Method for transferring a stress state (stress sensor) of an FE simulation result to a new FE mesh geometry of a modeled construction system in a simulation chain of production operations

Abstract

The invention relates to a method for transferring a stress state of an FE simulation result to a new FE mesh geometry of a simulated construction system, such as a component for motor vehicles that has a 3-D shape, in a simulation chain of production operations, comprising: a) providing a first data set, which describes the FE simulation result with a stress state of the FE simulation of the construction system or component of a first production operation, b) creating the new FE mesh geometry of the simulated construction system or component, which new FE mesh geometry is associated with a second production operation, c) transferring the stress state of the provided first data set to the new FE mesh geometry of the construction system or component, d) performing an equilibrium calculation by using the stress tensor in the FE mesh geometry, wherein deformation of the construction system or component results, which deformation differs from the deformation in the FE mesh by a shape alteration u>tolerance value ε, e) iteratively repeating the equilibrium calculation as a cyclic equilibrium iteration in the new FE mesh geometry (in the new target FE mesh) of the construction system or component, wherein, in each cycle, a new stress state is applied to the FE mesh geometry of the construction system or component and stress components that lead to undesired shape alterations are decreased until a displacement/termination criterion of shape alteration u<tolerance value ε is achieved, and f) displaying the fulfilled condition of u<ε.

Claims

1. A method comprising: a) providing a first data set, which describes a Finite Element (FE) simulation result with a stress state of a first FE simulation of a first production operation of a component, wherein a shape of the component results in a first FE mesh, b) creating a second FE mesh of the simulated component, which second FE mesh is associated with a second production operation, c) transferring the stress state of the provided first data set to the second FE mesh of the component, d) performing an equilibrium calculation by using the stress state in the second FE mesh, wherein the shape of the component varies by a shape variation u.sub.1>tolerance value ε between the shape in the first FE mesh and the shape in the second FE mesh due to a different mesh density, FE element type and material model in the second FE mesh prior to carrying out the second production operation simulation of the component, e) iteratively repeating the equilibrium calculation as a cyclic equilibrium iteration in the second FE mesh of the component prior to carrying out the second production operation simulation of the component, wherein, in each cycle, a respectively new stress state is applied to the second FE mesh of the component and, in so doing, stress components that lead to shape variations u.sub.2, . . . n−1 between the shape in the first FE mesh and the shape in the second FE mesh due to the different mesh density, FE element type and material model in the second FE mesh are decreased until a termination criterion of shape variation u.sub.n<tolerance value between the shape in the first FE mesh and the shape in the second FE mesh due to the different mesh density, FE element type and material model in the second FE mesh is achieved, and f) displaying of the fulfilled condition of u.sub.n<ε.

2. The method according to claim 1, wherein after achieving and/or displaying the fulfilled condition of u.sub.n<ε, a second data set is provided, which describes the stress state of the component with the second FE mesh, in which the termination criterion of shape alteration u.sub.n<tolerance ε is achieved.

3. The method according to claim 1, further comprising: determining a simulated blank of the component on the basis of the provided second data set.

4. The method according to claim 1, further comprising: simulated forming of a simulated blank of the component.

5. The method according to claim 1, comprising: real production of a real blank corresponding to the simulated blank for producing the component in the second production operation.

6. The method according to claim 1, wherein for providing the first data set a scanning and/or reading in of a model of the component takes place.

7. The method according to claim 1, wherein the first production operation is a pressing and/or deep drawing operation of materials of the component.

8. The method according to claim 1, wherein the second production operation is a painting operation of the component.

9. The method according to claim 1, the method further comprising: g) subsequently performing the second production operation simulation of the component in the second FE mesh.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is now explained with reference to the drawings. In these:

(2) FIG. 1 is a block diagram of the method for transferring a stress state (stress tensor) of an FE simulation result FE-N.sub.1 to a newly to be simulated new FE mesh geometry FE-N.sub.2 of a modeled construction system or component in a simulation chain of production operations according to at least one embodiment of the invention,

(3) FIG. 2 is a block diagram from which advantageous further developments of the method according to FIG. 1 according to at least one embodiment of the invention can be seen,

(4) FIG. 3 is a diagrammatic figure illustration of the stress transfer without undesired shape alteration according to steps d) to f) of the method according to FIG. 1, and

(5) FIG. 4 is a further diagrammatic illustration of a stress transfer (enhanced stress mapping) by means of steps c) to f) of the method according to FIG. 1.

EMBODIMENTS

(6) FIG. 1 shows a block diagram of the method for transferring a stress state (stress tensor) S.sub.1 of an FE simulation result FE-N.sub.1 of a modeled construction system or component 1 to a newly to be applied FE mesh geometry FE-N.sub.2 of the latest in the simulation chain of a production process according to at least one embodiment of the invention.

(7) Here, in a step a) a first data set D.sub.1 is provided, which describes the FE simulation result with a stress state of the FE simulation with the starting FE mesh FE-N.sub.1 of the construction system or component 1.

(8) In a step b) the new FE mesh geometry FE-N.sub.2 (new FE target mesh) is applied to the construction system or component 1, which is associated with a second production operation.

(9) Subsequently, in a step c) the stress state (stress tensor S.sub.1) of the first data set D.sub.1 provided in step a) is transferred to the new FE mesh geometry FE-N.sub.2 of the construction system or component 1 created in step b).

(10) Thereafter, in a step d) an equilibrium calculation R is carried out by using the stress tensor S.sub.1 in the FE mesh geometry FE-N.sub.2.

(11) Here, in a subsequent step e) a deformation of the construction system or component 1 results, which differs from the deformation in the FE mesh FE-N.sub.1. In so far as the shape alteration u is greater than a tolerance value ε, i.e. u>ε, the stress tensor is to be changed.

(12) From step e) therefore, as FIG. 1 shows, an iteration step Z firstly leads to the step d), in order to repeat the equilibrium calculation R, wherein a new stress state (stress tensor S.sub.2) is applied to the FE mesh geometry FE-N.sub.2 of the construction system or component 1 and, in so doing, stress components which lead to undesired shape alterations u, are reduced. Subsequently, the iteration loop leads back to step e).

(13) If a state of undesired shape alterations u>ε (display YES) continues to result from the equilibrium calculation R in step e), then the loop is run through iteratively several times, so that an iterative repetition of the equilibrium calculation R takes place according to step d) as a cyclic equilibrium iteration with stress tensors S.sub.3, S.sub.4, . . . , S.sub.n in the FE mesh geometry FE-N.sub.2 (in the new target FE mesh) of the construction system or component 1.

(14) In each cycle, therefore, a respectively new stress state (stress tensor S.sub.2, S.sub.3, S.sub.4, . . . , S.sub.n) is applied to the new FE mesh geometry FE-N.sub.2 of the construction system or component 1. At the same time, stress components which lead to undesired shape alterations u are further decreased until in step e) a displacement/termination criterion of shape alteration u<tolerance value ε is achieved and the latter is displayed in the subsequent step f).

(15) The displacement/termination criterion signals a stress state (stress tensor S.sub.n) in which stress components which lead to undesired shape alterations in the FE mesh geometry FE-N.sub.2 of the simulated construction system or component 1 associated with the second production operation are decreased.

(16) FIG. 2 shows a block diagram corresponding to FIG. 1, wherein, however, advantageous further developments of the method according to FIG. 1 are illustrated diagrammatically.

(17) Thus, as FIG. 2 illustrates, after the displaying of the displacement/termination criterion of shape alteration u<tolerance value ε in step f), the provision of a second data set D.sub.2 can take place in a step g), which describes the stress state (stress tensor S.sub.n) of the FE mesh geometry FE-N.sub.2 of the last repetition of the equilibrium calculation in step d), as a result of which the displacement criterion/termination criterion of shape alteration u<tolerance ε is achieved in step f).

(18) As FIG. 2 shows, advantageously a step h), in which a simulated blank of the construction system or component is determined on the basis of the second data set D.sub.2, and furthermore a step i) can be provided, in which a simulated forming of the simulated blank of the construction system or component 1 takes place.

(19) Furthermore, a step j) can be provided, in which a real production of a real blank, corresponding to the simulated blank, for the production of the construction system or component 1 takes place in the second production operation.

(20) FIG. 3 is a diagrammatic figure illustration of the stress transfer (enhanced stress mapping) without undesired shape alteration according to steps d) to f) and of the loop z for the iterative repetition of the equilibrium calculation R in the method sequence according to FIG. 1. Thus, FIG. 3 shows, bottom left, the simulated component 1 in step d) at the stage of the transferred stress state S.sub.1. A deformation and recovery has been previously simulated, wherein an equilibrium calculation has taken place iteratively in the starting FE mesh FE-N.sub.1.

(21) This results in the state of the component 1, illustrated bottom right in FIG. 3, in step e) with undesired shape alteration u>tolerance value ε as a result of the disequilibrium of the stress state, illustrated with 10-times exaggeration. After multiple running through of the loop z, symbolized by the arrows 2, 3 and 4, for the iterative repetition of the equilibrium calculation R and the gradual decreasing of stress components which lead to undesired shape alterations u in the FE mesh geometry FE-N.sub.2 of the component 1 (update of the stress state), the displacement/termination criterion of shape alteration u<tolerance value ε is reached, as can be seen from the square in the loop z top right in FIG. 3, and the fulfilling of this condition is displayed in step f).

(22) In FIG. 4, the stress transfer (enhanced stress mapping) by means of steps c) to f) of the method according to FIG. 1 is illustrated diagrammatically in detail.

(23) Here, the rectangle shown top left in FIG. 4, which symbolizes finite elements 7 in a closed tool forming these, embodies step c) of the method according to FIG. 1, in which the transfer of the stress state (stress tensor S.sub.1) of the first data set D.sub.1, provided in step a), to the new FE mesh geometry FE-N.sub.2, created in step b), of the construction system or component 1 takes place, wherein a disequilibrium of the transferred compressive stresses, symbolized by plus signs, and of the transferred tensile stress, symbolized by minus signs, is given.

(24) As is indicated by the arrow 5, subsequently in step d) of the method the carrying out of the equilibrium calculation R takes place by using the stress tensor S.sub.1 in the FE mesh geometry FE-N.sub.2 of step c), which in the step e) illustrated bottom left in FIG. 4 produces a shape alteration of the construction system or component 1, which differs from the shape alteration in the FE mesh FE-N.sub.1 in step a) by an undesired shape alteration of u>tolerance value ε as a result of the disequilibrium.

(25) By means of a loop, which is symbolized by the arrow z and comprises steps d) and e), subsequently, as shown top right in FIG. 4, a change (update) of the stress state takes place through iterative repetition of the equilibrium calculation R in step d) as a cyclic equilibrium iteration in the FE mesh geometry FE-N.sub.2 of the construction system or component 1, wherein in each cycle a respectively new stress state (stress tensor S.sub.3, S.sub.4, . . . S.sub.n) is applied to the new FE mesh geometry FE-N.sub.2 of the construction system or component 1, and stress components which lead to undesired shape alterations u are decreased until the required condition, i.e. the displacement/termination criterion of u<tolerance value ε is achieved and is displayed in step f), as can be seen from FIG. 4 bottom right.

(26) As is illustrated in FIG. 4, the stress tensor can be altered iteratively until the shape alteration u, which is caused by the transfer of the stress tensor S.sub.1 from the starting FE mesh FE-N.sub.1 into the target FE mesh FE-N.sub.2 falls below a predetermined tolerance value ε. The deformation of the construction system or component 1 with the stress tensor S in the target FE mesh FE-N.sub.2 corresponds substantially to the deformation of the construction system or component 1 with the stress tensor S.sub.n in the starting FE mesh FE-N.sub.1.

(27) It shall be understood that the embodiments of the present invention are not restricted to the specific structures, method steps or materials which are disclosed here, but rather can be extended to their equivalents, as is recognizable by an average specialist in the relevant fields.

(28) In addition, it shall be understood that the terminology which is used here is used solely for describing particular embodiments and is not to be construed as restrictive. The described features, structures or characteristics can be combined in any suitable manner in one or more embodiments.

LIST OF REFERENCE NUMBERS

(29) 1 construction system, component 2 arrow 3 arrow 4 arrow 5 arrow 6 arrow 7 finite elements a step b step c step d step e step f step g step h step i step j step z iteration loop D.sub.1 first data set D.sub.2 second data set FE-N.sub.1 FE mesh according to step a) FE-N.sub.2 FE mesh geometry, created in step c) R equilibrium calculation S.sub.1, S.sub.2, S.sub.3, S.sub.4 . . . S.sub.n stress tensor u shape alteration ε tolerance value