastic deformation in the differential equation (2) (hereinafter, referred to as “plastic dissipated energy f plast ”). It was found that cracks due to ductile fracture can be predicted by introducing the inclusion term.
- a crack prediction method applying the concept of the phase field method according to the present technology will be described.
- plastic dissipated energy f plast unlike elastic energy f elast, not a differential term. This is because the elastic energy f elast is released with time, whereas the plastic dissipation energy f plus is accumulated with time. In the differential equation (3), accumulation of the plastic dissipation energy f plast can be expressed by not using the plastic dissipation energy f plast as a differential term.
- the differential equation (3) the differential term of the elastic energy f elast representing the release rate of elastic energy f elast, the term plastic dissipated energy f plast representing the accumulation of plastic dissipated energy f plast, Is included. Therefore, by calculating the differential equation (3), it is possible to predict a crack in consideration of both brittle fracture and ductile fracture.
- the present technology it is possible to accurately predict a crack generated in the structure D configured using a material that is easily ductile fracture such as a metal material or a resin material.
- a material that is easily ductile fracture such as a metal material or a resin material.
- the crack prediction method according to the present technology as well as the crack prediction method based on the concept of the phase field method, it is possible to predict a crack that straddles the interface of a plurality of types of materials. It is possible to quickly predict the cracks that occur.
- the crack prediction method according to the present technology as in the crack prediction method based on the concept of the phase field method, since there is no restriction on the shape of the crack, high versatility can be obtained.
- FIG. 1 is a flowchart illustrating a crack prediction method according to an embodiment of the present technology.
- 2 to 9 are diagrams for explaining each step shown in FIG.
- the crack prediction method according to the present embodiment will be described with reference to FIGS.
- step S01 a model (structure model) MD that reproduces the structure of the structure D is generated. It is possible to reproduce the structure of any structure D by a structure model M D.
- the structure model M reproducible structures D its configuration by D, for example, various devices such as semiconductor devices.
- a finite element method Finite Element Method
- FDM Finite Difference Method
- An implicit method or an explicit method can be used.
- the finite element method can cope with an arbitrary shape, and high versatility can be obtained.
- the difference method is advantageous in that the computation can be easily parallelized and the computation is quick.
- the implicit method has the advantage of taking a large time step.
- a structure model M D is composed of a plurality of elements E.
- FIG. 2 is a diagram illustrating the structure model M D generated in step S01.
- 2 (A) is a perspective view of the structure model M D
- FIG. 2 (B) is a sectional view taken along the line A-A 'shown in FIG. 2 (A) of the structure model M D.
- the rough shape is a cube
- an initial crack extending in the Z-axis direction is formed at the center of the upper surface.
- the structure model M D, Y-axis direction upper surface of the X-axis direction central portion to the five elements E arranged in Z-axis direction is an element E1 with cracks, other elements E has no crack elements E0.
- the element E ⁇ b> 1 having a crack is indicated by oblique lines, and the element E ⁇ b> 0 having no crack is indicated by white.
- the element E having a free space such as a hole is preferably handled in the same manner as the element E1 having a crack.
- the step S01 may be omitted.
- step S02 In step S02, it acquires a structure model M D generated in step S01. Incidentally, in the case of not performing the step S01, it is possible to obtain a structure model M D etc.
- the present step S02 in the external device.
- step S03 it sets the crack variable ⁇ representing the presence or absence of cracks in the elements E of the obtained structure model M D in step S02.
- the element E0 having no cracks an element E1 having cracks with different crack variable ⁇ is set. That is, the crack variable ⁇ of the element E0 having no crack is set to “m”, and the crack variable ⁇ of the element E1 having the crack is set to “n” different from “m”. Either “m” or “n” may be large. As an example, the crack variable ⁇ of the element E0 having no crack is set to “0”, and the crack variable ⁇ of the element E1 having a crack is set to “1”.
- the step S03 may be omitted.
- step S04 each element E of the obtained structure model M D in step S02, sets the plastic dissipated energy f plast.
- the plastic dissipation energy f plas is not accumulated. Therefore, the plastic dissipation energy f plast of the element E1 is set to “0”.
- Plastic dissipated energy f plast in elements E0 without cracking is set based on the relationship between the equivalent stress ⁇ obtained experimentally depending on the material constituting the element E0 and the equivalent plastic strain epsilon p. Since the equivalent plastic strain ⁇ p depends on the crack variable ⁇ , the plastic dissipation energy f plast is expressed as a function of the crack variable ⁇ .
- FIG. 3 is a diagram illustrating an example of a method for expressing the plastic dissipation energy f plast set in the element E0 in step S04.
- FIG. 3 shows an example of an equivalent stress-equivalent plastic strain diagram obtained from the material forming the structure D.
- the vertical axis corresponds indicates stress sigma
- the horizontal axis represents the equivalent plastic strain epsilon p.
- FIG. 3 shows the yield stress ⁇ Y.
- Equivalent stress 3 - material equivalent plastic strain diagram is obtained, equivalent stress sigma is elastically deformed in the region of less than the yield stress sigma Y, equivalent stress sigma is plastically deformed by yield stress sigma Y or more regions.
- the plastic dissipative energy f plast expresses energy dissipated mainly as thermal energy due to plastic deformation of the material when the equivalent stress ⁇ is equal to or greater than the yield stress ⁇ Y.
- the plastic dissipation energy f plas can be defined as, for example, the area of a region indicated by hatching in FIGS. 3 (A) and 3 (B).
- the area of the region indicated by hatching in FIG. 3 (A), using the amount obtained by integrating the equivalent stress ⁇ at equivalent plastic strain epsilon p minute increments, for example can be calculated by equation (4). ... (4)
- the area of the region shown by hatching in FIG. 3B is calculated by, for example, the equation (5) using the product of the difference between the equivalent stress ⁇ and the yield stress ⁇ Y and the equivalent plastic strain ⁇ p. Is possible. ... (5)
- the plastic dissipation energy f plast when the equivalent stress ⁇ is smaller than the yield stress ⁇ Y is set to zero.
- the expression method of the plastic dissipation energy f plast can be properly used according to the material forming the structure D, the physical phenomenon, or the like so that the crack can be accurately predicted.
- the function expressing the plastic dissipation energy f plast is not limited to the equations (4) and (5), and can be appropriately created based on the relationship between the equivalent stress ⁇ and the equivalent plastic strain ⁇ p .
- the step S04 may be omitted.
- step S05 a differential equation is created using the crack variable ⁇ set in step S03 and the plastic dissipation energy f plast set in step S04.
- step S05 As an example of the differential equation generated in step S05, the above-described differential equation (3) can be cited.
- a differential equation (6) obtained by improving the differential equation (3) may be generated. ... (6)
- the differential equation (6), barrier energy f DOUB the differential term of the fittings constant w DOUB, elastic energy f elast the differential term of the fittings constant w elast, and plastic dissipated energy f plast sections fitting for constant w plast Has been introduced. Accordingly, the weighting of the differential term of the barrier energy f doub , the differential term of the elastic energy f elast , and the term of the plastic dissipation energy f plast can be optimized according to the structure of the structure D and the like. Is possible. Thereby, the crack generated in the structure D can be predicted more accurately.
- this step S05 may be omitted when a differential equation is generated in advance.
- step S06 a crack generated in the structure D is predicted by calculating the differential equation generated in step S05.
- produces in the structure D is estimated by calculating the differential equation acquired from the external apparatus etc. in this step S06.
- a stress condition is applied to the structure model MD by applying a load condition.
- Figure 4 shows an example of loading conditions to be applied to the structure model M D.
- the structure model M D while fixing the X-axis direction the left-hand side of the surface (restraint), added tensile load in the X-axis direction right side.
- the change of the crack variable ⁇ in each element E0 with the passage of time can be obtained.
- FIG. 5 shows an isoenergetic surface having the same plastic dissipation energy f.sub.plast .
- FIG. 6 in the case of applying a load condition in a structure model M D as shown in FIG. 4 shows the distribution of crack variable ⁇ at a certain time.
- FIG. 6 shows an equal crack variable surface having the same crack variable ⁇ .
- crack variable surface is spread in an elliptical arc shape extending from the Y-axis direction lower surface of an element E1 in the crack tip in the Y-axis direction downwards.
- the crack variable ⁇ is larger toward the inner equal crack variable surface.
- step S06 it is predicted that a crack will occur in the element E0 whose crack variable ⁇ is “1” or more after a predetermined time has elapsed. For example, if the crack variable ⁇ of the three elements E0 on the lower side in the Y-axis direction of the element E1 is “1” or more, it is assumed that a crack has occurred in the three elements E0 as shown in FIG. The three elements E0 are changed to element E1.
- step S06 by calculating the differential equations, the distribution of the elements E1 having cracks in a structure model M D after a predetermined time has elapsed can be obtained. Then, the distribution of the elements E1 having cracks in a structure model M D, it is possible to predict the crack generated in the structure D.
- the differential equation generated in step S05 is not limited to the differential equations (3) and (6) generated based on the concept of the phase field method, and can be changed as appropriate.
- modified examples of differential equations that can be used in the present technology will be described.
- step S05 the differential equation can be customized to eliminate unnecessary terms in accordance with the material forming the structure D, so that cracks occurring in the structure D can be predicted quickly and accurately. Become.
- the crack prediction method according to the present technology only needs to be able to predict a crack in the structure D configured using a material that is easily ductile fracture, such as a metal material or a resin material. For this reason, the differential equation generated in step S05 only needs to include at least a term proportional to the time derivative of the crack variable ⁇ and a term proportional to the plastic dissipation energy f plast set in step S04.
- the material which forms the structure D is not limited to the following thing, Arbitrary materials may be sufficient.
- the differential equations corresponding to the respective materials are not limited to those exemplified below, and can be arbitrarily customized.
- the differential equation (7) includes only the term of the time derivative of the crack variable ⁇ and the term of the plastic dissipation energy f plast . Note that the term plastic dissipated energy f plast, it may be included for fitting constants w plast. Thus, by using the differential equation (7) simplified by eliminating the terms other than the term of the plastic dissipation energy f plast , the calculation load can be greatly reduced.
- Equation (11) by treating the elastic modulus A as a tensor, the anisotropy of the elastic modulus A can be appropriately reflected in the prediction result. For this reason, the crack which generate
- the elastic energy f elast can be expressed by the equation (12) instead of the equation (11).
- ⁇ represents Poisson's ratio and ⁇ represents shear strain.
- the elastic modulus A in the equation (12) can be a function depending on the crack variable ⁇ as shown in FIG. 8, for example.
- the elastic modulus A decreases as the crack variable ⁇ increases.
- the function shown in FIG. 8 can express that the elasticity of the material forming the structure D decreases with the accumulation of the plastic dissipation energy f.sub.plast .
- (C) Material whose toughness value has anisotropy for example, the coefficient of the diffusion term is a function of the gradient of the crack variable ⁇ , that is, the normal of the interface A differential equation (13) as a function of direction can be used.
- Equation (16) the diffusion coefficient can be changed according to the direction of the interface, and the ease of crack progress can be changed depending on the direction. Thereby, the anisotropy of the toughness value can be appropriately reflected in the prediction result. For this reason, the crack which generate
- the structure D has a combination of brittle fracture and ductile fracture. Cracks occur.
- the differential equation (18) can be used to predict a crack due to a combination of brittle fracture and ductile fracture.
- the brittle fracture can be analyzed based on the release rate of the elastic energy f elast , and the ductile fracture can also be analyzed based on the accumulation of the plastic dissipation energy f plast . Therefore, by calculating the differential equation (18), it is possible to predict a crack due to a combination of brittle fracture and ductile fracture occurring in the structure D.
- Interface Stabilization In order to satisfactorily represent a crack in the structure D , it is preferable to stabilize the interface between the element E0 having no crack and the element E1 having a crack in the structure model MD. That is, the crack variable ⁇ of the element E0 having no crack is a value in the vicinity of “0”, the crack variable of the element E1 having the crack is a value in the vicinity of “1”, and any element E has a crack variable as much as possible. It is preferable that the state is not an intermediate value between “0” and “1”.
- FIG. 10 is a block diagram illustrating a configuration of a crack prediction apparatus (information processing apparatus) 10 that can realize the crack prediction method according to the embodiment.
- the crack prediction apparatus 10 includes a model generation unit 11, a model acquisition unit 12, a crack variable setting unit 13, a plastic dissipation energy setting unit 14, a differential equation generation unit 15, and a crack prediction unit 16.
- Each part of the crack prediction apparatus 10 is configured to be able to execute each step shown in FIG. 1 by a predetermined program.
- the model generation unit 11 is configured to be able to execute the model generation step S01.
- the model acquisition unit 12 is configured to be able to execute the model acquisition step S02.
- the crack variable setting unit 13 is configured to be able to execute a crack variable setting step S03.
- the plastic dissipation energy setting unit 14 is configured to be able to execute the plastic dissipation energy setting step S04.
- the differential equation generation unit 15 is configured to be able to execute a differential equation generation step S05.
- the crack prediction unit 16 is configured to be able to execute the crack prediction step S06.
- the crack prediction apparatus 10 should just be provided with the model acquisition part 12 and the crack prediction part 16 at least. That is, when steps S01 and S03 to S05 are not executed, the crack prediction apparatus 10 may not include the model generation unit 11, the crack variable setting unit 13, the plastic dissipation energy setting unit 14, and the differential equation generation unit 15. I do not care. Moreover, the crack prediction apparatus 10 may contain the structure other than the above as needed.
- the primary element of the element E of the structure model M D may be secondary elements.
- the element E of the structure model M D may be secondary elements.
- this technique can also take the following structures.
- a model acquisition unit for acquiring a structure model corresponding to a predetermined structure;
- a term that is set at each position of the structure model and is proportional to the time derivative of the crack variable expressing the presence or absence of a crack, and the energy that is set at each position of the structure model and is dissipated during plastic deformation is the crack variable.
- a crack prediction unit that predicts a crack generated in the structure by calculating a differential equation including a term proportional to plastic dissipation energy expressed using An information processing apparatus comprising: (2) The information processing apparatus according to (1) above, The plastic dissipation energy is set using an amount obtained by integrating an equivalent stress by a minute increment of an equivalent plastic strain.
- the plastic dissipation energy is set using the product of the difference between the equivalent stress and the yield stress and the equivalent plastic strain, and is zero when the equivalent stress is smaller than the yield stress.
- the differential equation further includes a term proportional to the second-order differential of the spatial coordinates. (5) Get a structure model corresponding to a given structure, A term that is set at each position of the structure model and is proportional to the time derivative of the crack variable expressing the presence or absence of a crack, and the energy that is set at each position of the structure model and is dissipated during plastic deformation is the crack variable.
- (6) In the information processing device, It is set at each position of the structure model corresponding to a given structure, and is set at each position of the structure model and a term proportional to the time derivative of the crack variable expressing the presence or absence of cracks, and is dissipated during plastic deformation. Predicting cracks occurring in the structure by calculating a differential equation including a term proportional to the plastic dissipation energy expressing the energy using the crack variables, program.
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Abstract
Description
上記モデル取得部は、所定の構造体に対応する構造体モデルを取得する。
上記亀裂予測部は、上記構造体モデルの各位置に設定され、亀裂の有無を表現する亀裂変数の時間微分に比例する項と、上記構造体モデルの各位置に設定され、塑性変形時に散逸されるエネルギーを上記亀裂変数を利用して表現する塑性散逸エネルギーに比例する項と、を含む微分方程式を計算することにより、上記構造体に発生する亀裂を予測する。
上記塑性散逸エネルギーは、相当応力と降伏応力との差と、相当塑性ひずみと、の積を利用して設定され、相当応力が降伏応力より小さい場合にゼロとされてもよい。
これらの構成では、構造体モデルの各位置における相当応力と相当塑性ひずみとの関係に基づいて塑性散逸エネルギーを設定可能である。
この構成により、構造体の亀裂をより良好に予測可能となる。
上記構造体モデルの各位置に設定され、亀裂の有無を表現する亀裂変数の時間微分に比例する項と、上記構造体モデルの各位置に設定され、塑性変形時に散逸されるエネルギーを上記亀裂変数を利用して表現する塑性散逸エネルギーに比例する項と、を含む微分方程式を計算することにより、上記構造体に発生する亀裂が予測される。
なお、ここに記載された効果は必ずしも限定されるものではなく、本開示中に記載されたいずれかの効果であってもよい。
図面には、適宜相互に直交するX軸、Y軸、及びZ軸が示されている。X軸、Y軸、及びZ軸は全図において共通である。
本技術に係る亀裂予測方法(情報処理方法)の概要について説明する。本技術に係る亀裂予測方法では、フェーズフィールド(Phase Field)法の考え方を応用して構造体Dに発生する亀裂を予測する。
まず、本技術に関連するフェーズフィールド法の考え方による亀裂予測方法について説明する。
構造体D内のエネルギーFは、障壁エネルギーfdoub、勾配エネルギーfgrad、及び弾性エネルギーfelastを利用して、式(1)で表される。
微分方程式(2)の右辺は、空間座標の2階微分の拡散項∇(ξ∇φ)と、障壁エネルギーfdoubの微分項と、弾性エネルギーfelastの微分項と、で構成されている。微分方程式(2)では、弾性エネルギーfelastの微分項によって、弾性エネルギーfelastの解放率が表現されている。
以下、本技術に係るフェーズフィールド法の考え方を応用した亀裂予測方法について説明する。
本技術に係るフェーズフィールド法の考え方を応用した亀裂予測方法では、微分方程式(2)に塑性散逸エネルギーfplastの項を導入した微分方程式(3)を利用する。
図1は、本技術の一実施形態に係る亀裂予測方法を示すフローチャートである。図2~9は、図1に示す各ステップを説明するための図である。以下、図1に沿って、図2~9を適宜参照しながら、本実施形態に係る亀裂予測方法について説明する。
ステップS01では、構造体Dの構成を再現したモデル(構造体モデル)MDを生成する。構造体モデルMDによって任意の構造体Dの構成を再現可能である。構造体モデルMDによってその構成を再現可能な構造体Dとしては、例えば、半導体デバイスなどの各種デバイスが挙げられる。
有限要素法では、任意の形状に対応可能であり、高い汎用性が得られる。差分法では、計算の並列化が容易であり、計算が早いというメリットが得られる。陰解法では、タイムステップを大きくとれるというメリットが得られる。
本実施形態では、有限要素法を用いるため、構造体モデルMDが複数の要素Eから構成される。
ステップS02では、ステップS01で生成した構造体モデルMDを取得する。
なお、ステップS01を行わない場合には、本ステップS02では外部機器などから構造体モデルMDを取得することができる。
ステップS03では、ステップS02で取得した構造体モデルMDの各要素Eに亀裂の有無を表現する亀裂変数φを設定する。
一例として、亀裂を有さない要素E0の亀裂変数φが「0」と設定され、亀裂を有する要素E1の亀裂変数φが「1」と設定される。
ステップS04では、ステップS02で取得した構造体モデルMDの各要素Eに、塑性散逸エネルギーfplastを設定する。
なお、既に亀裂を有する要素E1では、塑性変形が生じないため、塑性散逸エネルギーfplastが蓄積されない。このため、要素E1の塑性散逸エネルギーfplastは「0」と設定される。
図3(A)に斜線で示す領域の面積は、相当応力σを相当塑性ひずみεpの微小増分で積分した量を利用して、例えば式(4)によって算出可能である。
また、図3(B)に斜線で示す領域の面積は、相当応力σと降伏応力σYとの差と、相当塑性ひずみεpと、の積を利用して、例えば式(5)によって算出可能である。
ただし、式(5)において、相当応力σが降伏応力σYより小さい場合の塑性散逸エネルギーfplastをゼロとする。
ステップS05では、ステップS03で設定した亀裂変数φと、ステップS04で設定した塑性散逸エネルギーfplastと、を利用して微分方程式を作成する。
ステップS06では、ステップS05で生成した微分方程式を計算することにより、構造体Dに発生する亀裂を予測する。
なお、ステップS05を行わない場合には、本ステップS06では外部機器などから取得した微分方程式を計算することにより構造体Dに発生する亀裂を予測する。
図4は、構造体モデルMDに付与する荷重条件の一例を示している。図4に示す例では、構造体モデルMDにおいて、X軸方向左側の面を固定(拘束)した状態で、X軸方向右側の面に引張荷重を加える。
そして、この荷重条件下で微分方程式を計算することにより、時間の経過の伴う各要素E0における亀裂変数φの変化が得られる。
ステップS05で生成される微分方程式は、フェーズフィールド法の考え方に基づいて生成された微分方程式(3),(6)に限定されず、適宜変更可能である。以下、本技術で利用可能な微分方程式の変形例について説明する。
フェーズフィールド法の考え方に基づいて生成された微分方程式(3),(6)では、空間座標の2階微分に比例する拡散項や弾性エネルギーfelastの微分項が含まれているため、多岐にわたる材料で形成された構造体Dに適用可能である。つまり、微分方程式(3),(6)では、高い汎用性が得られる。
構造体Dを形成する材料が脆性破壊しにくい場合、例えば、塑性散逸エネルギーfplastの項以外の項を排除し、延性破壊のみを考慮した微分方程式(7)を用いることができる。
このように、塑性散逸エネルギーfplastの項以外の項を排除して簡単化された微分方程式(7)を用いることにより、計算負荷を大幅に小さくすることができる。
構造体Dを形成する材料の弾性率Aが異方性を有する場合、例えば、弾性率Aの異方性を考慮した微分方程式(8)を用いることができる。
微分方程式(8)中、系のエネルギーFsysは式(9)で表される。
式(9)中、勾配エネルギーfgradは式(10)で表され、弾性エネルギーfelastは式(11)で表される。
式(10)中、κは、材料定数を示す。
式(11)中、εは垂直ひずみを示す。
式(12)中、νはポアソン比を示し、γはせん断ひずみを示す。
構造体Dを形成する材料の靭性値が異方性を有する場合、例えば、拡散項の係数を亀裂変数φの勾配の関数、すなわち界面の法線方向の関数とする微分方程式(13)を用いることができる。
微分方程式(13)中、系のエネルギーFsysは式(14)で表される。
式(14)中、勾配エネルギーfgradは式(15)で表され、弾性エネルギーfelastは式(17)で表される。
式(15)中、κは、材料定数を示し、式(16)で表される。
式(16)中、aは異方性関数である。
式(17)中、νはポアソン比を示し、γはせん断ひずみを示す。
構造体Dが脆性破壊と延性破壊とが同時に進行する材料によって形成されている場合、構造体Dには脆性破壊と延性破壊との組み合わせによる亀裂が発生する。脆性破壊と延性破壊との組み合わせによる亀裂を予測するために、例えば、微分方程式(18)を用いることができる。
微分方程式(18)中、系のエネルギーFsysは式(19)で表される。
式(19)中、勾配エネルギーfgradは式(20)で表され、弾性エネルギーfelastは式(21)で表される。
式(20)中、κは材料定数を示す。
式(21)中、νはポアソン比を示し、εは垂直ひずみを示し、γはせん断ひずみを示す。
構造体Dにおける亀裂を良好に表現するために、構造体モデルMDにおいて亀裂を有さない要素E0と亀裂を有する要素E1との界面を安定化することが好ましい。つまり、亀裂を有さない要素E0の亀裂変数φが「0」近傍の値であり、亀裂を有する要素E1の亀裂変数が「1」近傍の値であり、いずれの要素Eもなるべく亀裂変数が「0」と「1」との中間の値である状態とならないことが好ましい。
微分方程式(22)中、系のエネルギーFsysは式(23)で表される。
式(23)中、障壁エネルギーfdoubは式(24)で表され、弾性エネルギーfelastは式(25)で表される。
式(24)中、κは材料定数を示す。
式(25)中、edoubはエネルギー障壁を示す。
図10は、上記実施形態に係る亀裂予測方法を実現可能な亀裂予測装置(情報処理装置)10の構成を示すブロック図である。亀裂予測装置10は、モデル生成部11と、モデル取得部12と、亀裂変数設定部13と、塑性散逸エネルギー設定部14と、微分方程式生成部15と、亀裂予測部16と、を具備する。亀裂予測装置10の各部は、所定のプログラムによって、図1に示す各ステップを実行可能に構成されている。
モデル取得部12は、モデル取得ステップS02を実行可能に構成されている。
亀裂変数設定部13は、亀裂変数設定ステップS03を実行可能に構成されている。
塑性散逸エネルギー設定部14は、塑性散逸エネルギー設定ステップS04を実行可能に構成されている。
微分方程式生成部15は、微分方程式生成ステップS05を実行可能に構成されている。
亀裂予測部16は、亀裂予測ステップS06を実行可能に構成されている。
また、亀裂予測装置10は、必要に応じて、上記以外の構成を含んでいてもよい。
以上、本技術の実施形態について説明したが、本技術は上述の実施形態にのみ限定されるものではなく、本技術の要旨を逸脱しない範囲内において種々変更を加え得ることは勿論である。
(1)
所定の構造体に対応する構造体モデルを取得するモデル取得部と、
上記構造体モデルの各位置に設定され、亀裂の有無を表現する亀裂変数の時間微分に比例する項と、上記構造体モデルの各位置に設定され、塑性変形時に散逸されるエネルギーを上記亀裂変数を利用して表現する塑性散逸エネルギーに比例する項と、を含む微分方程式を計算することにより、上記構造体に発生する亀裂を予測する亀裂予測部と、
を具備する情報処理装置。
(2)
上記(1)に記載の情報処理装置であって、
上記塑性散逸エネルギーは、相当応力を相当塑性ひずみの微小増分で積分した量を利用して設定される
情報処理装置。
(3)
上記(1)に記載の情報処理装置であって、
上記塑性散逸エネルギーは、相当応力と降伏応力との差と、相当塑性ひずみと、の積を利用して設定され、相当応力が降伏応力より小さい場合にゼロとされる
情報処理装置。
(4)
上記(1)から(3)のいずれか1つに記載の情報処理装置であって、
上記微分方程式は、空間座標の2階微分に比例する項を更に含む
情報処理装置。
(5)
所定の構造体に対応する構造体モデルを取得し、
上記構造体モデルの各位置に設定され、亀裂の有無を表現する亀裂変数の時間微分に比例する項と、上記構造体モデルの各位置に設定され、塑性変形時に散逸されるエネルギーを上記亀裂変数を利用して表現する塑性散逸エネルギーに比例する項と、を含む微分方程式を計算することにより、上記構造体に発生する亀裂を予測する
情報処理方法。
(6)
情報処理装置に、
所定の構造体に対応する構造体モデルの各位置に設定され、亀裂の有無を表現する亀裂変数の時間微分に比例する項と、上記構造体モデルの各位置に設定され、塑性変形時に散逸されるエネルギーを上記亀裂変数を利用して表現する塑性散逸エネルギーに比例する項と、を含む微分方程式を計算することにより、上記構造体に発生する亀裂を予測させる、
プログラム。
11…モデル生成部
12…モデル取得部
13…亀裂変数設定部
14…塑性散逸エネルギー設定部
15…微分方程式生成部
16…亀裂予測部
MD…構造体モデル
E,E0,E1…要素
Claims (6)
- 所定の構造体に対応する構造体モデルを取得するモデル取得部と、
前記構造体モデルの各位置に設定され、亀裂の有無を表現する亀裂変数の時間微分に比例する項と、前記構造体モデルの各位置に設定され、塑性変形時に散逸されるエネルギーを前記亀裂変数を利用して表現する塑性散逸エネルギーに比例する項と、を含む微分方程式を計算することにより、前記構造体に発生する亀裂を予測する亀裂予測部と、
を具備する情報処理装置。 - 請求項1に記載の情報処理装置であって、
前記塑性散逸エネルギーは、相当応力を相当塑性ひずみの微小増分で積分した量を利用して設定される
情報処理装置。 - 請求項1に記載の情報処理装置であって、
前記塑性散逸エネルギーは、相当応力と降伏応力との差と、相当塑性ひずみと、の積を利用して設定され、相当応力が降伏応力より小さい場合にゼロとされる
情報処理装置。 - 請求項1に記載の情報処理装置であって、
前記微分方程式は、空間座標の2階微分に比例する拡散項を更に含む
情報処理装置。 - 所定の構造体に対応する構造体モデルを取得し、
前記構造体モデルの各位置に設定され、亀裂の有無を表現する亀裂変数の時間微分に比例する項と、前記構造体モデルの各位置に設定され、塑性変形時に散逸されるエネルギーを前記亀裂変数を利用して表現する塑性散逸エネルギーに比例する項と、を含む微分方程式を計算することにより、前記構造体に発生する亀裂を予測する
情報処理方法。 - 情報処理装置に、
所定の構造体に対応する構造体モデルの各位置に設定され、亀裂の有無を表現する亀裂変数の時間微分に比例する項と、前記構造体モデルの各位置に設定され、塑性変形時に散逸されるエネルギーを前記亀裂変数を利用して表現する塑性散逸エネルギーに比例する項と、を含む微分方程式を計算することにより、前記構造体に発生する亀裂を予測させる、
プログラム。
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