CN100561490C - Assembly soldering plate welded seam finite element modeling method based on vehicle collision simulation - Google Patents

Abstract

A kind of automobile computer aided design techniques field build assembly soldering plate welded seam finite element modeling method based on vehicle collision simulation, may further comprise the steps: the first step, foundation plate modeling comprise foundation plate hard spot layout, foundation plate grid dividing, the translation of foundation plate grid; Second step, the modelling of double-deck beam weld seam comprise that space nodes is arranged, double-deck beam is made, beam is connected with foundation plate; The attribute assignment of the 3rd step, double-deck beam element comprises beam element material properties assignment, beam element cross section attribute assignment; The 4th goes on foot, the welding plate welding seams model of being set up is moved into together with the foundation plate grid model collide limited element calculation model.The present invention had not only considered the material properties of weld seam but also had considered the shape of weld seam, can accurately simulate the deformational behavior in collision simulation of weld seam, improved the vehicle collision simulation precision, and fast effectively, was convenient to the technician and grasps.

Description

Assembly soldering plate welded seam finite element modeling method based on vehicle collision simulation

Technical field

What the present invention relates to is the method in a kind of automobile computer aided design techniques field, particularly a kind of assembly soldering plate welded seam finite element modeling method based on vehicle collision simulation.

Background technology

The welding plate technique was risen the nineties in last century, was that the steel with several varying strengths, different-thickness are welded into an integral slab, to satisfy the different requirements of parts to material property.The welding plate technique is used on a large amount of medium-to-high grade cars at present, as POLO, and BUICK, MAZDA, CADILLAC or the like.The crashworthiness performance that obtains automobile for the starting stage in design is to satisfy more and more stricter national legislation, automobile computer Aided Design (CAE) technology is extensively applied to the evaluation of vehicle collision resistant energy, and it not only reduces experimentation cost but also can reduce the design cycle.For accurate simulation welding plate in car crass dynamic behavior so that obtain accurate believable simulation result, the modeling technique of welding plate welding seams model is very crucial, because it can have influence on the transmission of impact force in welding plate part and the distortion of welding slab integral.

Yet up to the present, but there are not scientific research personnel or technician that the analogy method of the welding plate welding seams in the car crass finite element simulation is studied.Even existing weld seam finite element model, also all set up at welding plate stamping and forming emulation, these weld seam models can be divided into two big classes basically, and a class is to have ignored the weld seam finite element model of weld material attribute and geometric configuration, comprise node and the model that is rigidly connected; Another kind of then is the weld seam finite element model of considering the weld seam type, comprises beam element model, shell unit model and solid element model.The maximum difference in stamping forming simulation and vehicle collision simulation of welding plate model of element is: in the stamping forming simulation, motherboard can disperse with arbitrarily small grid; And for vehicle collision simulation, consider and resolve efficiency that the minimum size of mesh opening of motherboard is generally 5mm, meanwhile, weld width generally only is about 1.5mm.During the weld seam mechanical behavior of above-mentioned model in simulated automotive collision, though the node and the counting yield height that is rigidly connected have been ignored weld material attribute and geometric configuration; Beam element can not be expressed the shape of weld seam; Shell unit only is suitable for the equal thickness plate; Though solid element is accurate, requires all solid modellings of two motherboards, the modeling process complexity, counting yield is low.If adopt shell unit or solid element,, can cause quality to increase excessive and out of true because the car crass finite element simulation generally all adopts quality convergent-divergent means; The grid length breadth ratio is too high to cause emulation to resolve instability owing to the narrow meeting of weld seam causes.Therefore, also there is not suitable weld seam model to be applicable to welding plate welding seams simulation in the vehicle collision simulation.

Through new, there be not the report of discovery to the welding plate welding seams modeling method in the vehicle collision simulation to looking into of prior art.

Summary of the invention

The objective of the invention is at the deficiencies in the prior art, a kind of assembly soldering plate welded seam finite element modeling method based on vehicle collision simulation is provided, the shape that makes it not only consider the material properties of weld seam but also consider weld seam, can accurately simulate the deformational behavior in collision simulation of weld seam, improve the vehicle collision simulation precision, and fast effectively, being convenient to the technician grasps.

The present invention is achieved by the following technical solutions, may further comprise the steps:

The first step, foundation plate modeling

A. the foundation plate hard spot is arranged: utilize the geometric manipulations module evenly to arrange hard spot at two foundation plates boundary that links to each other with weld seam, can make the link to each other foundation plate grid node correspondence one by one of boundary of weld seam like this.

Described hard spot is meant the point of arranging on geometrical line, these will be as the node of grid cell in Mesh Processing.

B. foundation plate grid dividing: use the grid dividing module that two foundation plates are carried out grid dividing.

C. foundation plate grid translation: wherein a foundation plate grid is motionless in maintenance, and another piece foundation plate grid of translation makes the central plane position of welding plate be consistent with actual.

Described welding plate is actually by the foundation plate more than two or two to be formed, and the foundation plate of indication is the sheet material that links to each other at a certain weld seam here.

Described geometric manipulations module, grid dividing module all can adopt existing techniques in realizing such as pre-processing software, such as commercially available HYPERMESH or ANSA.

Second step, the modelling of double-deck beam weld seam

A. space nodes is arranged: arrange two space nodes up and down in each hard spot position, by the accurate layout of space nodes, can accurately simulate the shape of weld seam;

B. double-deck beam is made: along bead direction two emptying intermediate node of two foundation plate upper and lowers are reduced beam (a kind of beam element form based on the 8 node solid elements of having degenerated) with Huges-liu and connect one by one, form beam element structure between two emptyings;

C. beam is connected with foundation plate: unit (Nodal-Rigid-Body) constrains in hard spot place node and the double-deck girder connection of being set up with being rigidly connected.

The attribute assignment of the 3rd step, double-deck beam element

A. beam element material properties assignment: welding plate welding seams material carries out assignment with isotropy and the irrelevant Ludwick-Hollomon material model (power exponent plastic material model) of rate to the double-deck beam element of built, and makes the weld seam cast material consistent with the actual welds material;

B. beam element cross section attribute assignment: according to size formula the double-deck beam element of build cross section attribute is carried out the parameter assignment, make weld seam and actual conditions have identical cross-sectional area, and then have the intensity identical with actual conditions.

The 4th goes on foot, the welding plate welding seams model of being set up is moved into together with the foundation plate grid model collide limited element calculation model, and double-deck beam element provides quick, correct weld seam finite element model.Resolve the emulation of program by finite element, finally can obtain correct welding plate part deformation pattern, and then car assisted structural design personnel rapidly, the crashworthiness performance of assessment welding plate part exactly, provide reliable cae analysis support for the further optimization of welding plate part improves.

The present invention has the following advantages: 1, modeling process is simple.After having set up the foundation plate grid model, only need carry out simple node layout, unit connection and attribute assignment, and parameter modification is easy.2, can correctly simulate dynamic behavior and the deformation pattern of weld seam under percussive action.Because the weld seam model generalization of setting up has been considered welds geometry and material properties, therefore can correctly simulate the dynamic behavior of weld seam in the impact process, and, make the deformation pattern of welding plate consistent with truth owing to the noncontinuity of having considered between the foundation plate.3, the efficient height is resolved in emulation.Double-deck beam weld seam model is made up of the Huges-liu beam and the unit that is rigidly connected, and these unit all have the very high efficient of resolving, and therefore do not increase substantially and resolve cost.4, emulation is resolved stable.The beam element of forming double-deck beam weld seam model has very high emulation and resolves stability, and the exit point that often occurs in shell unit and solid element, negative volume etc. resolves wild effect and can not occur in double-deck beam model.

Description of drawings

Fig. 1 is the inventive method process flow diagram

Fig. 2 is hat welding plate test specimen pictorial diagram

Fig. 3 arranges synoptic diagram for hard spot

Fig. 4 is the grid cell synoptic diagram

Fig. 5 is the cross sectional representation of welding plate

Fig. 6 is welding plate hat weir lattice model

Fig. 7 is double-deck beam element weld seam analogy method synoptic diagram

Fig. 8 is double-deck beam finite element model

Fig. 9 is the local coordinate system of beam element

Figure 10 is the deformation pattern comparison diagram of simulation result and test findings, and wherein: figure a is that conode weld seam model, b are that double-deck beam weld seam model, d are test findings for the weld seam model that is rigidly connected, c.

Embodiment

Below in conjunction with accompanying drawing embodiments of the invention are elaborated: present embodiment is being to implement under the prerequisite with the technical solution of the present invention, provided detailed embodiment and concrete operating process, but protection scope of the present invention is not limited to following embodiment.

Following examples are to implement according to flow process as shown in Figure 1, under the situation that the welding plate hat straight beam that simulation is made up of three sections foundation plates (foundation plate 1, foundation plate 2, foundation plate 3) is at one end fixed, it is dropping hammer with the initial velocity bump of 42km/h of 293.3kg that vertical direction is subjected to weight, hat beam length overall is 1000mm, be slit into the welding plate motherboard that thickness is respectively 0.7mm, 1.8mm and 1.2mm by two weld seams (weld seam 1, weld seam 2) average mark, sectional dimension is 100 * 75mm ², the test specimen material object as shown in Figure 2.Specific as follows:

1, foundation plate modeling

A. the foundation plate hard spot is arranged: utilize the geometric manipulations module evenly to arrange hard spot at the foundation plate boundary that links to each other with weld seam, this module is to adopt ALTAIR company specialty pre-processing software HYPERMESH (can directly buy from market) to realize, the hard spot spacing is consistent with the unit grid size of regulation, and the mode by mapping makes two hard spots on the foundation plate corresponding one by one, and the hard spot that Fig. 3 shows when being geometric manipulations is arranged synoptic diagram;

B. foundation plate grid dividing: use the grid dividing function of software HYPERMESH that two foundation plates are carried out grid dividing, the hard spot place arranges node, the grid that closes on welded seam area must keep vertical with bead direction, stress is correctly transmitted by the weld seam unit in computation process, and Fig. 4 is the grid cell synoptic diagram around the weld seam;

C. foundation plate grid translation: wherein a foundation plate grid is motionless in maintenance, utilizes another piece foundation plate grid of offset function translation, and the central plane position of welding plate is consistent with actual, and displacement is (t ₂-t ₁)/2, t ₁And t ₂Be respectively the thickness (see figure 5) of thin foundation plate and thick foundation plate.

Because three foundation plate thicknesss of slab are respectively 0.7mm, 1.8mm and 1.2mm in this example, therefore keep the thickest foundation plate motionless, other two foundation plates are moved respectively:

$d_1=\frac{1.8-0.7}{2}=0.55\mathrm{mm}$ With $d_2=\frac{1.8-1.2}{2}=0.3\mathrm{mm}$

The hat welding plate straight beam grid model of finally handling well as shown in Figure 6.

2, double-deck beam weld seam modelling

A. space nodes is arranged: arrange two space nodes up and down at each hard spot, these nodes will be as the end points on the beam element.Keep beam 1 parallel, make beam 2 press close to the upper surface (see figure 7) of weld seam simultaneously, suppose that thickness compares t with the foundation plate unit ₂: t ₁Be no more than 3, the vertical range of node and foundation plate central plane is:

$h_i=\left\{\begin{array}{cc}\frac{{3t}_1-t_2}{8},& i=\mathrm{1,3}\\ \frac{{3t}_2-t_1}{8},& i=\mathrm{2,4}\end{array}\right.$

H in the formula _iThe vertical range on (i=1,3) expression node i and thin basis, h _i(i=2,4) then are the vertical ranges of node i and thick motherboard.Bring known parameters into above-mentioned formula, can obtain (see figure 2) space nodes position, weld seam 1 place:

$h_1^1=h_3^1=0.5875\mathrm{mm}$ With $h_2^1=h_4^1=0.0375\mathrm{mm}$

And the space nodes position at weld seam 2 places:

$h_1^2=h_3^2=0.5250\mathrm{mm}$ With $h_2^2=h_4^2=0.2250\mathrm{mm}$

By the accurate layout of space nodes, can accurately simulate the shape of weld seam;

B. double-deck beam is made: along bead direction two emptying intermediate node of two foundation plate upper and lowers are reduced beam with Huges-liu and connect one by one, form beam element structure between two emptyings;

C. beam is connected with foundation plate: with the unit that is rigidly connected hard spot place node and the double-deck beam element joint constraint of being set up are in the same place, the weld seam model is combined together with the foundation plate model, the double-deck beam weld seam model of formation as shown in Figure 8.

3, the attribute assignment of double-deck beam element

A. beam element material properties assignment: welding plate welding seams material is with isotropy and the irrelevant Ludwick-Hollomon material model of rate, and promptly No. 18 material * MAT_POWER-LAW_PLASTICITY among the LS/DYNA carry out assignment:

σ＝Kε ⁿ

In the formula, σ is a true stress, and ε is logarithmic strain, and K and n are respectively strength factor and strain hardening exponent, and mode obtains by experiment, and K value and n value in this example are respectively 1165MPa and 0.1154;

B. beam element cross section attribute assignment: according to size formula beam element cross section attribute is carried out the parameter assignment, size formula is:

$t_{\mathrm{si}}=\frac{t_1+t_2}{4},i=\mathrm{1,2}$

$t_{\mathrm{ti}}=\frac{L}{N},i=\mathrm{1,2}$

T in the formula _SiAnd t _TiBe illustrated respectively in the thickness (see figure 9) of s direction and t direction upper beam i; L is a fusion length, and N is the number of the adjacent side shell unit of weld seam.Finally make weld seam and actual conditions have the identical materials volume, and then have the intensity identical with actual conditions.

Bring the parameter in this example into beam element thickness that above-mentioned size formula can obtain weld seam 1 place:

$t_{s1}^1=t_{s2}^1=0.625\mathrm{mm}$ With $t_{t1}^1=t_{t2}^1=5\mathrm{mm}$

And the beam element thickness at weld seam 2 places:

$t_{s1}^2=t_{s2}^2=0.750\mathrm{mm}$ With $t_{t1}^2=t_{t2}^2=5\mathrm{mm}$

4, the welding plate welding seams model of being set up is moved into the collision limited element calculation model together with the foundation plate grid model, simultaneously, for good contrast simulation result, having introduced the most frequently used in vehicle collision simulation at present in this example also is that the unique conode unit that can use and the unit that is rigidly connected carry out the emulation contrast as the weld seam model.By the emulation that commercial finite element is resolved program LS/DYNA (for prior art, can be directly commercial), finally can obtain the deformation result of hat welding plate straight beam, and itself and test findings are compared (see figure 10).Because complete conquassation takes place foundation plate 1, foundation plate 2 does not deform substantially, and therefore main difference is the deformation pattern of foundation plate 3.From the result, can find to adopt double-deck beam element being subjected to impacting its deformation pattern of back and test findings basically identical as the welding plate straight beam of weld seam model, comparatively speaking, adopt the deformation pattern and the test findings of the conode weld seam model and the weld seam model that is rigidly connected that bigger difference is arranged.

Because deformation pattern is that auto parts the most key and direct emulation in vehicle collision simulation fits the effect criterion, therefore, double-deck as can be seen beam element provides quick, correct weld seam finite element model, and then can car assisted structural design personnel assess the crashworthiness performance of welding the plate part rapidly, exactly, for improving, the further optimization of welding the plate part provides reliable cae analysis support.

Claims (3)

1, a kind of assembly soldering plate welded seam finite element modeling method based on vehicle collision simulation is characterized in that, may further comprise the steps:

The first step, foundation plate modeling

A. the foundation plate hard spot is arranged: utilize the geometric manipulations module evenly to arrange hard spot at two foundation plates boundary that links to each other with weld seam, make the link to each other foundation plate grid node correspondence one by one of boundary of weld seam;

B. foundation plate grid dividing: use the grid dividing module that two foundation plates are carried out grid dividing;

C. foundation plate grid translation: wherein a foundation plate grid is motionless in maintenance, and another piece foundation plate grid of translation makes the central plane position of welding plate be consistent with actual;

Described geometric manipulations module, grid dividing module all adopt pre-processing software to realize;

Second step, the modelling of double-deck beam weld seam

A. space nodes is arranged: arrange two space nodes up and down in each hard spot position, simulate the shape of weld seam by the accurate layout of space nodes;

B. double-deck beam is made: along bead direction two emptying intermediate node of two foundation plate upper and lowers are reduced beam with Huges-liu and connect one by one, form beam element structure between two emptyings;

C. beam is connected with foundation plate: the unit constrains in hard spot place node and the double-deck girder connection of being set up with being rigidly connected;

The attribute assignment of the 3rd step, double-deck beam element

A. beam element material properties assignment: welding plate welding seams material carries out assignment with isotropy and the irrelevant power exponent plastic material model of rate to the double-deck beam element of built, and makes the weld seam cast material consistent with the actual welds material;

B. beam element cross section attribute assignment: according to size formula the double-deck beam element of build cross section attribute is carried out the parameter assignment, make weld seam and actual conditions have identical cross-sectional area, and then have the intensity identical with actual conditions;

The 4th goes on foot, the welding plate welding seams model of being set up is moved into together with the foundation plate grid model collide limited element calculation model, by the emulation that finite element is resolved program, finally obtains correct welding plate part deformation pattern;

The irrelevant power exponent plastic material model of described isotropy and rate is the Ludwick-Hollomon material model, and promptly No. 18 material * MAT_POWER-LAW_PLASTICITY among the LS/DYNA carry out assignment:

σ＝Kε ⁿ

In the formula, σ is a true stress, and ε is logarithmic strain, and K and n are respectively strength factor and strain hardening exponent;

Described size formula is

$t_{\mathrm{si}}=\frac{t_1+t_2}{4},i=\mathrm{1,2}$

$t_{\mathrm{ti}}=\frac{L}{N},i=\mathrm{1,2}$

T in the formula _SiAnd t _TiBe illustrated respectively in the thickness of s direction and t direction upper beam i; L is a fusion length, and N is the number of the adjacent side shell unit of weld seam.

2, the assembly soldering plate welded seam finite element modeling method based on vehicle collision simulation according to claim 1 is characterized in that, described hard spot is meant the point of arranging on geometrical line, and these will be as the node of grid cell in Mesh Processing.

3, the assembly soldering plate welded seam finite element modeling method based on vehicle collision simulation according to claim 1, it is characterized in that, described welding plate is made up of the foundation plate more than two or two, and the foundation plate of indication is the sheet material that links to each other at a certain weld seam here.

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