CN101261653A - Simulation system for spot welding invalidity number value - Google Patents

Abstract

The invention relates to a spot-welding connection failure value simulation system in the car bodywork manufacturing engineering field. In the invention, a circle-stress failure criterion generating module obtains nugget circle stress distribution form according to the failure mode of the spot-welding connection in a strike process to generate the circle stress failure criterion; a failure extreme value stress and an index-parameter obtaining module obtain welding-spot critical failure stress extreme values and dimensionless stress sub-item index initial values under the condition of the peak values of four exterior loads; four types of sample value models which are pulling-cutting, pulling-extending, pulling-bending and pulling-twisting are established in a welding-spot connection value simulation module; an explicit dynamics analysis module couples circle stress failure criteria and obtains the continuous distributed inner stress of a welding-spot unit model and an extreme value stress borne by the welding-spot unit during failure time by simulation; a welding-spot failure material databank module stores the critical failure stress extreme values and the dimensionless stress sub-item index initial values of each stress component. The system not only can enhance the impact simulation precision without impact on the calculation efficiency, but also can reduce the design and exploitation cost.

Description

Simulation system for spot welding invalidity number value

Technical field

What the present invention relates to is the computer aided system in a kind of AE field, specifically is a kind of simulation system for spot welding invalidity number value.

Background technology

Resistance spot welding is one of assembling connected mode basic in the Hyundai Motor industry, body structure mainly is formed by connecting by solder joint by drawing quality steel sheet, comprise the solder joint about 4000-7000 in typical case's body structure, the weldering nuclear diameter is to be determined by the thin plate thickness of slab that is connected with spot pitch, usually the weldering nuclear diameter is between 3-7mm, and average is generally 6mm.In to the research of car crass attribute testing, find, the inefficacy of connected mode is very big to the test evaluation parameter influence, solder joint failure will influence the collision energy-absorbing characteristic and the mode of texturing of body construction to a certain extent, therefore how modeling and to select for use rational failure criteria to come this failure behaviour of real embodiment be one of engineering software development company and Automobile Design research and development department focus always in simulation analysis of computer.

Extensive CAE (computer-aided engineering analysis) technology is used and is started from early 1990s in the engineering, the analogue simulation of connected modes such as butt welding point is development thereupon also, and the simulation of Chinese scholars butt welding point mainly comprises following form: node coupling, bar, beam, spring, entity etc.The simulation of butt welding point considers that convenient and practicality mainly adopts beam element and solid element in the vehicle collision simulation analysis, and has developed the group of entities model in 2006.Solder joint failure in the impact process is very big to malformation and energy absorption influence, the solder joint model must cooperate accurately this failure procedure of simulation of rational failure criteria in the simulation analysis, and influence the subsequent calculations result, therefore the mechanical mechanism of Chinese scholars butt welding point inefficacy has carried out broad research, and it is integrated in the commercial finite element program, what be most widely used is the stress failures criterion of power failure criteria and Toyota Company's exploitation.

Find by prior art documents, " based on the spot welding annexation finite element analogy method of vehicle collision simulation " that Shi Yuliang etc. delivered on " mechanical engineering journal " 2007 the 43rd the 7th phases of volume utilizes the elastoplasticity beam element that simple test specimen has been carried out simulation analysis, and the robustness of analysis result is studied.This simulation process is mainly based on the power failure criteria of Particle Mechanics, can obtain rational simulation result to the destruction of the solder joint under static state and the quasistatic condition, but the solder joint failure emulation in the impact process, because such failure criteria is not considered the true geometric form of solder joint and material properties thereby is had certain defective, in the vehicle impact simulation process of variable Rate, can't consider the invigoration effect of strain rate effect butt welding point ultimate failure load, therefore the inefficacy critical value of solder joint can't be judged in the simulation process flexibly, in the analysis of car load level, the error of calculation largely can be brought.

Summary of the invention

The objective of the invention is at above-mentioned the deficiencies in the prior art, a kind of simulation system for spot welding invalidity number value has been proposed, concrete form according to solder joint failure, the stress failures criterion that a kind of circumference lost efficacy is proposed, utilize typical sample verification experimental verification and finite element method to resolve, obtain the failure criteria call parameter, impact the fracture failure behavior of judging solder joint portion in the simulation process more accurately at car load or component-level, improve the precision of whole Simulation Calculation, for vehicle early development design provides safeguard.

The present invention is achieved by the following technical solutions, the present invention includes: module, solder joint failure material base module are analysed in hoop stress failure criteria generation module, inefficacy extremum stress and index parameters acquisition module, solder joint connected mode numerical simulation module, explicit dynamical credit, wherein:

Hoop stress failure criteria generation module is connected the failure mode that the weldering nuclear circumference in the impact process is torn according to spot welding, cut in conjunction with drawing, stretching, stretch bending, draw the mechanical analysis of turning round combination stressed mode, obtain weldering nuclear hoop stress distribution form, generate the hoop stress failure criteria, and transfer to the explicit dynamical credit and analyse module;

Inefficacy extremum stress and index parameters obtain that module is cut by drawing, stretching, stretch bending, draw and turn round four kinds of load modes and test, acquisition is solder joint borderline failure maximum stress and dimensionless stress subitem index initial value under the peak value condition of four kinds of external applied loads, and transfers to the explicit dynamical credit and analyse module and solder joint failure material base module;

Solder joint connected mode numerical simulation module, it is in the simulation modeling process, the solder joint numerical model is selected entity (group) type solder joint unit, be based upon two-layer or the multilayered shell unit in the middle of, the metal sheet that the shell unit simulation connects, the true geometric form of simulating solder joint is set up to draw and is cut, stretching, stretch bending, draws to turn round four kinds of sample numerical models and transfer to the explicit dynamical credit and analyse module;

It is the calculating execution module that spot welding connects the inefficacy numerical simulation that module is analysed in the explicit dynamical credit, coupling hoop stress failure criteria, and according to inefficacy extremum stress, solder joint numerical model, realize that spot welding connects the numerical simulation process that lost efficacy, the extremum stress that emulation obtains the internal stress of solder joint model of element continuous distribution under the effect of carrying of various sample model outward and the moment solder joint unit that lost efficacy bears, and resulting simulation result is transferred to solder joint failure material base module, the spot welding in the analog physical process connects failure mode;

After solder joint failure material base module is analysed the explicit dynamical credit simulation result that module obtains and specimen test result and is analyzed, whether borderline failure maximum stress and the dimensionless stress subitem index initial value of judging each components of stress be reasonable, if satisfy the specimen test result, then above-mentioned parameter is stored in the solder joint failure material knowledge base, as not satisfying, adjust the parameter initial value and make simulation result satisfy test findings.

Described hoop stress failure criteria generation module comprises: hoop stress is determined submodule, criterion generation module, wherein:

Hoop stress determines that submodule connects the failure mode that the weldering nuclear circumference of metal plate parts in impact process torn according to spot welding, determine that weldering nuclear structure force way is to draw to cut, stretching, stretch bending, draw the combination of turning round to express, and obtains three kinds of solder joint hoop stress: radial stress σ according to various concrete stressed types _r, axial shear stress τ _z, circumferential shear stress τ _θ, and set up external force load and the relation between it respectively;

Three solder joint hoop stresses of criterion generation module coupling, and set up the hoop stress failure criteria with the dimensionless form, its formula of failure criteria is as follows:

${\left(\frac{{\mathrm{\σ}}_r\stackrel{\·}{\left({\mathrm{\ϵ}}_{\mathrm{eff}}^p\right)}}{{\mathrm{\σ}}_r^F\stackrel{\·}{\left({\mathrm{\ϵ}}_{\mathrm{eff}}^p\right)}}\right)}^{\mathrm{\ξ}}+{\left(\frac{{\mathrm{\τ}}_z\stackrel{\·}{\left({\mathrm{\ϵ}}_{\mathrm{eff}}^p\right)}}{{\mathrm{\τ}}_z^F\stackrel{\·}{\left({\mathrm{\ϵ}}_{\mathrm{eff}}^p\right)}}\right)}^{\mathrm{\ψ}}+{\left(\frac{{\mathrm{\τ}}_{\mathrm{\θ}}\stackrel{\·}{\left({\mathrm{\ϵ}}_{\mathrm{eff}}^p\right)}}{{\mathrm{\τ}}_{\mathrm{\θ}}^F\stackrel{\·}{\left({\mathrm{\ϵ}}_{\mathrm{eff}}^p\right)}}\right)}^{\mathrm{\ζ}}\≥1$

In the formula,

Be effective plastic strain rate that solder joint element integral point place is calculated, each stress σ _r, τ _z, τ _θThe function of all representing effective plastic strain rate, σ _r ^F, τ _z ^F, τ _θ ^FBe the borderline failure extremum stress (can be described as the relevant functional form of rate of strain in the high speed impact process) of each stress correspondence, ξ, ψ, ζ are the index parameters of each corresponding dimensionless stress subitem;

Described radial stress σ _r, its only with spot-welded structures draw the mode of cutting relevant, be used for the prediction draw cut the effect the following stress pattern;

Described axial shear stress τ _z, it is only relevant with stretching and two kinds of force way of stretch bending of spot-welded structures, is used to predict the weldering nuclear hoop stress distribution form under stretching and the stretch bending loading;

Described circumferential shear stress τ _θ, it only draws the mode of turning round relevant with spot-welded structures, is used to predict draw the stress pattern of turning round under the loading.

Described inefficacy extremum stress and index parameters obtain module, comprising: the inefficacy extremum stress obtains module, the inefficacy index parameters obtains module, wherein:

The inefficacy extremum stress obtains module, it is cut in sample, tensile sample and stretch bending sample, the single spot welding torsional specimen failure procedure drawing, write down the curve of each load and displacement, when load was in peak value, extreme value, the axial shear stress τ of circle distribution weldering nuclear of circle distribution radial stress constantly obtained losing efficacy _zExtreme value, the circumferential shear stress τ of circle distribution _θExtreme value;

The inefficacy index parameters obtains module, and according to the failure criteria equation, the dimensionless combination approximation of each lost efficacy stress and the ratio of corresponding maximum stress is the triaxial ellipsoid face, determines that each dimensionless stress subitem index ξ, ψ, ζ value are 2.

Described solder joint connected mode numerical simulation module, its selected solder joint cell node needn't directly be connected with the shell unit node, thereby can not cause the shape distortion of solder joint unit or increase the division difficulty of shell unit grid, be connected by the way of contact of Tie (bonding) type between solder joint unit and the shell unit.

Module is analysed in described explicit dynamical credit, it is the calculating execution module that spot welding connects the inefficacy numerical simulation, coupling hoop stress failure criteria is as the part of welding material model, selection is applicable to the elastic-plastic constitutive relation that metal material is described, and ensures that the solder joint model lost efficacy with reasonable failure mode in the follow-up simulation process; Obtain the sample numerical model set up in the data of module and the solder joint connected mode numerical simulation module according to inefficacy extremum stress and index parameters, in the computational analysis, calculate the stress value at solder joint element integral point place, by the borderline failure extremum stress comparison definite with experiment, after satisfying the hoop stress failure criteria, the solder joint connected mode lost efficacy, and the solder joint unit is deleted from the sample numerical model.

Described solder joint failure material base module, failure behaviour under different thicknesss of slab of different materials and the load form is verified, initial setting realistic model solder joint failure extremum stress and failure mode, if simulation result and test findings exist than mistake, in the 0-10% scope, adjust the parameter initial value, make simulation result satisfy test findings, and write down adjusted parameter value, be stored in the solder joint failure material knowledge base, final each parameter value that obtains deposits in the solder joint failure material knowledge base, uses for car load level or component-level simulation process.

When the present invention works, as should be in impact process, solder joint failure concentrates on supporting region, non-bearing district solder joint does not have failure phenomenon, therefore be the needs of EQUILIBRIUM CALCULATION FOR PROCESS efficient and computational accuracy, in the car load level collision impact simulation process, can adopt traditional beam type solder joint unit, save computing time in the non-bearing district; At supporting region, particularly the large deformation district adopts aforementioned entity or group of entities type solder joint unit, adopts distortion of solder joint hoop stress failure criteria simulating solder joint and failure behaviour simultaneously, guarantees simulation precision to greatest extent, and realistic design needs.And set up the solder joint numerical model by solder joint connected mode analog module, utilize the explicit dynamical credit to analyse module and carry out computational analysis, call borderline failure maximum stress and the dimensionless stress subitem index confirmed in the solder joint failure material base module in this process, cooperate the hoop stress failure criteria to differentiate spot welding and connect failure behaviour, improve and impact simulation accuracy.

Compared with prior art, the present invention has following beneficial effect: (1) solder joint hoop stress failure criteria is according to the considered repealed form of solder joint, take all factors into consideration solder joint failure stress distribution constantly under the multiple loading, the more destruction of real simulated solder joint; (2) this criterion is applicable to the typical solder joint unit form of existing software, can pass through the material model expansion module of calculation procedure, integrated with software, the convenient use, simulation result can improve the simulation accuracy about 20% of solder joint model near the mechanical behavior of actual physics model machine; (3) each parameter is determined conveniently in this criterion, cut by simply drawing, stretching, stretch bending, draw and turn round sample and can obtain relevant parameter, be convenient in the commercial production realize, and revise after the simulation analysis result comparison, can enter welding material inefficacy knowledge base, for the numerical modeling analysis provides technique guarantee; (4) this criterion and novel entity (group) solder joint unit are connected the inefficacy method for numerical simulation in conjunction with the spot welding that constitutes and can be used in flexibly in the Hyundai Motor industrial impact simulation analysis, do not reduce counting yield when improving simulation accuracy, reduce and design and develop cost, can in the design analysis process, widely use, in order to improve the precision of complete vehicle structure collision simulation, increase the design possibility of success, for enterprise brings more economic benefit.

Description of drawings

Fig. 1 is a system architecture diagram of the present invention;

Fig. 2 is weldering nuclear geometric format and hoop stress synoptic diagram;

Fig. 3 tests synoptic diagram and stress prediction distribution plan for drawing the mode of cutting;

Fig. 4 is stretching mode experiment synoptic diagram and stress prediction distribution plan;

Fig. 5 tests synoptic diagram and stress prediction distribution plan for the stretch bending mode;

Fig. 6 tests synoptic diagram and stress prediction distribution plan for drawing the mode of turning round;

Fig. 7 is solid element and shell unit connected mode;

Fig. 8 is three types group of entities solder joint unit.

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.

As shown in Figure 1, present embodiment comprises: module, solder joint failure material base module are analysed in hoop stress failure criteria generation module, inefficacy extremum stress and index parameters acquisition module, solder joint connected mode numerical simulation module, explicit dynamical credit, wherein:

Hoop stress failure criteria generation module is connected considered repealed mode in the impact process (weldering nuclear circumference is torn) according to spot welding, cut in conjunction with drawing, stretching, stretch bending, draw the mechanical analysis of turning round combination stressed mode, obtain weldering nuclear hoop stress distribution form, generate the hoop stress failure criteria, and transfer to the explicit dynamical credit and analyse module;

Inefficacy extremum stress and index parameters obtain that module is cut by drawing, stretching, stretch bending, draw and turn round four kinds of load modes and test, acquisition is solder joint borderline failure maximum stress and dimensionless stress subitem index initial value under the peak value condition of four kinds of external applied loads, and transfers to the explicit dynamical credit and analyse module and solder joint failure material base module;

Solder joint connected mode numerical simulation module, it is in the simulation modeling process, the solder joint numerical model is selected entity (group) type solder joint unit, be based upon two-layer or the multilayered shell unit in the middle of, the metal sheet that the shell unit simulation connects, the true geometric form of simulating solder joint is set up to draw and is cut, stretching, stretch bending, draws to turn round four kinds of sample numerical models and transfer to the explicit dynamical credit and analyse module;

It is the calculating execution module that spot welding connects the inefficacy numerical simulation that module is analysed in the explicit dynamical credit, coupling hoop stress failure criteria, and according to inefficacy extremum stress, solder joint numerical model, realize that spot welding connects the numerical simulation process that lost efficacy, the extremum stress that emulation obtains the internal stress of solder joint model of element continuous distribution under the effect of carrying of various sample model outward and the moment solder joint unit that lost efficacy bears, and resulting simulation result is transferred to solder joint failure material base module, the spot welding in the analog physical process connects failure mode;

After solder joint failure material base module is analysed the explicit dynamical credit simulation result that module obtains and specimen test result and is analyzed, whether borderline failure maximum stress and the dimensionless stress subitem index initial value of judging each components of stress be reasonable, if satisfy the specimen test result, then above-mentioned parameter is stored in the solder joint failure material knowledge base, as not satisfying, adjust the parameter initial value and make simulation result satisfy test findings.

Described hoop stress failure criteria generation module comprises: hoop stress is determined submodule, criterion generation module, wherein:

Hoop stress determines that submodule connects the considered repealed form (weldering nuclear circumference tear) of metal plate parts in impact process according to spot welding, as shown in Figure 2, be weldering nuclear geometric format and the hoop stress expression way constantly of losing efficacy, suppose that weldering nuclear is the standard round rod structure, weldering nuclear highly is welding sheet thickness sum.Determine that weldering nuclear structure force way is to draw to cut, stretching, stretch bending, draw the combination of turning round to express, and obtains three kinds of solder joint hoop stress: radial stress σ according to various concrete stressed types _r, axial shear stress τ _z, circumferential shear stress τ _θ, and set up external force load and the relation of the numerical expression between it respectively;

Described circle distribution radial stress σ _rOnly with spot-welded structures draw the mode of cutting (Fig. 3 (b)) relevant, suppose that its solder joint hoop stress distribution form (Fig. 3 (a)) satisfies:

σ _r＝σ _rmaxcosθ

Wherein: σ _RmaxBe maximum stress radially, θ carries lateral pull F outside for the circumferential corner of weldering nuclear cross section _SUnder the effect, interfacial stress is balance with it, obtains radially maximum stress and the numerical expression between outer year:

${\mathrm{\σ}}_{r\max }=\frac{F_S}{\mathrm{\πrt}}$

R is weldering nuclear height for weldering nuclear xsect inside radius, t;

Described axial shear stress τ _zRelevant with stretching (Fig. 4 (c)) and two kinds of force way of stretch bending (Fig. 5 (c)) of spot-welded structures.

Suppose under the tensile load effect weldering nuclear hoop stress distribution form between Fig. 4 (a) with (b), Fig. 4 (a) and (b) represent two kinds of ultimate limit states respectively, so the tensile load effect down weldering examine the hoop stress distribution and should satisfy respectively:

τ ' _z=τ ' _ZmaxCos θ and τ ' _z=τ ' _Zmax

τ ' _ZmaxBe axial maximum shear, carry axial tension F outside _AUnder the effect, interfacial stress is balance with it, and this moment is the numerical expression of maximum stress axially:

${\mathrm{\&tau;}}_{z\max }^{\&prime;}=\frac{F_A}{\mathrm{\&alpha;rt}},(4<\mathrm{\&alpha;}<2\mathrm{\&pi;})$

Wherein: r is weldering nuclear height for weldering nuclear xsect inside radius, t;

Suppose under the stretch bending loading weldering nuclear hoop stress distribution form between Fig. 5 (a) with (b), i.e. Fig. 5 (a) and (b) represent two kinds of ultimate limit states respectively, so stretch bending loading weldering down examines the hoop stress distribution and should satisfy respectively:

τ " _z=τ " _ZmaxCos θ and τ " _z=τ " _Zmax

Parameter is carried moment M as previously mentioned outside _BUnder the effect, interfacial stress is balance with it, and this moment is the numerical expression of maximum stress axially:

${\mathrm{\&tau;}}_{z\max }^{\&prime;\&prime;}=\frac{M_B}{\mathrm{\&beta;}{r}^{2}t},(\mathrm{\&pi;}<\mathrm{\&beta;}<4)$

Wherein: r is weldering nuclear height for weldering nuclear xsect inside radius, t;

Axially shearing is two kinds of loading sums, and the final numerical expression between axial maximum stress in coupling back and outer the carrying is:

${\mathrm{\&tau;}}_{z\max }=\frac{F_A}{4\mathrm{rt}}+\frac{M_B}{\mathrm{\&beta;}{r}^{2}t},(4<\mathrm{\&alpha;}<2\mathrm{\&pi;},\mathrm{\&pi;}<\mathrm{\&beta;}<4)$

Each meaning of parameters as previously mentioned in the formula;

Described circumferential shear stress τ _θOnly draw the mode of turning round (Fig. 6 (b)) relevant, suppose that its solder joint hoop stress distribution form (Fig. 6 (a)) satisfies with spot-welded structures:

τ _θ＝τ _θmax

τ _{θ max}For the circumferential maximum stress of weldering nuclear, carry circumferential moment of torsion M outside _TUnder the effect, interfacial stress is balance with it, obtains radially maximum stress and the numerical expression between outer year:

${\mathrm{\&tau;}}_{\mathrm{\&theta;}\max }=\frac{M_T}{2\mathrm{\&pi;}{r}^{2}t}$

Each meaning of parameters as previously mentioned in the formula;

The solder joint hoop stress that the criterion generation module is coupled under the described various load form is described, with dimensionless formal description solder joint stress failure criteria, arbitrary stress parameters all can be described as plastic strain rate function in this criterion, impact the rate of strain reinforcement behavior of emulation welding material to adapt to two-forty, this equation expression-form is:

${\left(\frac{{\mathrm{\&sigma;}}_r\stackrel{\&CenterDot;}{\left({\mathrm{\&epsiv;}}_{\mathrm{eff}}^p\right)}}{{\mathrm{\&sigma;}}_r^F\stackrel{\&CenterDot;}{\left({\mathrm{\&epsiv;}}_{\mathrm{eff}}^p\right)}}\right)}^{\mathrm{\&xi;}}+{\left(\frac{{\mathrm{\&tau;}}_z\stackrel{\&CenterDot;}{\left({\mathrm{\&epsiv;}}_{\mathrm{eff}}^p\right)}}{{\mathrm{\&tau;}}_z^F\stackrel{\&CenterDot;}{\left({\mathrm{\&epsiv;}}_{\mathrm{eff}}^p\right)}}\right)}^{\mathrm{\&psi;}}+{\left(\frac{{\mathrm{\&tau;}}_{\mathrm{\&theta;}}\stackrel{\&CenterDot;}{\left({\mathrm{\&epsiv;}}_{\mathrm{eff}}^p\right)}}{{\mathrm{\&tau;}}_{\mathrm{\&theta;}}^F\stackrel{\&CenterDot;}{\left({\mathrm{\&epsiv;}}_{\mathrm{eff}}^p\right)}}\right)}^{\mathrm{\&zeta;}}\&GreaterEqual;1$

Wherein,

Be effective plastic strain rate that solder joint element integral point place is calculated, aforementioned each components of stress all are expressed as the function of effective plastic strain rate in the formula; σ _r ^F, τ _z ^F, τ _θ ^FInefficacy extremum stress for aforementioned each stress correspondence; ξ, ψ, ζ are the index parameters of each corresponding dimensionless stress subitem.

Described inefficacy extremum stress and index parameters obtain module, comprising: the inefficacy extremum stress obtains module, the inefficacy index parameters obtains module, wherein:

The inefficacy extremum stress obtains module, it is cut in sample, tensile sample and stretch bending sample, the single spot welding torsional specimen failure procedure drawing, write down the curve of each load and displacement, when load was in peak value, extreme value, the axial shear stress τ of circle distribution weldering nuclear of circle distribution radial stress constantly obtained losing efficacy _zExtreme value, the circumferential shear stress τ of circle distribution _θExtreme value, specific as follows:

1. draw to cut in single spot welding to obtain the radial stress critical value in sample (Fig. 3 (the b)) failure procedure, record draws cuts process load-displacement curve, calculates the normal stress extreme value σ constantly that lost efficacy _r ^F

2. the failure procedure at reinforced dual U-shaped (using strengthening part to reduce the moment of flexure influence) tensile sample (Fig. 4 (c)) and reinforced two L shaped (using strengthening part to reduce the pulling force influence) stretch bending sample (Fig. 5 (c)) obtains axial shear stress critical value, the outer load peaks of carrying under the effect of record is calculated the shear stress extreme value τ of coupled mode constantly that lost efficacy _z ^F

3. draw at reinforced U-shaped (use strengthening part reduce medio-lateral instability) and turn round sample (Fig. 6 (b)) twist process and obtain circumferential shear stress critical value, load peaks, calculate the maximum stress τ under the torsional load effect _θ ^F

The inefficacy index parameters obtains module, and according to the failure criteria equation, the dimensionless combination approximation of each lost efficacy stress and the ratio of corresponding maximum stress is the triaxial ellipsoid face, determines that each dimensionless stress subitem index ξ, ψ, ζ value are 2.

Described solder joint connected mode numerical simulation module, in its simulation modeling process, the solder joint numerical model is selected entity or group of entities type solder joint unit, Fig. 7 is connected the middle solid type solder joint unit of two-layer shell unit, Fig. 8 is three types group of entities solder joint unit, the group of entities unit is the novel solder joint model of exploitation in 06 year, and the abundant true geometric form of simulating solder joint can obviously not reduce the counting yield of model in the time of the raising computational accuracy.Figure (a) and (b), (c) are respectively the group of entities solder joint unit that 4,8,16 entities are formed, the unit is based upon two-layer or multilayered shell unit (simulation connects metal sheet) is middle, the solder joint cell node needn't directly be connected with the shell unit node, thereby can not cause the shape distortion of solder joint unit or increase the division difficulty of shell unit grid, is connected by Tie (bonding) type way of contact realization between solder joint unit and the shell unit.The group of entities unit is novel solder joint model, and the abundant true geometric form of simulating solder joint can obviously not reduce the counting yield of model when improving computational accuracy.Set up four kinds of samples (draw and cut, stretching, stretch bending, draw and turn round) numerical model and transfer to the explicit dynamical credit and analyse software module.

Module is analysed in described explicit dynamical credit, each common finite element calculating degree has separately independently material model expansion module (UMAT), selection is applicable to the elastic-plastic constitutive relation that metal material is described, the hoop stress failure criteria that coupling hoop stress failure criteria generation module generates is as the part of welding material model.

The hoop stress failure criteria is applicable to the analogue simulation of the solder joint circumference failure behaviour under static state, quasistatic and the transient impact condition, can be integrated into the explicit dynamical credit analyses in the material model of module, by Cowper-Symonds model (or Johnson-Cook model) strain rate effect is described, confirm the invigoration effect of strain rate effect butt welding point material failure stress, simulate model parameter, for structural level (or car load level) spot-welded structures inefficacy simulation calculation is used.

The sample numerical model of setting up in parameter that inefficacy extremum stress and index parameters acquisition module obtain and the solder joint connected mode numerical simulation module all is passed to the demonstration dynamics analysis module, in the computational analysis, calculate the stress value at solder joint element integral point place, by the borderline failure extremum stress comparison definite with experiment, after satisfying the hoop stress failure criteria, the solder joint connected mode lost efficacy, and the solder joint unit is deleted from the sample numerical model.

Described solder joint failure material base module, by to explicit dynamical credit analyse after sample model spot welding that software module calculates connects failure mode and specimen test result and be analyzed, whether borderline failure maximum stress and the dimensionless stress subitem index initial value of confirming each components of stress be reasonable, after the correction, by different rates and different thickness of slab, material, single spot welding sample breaking test under the weldering nuclear diameter, repeat abovementioned steps, critical stress value and index parameters that record is corresponding, each parameter value that obtains enters in the solder joint failure material knowledge base, uses to make things convenient for component-level (or car load level) simulation process.

During present embodiment work, solder joint failure concentrates on supporting region in impact process, non-bearing district solder joint does not have failure phenomenon, therefore be the needs of EQUILIBRIUM CALCULATION FOR PROCESS efficient and computational accuracy, in the car load level collision simulation process, can adopt traditional beam type solder joint unit in the non-bearing district, no failure criteria is judged, saves computing time; At supporting region, particularly the large deformation district adopts entity or group of entities type solder joint unit, adopts described novel solder joint hoop stress failure criteria simulating solder joint distortion and failure behaviour simultaneously, guarantees simulation precision to greatest extent, and realistic design needs.And set up the solder joint numerical model by solder joint connected mode analog module, utilize the explicit dynamical credit to analyse module and carry out computational analysis, call borderline failure maximum stress and the dimensionless stress subitem index confirmed in the solder joint failure material base module in this process, cooperate the hoop stress failure criteria to differentiate spot welding and connect failure behaviour, improve and impact simulation accuracy.

Present embodiment compared with prior art can effectively be simulated the solder joint failure process in the impact process, takes all factors into consideration solder joint failure stress distribution constantly under the multiple loading, the destruction of real simulated solder joint; Be applicable to the various solder joint unit forms of existing software module, can not produce conflict with it, the counting yield height, be specially adapted to the collision simulation analysis of Hyundai Motor industry, improve the precision about 20% of car load level collision simulation, reduce to a certain extent and design and develop cost, for enterprise brings more economic benefit.

Claims (8)

1, a kind of simulation system for spot welding invalidity number value, it is characterized in that, comprise: module, solder joint failure material base module are analysed in hoop stress failure criteria generation module, inefficacy extremum stress and index parameters acquisition module, solder joint connected mode numerical simulation module, explicit dynamical credit, wherein:

Hoop stress failure criteria generation module is connected the failure mode that the weldering nuclear circumference in the impact process is torn according to spot welding, cut in conjunction with drawing, stretching, stretch bending, draw the mechanical analysis of turning round combination stressed mode, obtain weldering nuclear hoop stress distribution form, generate the hoop stress failure criteria, and transfer to the explicit dynamical credit and analyse module;

Inefficacy extremum stress and index parameters obtain that module is cut by drawing, stretching, stretch bending, draw and turn round four kinds of load modes and test, acquisition is solder joint borderline failure maximum stress and dimensionless stress subitem index initial value under the peak value condition of four kinds of external applied loads, and transfers to the explicit dynamical credit and analyse module and solder joint failure material base module;

Solder joint connected mode numerical simulation module, it is in the simulation modeling process, the solder joint numerical model is selected entity or group of entities type solder joint unit, be based upon two-layer or the multilayered shell unit in the middle of, the metal sheet that the shell unit simulation connects, the true geometric form of simulating solder joint is set up to draw and is cut, stretching, stretch bending, draws to turn round four kinds of sample numerical models and transfer to the explicit dynamical credit and analyse module;

It is the calculating execution module that spot welding connects the inefficacy numerical simulation that module is analysed in the explicit dynamical credit, coupling hoop stress failure criteria, and according to inefficacy maximum stress, solder joint numerical model, realize that spot welding connects the numerical simulation process that lost efficacy, the extremum stress that emulation obtains the internal stress of solder joint model of element continuous distribution under the effect of carrying of various sample model outward and the moment solder joint unit that lost efficacy bears, and resulting simulation result is transferred to solder joint failure material base module, the spot welding in the analog physical process connects failure mode;

After solder joint failure material base module is analysed the explicit dynamical credit simulation result that module obtains and specimen test result and is analyzed, whether borderline failure maximum stress and the dimensionless stress subitem index initial value of judging each components of stress be reasonable, if satisfy the specimen test result, then above-mentioned parameter is stored in the solder joint failure material knowledge base, as not satisfying, adjust the parameter initial value and make simulation result satisfy test findings.

2, simulation system for spot welding invalidity number value according to claim 1 is characterized in that, described hoop stress failure criteria generation module comprises: hoop stress is determined submodule, criterion generation module, wherein:

Hoop stress determines that submodule connects the failure mode of metal plate parts in impact process according to spot welding, determine that weldering nuclear structure force way is to draw to cut, stretching, stretch bending, draw the combination of turning round to express, and obtains three kinds of solder joint hoop stress: radial stress σ according to various concrete stressed types _r, axial shear stress τ _z, circumferential shear stress τ _θ, and set up external force load and the relation of the numerical expression between it respectively;

Three solder joint hoop stresses of criterion generation module coupling, and set up the hoop stress failure criteria with the dimensionless form, its formula of failure criteria is as follows:

${\left(\frac{{\mathrm{\&sigma;}}_r\stackrel{\&CenterDot;}{\left({\mathrm{\&epsiv;}}_{\mathrm{eff}}^p\right)}}{{\mathrm{\&sigma;}}_r^F\stackrel{\&CenterDot;}{\left({\mathrm{\&epsiv;}}_{\mathrm{eff}}^p\right)}}\right)}^{\mathrm{\&xi;}}+{\left(\frac{{\mathrm{\&tau;}}_z\stackrel{\&CenterDot;}{\left({\mathrm{\&epsiv;}}_{\mathrm{eff}}^p\right)}}{{\mathrm{\&tau;}}_z^F\stackrel{\&CenterDot;}{\left({\mathrm{\&epsiv;}}_{\mathrm{eff}}^p\right)}}\right)}^{\mathrm{\&psi;}}+{\left(\frac{{\mathrm{\&tau;}}_{\mathrm{\&theta;}}\stackrel{\&CenterDot;}{\left({\mathrm{\&epsiv;}}_{\mathrm{eff}}^p\right)}}{{\mathrm{\&tau;}}_{\mathrm{\&theta;}}^F\stackrel{\&CenterDot;}{\left({\mathrm{\&epsiv;}}_{\mathrm{eff}}^p\right)}}\right)}^{\mathrm{\&zeta;}}\&GreaterEqual;1$

In the formula,

Be effective plastic strain rate that solder joint element integral point place is calculated, each stress σ _r, τ _z, τ _θThe function of all representing effective plastic strain rate, σ _r ^F, τ _z ^F, τ _θ ^FBe the borderline failure extremum stress of each stress correspondence, be described as the relevant functional form of rate of strain in the high speed impact process, ξ, ψ, ζ are the index parameters of each corresponding dimensionless stress subitem.

3, simulation system for spot welding invalidity number value according to claim 2 is characterized in that, described radial stress σ _r, its only with spot-welded structures draw the mode of cutting relevant, be used for the prediction draw cut the effect the following stress pattern.

4, simulation system for spot welding invalidity number value according to claim 2 is characterized in that, described axial shear stress τ _z, it is only relevant with stretching and two kinds of force way of stretch bending of spot-welded structures, is used to predict the weldering nuclear hoop stress distribution form under stretching and the stretch bending loading.

5, simulation system for spot welding invalidity number value according to claim 2 is characterized in that, described circumferential shear stress τ _θ, it only draws the mode of turning round relevant with spot-welded structures, is used to predict draw the stress pattern of turning round under the loading.

6, simulation system for spot welding invalidity number value according to claim 1 is characterized in that, described inefficacy extremum stress and index parameters obtain module, comprising: the inefficacy extremum stress obtains module, the inefficacy index parameters obtains module, wherein:

The inefficacy extremum stress obtains module, it is cut in sample, tensile sample and stretch bending sample, the single spot welding torsional specimen failure procedure drawing, write down the curve of each load and displacement, when load was in peak value, extreme value, the axial shear stress τ of circle distribution weldering nuclear of circle distribution radial stress constantly obtained respectively losing efficacy _zExtreme value, the circumferential shear stress τ of circle distribution _θExtreme value;

The inefficacy index parameters obtains module, and according to the failure criteria equation, the dimensionless combination approximation of each lost efficacy stress and the ratio of corresponding maximum stress is the triaxial ellipsoid face, determines that each dimensionless stress subitem index ξ, ψ, ζ value are 2.

7, simulation system for spot welding invalidity number value according to claim 1 is characterized in that, described solder joint unit and shell unit connect by the adhesion type way of contact between the two.

8, simulation system for spot welding invalidity number value according to claim 1, it is characterized in that, described solder joint failure material base module, to various materials, failure behaviour under thickness of slab and the load form is verified, initial setting realistic model solder joint failure extremum stress and failure mode, if there are error in simulation result and test findings, in the 0-10% scope, adjust the parameter initial value, make simulation result satisfy test findings, and write down adjusted parameter value, be stored in the solder joint failure material knowledge base, final each parameter value that obtains deposits in the solder joint failure material knowledge base, uses for car load level or component-level simulation process.

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