2534VUMAT用戶子程序翻譯ABAQUS幫助手冊

1、25.3.4 VUMAT25.3.4 VUMATUser subroutine to define material behavior.定義材料本構用戶子程序Product: ABAQUS/Explicit  Warning:  The use of this user subroutine generally requires considerable expertise. You are cautioned that the implementation of any realistic constitutive model require

2、s extensive development and testing. Initial testing on a single-element model with prescribed traction loading is strongly recommended.注意：用戶子程序的使用通常需要一定的專長。用戶需要知道執(zhí)行任何實際的本構模型需要大量的試驗數(shù)據(jù)。強烈建議用戶對用戶子程序進行在指定拉力作用下單個單元的驗證測試。The component ordering of the symmetric and nonsymmetric tensors for the three-dimen

3、sional case using C3D8R elements is different from the ordering specified in , and the ordering used in ABAQUS/Standard.C3D8R單元三維軸對稱及非軸對稱張量成分順序與及ABAQUS/Standard中指定的順序不同。References· “User-defined mechanical m· *USER MATERIALOverviewUser subroutine VUMAT: 用戶子程序VUMAT· is used to define t

4、he mechanical constitutive behavior of a material;· 用來定義材料的力學本構關系· will be called for blocks of material calculation points for which the material is defined in a user subroutine ();· 可以被用戶子程序定義材料計算點調用· can use and update solution-dependent state variables;· 可以使用和更新結果依賴狀態(tài)變量&

5、#183; can use any field variables that are passed in;· 可以使用傳入的任何場變量· is described further in ; and· 在中詳細論述；· cannot be used in an adiabatic analysis.· 可以被用于絕熱分析Component ordering in tensors 張量組成順序The component ordering depends upon whether the tensor is symmetric or nonsymme

6、tric.張量組成順序取決于其是否為對稱或非對稱張量。Symmetric tensors 對稱張量For symmetric tensors such as the stress and strain tensors, there are ndir+nshr components, and the component order is given as a natural permutation of the indices of the tensor. The direct components are first and then the indirect components, begi

7、nning with the 12-component. For example, a stress tensor contains ndir direct stress components and nshr shear stress components, which are passed in as 對于如同應力及應變張量等的對稱張量，含有ndir+nshr分量，分量的序號按張量索引號的自然排序給出。首先是直接分量，然后是從12分量開始的間接分量。例如，包含ndir正應力分量及nshr的剪應力張量的應力張量被按照下面的順序傳入Component2-D Case3-D Case12345&

8、#160;6 The shear strain components in user subroutine VUMAT are stored as tensor components and not as engineering components; this is different from user subroutine UMAT in ABAQUS/Standard, which uses engineering components. Nonsymmetric tensors 非對稱張量For nonsymmetric tensors there are ndir+2*n

9、shr components, and the component order is given as a natural permutation of the indices of the tensor. The direct components are first and then the indirect components, beginning with the 12-component. For example, the deformation gradient is passed as 對于非對稱張量含有ndir+2*nshr分量，分量的順序按照張量索引號的自然排序給出。首先是

10、直接分量，其次是從12分量開始的間接分量。例如，位移剃度按照下面的順序傳遞Component2-D Case3-D Case123456 7 8 9 Initial calculations and checks 最初計算和檢查In the data check phase of the analysis ABAQUS/Explicit calls user subroutine VUMAT with a set of fictitious strains and a totalTime and stepTime both equal to 0.0. T

11、his is done as a check on your constitutive relation and to calculate the equivalent initial material properties, based upon which the initial elastic wave speeds are computed.在ABAQUS/Explicit調用用戶子程序VUMAT分析的數(shù)據(jù)檢查階段,小應變、總時間及時間步都為0。這作為對用戶本構關系的一個檢查，基于計算得到的初始材料波速來計算等效初始材料屬性。Defining local orientations 定義

12、局部方向All stresses, strains, stretches, and state variables are in the orientation of the local material axes. These local material axes form a basis system in which stress and strain components are stored. This represents a corotational coordinate system in which the basis system rotates with the mat

13、erial. If a user-specified coordinate system () is used, it defines the local material axes in the undeformed configuration.所有的應力、應變、延伸及狀態(tài)變量均按局部材料軸的方向。這些局部材料軸形成一個應力與應變分量存儲的基本系統(tǒng)。即這個基本系是隨著材料聯(lián)合轉動的坐標系。如果使用用戶指定坐標系，則它在無變形結構中定義局部材料軸。Special considerations for various element types不同單元類型的特殊考慮The use of user

14、 subroutine VUMAT requires special consideration for various element types.用戶子程序VUMAT的使用需要對不同的單元類型進行特殊的考慮。Shell and plane stress elements殼及平面應力單元You must define the stresses and internal state variables. In the case of shell or plane stress elements, you must define strainInc(*,3), the thickness str

15、ain increment. The internal energies can be defined if desired. If they are not defined, the energy balance provided by ABAQUS/Explicit will not be meaningful.用戶必須定義應力和初始狀態(tài)變量。在殼或平面應力單元的情況下，用戶必須定義應變包括（*,3），厚度應變增量。如果需要的話還需要定義初始能量。如果沒有定義，那么ABAQUS/Explicit提供的能量平衡將沒有意義。Shell elements殼單元When VUMAT is used

16、 to define the material response of shell elements, ABAQUS/Explicit cannot calculate a default value for the transverse shear stiffness of the element. Hence, you must define the element's transverse shear stiffness. See , for guidelines on choosing this stiffness.當使用VUMAT定義殼單元的材料響應時，ABAQUS/Expl

17、icit不能計算單元的缺省橫向剪切剛度。因此，用戶需要定義單元的橫向剪切剛度。關于選擇橫行剪切剛度的詳細資料請參考Beam elements梁單元For beam elements the stretch tensor and the deformation gradient tensor are not available. For beams in space you must define the thickness strains, strainInc(*,2) and strainInc(*,3). strainInc(*,4) is the shear strain associa

18、ted with twist. Thickness stresses, stressNew(*,2) and stressNew(*,3), are assumed to be zero and any values you assign are ignored.對于梁單元不能使用拉伸張量及位移剃度張量。對于空間梁，用戶必須定義厚度應變、應變增量（*，2）及應變增量（*，3）。應變增量（*，4）時與扭曲有關的剪應變。厚度應力，（*，2）及（*，3）假定為0，并且用戶分配的任何相關張量都被忽略。Deformation gradient 位移剃度The polar decomposition of

19、 the deformation gradient is written as , where and are the right and left symmetric stretch tensors, respectively. The constitutive model is defined in a corotational coordinate system in which the basis system rotates with the material. All stress and strain tensor quantities are defined with resp

20、ect to the corotational basis system. The right stretch tensor, , is used. The relative spin tensor represents the spin (the antisymmetric part of the velocity gradient) defined with respect to the corotational basis system.位移剃度寫成，其中及分別為右邊及左邊的對稱拉伸張量。本構模型定義為聯(lián)合旋轉坐標系，在該坐標系中基系隨著材料轉動。所有的應力和應變張量值按照聯(lián)合旋轉坐標系

21、定義。使用右邊的拉伸位移。相應的旋轉張量代表與聯(lián)合旋轉基系相應的轉動。Special considerations for hyperelasticity超彈性的特殊考慮Hyperelastic constitutive models in VUMAT should be defined in a corotational coordinate system in which the basis system rotates with the material. This is most effectively accomplished by formulating the hyperelas

22、tic constitutive model in terms of the stretch tensor, , instead of in terms of the deformation gradient, . Using the deformation gradient can present some difficulties because the deformation gradient includes the rotation tensor and the resulting stresses would need to be rotated back to the corot

23、ational basis. 在VUMAT中的超彈性本構模型可以被定義在聯(lián)合選擇坐標系中。這可以通過用拉伸張量表示的超彈性本構模型很好的實現(xiàn)，而不是使用位移剃度來表示。使用位移剃度可能會帶來一些困難，因為位移剃度包括旋轉張量并且導致應力需要選擇返回到聯(lián)合旋轉基系。Objective stress rates目標應力率The Green-Naghdi stress rate is used when the mechanical behavior of the material is defined using user subroutine VUMAT. The stress rate obt

24、ained with user subroutine VUMAT may differ from that obtained with a built-in ABAQUS material model. For example, most material models used with solid (continuum) elements in ABAQUS/Explicit employ the Jaumann stress rate. This difference in the formulation will cause significant differences in the

25、 results only if finite rotation of a material point is accompanied by finite shear. For a discussion of the objective stress rates used in ABAQUS, see “Stress rates,” Section 1.5.3 of the ABAQUS Theory Manual.在用戶子程序VUMAT中使用Green-Naghdi應力率來定義材料的力學本構關系。通過用戶子程序VUMAT獲得的應力率可能會與在ABAQUS建立的材料模型獲得的應力率有所不同。例

26、如，在ABAQUS/Explicit中大多數(shù)實體（連續(xù)）單元材料模型使用Jaumann應力率。只要材料點的有限旋轉伴隨有限剪切，這種表達方式的不同將導致計算結果的明顯差異。關于ABAQUS中使用的目標應力率的詳細討論參考“Stress rates,” Section 1.5.3 of the ABAQUS Theory Manual.Material point deletion 材料點刪除Material points that satisfy a user-defined failure criterion can be deleted from the model (see ). You

27、 must specify the state variable number controlling the element deletion flag when you allocate space for the solution-dependent state variables, as explained in . The deletion state variable should be set to a value of one or zero in VUMAT. A value of one indicates that the material point is active

28、, while a value of zero indicates that ABAQUS/Explicit should delete the material point from the model by setting the stresses to zero. The structure of the block of material points passed to user subroutine VUMAT remains unchanged during the analysis; deleted material points are not removed from th

29、e block. ABAQUS/Explicit will pass zero stresses and strain increments for all deleted material points. Once a material point has been flagged as deleted, it cannot be reactivated.滿足用戶定義的破壞準則的材料點可以被從模型中刪除（參考)。當用戶給結果依賴狀態(tài)變量分配空間時，用戶需要指定控制單元刪除標示的狀態(tài)變量號，在中進行詳細說明。在VUMAT中刪除狀態(tài)變量可以被賦予1或者0。1表示材料點時激活的，0表示ABAQUS

30、/Explicit將通過設定應力為0刪除材料點。在分析過程中傳遞給用戶子程序VUMAT的材料點結構保持不變；刪除的材料點沒有從塊中移走。ABAQUS/Explicit將傳遞0應力及應變給所有刪除的材料點。一旦一個材料點被標示為刪除，該材料點將不能夠被再次激活。User subroutine interface 用戶子程序 subroutine vumat(C Read only (unmodifiable)variables - 1 nblock, ndir, nshr, nstatev, nfieldv, nprops, lanneal, 2 stepTime, totalTime, dt,

31、 cmname, coordMp, charLength, 3 props, density, strainInc, relSpinInc, 4 tempOld, stretchOld, defgradOld, fieldOld, 5 stressOld, stateOld, enerInternOld, enerInelasOld, 6 tempNew, stretchNew, defgradNew, fieldNew,C Write only (modifiable) variables - 7 stressNew, stateNew, enerInternNew, enerInelasN

32、ew )C include 'vaba_param.inc'C dimension props(nprops), density(nblock), coordMp(nblock,*), 1 charLength(nblock), strainInc(nblock,ndir+nshr), 2 relSpinInc(nblock,nshr), tempOld(nblock), 3 stretchOld(nblock,ndir+nshr), 4 defgradOld(nblock,ndir+nshr+nshr), 5 fieldOld(nblock,nfieldv), stressO

33、ld(nblock,ndir+nshr), 6 stateOld(nblock,nstatev), enerInternOld(nblock), 7 enerInelasOld(nblock), tempNew(nblock), 8 stretchNew(nblock,ndir+nshr), 8 defgradNew(nblock,ndir+nshr+nshr), 9 fieldNew(nblock,nfieldv), 1 stressNew(nblock,ndir+nshr), stateNew(nblock,nstatev), 2 enerInternNew(nblock), enerIn

34、elasNew(nblock),C character*80 cmnameC do 100 km = 1,nblock user coding 100 continue return endVariables to be defined 被定義的變量stressNew (nblock, ndir+nshr) Stress tensor at each material point at the end of the increment.在增量結束時每個材料點的應力張量。stateNew (nblock, nstatev) State variables at each material poi

35、nt at the end of the increment. You define the size of this array by allocating space for it (see , for more information).增量結束時每個材料點的狀態(tài)變量。用戶通過分配空間來定義該矩陣的大?。ǜ嗟馁Y料參考）。Variables that can be updated 可以更新的變量enerInternNew (nblock) Internal energy per unit mass at each material point at the end of the incr

36、ement.增量結束時每個材料點單位質量的內能。enerInelasNew (nblock) Dissipated inelastic energy per unit mass at each material point at the end of the increment.增量結束時每個材料點單位質量的消散的無彈性能。Variables passed in for informationnblock Number of material points to be processed in this call to VUMAT.調用VUMAT的材料點號。ndir Number of dir

37、ect components in a symmetric tensor.對成張量的直接分量號。nshr Number of indirect components in a symmetric tensor.對稱張量的間接分量號。nstatev Number of user-defined state variables that are associated with this material type (you define this as described in ).與材料類型相關的用戶定義狀態(tài)變量號。nfieldv Number of user-defined external

38、field variables.用戶定義外部場變量號。nprops User-specified number of user-defined material properties.用戶定義材料屬性的用戶指定號。lanneal Flag indicating whether the routine is being called during an annealing process. lanneal=0 indicates that the routine is being called during a normal mechanics increment. lanneal=1 indi

39、cates that this is an annealing process and you should re-initialize the internal state variables, stateNew, if necessary. ABAQUS/Explicit will automatically set the stresses, stretches, and state to a value of zero during the annealing process.在退火處理過程中標示程序是否被調用。Laneal=0表明程序在正常力學增量過程中被調用。Laneal1表明這是

40、一個退火過程，并且如果需要的話用戶需要重新初始化內部狀態(tài)變量stateNew。ABAQUS/Explicit將自動設置應力，延展性及在退火過程中0值狀態(tài)。stepTime Value of time since the step began.從時間步開始時的的時間totalTime Value of total time. The time at the beginning of the step is given by totalTime - stepTime.總時間值。時間步開始時的時間定義為totalTime - stepTimedt Time increment size.時間增量大小

41、。cmname User-specified material name, left justified. It is passed in as an upper-case character string. Some internal material models are given names starting with the “ABQ_” character string. To avoid conflict, you should not use “ABQ_” as the leading string for cmname.用戶指定材料名。按照大寫字母傳入。有些內部材料本構以AB

42、Q_字母開頭賦名。為了避免沖突，用戶不能使用ABQ_作為cmname的開頭字母。coordMp(nblock,*) Material point coordinates. It is the midplane material point for shell elements and the centroid for beam elements.材料點坐標。對于殼單元為中平面材料點，對于梁單元為質心。charLength(nblock) Characteristic element length. This is a typical length of a line across an ele

43、ment. For beams and trusses, it is a characteristic length along the element axis. For membranes and shells, it is a characteristic length in the reference surface. For axisymmetric elements, it is a characteristic length in the plane only. For cohesive elements it is equal to the constitutive thick

44、ness.特征單元長度。它是一個穿過單元線的特殊長度。對于梁及桁架，它表示沿單元軸的特征長度。對于膜及殼，它表示參考面上的特征長度。對于對稱單元，它僅僅表示平面上的特征長度。對于粘聚單元它等于結構厚度。props(nprops) User-supplied material properties.用戶指定材料屬性density(nblock) Current density at the material points in the midstep configuration. This value may be inaccurate in problems where the volumet

45、ric strain increment is very small. If an accurate value of the density is required in such cases, the analysis should be run in double precision. This value of the density is not affected by mass scaling.材料點的當前密度。在體積應變增量非常小的情況下，該值可能出現(xiàn)精確性問題。在這種情況下如果需要精確的密度值，分析需要在雙精度下運行。密度值不受質量縮放比例的影響strainInc (nbloc

46、k, ndir+nshr) Strain increment tensor at each material point.每個材料點的應變增量張量。relSpinInc (nblock, nshr) Incremental relative rotation vector at each material point defined in the corotational system. Defined as , where is the antisymmetric part of the velocity gradient, , and . Stored in 3-D as and in 2

47、-D as .定義在聯(lián)合旋轉系中的每個材料點的增量相關選擇矢量。定義為，其中為速度剃度，的反對稱部分，在三維條件下存儲為，在二維條件下存儲為。tempOld(nblock) Temperatures at each material point at the beginning of the increment.增量開始時每個材料點的溫度。stretchOld (nblock, ndir+nshr) Stretch tensor, , at each material point at the beginning of the increment defined from the polar

48、decomposition of the deformation gradient by .增量開始時每個材料點的，拉伸張量。defgradOld (nblock,ndir+2*nshr) Deformation gradient tensor at each material point at the beginning of the increment. Stored in 3-D as (, , , , , , , , ) and in 2-D as (, , , , ).增量開始時每個材料點的位移剃度張量。在三維狀態(tài)下存儲為(, , , , , , , , ) 及在二維條件下存儲為(,

49、 , , , ).fieldOld (nblock, nfieldv) Values of the user-defined field variables at each material point at the beginning of the increment.增量開始時每個材料點的用戶定義場變量值。stressOld (nblock, ndir+nshr) Stress tensor at each material point at the beginning of the increment.增量開始時每個材料點的應力張量。stateOld (nblock, nstatev)

50、State variables at each material point at the beginning of the increment.增量開始時每個材料點的狀態(tài)變量。enerInternOld (nblock) Internal energy per unit mass at each material point at the beginning of the increment.增量開始時每個材料點的單位質量的內能enerInelasOld (nblock) Dissipated inelastic energy per unit mass at each material p

51、oint at the beginning of the increment.增量開始時每個材料點的單位質量消散的無彈性能。tempNew(nblock) Temperatures at each material point at the end of the increment.增量開始時每個材料點的溫度。stretchNew (nblock, ndir+nshr) Stretch tensor, , at each material point at the end of the increment defined from the polar decomposition of the

52、deformation gradient by .defgradNew (nblock,ndir+2*nshr) Deformation gradient tensor at each material point at the end of the increment. Stored in 3-D as (, , , , , , , , ) and in 2-D as (, , , INCLUDEPICTURE "http:/xwj:2080/v6.5/books/usb/graphics/usb_eqn00436.gif" * MERGEFORMAT , ).增量結束時

53、每個材料點的位移剃度張量。三維狀態(tài)下存儲為(, , , , , , , , ) ，二維狀態(tài)下存儲為 (, , , , )。fieldNew (nblock, nfieldv) Values of the user-defined field variables at each material point at the end of the increment.增量結束時每個材料點的用戶指定場變量值。Example: Using more than one user-defined material model例子：使用多個用戶定義材料模型To use more than one u

54、ser-defined material model, the variable cmname can be tested for different material names inside user subroutine VUMAT, as illustrated below:要使用多種用戶材料模型，用戶子程序VUMAT中使用cmname值代表不同的材料名，如下所述：if (cmname(1:4) .eq. 'MAT1') then call VUMAT_MAT1(argument_list)else if (cmname(1:4) .eq. 'MAT2'

55、) then call VUMAT_MAT2(argument_list)end ifVUMAT_MAT1 and VUMAT_MAT2 are the actual user material subroutines containing the constitutive material models for each material MAT1 and MAT2, respectively. Subroutine VUMAT merely acts as a directory here. The argument list can be the same as that used in

56、 subroutine VUMAT. The material names must be in upper case since cmname is passed in as an upper-case character string. VUMAT_MAT1 and VUMAT_MAT2分別為實際的包含MAT1及MAT2材料本構的用戶材料子程序。子程序VUMAT在此僅僅作為一個地址。Example: Elastic/plastic material with kinematic hardening例子：帶有運動硬化的彈性/塑性材料As a simple example of th

57、e coding of subroutine VUMAT, consider the generalized plane strain case for an elastic/plastic material with kinematic hardening. The basic assumptions and definitions of the model are as follows.作為子程序VUMAT的簡單例子代碼，考慮通用運動硬化彈性/塑性材料的平面應變問題。模型的基本假設及定義如下。Let be the current value of the stress and define

58、 INCLUDEPICTURE "http:/xwj:2080/v6.5/books/usb/graphics/usb_eqn00093.gif" * MERGEFORMAT to be the deviatoric part of the stress. The center of the yield surface in deviatoric stress space is given by the tensor , which has initial values of zero. The stress difference, , is the stress measured from the center of the yiel